Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2016	Feb. 17, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	AMERICAN TOWER CORP /MA/
Entity Central Index Key	0001053507
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		427,195,037
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 47.9

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 787,161	$ 320,686
Restricted cash	149,281	142,193
Short-term investments	4,026	0
Accounts receivable, net	308,369	227,354
Prepaid and other current assets	441,033	306,235
Total current assets	1,689,870	996,468
PROPERTY AND EQUIPMENT, net	10,517,258	9,866,424
GOODWILL	5,070,680	4,091,805
OTHER INTANGIBLE ASSETS, net	11,274,611	9,837,876
DEFERRED TAX ASSET	195,678	212,041
DEFERRED RENT ASSET	1,289,530	1,166,755
NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	841,523	732,903
TOTAL	30,879,150	26,904,272
CURRENT LIABILITIES:
Accounts payable	118,666	96,714
Accrued expenses	620,563	516,413
Distributions payable	250,550	210,027
Accrued interest	157,297	115,672
Current portion of long-term obligations	238,806	50,202
Unearned revenue	245,387	211,001
Total current liabilities	1,631,269	1,200,029
LONG-TERM OBLIGATIONS	18,294,659	17,068,807
ASSET RETIREMENT OBLIGATIONS	965,507	856,936
DEFERRED TAX LIABILITY	777,572	106,333
OTHER NON-CURRENT LIABILITIES	1,142,723	959,349
Total liabilities	22,811,730	20,191,454
COMMITMENTS AND CONTINGENCIES
REDEEMABLE NONCONTROLLING INTERESTS	1,091,220	0
EQUITY:
Common stock: $.01 par value; 1,000,000,000 shares authorized; 429,912,536 and 426,695,279 shares issued; and 427,102,510 and 423,885,253 shares outstanding, respectively	4,299	4,267
Additional paid-in capital	10,043,559	9,690,609
Distributions in excess of earnings	(1,076,965)	(998,535)
Accumulated other comprehensive loss	(1,999,332)	(1,836,996)
Treasury stock (2,810,026 shares at cost)	(207,740)	(207,740)
Total American Tower Corporation equity	6,763,895	6,651,679
Noncontrolling interests	212,305	61,139
Total equity	6,976,200	6,712,818
TOTAL	30,879,150	26,904,272
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock
EQUITY:
Preferred stock: $.01 par value: 20,000,000 authorized: 5.25%, Series A, 6,000,000 shares issued and outstanding; aggregate liquidation value of $600,000 - 5.50% Series B, 1,375,000 shares issued and outstanding, respectively; aggregate liquidation value of $1,375,000	60	60
Total equity	60	60
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock
EQUITY:
Preferred stock: $.01 par value: 20,000,000 authorized: 5.25%, Series A, 6,000,000 shares issued and outstanding; aggregate liquidation value of $600,000 - 5.50% Series B, 1,375,000 shares issued and outstanding, respectively; aggregate liquidation value of $1,375,000	14	14
Total equity	$ 14	$ 14

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	12 Months Ended
CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	429,912,536	426,695,279
Common stock, shares outstanding	427,102,510	423,885,253
Treasury stock, shares	2,810,026	2,810,026
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock \| Series A Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, dividend rate, percentage	5.25%	5.25%
Preferred stock, shares issued	6,000,000	6,000,000
Preferred stock, shares outstanding	6,000,000	6,000,000
Preferred stock, aggregate liquidation value	$ 600,000	$ 600,000
Preferred stock \| Series B Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, dividend rate, percentage	5.50%
Preferred stock, shares issued	1,375,000
Preferred stock, shares outstanding	1,375,000
Preferred stock, aggregate liquidation value	$ 1,375,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
REVENUES:
Property	$ 5,713,126	$ 4,680,388	$ 4,006,854
Services	72,542	91,128	93,194
Total operating revenues	5,785,668	4,771,516	4,100,048
OPERATING EXPENSES:
Property (including stock-based compensation expense of $1,750, $1,614 and $1,397, respectively)	1,762,694	1,275,436	1,056,177
Services (including stock-based compensation expense of $688, $439 and $440, respectively)	27,695	33,432	38,088
Depreciation, amortization and accretion	1,525,635	1,285,328	1,003,802
Selling, general, administrative and development expense (including stock-based compensation expense of $87,460, $88,484 and $78,316, respectively)	543,395	497,835	446,542
Other operating expenses	73,220	66,696	68,517
Total operating expenses	3,932,639	3,158,727	2,613,126
OPERATING INCOME	1,853,029	1,612,789	1,486,922
OTHER INCOME (EXPENSE):
Gain (loss) on retirement of long-term obligations	1,168	(79,606)	(3,473)
Other expense (including unrealized foreign currency losses of $23,439, $71,473 and $49,319, respectively)	(47,790)	(134,960)	(62,060)
Total other expense	(727,169)	(782,827)	(621,218)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	1,125,860	829,962	865,704
Income tax provision	(155,501)	(157,955)	(62,505)
NET INCOME	970,359	672,007	803,199
Net (income) loss attributable to noncontrolling interests	(13,934)	13,067	21,711
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	956,425	685,074	824,910
Dividends on preferred stock	(107,125)	(90,163)	(23,888)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 849,300	$ 594,911	$ 801,022
NET INCOME PER COMMON SHARE AMOUNTS:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 2.00	$ 1.42	$ 2.02
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 1.98	$ 1.41	$ 2.00
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
BASIC (in shares)	425,143	419	395,958
DILUTED (in shares)	429,283	423	400,086
TV Azteca
OTHER INCOME (EXPENSE):
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively	$ 10,960	$ 11,209	$ 10,547
Interest expense	(1,163)	(820)	(1,482)
Excluding TV Azteca
OTHER INCOME (EXPENSE):
Interest income	25,618	16,479	14,002
Interest expense	$ (717,125)	$ (595,949)	$ (580,234)

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-based compensation expense	$ 89,898,000	$ 90,537,000	$ 80,153,000.000
TV Azteca
Interest expense	1,163,000	820,000	1,482,000
Property
Stock-based compensation expense	1,750,000	1,614,000	1,397,000
Services
Stock-based compensation expense	688,000	439,000	440,000
Selling General Administrative And Development Expense
Stock-based compensation expense	87,460,000	88,484,000	78,316,000
Other Expense [Member]
Foreign currency gain (loss)	$ (23,439,000)	$ (71,473,000)	$ (49,319,000)

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 970,359	$ 672,007	$ 803,199
Other comprehensive (loss) income:
Changes in fair value of cash flow hedges, net of tax expense (benefit) of $0, $73 and $(151), respectively	(449)	948	(1,931)
Reclassification of unrealized losses on cash flow hedges to net income, net of tax expense (benefit) of $0, $84 and $(158), respectively	(291)	2,440	3,448
Foreign currency translation adjustments, net of tax expense (benefit) of $3,782, $(24,857) and $(14,247), respectively	(202,819)	(1,078,950)	(526,890)
Other comprehensive loss	(203,559)	(1,075,562)	(525,373)
Comprehensive income (loss)	766,800	(403,555)	277,826
Comprehensive loss attributable to noncontrolling interest	18,218	45,854	64,083
Comprehensive income (loss) attributable to American Tower Corporation stockholders	$ 785,018	$ (357,701)	$ 341,909

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Reclassification of unrealized losses on cash flow hedges to net income, tax	$ 0	$ 84,000	$ (158,000)
Foreign currency translation adjustments, tax	3,782,000	(24,857,000)	(14,247,000)
Net change in fair value of cash flow hedges, tax	$ 0	$ 73,000	$ (151,000)

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Earnings (Distributions) in Excess of Distributions (Earnings)	Noncontrolling Interest	Convertible Preferred Stock Subject to Mandatory Redemption	Convertible Preferred Stock Subject to Mandatory Redemption Accumulated Other Comprehensive (Loss) Income	Convertible Preferred Stock Subject to Mandatory Redemption Noncontrolling Interest	Series A Preferred Stock	Series A Preferred Stock Additional Paid-in Capital	Series A Preferred Stock Convertible Preferred Stock Subject to Mandatory Redemption Preferred Stock	Series B Preferred Stock Convertible Preferred Stock Subject to Mandatory Redemption	Series B Preferred Stock Convertible Preferred Stock Subject to Mandatory Redemption Preferred Stock	Series B Preferred Stock Convertible Preferred Stock Subject to Mandatory Redemption Additional Paid-in Capital	Common Class A	Common Class A Common Stock	Common Class A Additional Paid-in Capital
BALANCE at Dec. 31, 2013	$ 3,590,040	$ 3,976	$ (207,740)	$ 5,130,616	$ (311,220)	$ (1,081,467)	$ 55,875						$ 0		$ 0
BALANCE (shares) at Dec. 31, 2013		(397,674,350)	(2,810,026)										0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity	119,734	$ 18		119,716
Stock based compensation related activity (shares)		1,753,286
Issuance of common stock—stock purchase plan	5,718	$ 1		5,717
Issuance of common stock - stock purchase plan (shares)		81,115
Issuance of stock											$ 582,659	$ 582,599	$ 60
Issuance of stock (shares)													6,000,000
Changes in fair value of cash flow hedges, net of tax	(1,931)							$ (1,931)	$ (1,966)	$ 35
Reclassification of unrealized losses on cash flow hedges to net income	3,448				3,288		160
Foreign currency translation adjustment, net of tax	(526,890)				(484,323)		(42,567)
Contributions from noncontrolling interest	123,526						123,526
Distributions to noncontrolling interest	(566)						(566)
Purchase of noncontrolling interest	(64,822)			(49,862)			(14,960)
Common stock distributions declared	(556,875)					(556,875)
Preferred stock dividends declared	(23,888)					(23,888)
Net income	803,199					824,910	(21,711)
Net income (loss)	803,199
BALANCE at Dec. 31, 2014	4,053,352	$ 3,995	$ (207,740)	5,788,786	(794,221)	(837,320)	99,792						$ 60		$ 0
BALANCE (shares) at Dec. 31, 2014		(399,508,751)	(2,810,026)										(6,000,000)		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity	117,218	$ 12		117,206
Stock based compensation related activity (shares)		1,253,236
Issuance of common stock—stock purchase plan	6,618	$ 1		6,617
Issuance of common stock - stock purchase plan (shares)		83,292
Issuance of stock														$ 1,337,946	$ 14	$ 1,337,932	$ 2,440,327	$ 259	$ 2,440,068
Issuance of stock (shares)															1,375,000			25,850,000
Changes in fair value of cash flow hedges, net of tax	948				901		47
Reclassification of unrealized losses on cash flow hedges to net income	2,440				2,494		(54)
Foreign currency translation adjustment, net of tax	(1,078,950)				(1,046,170)		(32,780)
Contributions from noncontrolling interest	8,073						8,073
Distributions to noncontrolling interest	(872)						(872)
Common stock distributions declared	(769,517)					(769,517)
Preferred stock dividends declared	(76,772)					(76,772)
Net income	672,007					685,074	(13,067)
Net income (loss)	672,007
BALANCE at Dec. 31, 2015	6,712,818	$ 4,267	$ (207,740)	9,690,609	(1,836,996)	(998,535)	61,139						$ 60		$ 14
BALANCE (shares) at Dec. 31, 2015		(426,695,279)	(2,810,026)										(6,000,000)		(1,375,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity	155,071	$ 19		155,052
Stock based compensation related activity (shares)		1,959,123
Issuance of common stock—stock purchase plan	7,517	$ 1		7,516
Issuance of common stock - stock purchase plan (shares)		86,947
Issuance of stock																	$ 120,785	$ 12	$ 120,773
Issuance of stock (shares)																		1,171,187
Changes in fair value of cash flow hedges, net of tax	(449)				(449)
Reclassification of unrealized losses on cash flow hedges to net income	(291)				(291)
Foreign currency translation adjustments, net of tax, less amounts reclassified to APIC	(179,384)				(170,667)		(8,717)
Foreign currency translation adjustment, net of tax	(202,819)
Contributions from noncontrolling interest	239,484			69,609	9,071		160,804
Distributions to noncontrolling interest	(1,004)						(1,004)
Common stock distributions declared	(927,730)					(927,730)
Preferred stock dividends declared	(107,125)					(107,125)
Net income	970,359					956,425	83
Net income (loss)	956,508
BALANCE at Dec. 31, 2016	$ 6,976,200	$ 4,299	$ (207,740)	$ 10,043,559	$ (1,999,332)	$ (1,076,965)	$ 212,305						$ 60		$ 14
BALANCE (shares) at Dec. 31, 2016		(429,912,536)	(2,810,026)										(6,000,000)		(1,375,000)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 970,359,000	$ 672,007,000	$ 803,199,000
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, amortization and accretion	1,525,635,000	1,285,328,000	1,003,802,000
Stock-based compensation expense	89,898,000	90,537,000	80,153,000.000
Decrease in restricted cash	5,256,000	16,112,000	7,522,000
Loss on investments, unrealized foreign currency loss and other non-cash expense	127,377,000	146,170,000	64,133,000
Impairments, net loss on sale of long-lived assets, non-cash restructuring and merger related expenses	50,653,000	29,852,000	26,143,000
(Gain) loss on early retirement of long-term obligations	(1,168,000)	79,750,000	3,379,000
Amortization of deferred financing costs, debt discounts and premiums and other non-cash interest	17,702,000	6,932,000	(4,870,000)
Deferred income taxes	26,957,000	7,764,000	1,384,000
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	11,352,000	(56,312,000)	(84,529,000)
Prepaid and other assets	(83,229,000)	(91,113,000)	(1,437,000)
Deferred rent asset	(131,660,000)	(154,959,000)	(122,230,000)
Accounts payable and accrued expenses	(42,862,000)	95,858,000	34,711,000
Accrued interest	34,386,000	(15,641,000)	45,514,000
Unearned revenue	16,557,000	12,945,000	218,393,000
Deferred rent liability	67,764,000	56,076,000	38,378,000
Other non-current liabilities	18,627,000	1,746,000	20,944,000
Cash provided by operating activities	2,703,604,000	2,183,052,000	2,134,589,000
CASH FLOWS FROM INVESTING ACTIVITIES
Payments for purchase of property and equipment and construction activities	(682,505,000)	(728,753,000)	(974,404,000)
Payments for acquisitions, net of cash acquired	(1,416,373,000)	(1,961,056,000)	(1,010,637,000)
Payment for Verizon transaction	(4,748,000)	(5,059,462,000)	0
Proceeds from sale of assets, net of cash	0	0	15,464,000
Proceeds from sales of short-term investments and other non-current assets	13,056,000	1,032,320,000	1,434,831,000
Payments for short-term investments	(750,000)	(1,022,816,000)	(1,395,316,000)
Deposits, restricted cash and other	(16,126,000)	(1,968,000)	(19,486,000)
Cash used for investing activities	(2,107,446,000)	(7,741,735,000)	(1,949,548,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from short-term borrowings, net	0	9,043,000	0
Borrowings under credit facilities	2,446,845,000	6,126,618,000	2,187,000,000
Proceeds from issuance of senior notes, net	3,236,383,000	1,492,298,000	1,415,844,000
Proceeds from term loan	0	500,000,000	0
Proceeds from other borrowings	0	54,549,000	102,070,000
Proceeds from issuance of securities in securitization transaction	0	875,000,000	0
Repayments of notes payable, credit facilities, term loan, senior notes and capital leases	(5,093,747,000)	(6,393,405,000)	(3,903,144,000)
Contributions from noncontrolling interest holders, net	238,480,000	7,201,000	9,098,000
Proceeds from stock options and stock purchase plan	92,473,000	50,716,000	62,276,000
Distributions paid on common stock	(886,116,000)	(710,852,000)	(404,631,000)
Distributions paid on preferred stock	(107,125,000)	(84,647,000)	(16,013,000)
Proceeds from the issuance of common stock, net	0	2,440,327,000	0
Proceeds from the issuance of preferred stock, net	0	1,337,946,000	583,105,000
Purchase of preferred stock assumed in acquisition	0	0	(59,111,000)
Payment for early retirement of long-term obligations	(86,000)	(85,672,000)	(11,593,000)
Deferred financing costs and other financing activities	(26,401,000)	(30,021,000)	(34,670,000)
Purchase of noncontrolling interest	0	0	(64,822,000)
Cash (used for) provided by financing activities	(99,294,000)	5,589,101,000	(134,591,000)
Net effect of changes in foreign currency exchange rates on cash and cash equivalents	(30,389,000)	(23,224,000)	(30,534,000)
NET INCREASE IN CASH AND CASH EQUIVALENTS	466,475,000	7,194,000	19,916,000
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	320,686,000	313,492,000	293,576,000
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 787,161,000	$ 320,686,000	$ 313,492,000

Business and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Business and Summary of Significant Accounting Policies

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Business—American Tower Corporation (together with its subsidiaries, “ATC” or the “Company”) is one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries, which the Company refers to as its property operations. Additionally, the Company offers tower-related services in the United States, including site acquisition, zoning and permitting and structural analysis, which primarily support its site leasing business, including the addition of new tenants and equipment on its sites, which the Company refers to as its services operations.

The Company’s portfolio primarily consists of towers it owns and towers it operates pursuant to long-term lease arrangements, as well as distributed antenna system (“DAS”) networks, which provide seamless coverage solutions in certain in-building and outdoor wireless environments. In addition to the communications sites in its portfolio, the Company manages rooftop and tower sites for property owners under various contractual arrangements. The Company also holds other telecommunications infrastructure and property interests that it leases to communications service providers and third-party tower operators.

ATC is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and its joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures.

The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”). Accordingly, the Company generally is not subject to U.S. federal income taxes on income generated by its REIT operations, including the income derived from leasing space on its towers, as the Company receives a dividends paid deduction for distributions to stockholders that generally offsets its income and gains. However, the Company remains obligated to pay U.S. federal income taxes on earnings from its domestic taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, regardless of their designation for U.S. tax purposes, continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted.

The use of TRSs enables the Company to continue to engage in certain businesses while complying with REIT qualification requirements. The Company may, from time to time, change the election of previously designated TRSs to be included as part of the REIT. As of December 31, 2016, the Company’s REIT qualified businesses included its U.S. tower leasing business, most of its operations in Costa Rica, Germany and Mexico and a majority of its services segment and indoor DAS networks business.

Principles of Consolidation and Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity or cost method, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated. As of December 31, 2016, the Company has a controlling interest in two joint ventures in Ghana and Uganda with MTN Group Limited (“MTN Group”). The joint ventures are controlled by a holding company of which a wholly owned subsidiary of the Company holds a 51% controlling interest and a wholly owned subsidiary of MTN Group holds a 49% noncontrolling interest. In 2016, the Company established a joint venture (“ATC Europe”) with PGGM in which the Company holds a 51% controlling interest and PGGM holds a 49% noncontrolling interest. This transaction resulted in a reclassification of $9.1 million of foreign currency translation adjustment from Accumulated other comprehensive loss (“AOCI”) to additional paid-in capital. In addition, the Company holds an approximate 75% controlling interest, and South African investors hold an approximate 25% noncontrolling interest, in a subsidiary of the Company in South Africa. The Company holds a 51% controlling interest in ATC Telecom Infrastructure Private Limited (“ATC TIPL”), formerly known as Viom Networks Limited (“Viom”), and the Remaining Shareholders (as defined in note 6) hold a 49% noncontrolling interest.

Significant Accounting Policies and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying consolidated financial statements. The significant estimates in the accompanying consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense, stock-based compensation, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure.

Accounts Receivable and Deferred Rent Asset—The Company derives the largest portion of its revenues, corresponding accounts receivable and the related deferred rent asset from a relatively small number of tenants in the telecommunications industry, and 56% of its current year revenues are derived from four tenants.

The Company’s deferred rent asset is associated with non-cancellable tenant leases that contain fixed escalation clauses over the terms of the applicable lease in which revenue is recognized on a straight-line basis over the lease term.

The Company mitigates its concentrations of credit risk with respect to notes and trade receivables and the related deferred rent assets by actively monitoring the creditworthiness of its borrowers and tenants. In recognizing tenant revenue, the Company assesses the collectibility of both the amounts billed and the portion recognized in advance of billing on a straight-line basis. This assessment takes tenant credit risk and business and industry conditions into consideration to ultimately determine the collectibility of the amounts billed. To the extent the amounts, based on management’s estimates, may not be collectible, recognition is deferred until such point as collectibility is determined to be reasonably assured. Any amounts that were previously recognized as revenue and subsequently determined to be uncollectible are charged to bad debt expense included in Selling, general, administrative and development expense in the accompanying consolidated statements of operations.

Accounts receivable is reported net of allowances for doubtful accounts related to estimated losses resulting from a tenant’s inability to make required payments and allowances for amounts invoiced whose collectibility is not reasonably assured. These allowances are generally estimated based on payment patterns, days past due and collection history, and incorporate changes in economic conditions that may not be reflected in historical trends, such as tenants in bankruptcy, liquidation or reorganization. Receivables are written-off against the allowances when they are determined to be uncollectible. Such determination includes analysis and consideration of the particular conditions of the account. Changes in the allowances were as follows (in thousands):



	Year Ended December 31,
	2016			2015			2014
Balance as of January 1	$	23,096		$	17,306		$	19,895
Current year increases	49,966			19,878			8,243
Write-offs, recoveries and other (1)	(27,174		)	(14,088		)	(10,832		)
Balance as of December 31,	$	45,888		$	23,096		$	17,306

_______________


(1)	Recoveries includes recognition of revenue resulting from collections of previously reserved amounts.

Functional Currency—The functional currency of each of the Company’s foreign operating subsidiaries is the respective local currency, except for Costa Rica, where the functional currency is the U.S. Dollar. All foreign currency assets and liabilities held by the subsidiaries are translated into U.S. Dollars at the exchange rate in effect at the end of the applicable fiscal reporting period and all foreign currency revenues and expenses are translated at the average monthly exchange rates. Translation adjustments are reflected in equity as a component of AOCI in the consolidated balance sheets and included as a component of Comprehensive income (loss) in the consolidated statements of comprehensive income (loss).

Transactional gains and losses on foreign currency transactions are reflected in Other expense in the consolidated statements of operations. However, the effect from fluctuations in foreign currency exchange rates on intercompany debt that is considered to be permanently reinvested is reflected in AOCI in the consolidated balance sheets and included as a component of comprehensive income (loss). During the year ended December 31, 2016, the Company recorded net foreign currency losses of $153.9 million, of which $105.0 million was recorded in AOCI and $48.9 million was recorded in Other expense.

Cash and Cash Equivalents—Cash and cash equivalents include cash on hand, demand deposits and short-term investments with original maturities of three months or less. The Company maintains its deposits at high quality financial institutions and monitors the credit ratings of those institutions.

Restricted Cash—Restricted cash includes cash pledged as collateral to secure obligations and all cash whose use is otherwise limited by contractual provisions.

Short-Term Investments—Short-term investments consists of highly liquid investments with original maturities in excess of three months.

Property and Equipment—Property and equipment is recorded at cost or, in the case of acquired properties at estimated fair value on the date acquired. Cost for self-constructed towers includes direct materials and labor, capitalized interest and certain indirect costs associated with construction of the tower, such as transportation costs, employee benefits and payroll taxes. The Company begins the capitalization of costs during the pre-construction period, which is the period during which costs are incurred to evaluate the site, and continues to capitalize costs until the tower is substantially completed and ready for occupancy by a tenant. Labor costs capitalized for the years ended December 31, 2016, 2015 and 2014 were $47.7 million, $44.7 million and $48.5 million, respectively. Interest costs capitalized for the years ended December 31, 2016, 2015 and 2014 were $1.5 million, $1.8 million and $2.8 million, respectively.

Expenditures for repairs and maintenance are expensed as incurred. Augmentation and improvements that extend an asset’s useful life or enhance capacity are capitalized.

Depreciation expense is recorded using the straight-line method over the assets’ estimated useful lives. Towers and related assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease, taking into consideration lease renewal options and residual value.

Towers or assets acquired through capital leases are recorded net at the present value of future minimum lease payments or the fair value of the leased asset at the inception of the lease. Property and equipment and assets held under capital leases are amortized over the shorter of the applicable lease term or the estimated useful life of the respective assets for periods generally not exceeding twenty years.

The Company reviews its tower portfolio for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company reviews other long-lived assets for impairment whenever events, changes in circumstances or other evidence indicate that the carrying amount of the Company’s assets may not be recoverable. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.

Goodwill and Other Intangible Assets—The Company reviews goodwill for impairment at least annually (as of December 31) or whenever events or circumstances indicate the carrying value of an asset may not be recoverable.

Goodwill is recorded in the applicable segment and assessed for impairment at the reporting unit level. The Company utilizes the two-step impairment test when testing goodwill for impairment and employs a discounted cash flow analysis. The key assumptions utilized in the discounted cash flow analysis include current operating performance, terminal sales growth rate, management’s expectations of future operating results and cash requirements, the current weighted average cost of capital and an expected tax rate. Under the first step of this test, the Company compares the fair value of the reporting unit, as calculated under an income approach using future discounted cash flows, to the carrying amount of the applicable reporting unit. If the carrying amount exceeds the fair value, the Company conducts the second step of this test, in which the implied fair value of the applicable reporting unit’s goodwill is compared to the carrying amount of that goodwill. If the carrying amount of goodwill exceeds its implied fair value, an impairment loss would be recognized for the amount of the excess.

During the years ended December 31, 2016, 2015 and 2014, no potential impairment was identified under the first step of the test, as the fair value of each of the reporting units was in excess of its carrying amount.

Intangible assets that are separable from goodwill and are deemed to have a definite life are amortized over their useful lives, generally ranging from three to twenty years and are evaluated separately for impairment at least annually or whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable.

The Company reviews its network location intangible assets for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company monitors its tenant-related intangible assets (formerly referred to as customer-related intangible assets) on a tenant by tenant basis for indicators of impairment, such as high levels of turnover or attrition, non-renewal of a significant number of contracts or the cancellation or termination of a relationship. The Company assesses recoverability by determining whether the carrying amount of the related assets will be recovered primarily through projected undiscounted future cash flows. If the Company determines that the carrying amount of an asset may not be recoverable, the Company measures any impairment loss based on the projected future discounted cash flows to be provided from the asset or available market information relative to the asset’s fair value, as compared to the asset’s carrying amount. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.

Derivative Financial Instruments—Derivatives are recorded on the consolidated balance sheet at fair value. If a derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are recorded in AOCI, as well as a component of comprehensive income (loss), and are recognized in the results of operations when the hedged item affects earnings. Changes in fair value of the ineffective portions of cash flow hedges are recognized in the results of operations. For derivative instruments that are designated and qualify as fair value hedges, changes in value of the derivatives are recorded in Other expense in the consolidated statements of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments not designated as hedging instruments, changes in fair value are recognized in the results of operations in the period that the change occurs.

The primary risks managed through the use of derivative instruments is interest rate risk, exposure to changes in the fair value of debt attributable to interest rate risk and currency risk. From time to time, the Company enters into interest rate swap agreements or foreign currency contracts to manage exposure to these risks. Under these agreements, the Company is exposed to counterparty credit risk to the extent that a counterparty fails to meet the terms of a contract. The Company’s exposure is limited to the current value of the contract at the time the counterparty fails to perform. The Company assesses, both at the inception of the hedge and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows or fair values of hedged items. The Company does not hold derivatives for trading purposes.

Fair Value Measurements—The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

Asset Retirement Obligations—When required, the Company recognizes the fair value of obligations to remove its tower assets and remediate the leased land upon which certain of its tower assets are located. Generally, the associated retirement costs are capitalized as part of the carrying amount of the related tower assets and depreciated over their estimated useful lives and the liability is accreted through the obligation’s estimated settlement date. Fair value estimates of asset retirement obligations generally involve discounting of estimated future cash flows. Periodic accretion of such liabilities due to the passage of time is included in Depreciation, amortization and accretion expense in the consolidated statements of operations. Adjustments are also made to the asset retirement obligation liability to reflect changes in the estimates of timing and amount of expected cash flows, with an offsetting adjustment made to the related long-lived tangible asset. The significant assumptions used in estimating the Company’s aggregate asset retirement obligation are: timing of tower removals; cost of tower removals; timing and number of land lease renewals; expected inflation rates; and credit-adjusted, risk-free interest rates that approximate the Company’s incremental borrowing rate.

Income Taxes—As a REIT, the Company generally is not subject to U.S. federal income taxes on income generated by its U.S. REIT operations. However, the Company remains obligated to pay U.S. federal income taxes on certain earnings and continues to be subject to taxation in its foreign jurisdictions. Accordingly, the consolidated financial statements reflect provisions for federal, state, local and foreign income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, as well as operating loss and tax credit carryforwards. The Company measures deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities as a result of a change in tax rates is recognized in income in the period that includes the enactment date.

The Company periodically reviews its deferred tax assets, and provides valuation allowances if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Valuation allowances would be reversed as a reduction to the provision for income taxes if related deferred tax assets are deemed realizable based on changes in facts and circumstances relevant to the assets’ recoverability.

The Company classifies uncertain tax positions as non-current income tax liabilities unless expected to be paid within one year. The Company reports penalties and tax-related interest expense as a component of the income tax provision and interest income from tax refunds as a component of Other expense in the consolidated statements of operations.

Other Comprehensive Income (Loss)—Other comprehensive income (loss) refers to items excluded from net income that are recorded as an adjustment to equity, net of tax. The Company’s other comprehensive income (loss) primarily consisted of changes in fair value of effective derivative cash flow hedges, foreign currency translation adjustments and reclassification of unrealized losses on effective derivative cash flow hedges. The AOCI balance included foreign currency translation losses of $2.0 billion, $1.8 billion and $0.8 billion for the years ended December 31, 2016, 2015 and 2014, respectively.

Distributions—As a REIT, the Company must annually distribute to its stockholders an amount equal to at least 90% of its REIT taxable income (determined before the deduction for distributed earnings and excluding any net capital gain). Generally, the Company has distributed, and expects to continue to distribute, all or substantially all of its REIT taxable income after taking into consideration its utilization of net operating losses (“NOLs”).

The amount, timing and frequency of future distributions will be at the sole discretion of the Board of Directors and will depend upon various factors, a number of which may be beyond the Company’s control, including the Company’s financial condition and operating cash flows, the amount required to maintain its qualification for taxation as a REIT and reduce any income and excise taxes that the Company otherwise would be required to pay, limitations on distributions in the Company’s existing and future debt and preferred equity instruments, the Company’s ability to utilize NOLs to offset the Company’s distribution requirements, limitations on its ability to fund distributions using cash generated through its TRSs and other factors that the Board of Directors may deem relevant.

Acquisitions—For acquisitions that meet the definition of a business combination, the Company applies the acquisition method of accounting where assets acquired and liabilities assumed are recorded at fair value at the date of each acquisition, and the results of operations are included with those of the Company from the dates of the respective acquisitions. Any excess of the purchase price paid by the Company over the amounts recognized for assets acquired and liabilities assumed is recorded as goodwill. The Company continues to evaluate acquisitions for a period not to exceed one year after the applicable acquisition date of each transaction to determine whether any additional adjustments are needed to the allocation of the purchase price paid for the assets acquired and liabilities assumed. The fair value of the assets acquired and liabilities assumed is typically determined by using either estimates of replacement costs or discounted cash flow valuation methods. When determining the fair value of tangible assets acquired, the Company must estimate the cost to replace the asset with a new asset taking into consideration such factors as age, condition and the economic useful life of the asset. When determining the fair value of intangible assets acquired, the Company must estimate the applicable discount rate and the timing and amount of future tenant cash flows, including rate and terms of renewal and attrition.

Revenue Recognition—The Company’s revenue from leasing arrangements, including fixed escalation clauses present in non-cancellable lease agreements, is reported on a straight-line basis over the term of the respective leases when collectibility is reasonably assured. Escalation clauses tied to the Consumer Price Index (“CPI”) or other inflation-based indices, and other incentives present in lease agreements with the Company’s tenants are excluded from the straight-line calculation. Total property straight-line revenues for the years ended December 31, 2016, 2015 and 2014 were $131.7 million, $155.0 million and $123.7 million, respectively. Amounts billed upfront in connection with the execution of lease agreements are initially deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets and recognized as revenue over the terms of the applicable leases. Amounts billed or received for services prior to being earned are deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets until the criteria for recognition have been met.

Services revenues are derived under contracts or arrangements with customers that provide for billings either on a fixed price basis or a variable price basis, which includes factors such as time and expenses. Revenues are recognized as services are performed, and include estimates for percentage completed. Amounts billed or received for services prior to being earned are deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets until the criteria for recognition have been met.

Rent Expense—Many of the leases underlying the Company’s tower sites have fixed rent escalations, which provide for periodic increases in the amount of ground rent payable by the Company over time. In addition, certain of the Company’s tenant leases require the Company to exercise available renewal options pursuant to the underlying ground lease if the tenant exercises its renewal option. The Company calculates straight-line ground rent expense for these leases based on the fixed non-cancellable term of the underlying ground lease plus all periods, if any, for which failure to renew the lease imposes an economic penalty to the Company such that renewal appears to be reasonably assured.

Total property straight-line ground rent expense for the years ended December 31, 2016, 2015 and 2014 was $67.8 million, $56.1 million and $38.4 million, respectively. The Company records a liability for straight-line ground rent expense in Other non-current liabilities. The Company records prepaid ground rent in Prepaid and other current assets and Notes receivable and other non-current assets in the accompanying consolidated balance sheets according to the anticipated period of benefit.

Selling, General, Administrative and Development Expense—Selling, general and administrative expense consists of overhead expenses related to the Company’s property and services operations and corporate overhead costs not specifically allocable to any of the Company’s individual business operations. Development expense consists of costs related to the Company’s acquisition efforts, costs associated with new business initiatives and project cancellation costs.

Stock-Based Compensation—Stock-based compensation expense is measured at the accounting measurement date based on the fair value of the award and is generally recognized as an expense over the service period, which typically represents the vesting period. The Company provides for accelerated vesting and extended exercise periods of stock options and restricted stock units upon an employee’s death or permanent disability, or upon an employee’s qualified retirement, provided certain eligibility criteria are met. Accordingly, the Company recognizes compensation expense for stock options and time-based restricted stock units (“RSUs”) over the shorter of (i) the four-year vesting period or (ii) the period from the date of grant to the date the employee becomes eligible for such retirement benefits, which may occur upon grant. The expense recognized includes the impact of forfeitures as they occur.

In March 2015 and 2016, the Company granted performance-based restricted stock units (“PSUs”) to its executive officers. Threshold, target and maximum parameters were established for the metrics for each year in the three-year performance period for the March 2015 grants, and for a three-year performance period for the March 2016 grants. The metrics will be used to calculate the number of shares that will be issuable when the awards vest, which may range from zero to 200% of the target amounts. The Company recognizes compensation expense for PSUs over the three-year vesting period, subject to adjustment based on the date the employee becomes eligible for retirement benefits as well as performance relative to grant parameters.

The fair value of stock options is determined using the Black-Scholes option-pricing model and the fair value of restricted stock units is based on the fair value of the Company’s common stock on the date of grant. The Company recognizes all stock-based compensation expense in either Selling, general, administrative and development expense, costs of operations or as part of the costs associated with the construction of the tower assets.

In connection with the vesting of RSUs, the Company withholds from issuance a number of shares of common stock to satisfy certain employee tax withholding obligations arising from such vesting. The shares withheld are considered constructively retired. The Company recognizes the fair value of the shares withheld in Additional paid-in capital on the consolidated balance sheets. As of December 31, 2016, the Company has withheld from issuance an aggregate of 1,219,755 shares, including 218,063 shares related to the vesting of RSUs during the year ended December 31, 2016.

Litigation Costs—The Company periodically becomes involved in various claims and lawsuits that are incidental to its business. The Company regularly monitors the status of pending legal actions to evaluate both the magnitude and likelihood of any potential loss. The Company accrues for these potential losses when it is probable that a liability has been incurred and the amount of loss, or possible range of loss, can be reasonably estimated. Should the ultimate losses on contingencies or litigation vary from estimates, adjustments to those liabilities may be required. The Company also incurs legal costs in connection with these matters and records estimates of these expenses, which are reflected in Selling, general, administrative and development expense in the accompanying consolidated statements of operations.

Earnings Per Common Share—Basic and Diluted—Basic net income per common share represents net income attributable to American Tower Corporation common stockholders divided by the weighted average number of common shares outstanding during the period. Diluted net income per common share represents net income attributable to American Tower Corporation common stockholders divided by the weighted average number of common shares outstanding during the period and any dilutive common share equivalents, including (A) shares issuable upon (i) the vesting of RSUs, (ii) exercise of stock options, and (iii) conversion of the Company’s mandatory convertible preferred stock and (B) shares earned upon the achievement of the parameters established for the PSUs, each to the extent not anti-dilutive. Dilutive common share equivalents also include the dilutive impact of the shares issuable in the Alltel transaction, which is described in notes 15 and 18. The Company uses the treasury stock method to calculate the effect of its outstanding RSUs, PSUs and stock options and uses the if-converted method to calculate the effect of its outstanding mandatory convertible preferred stock.

Retirement Plan—The Company has a 401(k) plan covering substantially all employees who meet certain age and employment requirements. For the years ended December 31, 2016, 2015 and 2014, the Company matched 75% of the first 6% of a participant’s contributions. For the years ended December 31, 2016, 2015 and 2014, the Company contributed $9.1 million, $7.4 million and $6.5 million to the plan, respectively.

Accounting Standards Updates—In May 2014, the Financial Accounting Standards Board (the “FASB”) issued new revenue recognition guidance, which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the transfer of promised goods or services to customers. The standard will replace most existing revenue recognition guidance and will become effective for the Company on January 1, 2018. Early adoption is permitted for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method. Leases are not included in the scope of this standard. The revenue to which the Company must apply this standard is generally limited to services revenue, certain power and fuel charges not covered by lease agreements and other fees charged to customers. As of December 31, 2016, this revenue was approximately 12% of total revenue. Although the Company is still assessing the impact of this standard on its financial statements, it does not expect changes in the timing of revenue recognition to be material to its financial statements.

In January 2016, the FASB issued new guidance on the recognition and measurement of financial assets and financial liabilities. The guidance amends certain aspects of recognition, measurement, presentation and disclosure of financial instruments. This standard is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017. The Company does not expect the adoption of this guidance to have a material effect on its financial statements.

In February 2016, the FASB issued new guidance on the accounting for leases. The guidance amends the existing accounting standards for lease accounting, including the requirement that lessees recognize assets and liabilities for leases with terms greater than twelve months in the statement of financial position. Under the new guidance, lessor accounting is largely unchanged. This guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. The standard is required to be applied using a modified retrospective approach for all leases existing at, or entered into after, the beginning of the earliest comparative period presented. The Company is evaluating the impact this standard will have on its financial statements.

In March 2016, the FASB issued new guidance on the accounting for share-based payment transactions. The guidance amends the accounting for taxes related to stock-based compensation, including how excess tax benefits and a company’s payments for tax withholdings should be classified. This guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2016. The Company early adopted this standard in the second quarter of 2016 and elected to account for forfeitures as they occur, effective January 1, 2016. The adoption of this guidance was not material to the Company’s consolidated financial statements. Additionally, the Company elected to apply the prospective transition method to the amendments related to the presentation of excess tax benefits in the statements of cash flows.

In August 2016, the FASB issued new guidance on certain classifications within the statement of cash flows. The guidance addresses, among other things, how cash receipts and cash payments are presented and classified in the statement of cash flows, including payments for costs related to debt prepayments or extinguishment, as well as payments of contingent consideration after an acquisition. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company has early adopted this guidance for the year ended December 31, 2016, and it did not have a material effect on the Company’s financial statements. Prior periods were not retrospectively adjusted.

In November 2016, the FASB issued new guidance on amounts described as restricted cash or restricted cash equivalents within the statement of cash flows. The guidance requires amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period balances on the statement of cash flows. The guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017. The standard is required to be applied using a retrospective transition method to each period presented. The Company does not expect the adoption of this guidance to have a material effect on its financial statements.

In January 2017, the FASB issued new guidance that clarifies the definition of a business that an entity uses to determine whether a transaction should be accounted for as an asset acquisition (or disposal) or a business combination. The guidance is expected to cause fewer acquired sets of assets (and liabilities) to be identified as businesses. The guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted for transactions that meet certain requirements. The Company is evaluating the impact this standard will have on its financial statements.

In January 2017, the FASB issued new guidance that simplifies the accounting for goodwill impairments by eliminating Step 2 from the goodwill impairment test. The guidance requires, among other things, recognition of an impairment loss when the fair value of a reporting unit exceeds its carrying amount. The loss recognized is limited to the total amount of goodwill allocated to that reporting unit. The guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect the adoption of this guidance to have a material effect on its financial statements.

Property and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment

PROPERTY AND EQUIPMENT

Property and equipment (including assets held under capital leases) consisted of the following as of December 31, (in thousands):



	Estimated Useful Lives (years) (1)	2016			2015
Towers	Up to 20	$	11,740,479		$	10,726,656
Equipment	2 - 15	1,176,260			1,095,906
Buildings and improvements	3 - 32	621,874			607,661
Land and improvements (2)	Up to 20	1,909,732			1,728,115
Construction-in-progress		203,411			238,960
Total		15,651,756			14,397,298
Less accumulated depreciation		(5,134,498		)	(4,530,874		)
Property and equipment, net		$	10,517,258		$	9,866,424

_______________


(1)	Assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease taking into consideration lease renewal options and residual value.


(2)	Estimated useful lives apply to improvements only.

Depreciation expense for the years ended December 31, 2016, 2015 and 2014 was $758.9 million, $661.4 million and $551.8 million, respectively.

As of December 31, 2016, property and equipment included $4,735.3 million and $1,198.0 million of capital lease assets and accumulated depreciation, respectively. As of December 31, 2015, property and equipment included $5,112.4 million and $1,414.6 million of capital lease assets and accumulated depreciation, respectively. The decreases in capital lease assets and accumulated depreciation were primarily due to the Company exercising its option to purchase 1,523 communications towers that were previously subject to capital leases. See note 18 for further discussion of this transaction. As of December 31, 2016 and 2015, capital lease assets were primarily classified as towers and land and improvements.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

GOODWILL AND OTHER INTANGIBLE ASSETS

The changes in the carrying value of goodwill for the Company’s business segments were as follows (in thousands):



	Property												Services		Total
	U.S.		Asia				EMEA			Latin America			Services		Total
Balance as of January 1, 2015	$	3,356,096	$	178,521			$	78,647		$	416,922		$	1,988	$	4,032,174
Additions	23,067		610				68,663			122,345			—		214,685
Effect of foreign currency translation	—		(8,412		)		(14,740		)	(131,902		)	—		(155,054		)
Balance as of December 31, 2015	$	3,379,163	$	170,719			$	132,570		$	407,365		$	1,988	$	4,091,805
Additions (1)	—		881,783			(2)	40,386			53,575			—		975,744
Effect of foreign currency translation	—		(23,189		)		(22,445		)	48,765			—		3,131
Balance as of December 31, 2016	$	3,379,163	$	1,029,313			$	150,511		$	509,705		$	1,988	$	5,070,680

_______________


(1)	Additions consist of $975.6 million resulting from 2016 acquisitions and $0.1 million from revisions to prior year acquisitions resulting from measurement period adjustments.


(2)	Assumed in the acquisition of Viom (see note 6).

The Company’s other intangible assets subject to amortization consisted of the following (in thousands):



		As of December 31, 2016							As of December 31, 2015
	Estimated Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Book Value		Gross Carrying Value		Accumulated Amortization			Net Book Value
	(years)	(in thousands)
Acquired network location intangibles (1)	Up to 20	$	4,622,316	$	(1,280,284	)	$	3,342,032	$	3,980,281	$	(1,052,393	)	$	2,927,888
Acquired tenant-related intangibles	15-20	10,130,466		(2,224,119		)	7,906,347		8,640,554		(1,763,853		)	6,876,701
Acquired licenses and other intangibles	3-20	28,140		(4,827		)	23,313		28,293		(5,486		)	22,807
Economic Rights, TV Azteca	70	13,893		(10,974		)	2,919		21,688		(11,208		)	10,480
Total other intangible assets		$	14,794,815	$	(3,520,204	)	$	11,274,611	$	12,670,816	$	(2,832,940	)	$	9,837,876

_______________


(1)	Acquired network location intangibles are amortized over the shorter of the term of the corresponding ground lease taking into consideration lease renewal options and residual value or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.

The acquired network location intangibles represent the value to the Company of the incremental revenue growth that could potentially be obtained from leasing the excess capacity on acquired communications sites. The acquired tenant-related intangibles typically represent the value to the Company of tenant contracts and relationships in place at the time of an acquisition or similar transaction, including assumptions regarding estimated renewals. This item was previously referred to as customer-related intangibles.

The Company amortizes its acquired network location intangibles and tenant-related intangibles on a straight-line basis over the estimated useful lives. As of December 31, 2016, the remaining weighted average amortization period of the Company’s intangible assets, excluding the TV Azteca Economic Rights detailed in note 5, was 16 years. Amortization of intangible assets for the years ended December 31, 2016, 2015 and 2014 was $699.8 million, $568.3 million and $411.7 million, respectively. Based on current exchange rates, the Company expects to record amortization expense as follows over the next five years (in millions):



Year Ending December 31,
2017	$	710.5
2018	707.8
2019	705.1
2020	686.3
2021	676.8

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Notes Receivable and Other Non-current Assets

12 Months Ended

Dec. 31, 2016

Notes Receivable And Other Long Term Assets [Abstract]

Notes Receivable and Other Non-Current Assets

NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS

Notes receivable and other non-current assets consisted of the following as of December 31, (in thousands):



	2016		2015
Long-term prepaid ground rent	$	467,781	$	388,790
Notes receivable	83,736		83,658
Other miscellaneous assets	290,006		260,455
Notes receivable and other non-current assets	$	841,523	$	732,903

TV Azteca Note Receivable—In 2000, the Company loaned TV Azteca, S.A. de C.V. (“TV Azteca”), the owner of a major national television network in Mexico, $119.8 million. The loan has an interest rate of 13.11%, payable quarterly, which at the time of issuance was determined to be below market and therefore a corresponding discount was recorded. The term of the loan is 70 years; however, the loan may be prepaid by TV Azteca without penalty during the last 50 years of the agreement. The discount on the loan is being amortized to Interest income, TV Azteca, net of interest expense on the Company’s consolidated statements of operations, using the effective interest method over the 70-year term of the loan.

Since inception, TV Azteca has repaid $28.0 million of principal on the loan. As of December 31, 2016 and 2015, the outstanding balance on the loan was $91.8 million, or $82.9 million, net of discount.

TV Azteca Economic Rights—Simultaneous with the signing of the loan agreement, the Company also entered into a 70-year Economic Rights Agreement with TV Azteca regarding space not used by TV Azteca on approximately 190 of its broadcast towers. In exchange for the issuance of the below market interest rate loan and the annual payment of $1.5 million to TV Azteca (under the Economic Rights Agreement), the Company has the right to market and lease the unused tower space on the broadcast towers (the “Economic Rights”). TV Azteca retains title to these towers and is responsible for their operation and maintenance. The Company is entitled to 100% of the revenues generated from leases with tenants on the unused space and is responsible for any incremental operating expenses associated with those tenants.

The term of the Economic Rights Agreement is 70 years; however, TV Azteca has the right to purchase, at fair market value, the Economic Rights from the Company at any time during the last 50 years of the agreement. Should TV Azteca elect to purchase the Economic Rights, in whole or in part, it would also be obligated to repay a proportional amount of the loan discussed above at the time of such election. The Company’s obligation to pay TV Azteca $1.5 million annually would also be reduced proportionally.

The Company accounted for the annual payment of $1.5 million as a capital lease by initially recording an asset and a corresponding liability of $18.6 million. The capital lease asset also included the original discount on the note. The capital lease asset and original discount on the note aggregated $30.2 million at the time of the transaction and represents the cost to acquire the Economic Rights. The Economic Rights asset was recorded as an intangible asset and is being amortized over the 70-year life of the Economic Rights Agreement.

Acquisitions

12 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Acquisitions

ACQUISITIONS

The estimates of the fair value of the assets or rights acquired and liabilities assumed at the date of the applicable acquisition are subject to adjustment during the measurement period (up to one year from the particular acquisition date). The primary areas of the accounting for the acquisitions that are not yet finalized relate to the fair value of certain tangible and intangible assets acquired and liabilities assumed, which may include contingent consideration, residual goodwill and any related tax impact. The fair value of these net assets acquired are based on management’s estimates and assumptions, as well as other information compiled by management, including valuations that utilize customary valuation procedures and techniques. While the Company believes that such preliminary estimates provide a reasonable basis for estimating the fair value of assets acquired and liabilities assumed, it evaluates any necessary information prior to finalization of the fair value. During the measurement period, the Company will adjust assets or liabilities if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in the revised estimated values of those assets or liabilities as of that date.

Impact of current year acquisitions—The Company typically acquires communications sites from wireless carriers or other tower operators and subsequently integrates those sites into its existing portfolio of communications sites. The financial results of the Company’s acquisitions have been included in the Company’s consolidated statement of operations for the year ended December 31, 2016 from the date of the respective acquisition. The date of acquisition, and by extension the point at which the Company begins to recognize the results of an acquisition, may depend upon, among other things, the receipt of contractual consents, the commencement and extent of leasing arrangements and the timing of the transfer of title or rights to the assets, which may be accomplished in phases. Sites acquired from communications service providers may never have been operated as a business and may have been utilized solely by the seller as a component of its network infrastructure. An acquisition may or may not involve the transfer of business operations or employees.

The estimated aggregate impact of the 2016 acquisitions on the Company’s revenues and gross margin for the year ended December 31, 2016 was approximately $567.9 million and $241.1 million, respectively. The revenues and gross margin amounts also reflect incremental revenues from the addition of new tenants to such sites subsequent to the transaction date. Incremental amounts of segment selling, general, administrative and development expense subsequent to the transaction date have not been reflected.

For those acquisitions accounted for as business combinations, the Company recognizes acquisition and merger related expenses in the period in which they are incurred and services are received. Acquisition and merger related expenses may include finder’s fees, advisory, legal, accounting, valuation and other professional or consulting fees, fair value adjustments to contingent consideration and general administrative costs directly related to the transaction. Integration costs include incremental and nonrecurring costs necessary to convert data, retain employees and otherwise enable the Company to operate new businesses efficiently. The Company records acquisition and merger related expenses, as well as integration costs in Other operating expenses in the consolidated statements of operations.

During the years ended December 31, 2016, 2015 and 2014, the Company recorded the following acquisition and merger related expenses and integration costs (in thousands):



	Year Ended December 31,
	2016		2015		2014

Acquisition and merger related expenses	$	15,875	$	18,799	$	26,969
Integration costs	$	9,901	$	18,097	$	13,057

2016 Transactions

Viom Acquisition—On April 21, 2016, the Company, through its wholly owned subsidiary, ATC Asia Pacific Pte. Ltd. (“ATC Asia”), acquired a 51% controlling ownership interest in Viom, a telecommunications infrastructure company that owns and operates approximately 42,000 wireless communications towers and 200 indoor DAS networks in India, from certain Viom shareholders, including the managing shareholder, SREI Infrastructure Finance Limited, several other minority shareholders and Tata Teleservices Limited, pursuant to its previously announced share purchase agreement (the “Viom Acquisition”). Consideration for the acquisition included 76.4 billion INR in cash ($1.1 billion at the date of the Viom Acquisition), as well as the assumption of approximately 52.3 billion INR ($0.8 billion at the date of the Viom Acquisition) of existing debt, which included 1.7 billion INR ($25.1 million at the date of the Viom Acquisition) of mandatorily redeemable preference shares issued by Viom.

On April 21, 2016, the closing date of the Viom Acquisition, ATC Asia’s shareholders agreement (the “Shareholders Agreement”) with Viom and the following remaining Viom shareholders - Tata Sons Limited, Tata Teleservices Limited, IDFC Private Equity Fund III, Macquarie SBI Investments Pte Limited and SBI Macquarie Infrastructure Trust (collectively, the “Remaining Shareholders”) - became effective. The Shareholders Agreement provides that, among other things, the Remaining Shareholders will have certain governance, anti-dilution and contractual rights. The Remaining Shareholders have put options, and ATC Asia has a call option, subject to the time periods and conditions outlined in the Shareholders Agreement.

Other Acquisitions—During the year ended December 31, 2016, the Company acquired a total of 891 communications sites in the United States, Brazil, Chile, Germany, Mexico, Nigeria and South Africa, and a company holding urban telecommunications assets and fiber in Argentina, for an aggregate purchase price of $304.4 million (including contingent consideration of $8.8 million). Of the total purchase price, $12.1 million is reflected in Accounts payable in the consolidated balance sheet as of December 31, 2016. The purchase prices of certain transactions are subject to post-closing adjustments.

The following table summarizes the preliminary allocation of the purchase prices for fiscal year 2016 acquisitions based upon their estimated fair value at the date of acquisition (in thousands).



	Asia			Other
	Viom			Other
Current assets	$	276,560		$	25,477
Non-current assets	57,645			2,336
Property and equipment	701,988			81,521
Intangible assets (1):
Tenant-related intangible assets	1,369,580			105,557
Network location intangible assets	666,364			83,645
Current liabilities	(195,900		)	(14,782		)
Deferred tax liability	(619,070		)	(43,756		)
Other non-current liabilities	(102,751		)	(29,472		)
Net assets acquired	2,154,416			210,526
Goodwill (2)	881,783			93,856
Fair value of net assets acquired	3,036,199			304,382
Debt assumed	(786,889		)	—
Redeemable noncontrolling interests	(1,100,804		)	—
Purchase Price	$	1,148,506		$	304,382

_______________


(1)	Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.


(2)	Primarily results from purchase accounting adjustments, which are at least partially deductible for tax purposes in certain foreign jurisdictions.

2015 Transactions

Verizon Transaction—On March 27, 2015, the Company completed its acquisition of the exclusive right to lease, acquire or otherwise operate and manage 11,449 wireless communications sites from Verizon Communications Inc. (“Verizon”) in the United States (the “Verizon Transaction”) pursuant to the Master Agreement entered into on February 5, 2015 and the related Master Prepaid Lease, Management Agreement, Sale Site Master Lease Agreement and MPL Site Master Lease Agreement.

The Company, through its wholly-owned subsidiary, leased or subleased from certain Verizon subsidiaries 11,286 communications sites, including the interest in the land, the tower and certain related improvements and tower related assets pursuant to the Master Prepaid Lease. Under the Master Prepaid Lease, the Company has the exclusive right to lease and operate the Verizon communications sites for a weighted average term of approximately 28 years and the Company will have the option to purchase the communications sites in various tranches at the end of the respective lease or sublease terms at a fixed amount stated in the sublease for such tranche plus the fair market value of certain alterations made to the related towers. The Company accounted for the payment with respect to the leased sites as a capital lease and the respective lease and non-lease elements related to tower assets and intangible assets, as described below. In addition, the Company, through its wholly-owned subsidiary, acquired 163 communications sites. The Company accounted for these sites as a business combination and the purchase price is reflected below in “Other Acquisitions.”

Upon closing, the Company agreed to lease, sublease or otherwise make available collocation space at each of the communications sites to Verizon for an initial non-cancellable term of ten years, subject to automatic extension for eight additional five-year renewal terms. The initial collocation rent is $1,900 per month for each communications site, with annual increases of 2%.

The total consideration for the Verizon Transaction was $5.066 billion, which includes consideration for the sites under the Master Prepaid Lease as well as cash consideration for the 163 acquired sites. The allocation of the consideration transfered for the 11,286 communication sites under the Master Prepaid Lease was finalized during the year ended December 31, 2015.

Airtel Acquisition—During the year ended December 31, 2015, the Company acquired 4,716 communications sites in Nigeria from certain subsidiaries of Bharti Airtel Limited (“Airtel”) for an aggregate total purchase price of $1.112 billion, including value added tax. During the year ended December 31, 2016 there were no changes to the preliminary allocation of the purchase price and the measurement period expired.

The estimates of the fair value of the assets or rights acquired and liabilities assumed at the date of the applicable acquisition are subject to adjustment during the measurement period (up to one year from the applicable acquisition date). During the year ended December 31, 2016, the Company adopted new guidance on the accounting for measurement-period adjustments related to business combinations. This guidance requires that an acquirer make adjustments to the provisional amounts recognized at the acquisition date with a corresponding adjustment to goodwill in the current period. Additionally, the effects on earnings of all measurement-period adjustments are included in current period earnings.

During the year ended December 31, 2016, post-closing adjustments impacted the following 2015 acquisitions:

TIM Acquisition—On April 29, 2015, the Company acquired 4,176 communications sites from TIM Celular S.A. (“TIM”) for an initial aggregate purchase price of $644.3 million, which was subsequently reduced by $0.8 million during the year ended December 31, 2016. On September 30, 2015, the Company acquired an additional 1,125 communications sites from TIM for an initial aggregate purchase price of $130.9 million. On December 16, 2015, the Company acquired an additional 182 communications sites from TIM for an initial aggregate purchase price of $21.7 million.

Other Acquisitions—During the year ended December 31, 2015, the Company acquired a total of 439 communications sites and related assets in Brazil, India, Mexico and Uganda for an aggregate purchase price of $22.5 million (including $0.3 million for the estimated fair value of contingent consideration), which was satisfied with cash consideration and by the issuance of credits to be applied against trade accounts receivable. The Company also acquired a total of 210 communications sites and equipment, as well as four property interests, in the United States for an aggregate purchase price of $142.4 million (including $1.3 million for the estimated fair value of contingent consideration), which included the 163 communications sites acquired as part of the Verizon Transaction, described above. The initial aggregate purchase price of other acquisitions was subsequently reduced by $0.2 million during the year ended December 31, 2016.

The following table summarizes the preliminary and final allocations of the purchase prices paid and the amounts of assets acquired and liabilities assumed for the fiscal year 2015 acquisitions based upon their estimated fair value at the date of acquisition (in thousands).



	Preliminary Allocation						Final Allocation (1)
	Latin America			Other			Latin America			Other
	TIM			Other			TIM			Other
Current assets	$	—		$	1,113		$	—		$	1,113
Non-current assets	—			995			—			995
Property and equipment	275,630			42,716			274,530			42,716
Intangible assets (2):
Tenant-related intangible assets	361,822			63,001			361,765			62,832
Network location intangible assets	115,562			37,691			115,795			37,691
Current liabilities	(3,192		)	(624		)	(3,192		)	(624		)
Other non-current liabilities	(74,966		)	(4,028		)	(74,966		)	(4,028		)
Net assets acquired	674,856			140,864			673,932			140,695
Goodwill (3)	122,011			24,011			122,116			24,011
Fair value of net assets acquired	796,867			164,875			796,048			164,706
Debt assumed	—			—			—			—
Purchase Price	$	796,867		$	164,875		$	796,048		$	164,706

_______________


(1)	The allocation of the purchase prices was finalized during the year ended December 31, 2016.


(2)	Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.


(3)	Goodwill was allocated to the Company’s property segments. The Company expects goodwill recorded in its U.S. and Asia property segments will be deductible for local tax purposes. The Company expects goodwill recorded in its Latin America property segment will be deductible in certain jurisdictions for local tax purposes.

Pro Forma Consolidated Results (Unaudited)

The following table presents the unaudited pro forma financial results as if the 2016 acquisitions had occurred on January 1, 2015 and the 2015 acquisitions had occurred on January 1, 2014. The pro forma results do not include any anticipated cost synergies, costs or other integration impacts. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the transactions been completed on the dates indicated, nor are they indicative of the future operating results of the Company.



	Year Ended December 31,
	2016		2015
Pro forma revenues	$	6,055,187	$	5,886,691
Pro forma net income attributable to American Tower Corporation common stockholders	$	847,738	$	544,641
Pro forma net income per common share amounts:
Basic net income attributable to American Tower Corporation common stockholders	$	1.99	$	1.29
Diluted net income attributable to American Tower Corporation common stockholders	$	1.97	$	1.27

Other Signed Acquisitions

Airtel Tanzania—On March 17, 2016, the Company entered into a definitive agreement with Airtel, through its subsidiary company Airtel Tanzania Limited (“Airtel Tanzania”), pursuant to which the Company may acquire approximately 1,350 of Airtel Tanzania’s communications sites in Tanzania, for total consideration of approximately $179.0 million, subject to customary adjustments. Under the definitive agreement, the Company may pay additional consideration to acquire up to approximately 100 additional communications sites currently in development. The closing of this transaction is subject to customary closing conditions. In light of recent legislation in Tanzania, the Company is considering its options, including negotiating potential adjustments to the definitive agreement in the event a waiver of such legislation is not obtained.

FPS Towers France—On December 19, 2016, ATC Europe entered into a definitive agreement with Antin Infrastructure Partners and the individuals party thereto to acquire 100% of the outstanding shares of FPS Towers (“FPS”). FPS owns and operates approximately 2,400 wireless tower sites in France. This transaction closed on February 15, 2017 for total consideration of 713.9 million Euros ($757.1 million at the date of acquisition), a portion of which was funded by PGGM (see note 23).

Acquisition-Related Contingent Consideration

The Company may be required to pay additional consideration under certain agreements for the acquisition of communications sites if specific conditions are met or events occur. In Colombia and Ghana, the Company may be required to pay additional consideration upon the conversion of certain barter agreements with other wireless carriers to cash-paying lease agreements. In the United States, India and South Africa, the Company may be required to pay additional consideration if certain pre-designated tenant leases commence during a specified period of time.

A summary of the value of the Company’s contingent consideration is as follows (in thousands):



					Year Ended December 31, 2016
	Maximum potential value (1)		Estimated value at December 31, 2016 (2)		Additions (3)		Settlements			Change in Fair Value
Colombia	$	23,557	$	5,342	$	—	$	—		$	(4,964	)
Ghana	555		555		—		—			47
India	—		—		—		—			(161		)
South Africa	22,291		9,154		8,692		—			—
United States	393		393		119		(306		)	(1,294		)
Total	$	46,796	$	15,444	$	8,811	$	(306	)	$	(6,372	)

_______________


(1)	The maximum potential value is based on exchange rates at December 31, 2016. The minimum value could be zero.


(2)	Estimate is determined using a probability weighted average of expected outcomes as of December 31, 2016.


(3)	Based on preliminary acquisition accounting upon closing of certain acquisitions during the year ended December 31, 2016.

For more information regarding contingent consideration, see note 11.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Long-Term Obligations

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Long-Term Obligations

LONG-TERM OBLIGATIONS

Outstanding amounts under the Company’s long-term obligations, reflecting discounts, premiums, debt issuance costs and fair value adjustments due to interest rate swaps consisted of the following as of December 31, (in thousands):



	2016			2015			Contractual Interest Rate (1)		Maturity Date (1)
Series 2013-1A Securities (2)	$	498,642		$	497,478		1.551	%	March 15, 2018
Series 2013-2A Securities (3)	1,290,267			1,288,689			3.070	%	March 15, 2023
Series 2015-1 Notes (4)	347,108			346,262			2.350	%	June 15, 2020
Series 2015-2 Notes (5)	519,437			518,776			3.482	%	June 16, 2025
2012 GTP Notes (6) (7)	179,459			281,902			4.336% - 7.358%		March 15, 2019
Unison Notes (7) (8)	132,960			201,930			6.392% - 9.522%		April 15, 2020
India indebtedness (9)	549,528			8,752			8.15% - 11.70%		Various
Viom preference shares (10)	24,537			—			13.500	%	Various
Shareholder loans (11)	151,045			145,540			Various		Various
Other subsidiary debt (12)	286,009			219,902			Various		Various
Total American Tower subsidiary debt	3,978,992			3,509,231

2013 Credit Facility (13)	539,975			1,225,000			1.963	%	June 28, 2020
Term Loan (13)	993,936			1,993,601			2.020	%	January 31, 2022
2014 Credit Facility (13)	1,385,000			1,980,000			2.432	%	January 31, 2022
4.500% senior notes	998,676			997,693			4.500	%	January 15, 2018
3.40% senior notes	999,716			999,769			3.400	%	February 15, 2019
7.25% senior notes (7)	297,032			296,242			7.250	%	May 15, 2019
2.800% senior notes	744,917			743,557			2.800	%	June 1, 2020
5.050% senior notes	697,352			697,216			5.050	%	September 1, 2020
3.300% senior notes	744,762			—			3.300	%	February 15, 2021
3.450% senior notes	643,848			642,786			3.450	%	September 15, 2021
5.900% senior notes	497,343			497,188			5.900	%	November 1, 2021
2.250% senior notes	572,764			—			2.250	%	January 15, 2022
4.70% senior notes	696,013			695,374			4.700	%	March 15, 2022
3.50% senior notes	989,269			987,966			3.500	%	January 31, 2023
5.00% senior notes	1,002,742			1,003,453			5.000	%	February 15, 2024
4.000% senior notes	739,985			739,057			4.000	%	June 1, 2025
4.400% senior notes	495,212			—			4.400	%	February 15, 2026
3.375% senior notes	983,369			—			3.375	%	October 15, 2026
3.125% senior notes	396,713			—			3.125	%	January 15, 2027
Total American Tower Corporation debt	14,418,624			13,498,902
Other debt, including capital lease obligations	135,849			110,876
Total	18,533,465			17,119,009
Less current portion long-term obligations	(238,806		)	(50,202		)
Long-term obligations	$	18,294,659		$	17,068,807

_______________


(1)	Represents the interest rate or maturity date as of December 31, 2016; interest rate does not reflect the impact of interest rate swap agreements.


(2)	Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2043.


(3)	Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048.


(4)	Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2045.


(5)	Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050.


(6)	Secured debt assumed by the Company in connection with its acquisition of MIP Tower Holdings LLC (“MIPT”). Maturity date represents anticipated repayment date; final legal maturity is March 15, 2042.


(7)	Debt was repaid in full subsequent to December 31, 2016. For more information see note 23.


(8)	Secured debt assumed in connection with the acquisition of certain legal entities holding a portfolio of property interests from Unison Holdings, LLC and Unison Site Management II, L.L.C. (together, “Unison”). Maturity date reflects the anticipated repayment date; final legal maturity is April 15, 2040.


(9)	Denominated in Indian Rupees (“INR”). Debt includes India working capital facility, remaining debt assumed by the Company in connection with the Viom Acquisition and debt that has been entered into by ATC TIPL.


(10)	Mandatorily redeemable preference shares (the “Preference Shares”) classified as debt, assumed by the Company in connection with the Viom Acquisition. The shares are to be redeemed in equal parts on March 26, 2017 and March 26, 2018.

(11)

Reflects balances owed to the Company’s joint venture partners in Ghana and Uganda. The Ghana loan is denominated in Ghanaian Cedi (“GHS”) and the Uganda loan was denominated in U.S. Dollars (“USD”). The Uganda loan accrued interest at a variable rate. Effective January 1, 2017, this loan, which had an outstanding balance of $80.0 million, was converted by the holder to a new shareholder note for $31.8 million, bearing interest at 16.6% per annum. The remaining balance of the Uganda loan was converted into equity.

(12)

Includes the BR Towers Debentures (as defined below), which are denominated in Brazilian Reais (“BRL”) and amortize through October 15, 2023, the South African Credit Facility (as defined below), which is denominated in South African Rand (“ZAR”) and amortizes through December 17, 2020, the Colombian Credit Facility (as defined below), which is denominated in Colombian Pesos (“COP”) and amortizes through April 24, 2021 and the Brazil Credit Facility (as defined below), which is denominated in BRL and matures on January 15, 2022.


(13)	Debt accrues interest at a variable rate.

American Tower Subsidiary Debt

Subsidiary Debt

The Company has several securitizations in place. Cash flows generated by the sites that secure the securitized debt are only available for payment of such debt and are not available to pay the Company’s other obligations or the claims of its creditors. However, subject to certain restrictions, the Company holds the right to the excess cash flows not needed to pay the securitized debt and other obligations arising out of the securitizations. The securitized debt is the obligation of the issuers thereof or borrowers thereunder, as applicable, and their subsidiaries, and not of the Company or its other subsidiaries.

Secured Tower Revenue Securities, Series 2013-1A and Series 2013-2A—In March 2013, the Company completed a private issuance (the “2013 Securitization”) of $1.8 billion of Secured Tower Revenue Securities, Series 2013-1A and Series 2013-2A (the “2013 Securities”) issued by American Tower Trust I (the “Trust”), a trust established by American Tower Depositor Sub, LLC, a wholly owned special purpose subsidiary of the Company. The net proceeds of the transaction were $1.78 billion. The assets of the Trust consist of a nonrecourse loan (the “Loan”) to American Tower Asset Sub, LLC and American Tower Asset Sub II, LLC (the “AMT Asset Subs”), pursuant to a First Amended and Restated Loan and Security Agreement dated as of March 15, 2013 (the “Loan Agreement”).

The Loan is secured by (i) mortgages, deeds of trust and deeds to secure debt on substantially all of the 5,181 wireless and broadcast communications towers owned by the AMT Asset Subs (the “2013 Secured Towers”), (ii) a pledge of the AMT Asset Subs’ operating cash flows from the 2013 Secured Towers, (iii) a security interest in substantially all of the AMT Asset Subs’ personal property and fixtures and (iv) the AMT Asset Subs’ rights under the tenant leases and the management agreement entered into in connection with the 2013 Securitization. American Tower Holding Sub, LLC, whose only material assets are its equity interests in each of the AMT Asset Subs, and American Tower Guarantor Sub, LLC, whose only material asset are its equity interests in American Tower Holding Sub, LLC, each have guaranteed repayment of the Loan and pledged their equity interests in their respective subsidiary or subsidiaries as security for such payment obligations.

The 2013 Securities were issued in two separate series of the same class pursuant to a First Amended and Restated Trust and Servicing Agreement, with terms identical to the Loan. The effective weighted average life and interest rate of the 2013 Securities was 8.6 years and 2.648%, respectively, as of the date of issuance.

American Tower Secured Revenue Notes, Series 2015-1, Class A and Series 2015-2, Class A—In May 2015, GTP Acquisition Partners I, LLC (“GTP Acquisition Partners”), one of the Company’s wholly owned subsidiaries, refinanced existing debt with cash on hand and proceeds from a private issuance (the “2015 Securitization”) of $350.0 million of American Tower Secured Revenue Notes, Series 2015-1, Class A (the “Series 2015-1 Notes”) and $525.0 million of American Tower Secured Revenue Notes, Series 2015-2, Class A (the “Series 2015-2 Notes,” and together with the Series 2015-1 Notes, the “2015 Notes”).

The 2015 Notes are secured by (i) mortgages, deeds of trust and deeds to secure debt on substantially all of the 3,596 communications sites (the “2015 Secured Sites”) owned by GTP Acquisition Partners and its subsidiaries (the “GTP Entities”) and their operating cash flows, (ii) a security interest in substantially all of the personal property and fixtures of the GTP Entities, including GTP Acquisition Partners’ equity interests in its subsidiaries and (iii) the rights of the GTP Entities under a management agreement. American Tower Holding Sub II, LLC, whose only material assets are its equity interests in GTP Acquisition Partners, has guaranteed repayment of the 2015 Notes and pledged its equity interests in GTP Acquisition Partners as security for such payment obligations.

The 2015 Notes were issued by GTP Acquisition Partners pursuant to a Third Amended and Restated Indenture and related series supplements, each dated as of May 29, 2015 (collectively, the “2015 Indenture”), between the GTP Entities and The Bank of New York Mellon, as trustee. The effective weighted average life and interest rate of the 2015 Notes was 8.1 years and 3.029%, respectively, as of the date of issuance.

Under the terms of the Loan Agreement and 2015 Indenture, amounts due will be paid from the cash flows generated by the 2013 Secured Towers or the 2015 Secured Sites, respectively, which must be deposited into certain reserve accounts, and thereafter distributed solely pursuant to the terms of the Loan Agreement or 2015 Indenture, as applicable. On a monthly basis, after payment of all required amounts under the Loan Agreement or 2015 Indenture, as applicable, including interest payments, subject to the conditions described below, the excess cash flows generated from the operation of such assets are released to the AMT Asset Subs or GTP Acquisition Partners, as applicable, and can then be distributed to, and used by, the Company.

In order to distribute any excess cash flow to the Company, the AMT Asset Subs and GTP Acquisition Partners must each maintain a specified debt service coverage ratio (the “DSCR”), generally defined as the net cash flow divided by the amount of interest, servicing fees and trustee fees required to be paid over the succeeding 12 months on the principal amount of the Loan or the 2015 Notes, as applicable, that will be outstanding on the payment date following such date of determination. If the DSCR were equal to or below 1.30x (the “Cash Trap DSCR”) for any quarter, then all cash flow in excess of amounts required to make debt service payments, to fund required reserves, to pay management fees and budgeted operating expenses and to make other payments required under the applicable transaction documents, referred to as excess cash flow, will be deposited into a reserve account (the “Cash Trap Reserve Account”) instead of being released to the AMT Asset Subs or GTP Acquisition Partners, as applicable. The funds in the Cash Trap Reserve Account will not be released to the AMT Asset Subs or GTP Acquisition Partners unless the DSCR, as applicable, exceeds the Cash Trap DSCR for two consecutive calendar quarters.

Additionally, an “amortization period” commences if, as of the end of any calendar quarter, the DSCR falls below 1.15x (the “Minimum DSCR”) and will continue to exist until the DSCR exceeds the Minimum DSCR for two consecutive calendar quarters. With respect to the 2013 Securities, an “amortization period” also commences if, on the anticipated repayment date the component of the Loan corresponding to the applicable subclass of the 2013 Securities has not been repaid in full, provided that such amortization period shall apply with respect to such component that has not been repaid in full. If either series of the 2015 Notes have not been repaid in full on the applicable anticipated repayment date, additional interest will accrue on the unpaid principal balance of the applicable series of the 2015 Notes, and such series will begin to amortize on a monthly basis from excess cash flow. During an amortization period, all excess cash flow and any amounts then in the applicable Cash Trap Reserve Account would be applied to payment of the principal on the Loan or the 2015 Notes, as applicable.

The Loan and the 2015 Notes may be prepaid in whole or in part at any time, provided such payment is accompanied by the applicable prepayment consideration. If the prepayment occurs within 12 months of the anticipated repayment date with respect to the Series 2013-1A Securities or the Series 2015-1 Notes, or 18 months of the anticipated repayment date with respect to the Series 2013-2A Securities or the Series 2015-2 Notes, no prepayment consideration is due. The Loan may be defeased in whole at any time prior to the anticipated repayment date for any component of the Loan then outstanding.

The Loan Agreement and the 2015 Indenture include operating covenants and other restrictions customary for transactions subject to rated securitizations. Among other things, the AMT Asset Subs and the GTP Entities, as applicable, are prohibited from incurring other indebtedness for borrowed money or further encumbering their assets subject to customary carve-outs for ordinary course trade payables and permitted encumbrances (as defined in the Loan Agreement or the 2015 Indenture, as applicable). The organizational documents of the AMT Asset Subs and the GTP Entities contain provisions consistent with rating agency securitization criteria for special purpose entities, including the requirement that they maintain independent directors. The Loan Agreement and the 2015 Indenture also contain certain covenants that require the AMT Asset Subs or GTP Acquisition Partners, as applicable, to provide the respective trustee with regular financial reports and operating budgets, promptly notify such trustee of events of default and material breaches under the Loan Agreement and other agreements related to the 2013 Secured Towers or the 2015 Indenture and other agreements related to the 2015 Secured Sites, as applicable, and allow the applicable trustee reasonable access to the sites, including the right to conduct site investigations.

A failure to comply with the covenants in the Loan Agreement or the 2015 Indenture could prevent the AMT Asset Subs or GTP Acquisition Partners from distributing excess cash flow to the Company. Furthermore, if the AMT Asset Subs or GTP Acquisition Partners were to default on the Loan or a series of the 2015 Notes, the applicable trustee may seek to foreclose upon or otherwise convert the ownership of all or any portion of the 2013 Secured Towers or the 2015 Secured Sites, respectively, in which case the Company could lose the revenue associated with those assets. With respect to the 2015 Notes, upon occurrence and during an event of default, the trustee may, in its discretion or at direction of holders of more than 50% of the aggregate outstanding principal of any series of the 2015 Notes, declare such series of 2015 Notes immediately due and payable, in which case any excess cash flow would need to be used to pay holders of such notes.

Further, under the Loan Agreement and the 2015 Indenture, the AMT Asset Subs or GTP Acquisition Partners, respectively, are required to maintain reserve accounts, including for amounts received or due from tenants related to future periods, property taxes, insurance, ground rents, certain expenses and debt service. Based on the terms of the Loan Agreement and the 2015 Indenture, all rental cash receipts received for each month are reserved for the succeeding month and held in an account controlled by the applicable trustee and then released. The $82.7 million held in the reserve accounts with respect to the 2013 Securitization and the $16.8 million held in the reserve accounts with respect to the 2015 Securitization as of December 31, 2016 are classified as Restricted cash on the Company’s accompanying consolidated balance sheets.

2012 GTP Notes—In connection with the acquisition of MIPT, the Company assumed existing indebtedness issued by certain subsidiaries of Global Tower Partners in several securitization transactions. During the year ended December 31, 2016, the Company repaid $94.1 million of these notes and released 472 sites in connection with this repayment. As of December 31, 2016, the aggregate amount outstanding was $173.7 million plus $5.7 million of unamortized premium. As discussed in note 23, all amounts outstanding under these notes were repaid subsequent to December 31, 2016.

Unison Notes—In connection with the acquisition of Unison, the Company assumed $196.0 million of existing securitized indebtedness. In October 2016, the Company repaid $67.0 million of these notes. As of December 31, 2016, the aggregate amount outstanding was $129.0 million plus $4.0 million of unamortized premium. As discussed in note 23, all amounts outstanding under these notes were repaid subsequent to December 31, 2016.

India indebtedness—Amounts outstanding and key terms of the India indebtedness consisted of the following as of December 31, 2016 (in millions, except percentages):



	Amount Outstanding (INR)	Amount Outstanding (USD)		Interest Rate (Range)		Maturity Date (Range)
Term loans	31,326	$	461.2	8.15% - 11.15%		March 31, 2017 - November 30, 2024
Debenture	6,000	$	88.3	9.90	%	April 28, 2020
Working capital facilities	0	$	0	8.70% - 11.70%		January 31, 2017 - October 23, 2017

The India indebtedness includes several term loans, ranging from one to ten years, which are generally secured by the borrower’s short-term and long-term assets. Each of the term loans bear interest at the applicable bank’s Marginal Cost of Funds based Lending Rate (as defined in the applicable agreement) or base rate, plus a spread. Interest rates on the term loans are fixed until certain reset dates. Generally, the term loans can be repaid without penalty on the reset dates; repayments at dates other than the reset dates are subject to prepayment penalties, typically of 1% to 2%. Scheduled repayment terms include either ratable or staggered amortization with repayments typically commencing between six and 36 months after the initial disbursement of funds.

The debenture is secured by the borrower’s long-term assets, including property and equipment and intangible assets. The debenture bears interest at a base rate plus a spread of 0.6%. The base rate is set in advance for each quarterly coupon period. Should the actual base rate be between 9.75% and 10.25%, the revised base rate is assumed to be 10.00% for purposes of the reset. Additionally, the spread is subject to reset 36 and 48 months from the issuance date of April 27, 2015. The holders of the debenture must reach a consensus on the revised spread and the borrower must redeem all of the debentures held by holders from whom consensus is not achieved. Additionally, the debenture is required to be redeemed by the borrower if it does not maintain a minimum credit rating.

The India indebtedness includes several working capital facilities, most of which are subject to annual renewal, and which are generally secured by the borrower’s short-term and long-term assets. The working capital facilities bear interest at rates that are comprised of the applicable bank’s Marginal Cost of Funds based Lending Rate (as defined in the applicable agreement) or base rate, plus a spread. Generally, the working capital facilities are payable on demand prior to maturity.

Viom preference shares—As of December 31, 2016, ATC TIPL had 166,666,666 Preference Shares outstanding, which are required to be redeemed in cash. Accordingly, the Company recognized debt of 1.67 billion INR ($24.5 million) related to the Preference Shares outstanding on the consolidated balance sheet.

Unless redeemed earlier, the Preference Shares will be redeemed in two equal installments on March 26, 2017 and March 26, 2018 in an amount equal to ten INR per share along with a redemption premium, as defined in the investment agreement, which equates to a compounded return of 13.5% per annum. ATC TIPL, at its option, may redeem the Preference Shares prior to the aforementioned dates, subject to an additional 2% redemption premium.

Other Subsidiary Debt—The Company’s other subsidiary debt includes (i) publicly issued simple debentures in Brazil (the “BR Towers Debentures”) issued by a subsidiary of BR Towers and assumed by the Company in its acquisition of BR Towers, (ii) a credit facility entered into by one of the Company’s South African subsidiaries in December 2015, as amended (the “South African Credit Facility”), (iii) a long-term credit facility entered into by one of the Company’s Colombian subsidiaries in October 2014 (the “Colombian Credit Facility”) and (iv) a credit facility entered into by one of the Company’s Brazilian subsidiaries in December 2014 (the “Brazil Credit Facility”) with Banco Nacional de Desenvolvimento Econômico e Social.

Amounts outstanding and key terms of other subsidiary debt consisted of the following as of December 31, 2016 (in millions, except percentages):



	Amount Outstanding (Functional Currency)		Amount Outstanding (USD) (1)				Interest Rate		Maturity Date
	2016	2015	2016		2015
BR Towers Debentures (2)	329.3	332.8	$	101.0	$	85.2	7.400	%	October 15, 2023
South African Credit Facility (3)	1,164.0	830.0	$	84.3	$	53.2	9.308	%	December 17, 2020
Colombian Credit Facility (4)	170,000.0	190,000.0	$	56.1	$	59.6	10.920	%	April 24, 2021
Brazil Credit Facility (5)	147.7	85.4	$	44.6	$	21.9	Various		January 15, 2022

_______________


(1)	Includes applicable deferred financing costs.


(2)	Denominated in BRL, with an original principal amount of 300.0 million BRL. Debt accrues interest at a variable rate. The aggregate principal amount of the BR Towers Debentures may be adjusted periodically relative to changes in the National Extended Consumer Price Index.


(3)	Denominated in ZAR, with an original principal amount of 830.0 million ZAR. On December 23, 2016, the borrower borrowed an additional 500.0 million ZAR, with the ability to request an additional 330.0 million ZAR. Debt accrues interest at a variable rate.


(4)	Denominated in COP, with an original principal amount of 200.0 billion COP. Debt accrues interest at a variable rate. The loan agreement for the Colombian Credit Facility requires that the borrower manage exposure to variability in interest rates on certain of the amounts outstanding under the Colombian Credit Facility.


(5)	Denominated in BRL, with an original principal amount of 271.0 million BRL. Debt accrues interest at a variable rate. As of December 30, 2016, the borrower no longer maintains the ability to draw on the Brazil Credit Facility.

Pursuant to the agreements governing the BR Towers Debentures, the South African Credit Facility and the Colombian Credit Facility, payments of principal and interest are payable quarterly in arrears. Outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. The BR Towers Debentures may be redeemed beginning on October 15, 2018 at the then outstanding principal amount plus a surcharge and all accrued and unpaid interest thereon. The South African Credit Facility may be prepaid in whole or in part without prepayment consideration. The Colombian Credit Facility may be prepaid in whole or in part at any time, subject to certain limitations and prepayment consideration.

The South African Credit Facility, the Colombian Credit Facility and the Brazil Credit Facility are secured by, among other things, liens on towers owned by the applicable borrower. The BR Towers Debentures are secured by (i) 100% of the shares of the issuer thereof and (ii) all proceeds and rights from the issuance of the BR Towers Debentures, including amounts in a Resource Account, as defined in the applicable agreement.

Each of the agreements governing the other subsidiary debt contains contractual covenants and other restrictions. Failure to comply with certain of the financial and operating covenants could constitute a default under the applicable debt agreement, which could result in, among other things, the amounts outstanding, including all accrued interest and unpaid fees, becoming immediately due and payable.

Shareholder Loans—In connection with the establishment of certain of the Company’s joint ventures and related acquisitions of communications sites in Ghana and Uganda, the Company’s majority owned subsidiaries entered into shareholder loan agreements, as borrowers, with wholly owned subsidiaries of the Company and of the Company’s joint venture partners, as lenders. The portions of the loans made by the Company’s wholly owned subsidiaries are eliminated in consolidation and the portions of the loans made by each of the Company’s joint venture partner’s wholly owned subsidiaries are reported as outstanding debt of the Company. Outstanding amounts under each of the Company’s shareholder loans consisted of the following as of December 31, (in thousands):



	2016		2015		Contractual Interest Rate		Maturity Date
Ghana loan (1)	$	71,047	$	70,314	21.87	%	December 31, 2019
Uganda loan (2)(3)	79,998		75,226		6.52	%	June 29, 2019

_______________


(1)	Denominated in GHS. As of December 31, 2016, the aggregate principal amount outstanding under the Ghana loan was 300.9 million GHS.


(2)	Interest accrues at a variable rate.


(3)	Includes $4.8 million of interest which was capitalized during the year ended December 31, 2016.

American Tower Corporation Debt

Bank Facilities—In November 2016, the Company entered into amendment agreements (the “Credit Facility Amendments”) with respect to (i) its multicurrency senior unsecured revolving credit facility entered into in June 2013, as amended (the “2013 Credit Facility”), (ii) its senior unsecured revolving credit facility entered into in January 2012, as amended and restated in September 2014, as further amended (the “2014 Credit Facility”) and (iii) its unsecured term loan entered into in October 2013, as amended (the “Term Loan”), which, among other things, (i) extend the maturity dates by one year to June 28, 2020, January 31, 2022 and January 31, 2022, respectively, (ii) increase the maximum Revolving Loan Commitments, after giving effect to any Incremental Commitments (each as defined in the loan agreements for each of the 2013 Credit Facility and the 2014 Credit Facility) to $4.25 billion and $3.00 billion under the 2013 Credit Facility and the 2014 Credit Facility, respectively, (iii) amend the limitation on indebtedness of, and guaranteed by, the Company’s subsidiaries to the greater of (x) $2.25 billion and (y) 50% of Adjusted EBITDA (as defined in the agreements for each of the 2013 Credit Facility, the 2014 Credit Facility and the Term Loan) of the Company and its subsidiaries on a consolidated basis and (iv) amend the limitation of the Company's permitted ratio of Total Debt to Adjusted EBITDA (each as defined in the agreements for each of the 2013 Credit Facility, the 2014 Credit Facility and the Term Loan) to be no greater than (x) 6.00 to 1.00 as of the end of each fiscal quarter or (y) 7.00 to 1.00 as of the specified time periods after the occurrence of a Qualified Acquisition (as defined in each of the Credit Facility Amendments).

2013 Credit Facility—The Company has the ability to borrow up to $2.75 billion under the 2013 Credit Facility, which includes a $1.0 billion sublimit for multicurrency borrowings, a $200.0 million sublimit for letters of credit and a $50.0 million sublimit for swingline loans. During the year ended December 31, 2016, the Company borrowed an aggregate of $1.9 billion and repaid an aggregate of $2.6 billion of revolving indebtedness under the 2013 Credit Facility. The Company primarily used the borrowings to fund the Viom Acquisition and general corporate purposes.

2014 Credit Facility—The Company has the ability to borrow up to $2.0 billion under the 2014 Credit Facility, which includes a $200.0 million sublimit for letters of credit and a $50.0 million sublimit for swingline loans. During the year ended December 31, 2016, the Company borrowed an aggregate of $245.0 million and repaid an aggregate of $840.0 million of revolving indebtedness under the 2014 Credit Facility.

Term Loan—During the year ended December 31, 2016, the Company repaid $1.0 billion of indebtedness under the Term Loan.

The Term Loan, the 2013 Credit Facility and the 2014 Credit Facility do not require amortization of principal and may be paid prior to maturity in whole or in part at the Company’s option without penalty or premium. The Company has the option of choosing either a defined base rate or the London Interbank Offered Rate (“LIBOR”) as the applicable base rate for borrowings under the Term Loan, the 2013 Credit Facility and the 2014 Credit Facility. The interest rates range between 1.000% to 2.000% above LIBOR for LIBOR based borrowings or up to 1.000% above the defined base rate for base rate borrowings, in each case based upon our debt ratings.

As of December 31, 2016, the key terms under the 2013 Credit Facility, the 2014 Credit Facility and the Term Loan were as follows:



	Outstanding Principal Balance (in millions)			Undrawn letters of credit (in millions)		Maturity Date		Current margin over LIBOR and base rate	Current commitment fee (1)
2013 Credit Facility	$	540.0	(2)	$	3.2	June 28, 2020	(3)	1.250% and 0.250%	0.150	%
2014 Credit Facility	$	1,385.0	(4)	$	7.3	January 31, 2022	(3)	1.250% and 0.250%	0.150	%
Term Loan	$	1,000.0	(2)	$	—	January 31, 2022		1.250% and 0.250%	N/A

_______________

(1) Fee on undrawn portion of each credit facility.

(2) Borrowed at LIBOR.

(3) Subject to two optional renewal periods.

(4) Includes $1,095.0 million borrowed at LIBOR and $290.0 million borrowed at the base rate.

Senior Notes

3.300% Notes and 4.400% Notes Offerings—On January 12, 2016, the Company completed registered public offerings of $750.0 million aggregate principal amount of 3.300% senior unsecured notes due 2021 (the “3.300% Notes”) and $500.0 million aggregate principal amount of 4.400% senior unsecured notes due 2026 (the “4.400% Notes”). The net proceeds from these offerings were approximately $1,237.2 million, after deducting commissions and estimated expenses. The Company used the proceeds to repay existing indebtedness under the 2013 Credit Facility and for general corporate purposes.

3.375% Notes Offering—On May 13, 2016, the Company completed a registered public offering of $1.0 billion aggregate principal amount of 3.375% senior unsecured notes due 2026 (the “3.375% Notes”). The net proceeds from this offering were approximately $981.5 million, after deducting commissions and estimated expenses. The Company used the proceeds to repay existing indebtedness under the 2013 Credit Facility.

2.250% Notes and 3.125% Notes Offerings—On September 30, 2016, the Company completed registered public offerings of $600.0 million aggregate principal amount of 2.250% senior unsecured notes due 2022 (the “2.250% Notes”) and $400.0 million aggregate principal amount of 3.125% senior unsecured notes due 2027 (the “3.125% Notes”). The net proceeds from these offerings were approximately $990.6 million, after deducting commissions and estimated expenses. The Company used the proceeds to repay existing indebtedness under the Term Loan.

The Company entered into interest rate swap agreements, which were designated as fair value hedges at inception, to hedge against changes in fair value of the 2.250% Notes resulting from changes in interest rates. As of December 31, 2016, the interest rate on the 2.250% Notes, after giving effect to the interest rate swap agreements, was 1.97%.

The following table outlines key terms related to the Company’s outstanding senior notes as of December 31, 2016:



			Adjustments to Principal Amount (1)
	Aggregate Principal Amount		2016			2015			Semi-annual interest payments due	Issue Date	Par Call Date (2)
	(in thousands)
4.500% Notes	$	1,000,000	$	(1,324	)	$	(2,307	)	January 15 and July 15	December 7, 2010	N/A
3.40% Notes (3)	1,000,000		(284		)	(231		)	February 15 and August 15	August 19, 2013	N/A
7.25% Notes	300,000		(2,968		)	(3,758		)	May 15 and November 15	June 10, 2009	N/A
2.800% Notes	750,000		(5,083		)	(6,443		)	June 1 and December 1	May 7, 2015	May 1, 2020
5.050% Notes	700,000		(2,648		)	(2,784		)	March 1 and September 1	August 16, 2010	N/A
3.300% Notes	750,000		(5,238		)	—			February 15 and August 15	January 12, 2016	January 15, 2021
3.450% Notes	650,000		(6,152		)	(7,214		)	March 15 and September 15	August 7, 2014	N/A
5.900% Notes	500,000		(2,657		)	(2,812		)	May 1 and November 1	October 6, 2011	N/A
2.250% Notes (4)	600,000		(27,236		)	—			January 15 and July 15	September 30, 2016	N/A
4.70% Notes	700,000		(3,987		)	(4,626		)	March 15 and September 15	March 12, 2012	N/A
3.50% Notes	1,000,000		(10,731		)	(12,034		)	January 31 and July 31	January 8, 2013	N/A
5.00% Notes (3)	1,000,000		2,742			3,453			February 15 and August 15	August 19, 2013	N/A
4.000% Notes	750,000		(10,015		)	(10,943		)	June 1 and December 1	May 7, 2015	March 1, 2025
4.400% Notes	500,000		(4,788		)	—			February 15 and August 15	January 12, 2016	November 15, 2025
3.375% Notes	1,000,000		(16,631		)	—			April 15 and October 15	May 13, 2016	July 15, 2026
3.125% Notes	400,000		(3,287		)	—			January 15 and July 15	September 30, 2016	October 15, 2026

_______________


(1)	Includes unamortized discounts, premiums and debt issuance costs and fair value adjustments due to interest rate swaps.


(2)	The Company will not be required to pay a make-whole premium if redeemed on or after the par call date.


(3)	The original issue date for the 3.40% Notes and the 5.00% Notes was August 19, 2013. The issue date for the reopened 3.40% Notes and the reopened 5.00% Notes was January 10, 2014.


(4)	Includes $22.3 million fair value adjustment due to interest rate swaps.

The Company may redeem each series of notes at any time, subject to the terms of the applicable supplemental indenture, in whole or in part, at a redemption price equal to 100% of the principal amount of the notes plus a make-whole premium, together with accrued interest to the redemption date. In addition, if the Company undergoes a change of control and corresponding ratings decline, each as defined in the applicable supplemental indenture, it may be required to repurchase all of the applicable notes at a purchase price equal to 101% of the principal amount of such notes, plus accrued and unpaid interest (including additional interest, if any), up to but not including the repurchase date. The notes rank equally with all of the Company’s other senior unsecured debt and are structurally subordinated to all existing and future indebtedness and other obligations of its subsidiaries.

Each applicable supplemental indenture for the notes contains certain covenants that restrict the Company’s ability to merge, consolidate or sell assets and its (together with its subsidiaries’) ability to incur liens. These covenants are subject to a number of exceptions, including that the Company, and its subsidiaries, may incur certain liens on assets, mortgages or other liens securing indebtedness if the aggregate amount of such liens does not exceed 3.5x Adjusted EBITDA, as defined in the applicable supplemental indenture.

Capital Lease and Other Obligations—The Company’s capital lease and other obligations approximated $135.8 million and $110.9 million as of December 31, 2016 and 2015, respectively. These obligations are secured by the related assets, bear interest at rates of 2.40% to 9.50%, and mature in periods ranging from less than one year to approximately seventy years.

Maturities—Aggregate principal maturities of long-term debt, including capital leases, for the next five years and thereafter are expected to be (in thousands):



Year Ending December 31,
2017	$	238,806
2018	1,649,137
2019	1,759,808
2020	2,677,594
2021	1,976,976
Thereafter	10,350,583

Total cash obligations	18,652,904
Unamortized discounts, premiums and debt issuance costs and fair value adjustments, net	(119,439		)

Balance as of December 31, 2016	$	18,533,465

Asset Retirement Obligations

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligation [Abstract]

Asset Retirement Obligations

ASSET RETIREMENT OBLIGATIONS

The changes in the carrying amount of the Company’s asset retirement obligations were as follows (in thousands):



	2016			2015
Beginning balance as of January 1,	$	856,936		$	609,035
Additions	64,092			277,982
Accretion expense	67,010			55,592
Revisions in estimates (1)	(21,130		)	(83,636		)
Settlements	(1,401		)	(2,037		)
Balance as of December 31,	$	965,507		$	856,936

_______________


(1)	Revisions in estimates include an increase in the liability of $9.6 million for the year ended December 31, 2016 and a decrease in the liability of $81.7 million for the year ended December 31, 2015 related to foreign currency translation.

As of December 31, 2016, the estimated undiscounted future cash outlay for asset retirement obligations was $2.5 billion.

Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Below are the three levels of inputs that may be used to measure fair value:



	Level 1	Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

	Level 2	Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

	Level 3	Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Items Measured at Fair Value on a Recurring Basis—The fair value of the Company’s financial assets and liabilities that are required to be measured on a recurring basis at fair value was as follows (in thousands):



	December 31, 2016						December 31, 2015
	Fair Value Measurements Using						Fair Value Measurements Using
	Level 1		Level 2		Level 3		Level 1	Level 2		Level 3
Assets:
Short-term investments (1)	$	4,026	—		—		—	—		—
Interest rate swap agreements	—		$	3	—		—	$	692	—
Embedded derivative in lease agreement	—		—		$	13,290	—	—		$	14,176
Liabilities:
Interest rate swap agreements	—		$	24,682	—		—	—		—
Acquisition-related contingent consideration	—		—		$	15,444	—	—		$	12,436

_______________


(1)	Consists of highly liquid investments with original maturities in excess of three months.

Interest Rate Swap Agreements

The fair value of the Company’s interest rate swap agreements is determined using pricing models with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data. For derivative instruments that are designated and qualify as fair value hedges, changes in value of the derivatives are recognized in the consolidated statement of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments that are designated and qualify as a cash flow hedges, the Company records the change in fair value for the effective portion of the cash flow hedges in AOCI in the consolidated balance sheets and reclassifies a portion of the value from AOCI into Interest expense on a quarterly basis as the cash flows from the hedged item affects earnings. The Company records the settlement of interest rate swap agreements in Gain (loss) on retirement of long-term obligations in the consolidated statements of operations in the period in which the settlement occurs.

The Company entered into three interest rate swap agreements with an aggregate notional value of $600.0 million related to the 2.250% Notes. These interest rate swaps, which were designated as fair value hedges at inception, were entered into to hedge against changes in fair value of the 2.250% Notes resulting from changes in interest rates. The interest rate swap agreements require the Company to pay interest at a variable interest rate of one-month LIBOR plus applicable spreads and to receive fixed interest at a rate of 2.250% through January 15, 2022. During the year ended December 31, 2016, the Company recorded a $2.4 million fair value adjustment which was recorded in Other expense in the consolidated statement of operations. As of December 31, 2016, the interest rate swap agreements in the U.S. were included in Other non-current liabilities on the consolidated balance sheet.

One of the Company’s Colombian subsidiaries entered into an interest rate swap agreement with an aggregate notional value of 100.0 billion COP ($33.3 million) with certain of the lenders under the Colombian Credit Facility. The interest rate swap agreement, which was designated as a cash flow hedge at inception, was entered into to manage exposure to variability in interest rates on debt. The interest rate swap agreement requires the payment of a fixed interest rate of 5.74% and pays variable interest at the three-month Inter-bank Rate (IBR) through the earlier of termination of the underlying debt or April 24, 2021. The notional value is reduced in accordance with the repayment schedule under the Colombian Credit Facility.

The notional amount and fair value of the Colombian interest rate swap agreements were as follows as of December 31, (in thousands):



	2016			2015
	Local	USD		Local	USD
Colombia (COP) (1)
Notional	85,000,000	$	28,327	95,000,000	$	30,164
Fair Value	8,763	3		2,179,374	692

_______________


(1)	As of December 31, 2016 and 2015, the interest rate swap agreement in Colombia was included in Notes receivable and other non-current assets on the consolidated balance sheet.

Embedded Derivative in Lease Agreement

In connection with the acquisition of communications sites in Nigeria, the Company entered into a site lease agreement where a portion of the monthly rent to be received is escalated based on an index outside the lessor’s economic environment. The fair value of the portion of the lease tied to the U.S. CPI was $14.6 million at the date of acquisition and was recorded in Notes receivable and other non-current assets on the consolidated balance sheet. The fair value of the Company’s embedded derivative is determined using a discounted cash flow approach, which takes into consideration Level 3 unobservable inputs, including expected future cash flows over the period in which the associated payment is expected to be received and applies a discount factor that captures uncertainties in the future periods associated with the expected payment. During the year ended December 31, 2016, the Company recorded $0.9 million of a fair value adjustment, which was recorded in Other expense in the consolidated statement of operations.

Acquisition-Related Contingent Consideration

Acquisition-related contingent consideration is initially measured and recorded at fair value as an element of consideration paid in connection with an acquisition with subsequent adjustments recognized in Other operating expenses in the consolidated statements of operations. The fair value of acquisition-related contingent consideration, and any subsequent changes in fair value, is determined by using a discounted probability-weighted approach, which takes into consideration Level 3 unobservable inputs, including assessments of expected future cash flows over the period in which the obligation is expected to be settled, and applies a discount factor that captures the uncertainties associated with the obligation. Changes in the unobservable inputs of Level 3 assets or liabilities could significantly impact the fair value of these assets or liabilities recorded in the accompanying consolidated balance sheets, with the adjustments being recorded in the consolidated statements of operations.

As of December 31, 2016, the Company estimates that the value of all potential acquisition-related contingent consideration required payments to be between zero and $46.8 million. The changes in fair value of the contingent consideration were as follows during the years ended December 31, (in thousands):



	2016			2015
Balance as of January 1	$	12,436		$	28,524
Additions	8,811			1,626
Settlements	(306		)	(7,943		)
Change in fair value	(6,372		)	(4,781		)
Foreign currency translation adjustment	875			(4,990		)
Balance as of December 31	$	15,444		$	12,436

Items Measured at Fair Value on a Nonrecurring Basis

Assets Held and Used—The Company’s long-lived assets are recorded at amortized cost and, if impaired, are adjusted to fair value using Level 3 inputs. During the year ended December 31, 2016, certain long-lived assets held and used with a carrying value of $12.7 billion were written down to their net realizable value as a result of an asset impairment charge of $28.5 million. During the year ended December 31, 2015, certain long-lived assets held and used with a carrying value of $12.6 billion were written down to their net realizable value as a result of an asset impairment charge of $15.1 million. The asset impairment charges are recorded in Other operating expenses in the accompanying consolidated statements of operations. These adjustments were determined by comparing the estimated fair value utilizing projected future discounted cash flows to be provided from the long-lived assets to the asset’s carrying value.

There were no other items measured at fair value on a nonrecurring basis during the year ended December 31, 2016.

Fair Value of Financial Instruments—The Company’s financial instruments for which the carrying value reasonably approximates fair value at December 31, 2016 and 2015 include cash and cash equivalents, restricted cash, accounts receivable and accounts payable. The Company’s estimates of fair value of its long-term obligations, including the current portion, are based primarily upon reported market values. For long-term debt not actively traded, fair value is estimated using either indicative price quotes or a discounted cash flow analysis using rates for debt with similar terms and maturities. As of December 31, 2016, the carrying value and fair value of long-term obligations, including the current portion, were $18.5 billion and $18.8 billion, respectively, of which $11.8 billion was measured using Level 1 inputs and $7.0 billion was measured using Level 2 inputs. As of December 31, 2015, the carrying value and fair value of long-term obligations, including the current portion, were $17.1 billion and $17.4 billion, respectively, of which $8.7 billion was measured using Level 1 inputs and $8.7 billion was measured using Level 2 inputs.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

INCOME TAXES

The Company has filed, for prior taxable years through its taxable year ended December 31, 2011, consolidated U.S. federal tax returns, which included all of its then wholly owned domestic subsidiaries. For its taxable year commencing January 1, 2012, the Company filed, and intends to continue to file, as a REIT, and its domestic TRSs filed, and intend to continue to file, separate tax returns as required. The Company also files tax returns in various states and countries. The Company’s state tax returns reflect different combinations of the Company’s subsidiaries and are dependent on the connection each subsidiary has with a particular state and form of organization. The following information pertains to the Company’s income taxes on a consolidated basis.

The income tax provision from continuing operations consisted of the following for the years ended December 31, (in thousands):



	2016			2015			2014
Current:
Federal	$	(26,494	)	$	(73,930	)	$	(2,390	)
State	(1,976		)	(21,216		)	(797		)
Foreign	(100,074		)	(55,045		)	(57,934		)
Deferred:
Federal	(616		)	9,131			(4,180		)
State	(259		)	8			(973		)
Foreign	(26,082		)	(16,903		)	3,769
Income tax provision	$	(155,501	)	$	(157,955	)	$	(62,505	)

The effective tax rate (“ETR”) on income from continuing operations for the years ended December 31, 2016, 2015 and 2014 differs from the federal statutory rate primarily due to the Company’s qualification for taxation as a REIT, as well as adjustments for foreign items. As a REIT, the Company may deduct earnings distributed to stockholders against the income generated by its REIT operations. In addition, the Company is able to offset certain income by utilizing its NOLs, subject to specified limitations.

Reconciliation between the U.S. statutory rate and the effective rate from continuing operations is as follows for the years ended December 31:



	2016		2015		2014
Statutory tax rate	35	%	35	%	35	%
Adjustment to reflect REIT status (1)	(35	)	(35	)	(35	)
Foreign taxes	5		3		2
Foreign withholding taxes	4		3		3
Uncertain tax positions	5		—		—
Change in tax law	—		2		—
MIPT tax election (2)	—		11		—
Other	—		—		2
Effective tax rate	14	%	19	%	7	%

_______________

(1) Includes 29%, 36% and 24% from dividend paid deductions in 2016, 2015 and 2014, respectively.

(2) Includes federal and state taxes, net of federal benefit.

The domestic and foreign components of income from continuing operations before income taxes are as follows for the years ended December 31, (in thousands):



	2016		2015		2014
United States	$	882,552	$	785,201	$	857,457
Foreign	243,308		44,761		8,247
Total	$	1,125,860	$	829,962	$	865,704

The components of the net deferred tax asset and liability and related valuation allowance were as follows as of December 31, (in thousands):



	2016			2015
Assets:
Net operating loss carryforwards	$	278,674		$	277,977
Accrued asset retirement obligations	130,014			92,295
Stock-based compensation	4,267			3,889
Unearned revenue	29,003			25,654
Unrealized loss on foreign currency	26,883			37,440
Other accruals and allowances	45,578			13,824
Items not currently deductible and other	26,886			17,608
Liabilities:
Depreciation and amortization	(942,409		)	(194,230		)
Deferred rent	(27,099		)	(20,720		)
Other	(9,294		)	(11,077		)
Subtotal	(437,497		)	242,660
Valuation allowance	(144,397		)	(136,952		)
Net deferred tax (liabilities) assets	$	(581,894	)	$	105,708

As described in note 1, effective January 1, 2016, the Company adopted new guidance on the accounting for share-based payment transactions. As part of this new guidance, excess windfall tax benefits and tax deficiencies related to the Company’s stock option exercises and restricted stock unit vestings are recognized as an income tax benefit or expense in the consolidated statement of operations in the period in which the deduction occurs. Excess windfall tax benefits and tax deficiencies are therefore not anticipated when determining the annual ETR and are instead recognized in the interim period in which those items occur.

At December 31, 2016 and 2015, the Company has provided a valuation allowance of $144.4 million and $137.0 million, respectively, which primarily relates to foreign items. During 2016, the Company increased the amounts recorded as valuation allowances due to the uncertainty as to the timing of, and the Company’s ability to recover, net deferred tax assets in certain foreign operations in the foreseeable future. The increase in the valuation allowance for the year ending December 31, 2016, is offset by fluctuations in foreign currency exchange rates and by a removal of previously reserved deferred tax assets resulting from a restructuring in Germany. The amount of deferred tax assets considered realizable, however, could be adjusted if objective evidence in the form of cumulative losses is no longer present and additional weight may be given to subjective evidence such as the Company’s projections for growth.

A summary of the activity in the valuation allowance is as follows (in thousands):



	2016			2015			2014
Balance as of January 1,	$	136,952		$	141,241		$	136,006
Additions (1)	14,118			19,512			40,124
Reversals	—			—			(10,769		)
Foreign currency translation	(6,673		)	(23,801		)	(24,120		)
Balance as of December 31,	$	144,397		$	136,952		$	141,241

_______________

(1) Includes net charges to expense and allowances established through goodwill at acquisition.

The recoverability of the Company’s deferred tax assets has been assessed utilizing projections based on its current operations. Accordingly, the recoverability of the deferred tax assets is not dependent on material asset sales or other non-routine transactions. Based on its current outlook of future taxable income during the carryforward period, the Company believes that deferred tax assets, other than those for which a valuation allowance has been recorded, will be realized.

The Company considers the earnings of certain non-U.S. subsidiaries to be indefinitely invested outside of the United States on the basis of estimates that future domestic cash generation will be sufficient to meet future domestic cash needs. The Company has not recorded a deferred tax liability related to the U.S. federal and state income taxes and foreign withholding taxes on $648.7 million of undistributed earnings of foreign subsidiaries indefinitely invested outside of the United States. Should the Company decide to repatriate the foreign earnings, it may have to adjust the income tax provision in the period it determined that the earnings will no longer be indefinitely invested outside of the United States.

At December 31, 2016, the Company had net federal, state and foreign operating loss carryforwards available to reduce future taxable income. If not utilized, the Company’s NOLs expire as follows (in thousands):



Years ended December 31,	Federal		State		Foreign
2017 to 2021	$	—	$	59,213	$	8,950
2022 to 2026	—		388,695		184,611
2027 to 2031	146,763		98,538		—
2032 to 2036	16,604		32,345		—
Indefinite carryforward	—		—		831,185
Total	$	163,367	$	578,791	$	1,024,746

In addition, the Company has Mexican tax credits of $0.9 million, which if not utilized will expire in 2017.

As of December 31, 2016 and 2015, the total amount of unrecognized tax benefits that would impact the ETR, if recognized, is $102.9 million and $28.1 million, respectively. The amount of unrecognized tax benefits for the year ended December 31, 2016, includes additions to the Company’s existing tax positions of $82.9 million, which includes $23.8 million assumed through acquisition.

The Company expects the unrecognized tax benefits to change over the next 12 months if certain tax matters ultimately settle with the applicable taxing jurisdiction during this timeframe, or if the applicable statute of limitations lapses. The impact of the amount of such changes to previously recorded uncertain tax positions could range from zero to $10.8 million.

A reconciliation of the beginning and ending amount of unrecognized tax benefits are as follows for the years ended December 31, (in thousands):



	2016			2015			2014
Balance at January 1	$	28,114		$	31,947		$	32,545
Additions based on tax positions related to the current year	82,912			5,042			4,187
Additions for tax positions of prior years	—			—			3,780
Foreign currency	(307		)	(5,371		)	(3,216		)
Reduction as a result of the lapse of statute of limitations and effective settlements	(3,168		)	(3,504		)	(5,349		)
Balance at December 31	$	107,551		$	28,114		$	31,947

During the years ended December 31, 2016, 2015 and 2014, the statute of limitations on certain unrecognized tax benefits lapsed and certain positions were effectively settled, which resulted in a decrease of $3.2 million, $3.5 million and $5.3 million, respectively, in the liability for uncertain tax benefits, all of which reduced the income tax provision.

The Company recorded penalties and tax-related interest expense to the tax provision of $9.2 million, $3.2 million and $6.5 million for the years ended December 31, 2016, 2015 and 2014, respectively. In addition, due to the expiration of the statute of limitations in certain jurisdictions, the Company reduced its liability for penalties and income tax-related interest expense related to uncertain tax positions during the years ended December 31, 2016, 2015 and 2014 by $3.4 million, $3.1 million and $9.9 million, respectively.

As of December 31, 2016 and 2015, the total amount of accrued income tax-related interest and penalties included in the consolidated balance sheets were $24.3 million and $20.2 million, respectively.

The Company has filed for prior taxable years, and for its taxable year ended December 31, 2016 will file, numerous consolidated and separate income tax returns, including U.S. federal and state tax returns and foreign tax returns. The Company is subject to examination in the U.S. and various state and foreign jurisdictions for certain tax years. As a result of the Company’s ability to carryforward federal, state and foreign NOLs, the applicable tax years generally remain open to examination several years after the applicable loss carryforwards have been used or have expired. The Company regularly assesses the likelihood of additional assessments in each of the tax jurisdictions resulting from these examinations. The Company believes that adequate provisions have been made for income taxes for all periods through December 31, 2016.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

STOCK-BASED COMPENSATION

Summary of Stock-Based Compensation Plans—The Company maintains equity incentive plans that provide for the grant of stock-based awards to its directors, officers and employees. The 2007 Equity Incentive Plan (the “2007 Plan”) provides for the grant of non-qualified and incentive stock options, as well as restricted stock units, restricted stock and other stock-based awards. Exercise prices in the case of non-qualified and incentive stock options are not less than the fair value of the underlying common stock on the date of grant. Equity awards typically vest ratably, generally over four years for RSUs and stock options and three years for PSUs. Stock options generally expire 10 years from the date of grant. As of December 31, 2016, the Company had the ability to grant stock-based awards with respect to an aggregate of 9.5 million shares of common stock under the 2007 Plan. In addition, the Company maintains an employee stock purchase plan (the “ESPP”) pursuant to which eligible employees may purchase shares of the Company’s common stock on the last day of each bi-annual offering period at a discount of the lower of the closing market value on the first or last day of such offering period. The offering periods run from June 1 through November 30 and from December 1 through May 31 of each year.

During the years ended December 31, 2016, 2015 and 2014, the Company recorded and capitalized the following stock-based compensation expenses (in thousands):



	2016		2015		2014
Stock-based compensation expense	$	89,898	$	90,537	$	80,153
Stock-based compensation expense capitalized as property and equipment	1,443		2,052		1,589

Stock Options—The fair value of each option granted during the period was estimated on the date of grant using the Black-Scholes option pricing model based on the assumptions noted in the table below. The expected life of stock options (estimated period of time outstanding) was estimated using the vesting term and historical exercise behavior of the Company’s employees. The risk-free interest rate was based on the U.S. Treasury yield with a term that approximated the estimated life in effect at the accounting measurement date. The expected volatility of the underlying stock price was based on historical volatility for a period equal to the expected life of the stock options. The expected annual dividend yield was the Company’s best estimate of expected future dividend yield.

Key assumptions used to apply this pricing model were as follows:



	2016	2015	2014
Range of risk-free interest rate	1.00% - 1.73%	1.32% - 1.62%	1.46% - 1.74%
Weighted average risk-free interest rate	1.44%	1.61%	1.64%
Range of expected life of stock options	4.5 - 5.2 years	4.5 years	4.5 years
Range of expected volatility of the underlying stock price	20.59% - 21.45%	21.09% - 21.24%	21.94% - 23.35%
Weighted average expected volatility of underlying stock price	21.43%	21.09%	23.08%
Range of expected annual dividend yield	1.85% - 2.40%	1.50% - 1.85%	1.50%

The weighted average grant date fair value per share during the years ended December 31, 2016, 2015 and 2014 was $14.60, $15.06 and $14.86, respectively. The intrinsic value of stock options exercised during the years ended December 31, 2016, 2015 and 2014 was $77.6 million, $32.1 million and $58.0 million, respectively. As of December 31, 2016, total unrecognized compensation expense related to unvested stock options was $25.6 million and is expected to be recognized over a weighted average period of approximately two years. The amount of cash received from the exercise of stock options was $84.9 million during the year ended December 31, 2016.

The Company’s option activity for the year ended December 31, 2016 was as follows:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Life (Years)	Aggregate Intrinsic Value (in millions)
Outstanding as of January 1, 2016	7,680,819			$71.10
Granted	1,161,370		95.16
Exercised	(1,520,541	)	55.86
Forfeited	(51,472	)	90.10
Expired	(800	)	33.96
Outstanding as of December 31, 2016	7,269,376			$78.00	6.73		$201.4
Exercisable as of December 31, 2016	3,519,976			$64.93	5.24		$143.4
Vested or expected to vest as of December 31, 2016	7,269,376			$78.00	6.73		$201.4

The following table sets forth information regarding options outstanding at December 31, 2016:



Options Outstanding					Options Exercisable
Outstanding Number of Options	Range of Exercise Price Per Share	Weighted Average Exercise Price Per Share		Weighted Average Remaining Life (Years)	Options Exercisable	Weighted Average Exercise Price Per Share
733,732	$28.39 - $43.11	$	37.01	2.35	733,732	$	37.01
1,130,308	44.92 - 62.00	56.55		4.55	1,130,308	56.55
916,991	64.01 - 76.90	76.74		6.18	621,338	76.69
1,428,834	77.42- 81.18	81.12		7.14	589,547	81.13
1,900,077	81.46 - 94.57	94.35		8.15	441,405	94.34
1,159,434	94.71 - 113.60	95.21		9.19	3,646	99.14
7,269,376	$28.39 - $113.60	$	78.00	6.73	3,519,976	$	64.93

Restricted Stock Units and Performance-Based Restricted Stock Units—The Company’s RSU and PSU activity for the year ended December 31, 2016 was as follows:



	RSUs		Weighted Average Grant Date Fair Value		PSUs	Weighted Average Grant Date Fair Value
Outstanding as of January 1, 2016 (1)	1,656,993		$	84.12	33,377	$	94.57
Granted (2)	784,178		95.15		209,380	93.81
Vested	(656,645	)	79.36		—	—
Forfeited	(120,783	)	90.18		—	—
Outstanding as of December 31, 2016	1,663,743		$	90.76	242,757	$	93.92
Expected to vest as of December 31, 2016	1,663,743		$	90.76	242,757	$	93.92

_______________


(1)	PSUs represent the shares issuable for the 2015 PSUs (as defined below) at the end of the three-year performance cycle based on exceeding the performance metric for the first year’s performance period.


(2)	PSUs represent the shares issuable for the 2015 PSUs at the end of the three-year performance cycle based on exceeding the performance metric for the second year’s performance period and the target number of shares issuable at the end of the three-year performance cycle for the 2016 PSUs (as defined below).

Restricted Stock Units—The total fair value of RSUs that vested during the year ended December 31, 2016 was $63.8 million.

As of December 31, 2016, total unrecognized compensation expense related to unvested RSUs granted under the 2007 Plan was $86.1 million and is expected to be recognized over a weighted average period of approximately two years.

Performance-Based Restricted Stock Units—During the year ended December 31, 2016, the Company’s Compensation Committee granted an aggregate of 169,340 PSUs to its executive officers (the “2016 PSUs”) and established the performance metrics for this award. During the year ended December 31, 2015, the Company’s Compensation Committee granted an aggregate of 70,135 PSUs to its executive officers (the “2015 PSUs”) and established the performance metric for this award. Threshold, target and maximum parameters were established for the metrics for a three-year performance period with respect to the 2016 PSUs and for each year in the three-year performance period with respect to the 2015 PSUs and will be used to calculate the number of shares that will be issuable when the award vests, which may range from 0% to 200% of the target amounts. At the end of the three-year performance period, the number of shares that vest will depend on the degree of achievement against the pre-established performance goals. PSUs will be paid out in common stock at the end of the performance period, subject to the executive’s continued employment. In the event of the executive’s death, disability or qualifying retirement, PSUs will be paid out pro rata in accordance with the terms of the applicable award agreement. PSUs will accrue dividend equivalents prior to vesting, which will be paid out only in respect of shares actually vested.

The performance metric related to the 2015 PSUs is tied to year-over-year growth, and actual results for the metric cannot be determined until the end of each respective fiscal year. As a result, as of December 31, 2016, the Company was unable to determine the annual target for the third year of the performance period for this award. Accordingly, an aggregate of

23,377 PSUs was not included in the table above.

During the year ended December 31, 2016, the Company recorded $8.4 million in stock-based compensation expense for equity awards in which the performance goals have been established and were probable of being achieved. The remaining unrecognized compensation expense related to these awards at December 31, 2016, was $12.0 million based on the Company’s current assessment of the probability of achieving the performance goals. The weighted-average period over which the cost will be recognized is approximately two years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Redeemable Noncontrolling Interests

12 Months Ended

Dec. 31, 2016

Temporary Equity Disclosure [Abstract]

Redeemable Noncontrolling Interests

REDEEMABLE NONCONTROLLING INTERESTS

Redeemable Noncontrolling Interests—In connection with the Viom Acquisition, ATC Asia entered into the Shareholders Agreement with Viom and the Remaining Shareholders. The Shareholders Agreement provides for, among other things, put options held by certain of the Remaining Shareholders, which allow the Remaining Shareholders to sell outstanding shares of ATC TIPL, and a call option held by the Company, which allows the Company to buy the noncontrolling shares of ATC TIPL. The put options, which are not under the Company’s control, cannot be separated from the noncontrolling interests. As a result, the combination of the noncontrolling interests and the redemption feature require classification as redeemable noncontrolling interests in the consolidated balance sheet, separate from equity.

Given the provisions governing the put rights, the redeemable noncontrolling interests are recorded outside of permanent equity at their redemption value. The noncontrolling interests become redeemable after the passage of time, and therefore, the Company records the carrying amount of the noncontrolling interests at the greater of (i) the initial carrying amount, increased or decreased for the noncontrolling interests’ share of net income or loss and foreign currency translation adjustments, or (ii) the redemption value. If required, the Company will adjust the redeemable noncontrolling interests to redemption value on each balance sheet date with changes in redemption value recognized as an adjustment to Distributions in excess of earnings.

The put options may be exercised, requiring the Company to purchase the Remaining Shareholders’ equity interests, on specified dates beginning April 1, 2018 through March 31, 2021. The price of the put options will be based on the fair market value of the exercising Remaining Shareholder’s interest in the Company’s India operations at the time the option is exercised. Put options held by certain of the Remaining Shareholders are subject to a floor price of 216 INR per share.

The following is a reconciliation of the changes in the Redeemable noncontrolling interests (in thousands):



Balance as of January 1, 2016	$	—
Fair value at acquisition	1,100,804
Net income attributable to noncontrolling interests	13,851
Foreign currency translation adjustment attributable to noncontrolling interests	(23,435		)
Balance as of December 31, 2016	$	1,091,220

Equity

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Equity

EQUITY

Common Stock Issuance—On December 8, 2016, the Company issued 1,171,187 shares of its common stock directly to ALLTEL Communications, LLC (“Alltel”), a subsidiary of Verizon Wireless, in consideration of the Company's exercise of its purchase option related to 1,523 communications towers pursuant to its agreement with Alltel (see note 18).

Series A Preferred Stock—The Company has 6,000,000 shares outstanding of its 5.25% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share (the “Series A Preferred Stock”), which was originally issued on May 12, 2014.

Unless converted earlier, each share of the Series A Preferred Stock will automatically convert on May 15, 2017, into between 0.9272 and 1.1591 shares of the Company’s common stock, depending on the applicable market value of the Company’s common stock and subject to anti-dilution adjustments. Subject to certain restrictions, at any time prior to May 15, 2017, holders of the Series A Preferred Stock may elect to convert all or a portion of their shares into common stock at the minimum conversion rate then in effect.

Dividends on shares of the Series A Preferred Stock are payable on a cumulative basis when, as, and if declared by the Company’s Board of Directors at an annual rate of 5.25% on the liquidation preference of $100.00 per share, on February 15, May 15, August 15 and November 15 of each year, commencing on August 15, 2014 to, and including, May 15, 2017.

Series B Preferred Stock—The Company has 13,750,000 depositary shares, each representing a 1/10th interest in a share of its 5.50% Mandatory Convertible Preferred Stock, Series B, par value $0.01 per share (the “Series B Preferred Stock” and, together with the Series A Preferred Stock, the “Mandatory Convertible Preferred Stock”), which was originally issued on March 3, 2015.

Unless converted or redeemed earlier, each share of the Series B Preferred Stock will convert automatically on February 15, 2018, into between 8.5911 and 10.3093 shares of common stock, depending on the applicable market value of the Company’s common stock and subject to anti-dilution adjustments. Subject to certain restrictions, at any time prior to February 15, 2018, holders of the Series B Preferred Stock may elect to convert all or a portion of their shares into common stock at the minimum conversion rate then in effect.

Dividends on shares of the Series B Preferred Stock are payable on a cumulative basis when, as, and if declared by the Company’s Board of Directors at an annual rate of 5.50% on the liquidation preference of $1,000.00 per share (and, correspondingly, $100.00 per share with respect to the depositary shares) on February 15, May 15, August 15 and November 15 of each year, commencing on May 15, 2015 to, and including, February 15, 2018.

The Company may pay dividends on its Mandatory Convertible Preferred Stock in cash or, subject to certain limitations, in shares of common stock or any combination of cash and shares of common stock. The terms of the Mandatory Convertible Preferred Stock provide that, unless full cumulative dividends have been paid or set aside for payment on all outstanding Mandatory Convertible Preferred Stock for all prior dividend periods, no dividends may be declared or paid on common stock.

Stock Repurchase Program—In March 2011, the Board of Directors approved a $1.5 billion stock repurchase program, pursuant to which the Company is authorized to purchase up to an additional $1.1 billion of the Company’s common stock. The Company temporarily suspended repurchases under the program in September 2013. However, the Company may, at any time, elect to resume repurchases under the program.

Sales of Equity Securities—The Company receives proceeds from sales of its equity securities pursuant to the ESPP and upon exercise of stock options granted under its equity incentive plans.

Distributions—During the years ended December 31, 2016, 2015 and 2014, the Company declared the following cash distributions:



	For the year ended December 31,
	2016				2015				2014
	Distribution per share		Aggregate Payment Amount (in millions)		Distribution per share		Aggregate Payment Amount (in millions)		Distribution per share		Aggregate Payment Amount (in millions)
Common Stock	$	2.17	$	923.7	$	1.81	$	766.4	$	1.40	$	554.6
Series A Preferred Stock	$	5.25	$	31.5	$	3.94	$	23.7	$	3.98	$	23.9
Series B Preferred Stock	$	55.00	$	75.6	$	38.65	$	53.1	$	—	$	—

The following table characterizes the tax treatment of distributions declared per share of common stock and Mandatory Convertible Preferred Stock.



		For the year ended December 31,
		2016					2015					2014 (1)
		Per Share			%		Per Share			%		Per Share		%
Common Stock
	Ordinary dividend	$	2.1700	(2)	100.00	%	$	1.2694		70.13	%	$	1.4000	100.00	%
	Capital gains distribution	—			—		0.5406			29.87		—		—
	Total	$	2.1700		100.00	%	$	1.8100		100.00	%	$	1.4000	100.00	%
Series A Preferred Stock
	Ordinary dividend	$	6.4578	(3)	100.00	%	$	3.6818	(4)	70.13	%	$	2.6688	100.00	%
	Capital gains distribution	—			—		1.5682			29.87		—		—
	Total	$	6.4578		100.00	%	$	5.2500		100.00	%	$	2.6688	100.00	%
Series B Preferred Stock (5)
	Ordinary dividend	$	5.5000		100.00	%	$	2.7107		70.13	%	$	—	—	%
	Capital gains distribution	—			—		1.1546			29.87		—		—
	Total	$	5.5000		100.00	%	$	3.8653		100.00	%	$	—	—	%

_______________


(1)	The Company had no Series B Preferred Stock outstanding during the year ended December 31, 2014.


(2)	Includes dividend declared on December 14, 2016 of $0.58 per share, which was paid on January 13, 2017 to common stockholders of record at the close of business on December 28, 2016.


(3)	Includes a deemed distribution as a result of a conversion rate adjustment triggered on June 17, 2016.


(4)	Includes dividend declared on December 2, 2014 of $1.3125 per share, which was paid on February 16, 2015 to preferred stockholders of record at the close of business on February 1, 2015.


(5)	Represents the tax treatment on dividends per depositary share, each of which represents a 1/10th interest in a share of Series B Preferred Stock.

The Company accrues distributions on unvested restricted stock units, which are payable upon vesting. As of December 31, 2016, the amount accrued for distributions payable related to unvested restricted stock units was $6.7 million. During the year ended December 31, 2016, the Company paid $2.4 million of distributions payable upon the vesting of restricted stock units.

To maintain its qualification for taxation as a REIT, the Company expects to continue paying distributions, the amount, timing and frequency of which will be determined and subject to adjustment by the Company’s Board of Directors.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Impairments, Net Loss on Sale of Long-Lived Assets	12 Months Ended
Impairments, Net Loss on Sale of Long-Lived Assets	Dec. 31, 2016
Property, Plant and Equipment Impairment or Disposal [Abstract]
Impairments, Net Loss on Sale of Long-lived Assets	IMPAIRMENTS, NET LOSS ON SALES OF LONG-LIVED ASSETS During the years ended December 31, 2016, 2015 and 2014, the Company recorded impairment charges and net losses on sales or disposals of long-lived assets of $53.6 million, $29.8 million and $28.5 million, respectively. These charges were primarily related to assets included in the Company’s U.S. property segment and are included in Other operating expenses in the consolidated statements of operations. Included in these amounts were impairment charges of $28.5 million, $15.1 million and $15.3 million for the years ended December 31, 2016, 2015 and 2014, respectively, to write down certain assets to net realizable value after an indicator of impairment was identified. These assets consisted primarily of towers, which are assessed on an individual basis, and network location intangibles, which relate directly to towers. For the year ended December 31, 2016, impairment charges also included amounts related to land easements. Also included in these amounts were net losses associated with the sale or disposal of certain non-core towers, other assets and other miscellaneous items of $25.1 million, $14.7 million and $13.2 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Earnings Per Common Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Earnings Per Common Share

EARNINGS PER COMMON SHARE

The following table sets forth basic and diluted net income per common share computational data for the years ended December 31, (in thousands, except per share data):



	2016			2015			2014
Net income attributable to American Tower Corporation stockholders	$	956,425		$	685,074		$	824,910
Dividends on preferred stock	(107,125		)	(90,163		)	(23,888		)
Net income attributable to American Tower Corporation common stockholders	849,300			594,911			801,022
Basic weighted average common shares outstanding	425,143			418,907			395,958
Dilutive securities	4,140			4,108			4,128
Diluted weighted average common shares outstanding	429,283			423,015			400,086
Basic net income attributable to American Tower Corporation common stockholders per common share	$	2.00		$	1.42		$	2.02
Diluted net income attributable to American Tower Corporation common stockholders per common share	$	1.98		$	1.41		$	2.00

Shares Excluded From Dilutive Effect

The following shares were not included in the computation of diluted earnings per share because the effect would be anti-dilutive for the years ended December 31, (in thousands, on a weighted average basis):



	2016	2015	2014
Restricted stock awards	6	—	5
Stock options	817	1,606	1,290
Preferred stock	17,509	15,408	4,303

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

COMMITMENTS AND CONTINGENCIES

Litigation—The Company periodically becomes involved in various claims, lawsuits and proceedings that are incidental to its business. In the opinion of Company management, after consultation with counsel, there are no matters currently pending that would, in the event of an adverse outcome, materially impact the Company’s consolidated financial position, results of operations or liquidity.

Verizon Transaction—On March 27, 2015, the Company entered into an agreement with various operating entities of Verizon that provides for the lease, sublease or management of 11,286 wireless communications sites from Verizon commencing March 27, 2015. The average term of the lease or sublease for all sites at the inception of the agreement was approximately 28 years, assuming renewals or extensions of the underlying ground leases for the sites. The Company has the option to purchase the leased sites in tranches, subject to the applicable lease, sublease or management right upon its scheduled expiration. Each tower is assigned to an annual tranche, ranging from 2034 to 2047, which represents the outside expiration date for the sublease rights to the towers in each tranche. The purchase price for each tranche is a fixed amount stated in the lease for such tranche plus the fair market value of certain alterations made to the related towers. The aggregate purchase option price for the towers leased and subleased is approximately $5.0 billion. Verizon will occupy the sites as a tenant for an initial term of ten years with eight optional successive five-year terms; each such term shall be governed by standard master lease agreement terms established as a part of the transaction.

AT&T Transaction—The Company has an agreement with SBC Communications Inc., a predecessor entity to AT&T Inc. (“AT&T”), that currently provides for the lease or sublease of approximately 2,350 towers from AT&T with the lease commencing between December 2000 and August 2004. Substantially all of the towers are part of the 2013 Securitization. The average term of the lease or sublease for all sites at the inception of the agreement was approximately 27 years, assuming renewals or extensions of the underlying ground leases for the sites. The Company has the option to purchase the sites subject to the applicable lease or sublease upon its expiration. Each tower is assigned to an annual tranche, ranging from 2013 to 2032, which represents the outside expiration date for the sublease rights to that tower. The purchase price for each site is a fixed amount stated in the lease for that site plus the fair market value of certain alterations made to the related tower by AT&T. As of December 31, 2016, the Company has purchased an aggregate of 77 of the subleased towers upon expiration of the applicable agreement. The aggregate purchase option price for the remaining towers leased and subleased is $760.1 million and will accrete at a rate of 10% per annum through the applicable expiration of the lease or sublease of a site. For all such sites purchased by the Company prior to June 30, 2020, AT&T will continue to lease the reserved space at the then-current monthly fee which shall escalate in accordance with the standard master lease agreement for the remainder of AT&T’s tenancy. Thereafter, AT&T shall have the right to renew such lease for up to four successive five-year terms. For all such sites purchased by the Company subsequent to June 30, 2020, AT&T has the right to continue to lease the reserved space for successive one-year terms at a rent equal to the lesser of the agreed upon market rate and the then-current monthly fee, which is subject to an annual increase based on changes in the U.S. Consumer Price Index.

Alltel Transaction—In December 2000, the Company entered into an agreement with Alltel, to acquire towers through a 15-year sublease agreement. Pursuant to the agreement, as amended, with Verizon Wireless, the Company acquired rights to approximately 1,800 towers in tranches between April 2001 and March 2002. The Company has the option to purchase each tower at the expiration of the applicable sublease. The Company exercised the purchase options for 1,523 towers in a single closing which occurred on December 8, 2016. The Company has provided notice to the tower owner of its intent to exercise the purchase options related to the 243 remaining towers. As of December 31, 2016, the purchase price per tower was $42,844 payable in cash or, at the tower owner’s option, with 769 shares of the Company’s common stock per tower. The aggregate cash purchase option price for the remaining subleased towers was $10.4 million as of December 31, 2016.

Other Contingencies—The Company is subject to income tax and other taxes in the geographic areas where it operates, and periodically receives notifications of audits, assessments or other actions by taxing authorities. The Company evaluates the circumstances of each notification based on the information available and records a liability for any potential outcome that is probable or more likely than not unfavorable if the liability is also reasonably estimable. On December 5, 2016, the Company received an income tax assessment of Essar Telecom Infrastructure Private Limited (“ETIPL”) for the fiscal year ending 2008 in the amount of 4.75 billion INR ($69.8 million on the date of assessment) related to capital contributions. The Company is challenging the assessment before India’s tax authority Commissioner of Income Tax (Appeals) and estimates that there is a more likely than not probability that the Company’s position will be sustained. Accordingly, no such liability has been recorded. Additionally, the assessment was made with respect to transactions that took place in the tax year commencing in 2007, prior to the Company’s acquisition of ETIPL. Under the Company’s definitive acquisition agreement of ETIPL, the seller is obligated to indemnify and defend the Company with respect to any tax-related liability that may arise from activities prior to March 31, 2010.

Lease Obligations—The Company leases certain land, office and tower space under operating leases that expire over various terms. Many of the leases contain renewal options with specified increases in lease payments upon exercise of the renewal option. Escalation clauses present in operating leases, excluding those tied to CPI or other inflation-based indices, are recognized on a straight-line basis over the non-cancellable term of the leases.

Future minimum rental payments under non-cancellable operating leases include payments for certain renewal periods at the Company’s option because failure to renew could result in a loss of the applicable communications sites and related revenues from tenant leases, thereby making it reasonably assured that the Company will renew the leases. Such payments at December 31, 2016 are as follows (in millions):



Year Ending December 31,
2017	$	869
2018	846
2019	816
2020	776
2021	737
Thereafter	6,638
Total	$	10,682

Aggregate rent expense (including the effect of straight-line rent expense) under operating leases for the years ended December 31, 2016, 2015 and 2014 approximated $986.2 million, $804.8 million and $655.0 million, respectively.

Future minimum payments under capital leases in effect at December 31, 2016 were as follows (in millions):



Year Ending December 31,
2017	$	28
2018	24
2019	22
2020	18
2021	14
Thereafter	163
Total minimum lease payments	269
Less amounts representing interest	(132		)
Present value of capital lease obligations	$	137

Tenant Leases—The Company’s lease agreements with its tenants vary depending upon the region and the industry of the tenant, and generally have initial terms of ten years with multiple renewal terms at the option of the tenant.

Future minimum rental receipts expected from tenants under non-cancellable operating lease agreements in effect at December 31, 2016 were as follows (in millions):



Year Ending December 31,
2017	$	4,646
2018	4,502
2019	4,240
2020	3,905
2021	3,372
Thereafter	10,477
Total	$	31,142

Guaranties and Indemnifications—The Company enters into agreements from time to time in the ordinary course of business pursuant to which it agrees to guarantee or indemnify third parties for certain claims. The Company has also entered into purchase and sale agreements relating to the sale or acquisition of assets containing customary indemnification provisions. The Company’s indemnification obligations under these agreements generally are limited solely to damages resulting from breaches of representations and warranties or covenants under the applicable agreements, but do not guarantee future performance. In addition, payments under such indemnification clauses are generally conditioned on the other party making a claim that is subject to whatever defenses the Company may have and are governed by dispute resolution procedures specified in the particular agreement. Further, the Company’s obligations under these agreements may be limited in duration and amount, and in some instances, the Company may have recourse against third parties for payments made by the Company. The Company has not historically made any material payments under these agreements and, as of December 31, 2016, is not aware of any agreements that could result in a material payment.

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2016

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

SUPPLEMENTAL CASH FLOW INFORMATION

Supplemental cash flow information and non-cash investing and financing activities are as follows for the years ended December 31, (in thousands):



	2016			2015		2014
Supplemental cash flow information:
Cash paid for interest	$	645,092		$	577,952	$	548,089
Cash paid for income taxes (net of refunds of $19,554, $7,053 and $8,476, respectively)	96,241			157,058		69,212
Non-cash investing and financing activities:
(Decrease) increase in accounts payable and accrued expenses for purchases of property and equipment and construction activities	(18,973		)	2,780		1,121
Purchases of property and equipment under capital leases	55,635			36,851		36,486
Fair value of debt assumed through acquisitions	786,889			—		463,135
Exercise of purchase option for property and equipment for common shares issued	120,785			—		—
Settlement of accounts receivable related to acquisitions	—			899		31,849
Conversion of third-party debt to equity	—			—		111,181

Business Segments

12 Months Ended

Dec. 31, 2016

Segment Reporting, Measurement Disclosures [Abstract]

Business Segments

BUSINESS SEGMENTS

The Company’s primary business is leasing space on multitenant communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. This business is referred to as the Company’s property operations, which as of December 31, 2016, consisted of the following:


•	U.S.: property operations in the United States;


•	Asia: property operations in India;


•	EMEA: property operations in Germany, Ghana, Nigeria, South Africa and Uganda; and


•	Latin America: property operations in Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico and Peru.

The Company has applied the aggregation criteria to operations within the EMEA and Latin America property operating segments on a basis that is consistent with management’s review of information and performance evaluations of these regions.

The Company’s services segment offers tower-related services in the United States, including site acquisition, zoning and permitting services and structural analysis services, which primarily support its site leasing business, including the addition of new tenants and equipment on its sites. The services segment is a strategic business unit that offers different services from, and requires different resources, skill sets and marketing strategies than, the property operating segments.

The accounting policies applied in compiling segment information below are similar to those described in note 1. Among other factors, in evaluating financial performance in each business segment, management uses segment gross margin and segment operating profit. The Company defines segment gross margin as segment revenue less segment operating expenses excluding stock-based compensation expense recorded in costs of operations; Depreciation, amortization and accretion; Selling, general, administrative and development expense; and Other operating expenses. The Company defines segment operating profit as segment gross margin less Selling, general, administrative and development expense attributable to the segment, excluding stock-based compensation expense and corporate expenses. For reporting purposes, the Latin America property segment gross margin and segment operating profit also include Interest income, TV Azteca, net. These measures of segment gross margin and segment operating profit are also before Interest income, Interest expense, Gain (loss) on retirement of long-term obligations, Other expense, Net income (loss) attributable to noncontrolling interests and Income tax benefit (provision). The categories of expenses indicated above, such as depreciation, have been excluded from segment operating performance as they are not considered in the review of information or the evaluation of results by management. There are no significant revenues resulting from transactions between the Company’s operating segments. All intercompany transactions are eliminated to reconcile segment results and assets to the consolidated statements of operations and consolidated balance sheets.

Summarized financial information concerning the Company’s reportable segments for the years ended December 31, 2016, 2015 and 2014 is shown in the following tables. The “Other” column (i) represents amounts excluded from specific segments, such as business development operations, stock-based compensation expense and corporate expenses included in Selling, general, administrative and development expense; Other operating expenses; Interest income; Interest expense; Gain (loss) on retirement of long-term obligations; and Other expense, as the amounts are not utilized in assessing each segment’s performance, and (ii) reconciles segment operating profit to Income from continuing operations before income taxes.



	Property								Total Property		Services		Other		Total
Year ended December 31, 2016	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	3,370,033	$	827,627	$	529,531	$	985,935	$	5,713,126	$	72,542			$	5,785,668
Segment operating expenses (1)	733,403		465,938		223,716		337,887		1,760,944		27,007				1,787,951
Interest income, TV Azteca, net	—		—		—		10,960		10,960		—				10,960
Segment gross margin	2,636,630		361,689		305,815		659,008		3,963,142		45,535				4,008,677
Segment selling, general, administrative and development expense (1)	147,559		48,238		60,903		60,690		317,390		12,510				329,900
Segment operating profit	$	2,489,071	$	313,451	$	244,912	$	598,318	$	3,645,752	$	33,025			$	3,678,777
Stock-based compensation expense													$	89,898	89,898
Other selling, general, administrative and development expense													126,035		126,035
Depreciation, amortization and accretion													1,525,635		1,525,635
Other expense (2)													811,349		811,349
Income from continuing operations before income taxes															$	1,125,860
Capital expenditures (3)	$	310,744	$	115,508	$	86,128	$	172,568	$	684,948	$	—	$	16,439	$	701,387

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.4 million and $87.5 million, respectively.


(2)	Primarily includes interest expense.


(3)	Includes $18.9 million of capital lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes and capital leases in the cash flow from financing activities in our consolidated statement of cash flows.



	Property								Total Property		Services		Other		Total
Year ended December 31, 2015	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	3,157,501	$	242,223	$	395,092	$	885,572	$	4,680,388	$	91,128			$	4,771,516
Segment operating expenses (1)	678,499		126,874		163,820		304,629		1,273,822		32,993				1,306,815
Interest income, TV Azteca, net	—		—		—		11,209		11,209		—				11,209
Segment gross margin	2,479,002		115,349		231,272		592,152		3,417,775		58,135				3,475,910
Segment selling, general, administrative and development expense (1)	138,617		22,771		48,672		62,111		272,171		15,724				287,895
Segment operating profit	$	2,340,385	$	92,578	$	182,600	$	530,041	$	3,145,604	$	42,411			$	3,188,015
Stock-based compensation expense													$	90,537	90,537
Other selling, general, administrative and development expense													121,456		121,456
Depreciation, amortization and accretion													1,285,328		1,285,328
Other expense (2)													860,732		860,732
Income from continuing operations before income taxes															$	829,962
Capital expenditures	$	367,663	$	75,407	$	66,625	$	201,806	$	711,501	$	—	$	17,252	$	728,753

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.1 million and $88.5 million, respectively.


(2)	Primarily includes interest expense.



	Property								Total Property		Services		Other		Total
Year ended December 31, 2014	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	2,639,790	$	219,566	$	315,053	$	832,445	$	4,006,854	$	93,194			$	4,100,048
Segment operating expenses (1)	515,742		121,797		126,714		290,527		1,054,780		37,648				1,092,428
Interest income, TV Azteca, net	—		—		—		10,547		10,547		—				10,547
Segment gross margin	2,124,048		97,769		188,339		552,465		2,962,621		55,546				3,018,167
Segment selling, general, administrative and development expense (1)	124,944		19,632		39,553		66,890		251,019		12,469				263,488
Segment operating profit	$	1,999,104	$	78,137	$	148,786	$	485,575	$	2,711,602	$	43,077			$	2,754,679
Stock-based compensation expense													$	80,153	80,153
Other selling, general, administrative and development expense (2)													104,738		104,738
Depreciation, amortization and accretion													1,003,802		1,003,802
Other expense (3)													700,282		700,282
Income from continuing operations before income taxes															$	865,704
Capital expenditures	$	576,153	$	74,334	$	70,126	$	229,645	$	950,258	$	—	$	24,146	$	974,404

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.8 million and $78.3 million, respectively.


(2)	Includes $7.9 million of expense previously recorded as segment selling, general, administrative and development expense.


(3)	Primarily includes interest expense.

Additional information relating to the total assets of the Company’s operating segments is as follows for the years ended December 31, (in thousands):



	2016		2015		2014
U.S. property	$	18,846,941	$	19,286,465	$	14,335,731
Asia property (1)	4,535,293		736,149		738,290
EMEA property (1)	2,062,399		2,249,634		1,275,253
Latin America property (1)	4,938,064		4,401,258		4,700,357
Services	48,327		68,388		57,367
Other (2)	448,126		162,378		156,567
Total assets	$	30,879,150	$	26,904,272	$	21,263,565

_______________


(1)	Balances are translated at the applicable period end exchange rate, which may impact comparability between periods.


(2)	Balances include corporate assets such as cash and cash equivalents, certain tangible and intangible assets and income tax accounts that have not been allocated to specific segments.

Summarized geographic information related to the Company’s operating revenues for the years ended December 31, 2016, 2015 and 2014 and long-lived assets as of December 31, 2016 and 2015 is as follows (in thousands):



	2016		2015		2014
Operating Revenues:
United States	$	3,442,575	$	3,248,629	$	2,732,984
Asia (1):
India	827,627		242,223		219,566
EMEA (1):
Germany	60,163		55,965		64,946
Ghana	116,219		94,549		95,486
Nigeria	215,402		109,701		—
South Africa	80,006		80,510		98,334
Uganda	57,741		54,367		56,287
Latin America (1):
Argentina	1,065		—		—
Brazil	506,182		408,644		331,089
Chile	33,831		29,650		31,756
Colombia	79,755		78,351		89,421
Costa Rica	18,968		17,244		16,742
Mexico	331,173		340,461		354,116
Panama (2)	—		—		1,243
Peru	14,961		11,222		8,078
Total International	2,343,093		1,522,887		1,367,064
Total operating revenues	$	5,785,668	$	4,771,516	$	4,100,048

_______________


(1)	Balances are translated at the applicable exchange rate, which may impact comparability between periods.


(2)	In September 2014, the Company completed the sale of its operations in Panama.



	2016		2015
Long-Lived Assets (1):
United States	$	16,969,558	$	17,516,535
Asia (2):
India	4,094,190		619,370
EMEA (2):
Germany	397,317		388,727
Ghana	192,158		217,530
Nigeria	640,634		1,018,980
South Africa	271,760		133,088
Uganda	141,533		162,346
Latin America (2):
Argentina	137,588		—
Brazil	2,626,431		2,204,494
Chile	137,170		121,938
Colombia	272,338		256,892
Costa Rica	117,481		120,292
Mexico	797,798		976,707
Peru	66,593		59,206
Total International	9,892,991		6,279,570
Total long-lived assets	$	26,862,549	$	23,796,105

_______________


(1)	Includes Property and equipment, net, Goodwill and Other intangible assets, net.


(2)	Balances are translated at the applicable period end exchange rate, which may impact comparability between periods.

The following tenants within the property segments and services segment individually accounted for 10% or more of the Company’s consolidated operating revenues for the years ended December 31, is as follows:



	2016		2015		2014
AT&T	21	%	24	%	20	%
Verizon Wireless	15	%	16	%	11	%
Sprint	11	%	13	%	15	%
T-Mobile	9	%	10	%	10	%

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8906-108599

+ Details

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2016
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS During the years ended December 31, 2016, 2015 and 2014, the Company had no significant related party transactions.

Selected Quarterly Financial Data

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Information [Abstract]

Selected Quarterly Financial Data (Unaudited)

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)

Selected quarterly financial data for the years ended December 31, 2016 and 2015 is as follows (in thousands, except per share data):



	Three Months Ended												Year Ended December 31,
	March 31,			June 30,			September 30,			December 31,			Year Ended December 31,
2016:
Operating revenues	$	1,289,047		$	1,442,227		$	1,514,845		$	1,539,549		$	5,785,668
Costs of operations (1)	351,445			459,711			491,237			487,996			1,790,389
Operating income	451,853			432,806			479,074			489,296			1,853,029
Net income	281,307			192,464			263,735			232,853			970,359
Net income attributable to American Tower Corporation stockholders	275,159			187,550			264,509			229,207			956,425
Dividends on preferred stock	(26,781		)	(26,782		)	(26,781		)	(26,781		)	(107,125		)
Net income attributable to American Tower Corporation common stockholders	248,378			160,768			237,728			202,426			849,300
Basic net income per share attributable to American Tower Corporation common stockholders	0.59			0.38			0.56			0.48			2.00
Diluted net income per share attributable to American Tower Corporation common stockholders	0.58			0.37			0.55			0.47			1.98



	Three Months Ended												Year Ended December 31,
	March 31,			June 30,			September 30,			December 31,			Year Ended December 31,
2015:
Operating revenues	$	1,079,190		$	1,174,375		$	1,237,910		$	1,280,041		$	4,771,516
Costs of operations (1)	264,640			322,458			365,389			356,381			1,308,868
Operating income	419,966			389,774			400,925			402,124			1,612,789
Net income	195,492			157,180			97,740			221,595			672,007
Net income attributable to American Tower Corporation stockholders	193,317			156,056			102,999			232,702			685,074
Dividends on preferred stock	(9,819		)	(26,782		)	(26,781		)	(26,781		)	(90,163		)
Net income attributable to American Tower Corporation common stockholders	183,498			129,274			76,218			205,921			594,911
Basic net income per share attributable to American Tower Corporation common stockholders	0.45			0.31			0.18			0.49			1.42
Diluted net income per share attributable to American Tower Corporation common stockholders	0.45			0.30			0.18			0.48			1.41

_______________


(1)	Represents Operating expenses, exclusive of Depreciation, amortization and accretion, Selling, general, administrative and development expense, and Other operating expenses.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Redemption of 7.25% Senior Notes—On February 10, 2017, the Company redeemed all of the outstanding 7.25% senior unsecured notes due 2019 (the “7.25% Notes”) at a price equal to 112.0854% of the principal amount, plus accrued and unpaid interest up to, but excluding, February 10, 2017, for an aggregate redemption price of $341.4 million, including $5.1 million in accrued and unpaid interest. The Company expects to record a loss on retirement of long-term obligations of approximately $39.1 million, which includes prepayment consideration of $36.3 million, and the remaining portion of the unamortized discount and deferred financing costs. The redemption was funded with borrowings under the 2013 Credit Facility and cash on hand. Upon completion of the redemption, none of the 7.25% Notes remained outstanding. Repayment of 2012 GTP Notes—On February 15, 2017, the Company repaid the $173.5 million remaining principal amount outstanding under the Secured Cellular Site Revenue Notes, Series 2012-2 Class A, Series 2012-2 Class B and Series 2012-2 Class C issued by GTP Cellular Sites, LLC, plus prepayment consideration and accrued and unpaid interest. The Company expects to record a loss on retirement of long-term obligations of approximately $1.8 million, which includes prepayment consideration of $7.2 million offset by the remaining portion of the unamortized premium. The repayment was funded with borrowings under the 2013 Credit Facility and cash on hand. Repayment of Unison Notes—On February 15, 2017, the Company repaid the $129.0 million principal amount outstanding under the Secured Cellular Site Revenue Notes, Series 2010-2, Class C and Series 2010-2, Class F issued by Unison Ground Lease Funding, LLC, plus prepayment consideration and accrued and unpaid interest. The Company expects to record a loss on retirement of long-term obligations of approximately $14.5 million, which includes prepayment consideration of $18.3 million offset by the remaining portion of the unamortized premium. The repayment was funded with borrowings under the 2013 Credit Facility and cash on hand. FPS Towers Acquisition—On February 15, 2017, ATC Europe acquired 100% of the outstanding shares of FPS for total consideration of 713.9 million Euros ($757.1 million at the date of acquisition). The acquisition was funded by the Company and its equity partner, PGGM. The Company made a loan to ATC Europe to fund 225.0 million Euros ($238.6 million at the date of acquisition) of the total consideration. The remainder of the purchase price was funded by the Company and PGGM in proportion to their respective interests in ATC Europe. The Company funded its portion of the purchase price with borrowings under the 2013 Credit Facility and cash on hand. The acquisition is consistent with the Company’s strategy to expand in selected geographic areas. A preliminary purchase price allocation is not available due to the timing of the closing.

Schedule III - Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2016

SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]

Real Estate and Accumulated Depreciation Disclosure

AMERICAN TOWER CORPORATION AND SUBSIDIARIES

SCHEDULE III—SCHEDULE OF REAL ESTATE

AND ACCUMULATED DEPRECIATION

(dollars in thousands)



Description		Encumbrances			Initial cost to company	Cost capitalized subsequent to acquisition	Gross amount carried at close of current period			Accumulated depreciation at close of current period			Date of construction	Date acquired	Life on which depreciation in latest income statements is computed
144,119	sites (1)	$	3,815,002	(2)	(3)	(3)	$	14,276,973	(4)	$	(4,548,096	)	Various	Various	Up to 20 years

_______________

(1) No single site exceeds 5% of the total amounts indicated in the table above.

(2) Certain assets secure debt of $3.8 billion.

(3) The Company has omitted this information, as it would be impracticable to compile such information on a site-by-site basis.

(4) Does not include those sites under construction.



	2016			2015				2014
Gross amount at beginning	$	13,046,291		$	10,434,326		(1)	$	9,921,276		(1)
Additions during period:
Acquisitions	787,206			2,620,778				397,837
Discretionary capital projects (2)	105,279			210,421				437,720
Discretionary ground lease purchases (3)	168,133			144,695				159,637
Redevelopment capital expenditures (4)	136,821			114,089				96,782
Capital improvements (5)	81,790			42,417				41,967
Start-up capital expenditures (6)	128,707			35,561				21,173
Other (7)	139,356			201,118				22,069
Total additions	1,547,292			3,369,079				1,177,185
Deductions during period:
Cost of real estate sold or disposed	(85,789		)	(60,975		)		(60,147		)
Other (8)	(230,821		)	(696,139		)		(569,107		)
Total deductions:	(316,610		)	(757,114		)		(629,254		)
Balance at end	$	14,276,973		$	13,046,291			$	10,469,207



	2016			2015			2014
Gross amount of accumulated depreciation at beginning	$	(3,994,874	)	$	(3,613,078	)	$	(3,297,033	)
Additions during period:
Depreciation	(647,910		)	(557,052		)	(457,135		)
Other	—			—			(761		)
Total additions	(647,910		)	(557,052		)	(457,896		)
Deductions during period:
Amount of accumulated depreciation for assets sold or disposed	24,911			30,083			20,953
Other (8)	69,777			145,173			120,898
Total deductions	94,688			175,256			141,851
Balance at end	$	(4,548,096	)	$	(3,994,874	)	$	(3,613,078	)

_______________


(1)	Beginning balance has been revised to reflect purchase accounting measurement period adjustments.


(2)	Includes amounts incurred primarily for the construction of new sites.


(3)	Includes amounts incurred to purchase or otherwise secure the land under communications sites.


(4)	Includes amounts incurred to increase the capacity of existing sites, which results in new incremental tenant revenue.


(5)	Includes amounts incurred to enhance existing sites by adding additional functionality, capacity or general asset improvements.


(6)	Includes amounts incurred in connection with acquisitions or new market launches. Start-up capital expenditures includes non-recurring expenditures contemplated in acquisitions or new market launch business cases.


(7)	Primarily includes regional improvements and other additions.


(8)	Primarily includes foreign currency exchange rate fluctuations and other deductions.

Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business—American Tower Corporation (together with its subsidiaries, “ATC” or the “Company”) is one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries, which the Company refers to as its property operations. Additionally, the Company offers tower-related services in the United States, including site acquisition, zoning and permitting and structural analysis, which primarily support its site leasing business, including the addition of new tenants and equipment on its sites, which the Company refers to as its services operations. The Company’s portfolio primarily consists of towers it owns and towers it operates pursuant to long-term lease arrangements, as well as distributed antenna system (“DAS”) networks, which provide seamless coverage solutions in certain in-building and outdoor wireless environments. In addition to the communications sites in its portfolio, the Company manages rooftop and tower sites for property owners under various contractual arrangements. The Company also holds other telecommunications infrastructure and property interests that it leases to communications service providers and third-party tower operators. ATC is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and its joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures. The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”). Accordingly, the Company generally is not subject to U.S. federal income taxes on income generated by its REIT operations, including the income derived from leasing space on its towers, as the Company receives a dividends paid deduction for distributions to stockholders that generally offsets its income and gains. However, the Company remains obligated to pay U.S. federal income taxes on earnings from its domestic taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, regardless of their designation for U.S. tax purposes, continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted. The use of TRSs enables the Company to continue to engage in certain businesses while complying with REIT qualification requirements. The Company may, from time to time, change the election of previously designated TRSs to be included as part of the REIT. As of December 31, 2016, the Company’s REIT qualified businesses included its U.S. tower leasing business, most of its operations in Costa Rica, Germany and Mexico and a majority of its services segment and indoor DAS networks business.
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity or cost method, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated. As of December 31, 2016, the Company has a controlling interest in two joint ventures in Ghana and Uganda with MTN Group Limited (“MTN Group”). The joint ventures are controlled by a holding company of which a wholly owned subsidiary of the Company holds a 51% controlling interest and a wholly owned subsidiary of MTN Group holds a 49% noncontrolling interest. In 2016, the Company established a joint venture (“ATC Europe”) with PGGM in which the Company holds a 51% controlling interest and PGGM holds a 49% noncontrolling interest. This transaction resulted in a reclassification of $9.1 million of foreign currency translation adjustment from Accumulated other comprehensive loss (“AOCI”) to additional paid-in capital. In addition, the Company holds an approximate 75% controlling interest, and South African investors hold an approximate 25% noncontrolling interest, in a subsidiary of the Company in South Africa. The Company holds a 51% controlling interest in ATC Telecom Infrastructure Private Limited (“ATC TIPL”), formerly known as Viom Networks Limited (“Viom”), and the Remaining Shareholders (as defined in note 6) hold a 49% noncontrolling interest.
Significant Accounting Policies and Use of Estimates	Significant Accounting Policies and Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying consolidated financial statements. The significant estimates in the accompanying consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense, stock-based compensation, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure.
Accounts Receivable and Deferred Rent Asset	Accounts Receivable and Deferred Rent Asset—The Company derives the largest portion of its revenues, corresponding accounts receivable and the related deferred rent asset from a relatively small number of tenants in the telecommunications industry, and 56% of its current year revenues are derived from four tenants. The Company’s deferred rent asset is associated with non-cancellable tenant leases that contain fixed escalation clauses over the terms of the applicable lease in which revenue is recognized on a straight-line basis over the lease term. The Company mitigates its concentrations of credit risk with respect to notes and trade receivables and the related deferred rent assets by actively monitoring the creditworthiness of its borrowers and tenants. In recognizing tenant revenue, the Company assesses the collectibility of both the amounts billed and the portion recognized in advance of billing on a straight-line basis. This assessment takes tenant credit risk and business and industry conditions into consideration to ultimately determine the collectibility of the amounts billed. To the extent the amounts, based on management’s estimates, may not be collectible, recognition is deferred until such point as collectibility is determined to be reasonably assured. Any amounts that were previously recognized as revenue and subsequently determined to be uncollectible are charged to bad debt expense included in Selling, general, administrative and development expense in the accompanying consolidated statements of operations. Accounts receivable is reported net of allowances for doubtful accounts related to estimated losses resulting from a tenant’s inability to make required payments and allowances for amounts invoiced whose collectibility is not reasonably assured. These allowances are generally estimated based on payment patterns, days past due and collection history, and incorporate changes in economic conditions that may not be reflected in historical trends, such as tenants in bankruptcy, liquidation or reorganization. Receivables are written-off against the allowances when they are determined to be uncollectible. Such determination includes analysis and consideration of the particular conditions of the account.
Functional Currency	Functional Currency—The functional currency of each of the Company’s foreign operating subsidiaries is the respective local currency, except for Costa Rica, where the functional currency is the U.S. Dollar. All foreign currency assets and liabilities held by the subsidiaries are translated into U.S. Dollars at the exchange rate in effect at the end of the applicable fiscal reporting period and all foreign currency revenues and expenses are translated at the average monthly exchange rates. Translation adjustments are reflected in equity as a component of AOCI in the consolidated balance sheets and included as a component of Comprehensive income (loss) in the consolidated statements of comprehensive income (loss). Transactional gains and losses on foreign currency transactions are reflected in Other expense in the consolidated statements of operations. However, the effect from fluctuations in foreign currency exchange rates on intercompany debt that is considered to be permanently reinvested is reflected in AOCI in the consolidated balance sheets and included as a component of comprehensive income (loss).
Cash and Cash Equivalents	Cash and Cash Equivalents—Cash and cash equivalents include cash on hand, demand deposits and short-term investments with original maturities of three months or less. The Company maintains its deposits at high quality financial institutions and monitors the credit ratings of those institutions.
Restricted Cash	Restricted Cash—Restricted cash includes cash pledged as collateral to secure obligations and all cash whose use is otherwise limited by contractual provisions.
Short-Term Investments	Short-Term Investments—Short-term investments consists of highly liquid investments with original maturities in excess of three months.
Property and Equipment	Property and Equipment—Property and equipment is recorded at cost or, in the case of acquired properties at estimated fair value on the date acquired. Cost for self-constructed towers includes direct materials and labor, capitalized interest and certain indirect costs associated with construction of the tower, such as transportation costs, employee benefits and payroll taxes. The Company begins the capitalization of costs during the pre-construction period, which is the period during which costs are incurred to evaluate the site, and continues to capitalize costs until the tower is substantially completed and ready for occupancy by a tenant. Labor costs capitalized for the years ended December 31, 2016, 2015 and 2014 were $47.7 million, $44.7 million and $48.5 million, respectively. Interest costs capitalized for the years ended December 31, 2016, 2015 and 2014 were $1.5 million, $1.8 million and $2.8 million, respectively. Expenditures for repairs and maintenance are expensed as incurred. Augmentation and improvements that extend an asset’s useful life or enhance capacity are capitalized. Depreciation expense is recorded using the straight-line method over the assets’ estimated useful lives. Towers and related assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease, taking into consideration lease renewal options and residual value. Towers or assets acquired through capital leases are recorded net at the present value of future minimum lease payments or the fair value of the leased asset at the inception of the lease. Property and equipment and assets held under capital leases are amortized over the shorter of the applicable lease term or the estimated useful life of the respective assets for periods generally not exceeding twenty years. The Company reviews its tower portfolio for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company reviews other long-lived assets for impairment whenever events, changes in circumstances or other evidence indicate that the carrying amount of the Company’s assets may not be recoverable. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets—The Company reviews goodwill for impairment at least annually (as of December 31) or whenever events or circumstances indicate the carrying value of an asset may not be recoverable. Goodwill is recorded in the applicable segment and assessed for impairment at the reporting unit level. The Company utilizes the two-step impairment test when testing goodwill for impairment and employs a discounted cash flow analysis. The key assumptions utilized in the discounted cash flow analysis include current operating performance, terminal sales growth rate, management’s expectations of future operating results and cash requirements, the current weighted average cost of capital and an expected tax rate. Under the first step of this test, the Company compares the fair value of the reporting unit, as calculated under an income approach using future discounted cash flows, to the carrying amount of the applicable reporting unit. If the carrying amount exceeds the fair value, the Company conducts the second step of this test, in which the implied fair value of the applicable reporting unit’s goodwill is compared to the carrying amount of that goodwill. If the carrying amount of goodwill exceeds its implied fair value, an impairment loss would be recognized for the amount of the excess. During the years ended December 31, 2016, 2015 and 2014, no potential impairment was identified under the first step of the test, as the fair value of each of the reporting units was in excess of its carrying amount. Intangible assets that are separable from goodwill and are deemed to have a definite life are amortized over their useful lives, generally ranging from three to twenty years and are evaluated separately for impairment at least annually or whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. The Company reviews its network location intangible assets for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company monitors its tenant-related intangible assets (formerly referred to as customer-related intangible assets) on a tenant by tenant basis for indicators of impairment, such as high levels of turnover or attrition, non-renewal of a significant number of contracts or the cancellation or termination of a relationship. The Company assesses recoverability by determining whether the carrying amount of the related assets will be recovered primarily through projected undiscounted future cash flows. If the Company determines that the carrying amount of an asset may not be recoverable, the Company measures any impairment loss based on the projected future discounted cash flows to be provided from the asset or available market information relative to the asset’s fair value, as compared to the asset’s carrying amount. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.
Derivatives Financial Instruments	Derivative Financial Instruments—Derivatives are recorded on the consolidated balance sheet at fair value. If a derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are recorded in AOCI, as well as a component of comprehensive income (loss), and are recognized in the results of operations when the hedged item affects earnings. Changes in fair value of the ineffective portions of cash flow hedges are recognized in the results of operations. For derivative instruments that are designated and qualify as fair value hedges, changes in value of the derivatives are recorded in Other expense in the consolidated statements of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments not designated as hedging instruments, changes in fair value are recognized in the results of operations in the period that the change occurs. The primary risks managed through the use of derivative instruments is interest rate risk, exposure to changes in the fair value of debt attributable to interest rate risk and currency risk. From time to time, the Company enters into interest rate swap agreements or foreign currency contracts to manage exposure to these risks. Under these agreements, the Company is exposed to counterparty credit risk to the extent that a counterparty fails to meet the terms of a contract. The Company’s exposure is limited to the current value of the contract at the time the counterparty fails to perform. The Company assesses, both at the inception of the hedge and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows or fair values of hedged items. The Company does not hold derivatives for trading purposes.
Fair Value Measurements	Fair Value Measurements—The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.
Asset Retirement Obligations	Asset Retirement Obligations—When required, the Company recognizes the fair value of obligations to remove its tower assets and remediate the leased land upon which certain of its tower assets are located. Generally, the associated retirement costs are capitalized as part of the carrying amount of the related tower assets and depreciated over their estimated useful lives and the liability is accreted through the obligation’s estimated settlement date. Fair value estimates of asset retirement obligations generally involve discounting of estimated future cash flows. Periodic accretion of such liabilities due to the passage of time is included in Depreciation, amortization and accretion expense in the consolidated statements of operations. Adjustments are also made to the asset retirement obligation liability to reflect changes in the estimates of timing and amount of expected cash flows, with an offsetting adjustment made to the related long-lived tangible asset. The significant assumptions used in estimating the Company’s aggregate asset retirement obligation are: timing of tower removals; cost of tower removals; timing and number of land lease renewals; expected inflation rates; and credit-adjusted, risk-free interest rates that approximate the Company’s incremental borrowing rate.
Income Taxes	Income Taxes—As a REIT, the Company generally is not subject to U.S. federal income taxes on income generated by its U.S. REIT operations. However, the Company remains obligated to pay U.S. federal income taxes on certain earnings and continues to be subject to taxation in its foreign jurisdictions. Accordingly, the consolidated financial statements reflect provisions for federal, state, local and foreign income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, as well as operating loss and tax credit carryforwards. The Company measures deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities as a result of a change in tax rates is recognized in income in the period that includes the enactment date. The Company periodically reviews its deferred tax assets, and provides valuation allowances if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Valuation allowances would be reversed as a reduction to the provision for income taxes if related deferred tax assets are deemed realizable based on changes in facts and circumstances relevant to the assets’ recoverability. The Company classifies uncertain tax positions as non-current income tax liabilities unless expected to be paid within one year. The Company reports penalties and tax-related interest expense as a component of the income tax provision and interest income from tax refunds as a component of Other expense in the consolidated statements of operations.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss)—Other comprehensive income (loss) refers to items excluded from net income that are recorded as an adjustment to equity, net of tax. The Company’s other comprehensive income (loss) primarily consisted of changes in fair value of effective derivative cash flow hedges, foreign currency translation adjustments and reclassification of unrealized losses on effective derivative cash flow hedges.
Distributions	Distributions—As a REIT, the Company must annually distribute to its stockholders an amount equal to at least 90% of its REIT taxable income (determined before the deduction for distributed earnings and excluding any net capital gain). Generally, the Company has distributed, and expects to continue to distribute, all or substantially all of its REIT taxable income after taking into consideration its utilization of net operating losses (“NOLs”). The amount, timing and frequency of future distributions will be at the sole discretion of the Board of Directors and will depend upon various factors, a number of which may be beyond the Company’s control, including the Company’s financial condition and operating cash flows, the amount required to maintain its qualification for taxation as a REIT and reduce any income and excise taxes that the Company otherwise would be required to pay, limitations on distributions in the Company’s existing and future debt and preferred equity instruments, the Company’s ability to utilize NOLs to offset the Company’s distribution requirements, limitations on its ability to fund distributions using cash generated through its TRSs and other factors that the Board of Directors may deem relevant.
Acquisitions	Acquisitions—For acquisitions that meet the definition of a business combination, the Company applies the acquisition method of accounting where assets acquired and liabilities assumed are recorded at fair value at the date of each acquisition, and the results of operations are included with those of the Company from the dates of the respective acquisitions. Any excess of the purchase price paid by the Company over the amounts recognized for assets acquired and liabilities assumed is recorded as goodwill. The Company continues to evaluate acquisitions for a period not to exceed one year after the applicable acquisition date of each transaction to determine whether any additional adjustments are needed to the allocation of the purchase price paid for the assets acquired and liabilities assumed. The fair value of the assets acquired and liabilities assumed is typically determined by using either estimates of replacement costs or discounted cash flow valuation methods. When determining the fair value of tangible assets acquired, the Company must estimate the cost to replace the asset with a new asset taking into consideration such factors as age, condition and the economic useful life of the asset. When determining the fair value of intangible assets acquired, the Company must estimate the applicable discount rate and the timing and amount of future tenant cash flows, including rate and terms of renewal and attrition.
Revenue Recognition	Revenue Recognition—The Company’s revenue from leasing arrangements, including fixed escalation clauses present in non-cancellable lease agreements, is reported on a straight-line basis over the term of the respective leases when collectibility is reasonably assured. Escalation clauses tied to the Consumer Price Index (“CPI”) or other inflation-based indices, and other incentives present in lease agreements with the Company’s tenants are excluded from the straight-line calculation. Total property straight-line revenues for the years ended December 31, 2016, 2015 and 2014 were $131.7 million, $155.0 million and $123.7 million, respectively. Amounts billed upfront in connection with the execution of lease agreements are initially deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets and recognized as revenue over the terms of the applicable leases. Amounts billed or received for services prior to being earned are deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets until the criteria for recognition have been met. Services revenues are derived under contracts or arrangements with customers that provide for billings either on a fixed price basis or a variable price basis, which includes factors such as time and expenses. Revenues are recognized as services are performed, and include estimates for percentage completed. Amounts billed or received for services prior to being earned are deferred and reflected in Unearned revenue in the accompanying consolidated balance sheets until the criteria for recognition have been met.
Rent Expense	Rent Expense—Many of the leases underlying the Company’s tower sites have fixed rent escalations, which provide for periodic increases in the amount of ground rent payable by the Company over time. In addition, certain of the Company’s tenant leases require the Company to exercise available renewal options pursuant to the underlying ground lease if the tenant exercises its renewal option. The Company calculates straight-line ground rent expense for these leases based on the fixed non-cancellable term of the underlying ground lease plus all periods, if any, for which failure to renew the lease imposes an economic penalty to the Company such that renewal appears to be reasonably assured. Total property straight-line ground rent expense for the years ended December 31, 2016, 2015 and 2014 was $67.8 million, $56.1 million and $38.4 million, respectively. The Company records a liability for straight-line ground rent expense in Other non-current liabilities. The Company records prepaid ground rent in Prepaid and other current assets and Notes receivable and other non-current assets in the accompanying consolidated balance sheets according to the anticipated period of benefit.
Selling, General, Administrative and Development Expense	Selling, General, Administrative and Development Expense—Selling, general and administrative expense consists of overhead expenses related to the Company’s property and services operations and corporate overhead costs not specifically allocable to any of the Company’s individual business operations. Development expense consists of costs related to the Company’s acquisition efforts, costs associated with new business initiatives and project cancellation costs.
Stock-based Compensation	Stock-Based Compensation—Stock-based compensation expense is measured at the accounting measurement date based on the fair value of the award and is generally recognized as an expense over the service period, which typically represents the vesting period. The Company provides for accelerated vesting and extended exercise periods of stock options and restricted stock units upon an employee’s death or permanent disability, or upon an employee’s qualified retirement, provided certain eligibility criteria are met. Accordingly, the Company recognizes compensation expense for stock options and time-based restricted stock units (“RSUs”) over the shorter of (i) the four-year vesting period or (ii) the period from the date of grant to the date the employee becomes eligible for such retirement benefits, which may occur upon grant. The expense recognized includes the impact of forfeitures as they occur. In March 2015 and 2016, the Company granted performance-based restricted stock units (“PSUs”) to its executive officers. Threshold, target and maximum parameters were established for the metrics for each year in the three-year performance period for the March 2015 grants, and for a three-year performance period for the March 2016 grants. The metrics will be used to calculate the number of shares that will be issuable when the awards vest, which may range from zero to 200% of the target amounts. The Company recognizes compensation expense for PSUs over the three-year vesting period, subject to adjustment based on the date the employee becomes eligible for retirement benefits as well as performance relative to grant parameters. The fair value of stock options is determined using the Black-Scholes option-pricing model and the fair value of restricted stock units is based on the fair value of the Company’s common stock on the date of grant. The Company recognizes all stock-based compensation expense in either Selling, general, administrative and development expense, costs of operations or as part of the costs associated with the construction of the tower assets.
Litigation Costs	Litigation Costs—The Company periodically becomes involved in various claims and lawsuits that are incidental to its business. The Company regularly monitors the status of pending legal actions to evaluate both the magnitude and likelihood of any potential loss. The Company accrues for these potential losses when it is probable that a liability has been incurred and the amount of loss, or possible range of loss, can be reasonably estimated. Should the ultimate losses on contingencies or litigation vary from estimates, adjustments to those liabilities may be required. The Company also incurs legal costs in connection with these matters and records estimates of these expenses, which are reflected in Selling, general, administrative and development expense in the accompanying consolidated statements of operations.
Earnings Per Common Share-Basic and Diluted	Earnings Per Common Share—Basic and Diluted—Basic net income per common share represents net income attributable to American Tower Corporation common stockholders divided by the weighted average number of common shares outstanding during the period. Diluted net income per common share represents net income attributable to American Tower Corporation common stockholders divided by the weighted average number of common shares outstanding during the period and any dilutive common share equivalents, including (A) shares issuable upon (i) the vesting of RSUs, (ii) exercise of stock options, and (iii) conversion of the Company’s mandatory convertible preferred stock and (B) shares earned upon the achievement of the parameters established for the PSUs, each to the extent not anti-dilutive. Dilutive common share equivalents also include the dilutive impact of the shares issuable in the Alltel transaction, which is described in notes 15 and 18. The Company uses the treasury stock method to calculate the effect of its outstanding RSUs, PSUs and stock options and uses the if-converted method to calculate the effect of its outstanding mandatory convertible preferred stock.
Retirement Plan	Retirement Plan—The Company has a 401(k) plan covering substantially all employees who meet certain age and employment requirements. For the years ended December 31, 2016, 2015 and 2014, the Company matched 75% of the first 6% of a participant’s contributions.
Accounting Standards Updates	Accounting Standards Updates—In May 2014, the Financial Accounting Standards Board (the “FASB”) issued new revenue recognition guidance, which requires an entity to recognize revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for the transfer of promised goods or services to customers. The standard will replace most existing revenue recognition guidance and will become effective for the Company on January 1, 2018. Early adoption is permitted for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method. Leases are not included in the scope of this standard. The revenue to which the Company must apply this standard is generally limited to services revenue, certain power and fuel charges not covered by lease agreements and other fees charged to customers. As of December 31, 2016, this revenue was approximately 12% of total revenue. Although the Company is still assessing the impact of this standard on its financial statements, it does not expect changes in the timing of revenue recognition to be material to its financial statements. In January 2016, the FASB issued new guidance on the recognition and measurement of financial assets and financial liabilities. The guidance amends certain aspects of recognition, measurement, presentation and disclosure of financial instruments. This standard is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017. The Company does not expect the adoption of this guidance to have a material effect on its financial statements. In February 2016, the FASB issued new guidance on the accounting for leases. The guidance amends the existing accounting standards for lease accounting, including the requirement that lessees recognize assets and liabilities for leases with terms greater than twelve months in the statement of financial position. Under the new guidance, lessor accounting is largely unchanged. This guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. The standard is required to be applied using a modified retrospective approach for all leases existing at, or entered into after, the beginning of the earliest comparative period presented. The Company is evaluating the impact this standard will have on its financial statements. In March 2016, the FASB issued new guidance on the accounting for share-based payment transactions. The guidance amends the accounting for taxes related to stock-based compensation, including how excess tax benefits and a company’s payments for tax withholdings should be classified. This guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2016. The Company early adopted this standard in the second quarter of 2016 and elected to account for forfeitures as they occur, effective January 1, 2016. The adoption of this guidance was not material to the Company’s consolidated financial statements. Additionally, the Company elected to apply the prospective transition method to the amendments related to the presentation of excess tax benefits in the statements of cash flows. In August 2016, the FASB issued new guidance on certain classifications within the statement of cash flows. The guidance addresses, among other things, how cash receipts and cash payments are presented and classified in the statement of cash flows, including payments for costs related to debt prepayments or extinguishment, as well as payments of contingent consideration after an acquisition. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company has early adopted this guidance for the year ended December 31, 2016, and it did not have a material effect on the Company’s financial statements. Prior periods were not retrospectively adjusted.

Prepaid And Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2016

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid and other current assets

Prepaid and other current assets consisted of the following as of December 31, (in thousands):



	2016		2015
Prepaid operating ground leases	$	134,167	128,542
Prepaid income tax	127,142		45,056
Unbilled receivables	57,661		34,173
Prepaid assets	36,300		32,892
Value added tax and other consumption tax receivables	31,570		30,239
Other miscellaneous current assets	54,193		35,333
Prepaids and other current assets	$	441,033	$	306,235

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property and equipment

Property and equipment (including assets held under capital leases) consisted of the following as of December 31, (in thousands):



	Estimated Useful Lives (years) (1)	2016			2015
Towers	Up to 20	$	11,740,479		$	10,726,656
Equipment	2 - 15	1,176,260			1,095,906
Buildings and improvements	3 - 32	621,874			607,661
Land and improvements (2)	Up to 20	1,909,732			1,728,115
Construction-in-progress		203,411			238,960
Total		15,651,756			14,397,298
Less accumulated depreciation		(5,134,498		)	(4,530,874		)
Property and equipment, net		$	10,517,258		$	9,866,424

_______________


(1)	Assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease taking into consideration lease renewal options and residual value.


(2)	Estimated useful lives apply to improvements only.

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in the carrying value of goodwill

The changes in the carrying value of goodwill for the Company’s business segments were as follows (in thousands):



	Property												Services		Total
	U.S.		Asia				EMEA			Latin America			Services		Total
Balance as of January 1, 2015	$	3,356,096	$	178,521			$	78,647		$	416,922		$	1,988	$	4,032,174
Additions	23,067		610				68,663			122,345			—		214,685
Effect of foreign currency translation	—		(8,412		)		(14,740		)	(131,902		)	—		(155,054		)
Balance as of December 31, 2015	$	3,379,163	$	170,719			$	132,570		$	407,365		$	1,988	$	4,091,805
Additions (1)	—		881,783			(2)	40,386			53,575			—		975,744
Effect of foreign currency translation	—		(23,189		)		(22,445		)	48,765			—		3,131
Balance as of December 31, 2016	$	3,379,163	$	1,029,313			$	150,511		$	509,705		$	1,988	$	5,070,680

_______________


(1)	Additions consist of $975.6 million resulting from 2016 acquisitions and $0.1 million from revisions to prior year acquisitions resulting from measurement period adjustments.


(2)	Assumed in the acquisition of Viom (see note 6).

Finite Intangible Assets

The Company’s other intangible assets subject to amortization consisted of the following (in thousands):



		As of December 31, 2016							As of December 31, 2015
	Estimated Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Book Value		Gross Carrying Value		Accumulated Amortization			Net Book Value
	(years)	(in thousands)
Acquired network location intangibles (1)	Up to 20	$	4,622,316	$	(1,280,284	)	$	3,342,032	$	3,980,281	$	(1,052,393	)	$	2,927,888
Acquired tenant-related intangibles	15-20	10,130,466		(2,224,119		)	7,906,347		8,640,554		(1,763,853		)	6,876,701
Acquired licenses and other intangibles	3-20	28,140		(4,827		)	23,313		28,293		(5,486		)	22,807
Economic Rights, TV Azteca	70	13,893		(10,974		)	2,919		21,688		(11,208		)	10,480
Total other intangible assets		$	14,794,815	$	(3,520,204	)	$	11,274,611	$	12,670,816	$	(2,832,940	)	$	9,837,876

_______________


(1)	Acquired network location intangibles are amortized over the shorter of the term of the corresponding ground lease taking into consideration lease renewal options and residual value or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.

Expected future amortization expenses

Based on current exchange rates, the Company expects to record amortization expense as follows over the next five years (in millions):



Year Ending December 31,
2017	$	710.5
2018	707.8
2019	705.1
2020	686.3
2021	676.8

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Schedule of merger and acquisition related costs

During the years ended December 31, 2016, 2015 and 2014, the Company recorded the following acquisition and merger related expenses and integration costs (in thousands):



	Year Ended December 31,
	2016		2015		2014

Acquisition and merger related expenses	$	15,875	$	18,799	$	26,969
Integration costs	$	9,901	$	18,097	$	13,057

Schedule of recognized identified assets acquired and liabilities assumed

The following table summarizes the preliminary allocation of the purchase prices for fiscal year 2016 acquisitions based upon their estimated fair value at the date of acquisition (in thousands).



	Asia			Other
	Viom			Other
Current assets	$	276,560		$	25,477
Non-current assets	57,645			2,336
Property and equipment	701,988			81,521
Intangible assets (1):
Tenant-related intangible assets	1,369,580			105,557
Network location intangible assets	666,364			83,645
Current liabilities	(195,900		)	(14,782		)
Deferred tax liability	(619,070		)	(43,756		)
Other non-current liabilities	(102,751		)	(29,472		)
Net assets acquired	2,154,416			210,526
Goodwill (2)	881,783			93,856
Fair value of net assets acquired	3,036,199			304,382
Debt assumed	(786,889		)	—
Redeemable noncontrolling interests	(1,100,804		)	—
Purchase Price	$	1,148,506		$	304,382

_______________


(1)	Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.


(2)	Primarily results from purchase accounting adjustments, which are at least partially deductible for tax purposes in certain foreign jurisdictions.

Schedule of contingent consideration changes

The changes in fair value of the contingent consideration were as follows during the years ended December 31, (in thousands):



	2016			2015
Balance as of January 1	$	12,436		$	28,524
Additions	8,811			1,626
Settlements	(306		)	(7,943		)
Change in fair value	(6,372		)	(4,781		)
Foreign currency translation adjustment	875			(4,990		)
Balance as of December 31	$	15,444		$	12,436

Long-Term Obligations (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments



	2016			2015			Contractual Interest Rate (1)		Maturity Date (1)
Series 2013-1A Securities (2)	$	498,642		$	497,478		1.551	%	March 15, 2018
Series 2013-2A Securities (3)	1,290,267			1,288,689			3.070	%	March 15, 2023
Series 2015-1 Notes (4)	347,108			346,262			2.350	%	June 15, 2020
Series 2015-2 Notes (5)	519,437			518,776			3.482	%	June 16, 2025
2012 GTP Notes (6) (7)	179,459			281,902			4.336% - 7.358%		March 15, 2019
Unison Notes (7) (8)	132,960			201,930			6.392% - 9.522%		April 15, 2020
India indebtedness (9)	549,528			8,752			8.15% - 11.70%		Various
Viom preference shares (10)	24,537			—			13.500	%	Various
Shareholder loans (11)	151,045			145,540			Various		Various
Other subsidiary debt (12)	286,009			219,902			Various		Various
Total American Tower subsidiary debt	3,978,992			3,509,231

2013 Credit Facility (13)	539,975			1,225,000			1.963	%	June 28, 2020
Term Loan (13)	993,936			1,993,601			2.020	%	January 31, 2022
2014 Credit Facility (13)	1,385,000			1,980,000			2.432	%	January 31, 2022
4.500% senior notes	998,676			997,693			4.500	%	January 15, 2018
3.40% senior notes	999,716			999,769			3.400	%	February 15, 2019
7.25% senior notes (7)	297,032			296,242			7.250	%	May 15, 2019
2.800% senior notes	744,917			743,557			2.800	%	June 1, 2020
5.050% senior notes	697,352			697,216			5.050	%	September 1, 2020
3.300% senior notes	744,762			—			3.300	%	February 15, 2021
3.450% senior notes	643,848			642,786			3.450	%	September 15, 2021
5.900% senior notes	497,343			497,188			5.900	%	November 1, 2021
2.250% senior notes	572,764			—			2.250	%	January 15, 2022
4.70% senior notes	696,013			695,374			4.700	%	March 15, 2022
3.50% senior notes	989,269			987,966			3.500	%	January 31, 2023
5.00% senior notes	1,002,742			1,003,453			5.000	%	February 15, 2024
4.000% senior notes	739,985			739,057			4.000	%	June 1, 2025
4.400% senior notes	495,212			—			4.400	%	February 15, 2026
3.375% senior notes	983,369			—			3.375	%	October 15, 2026
3.125% senior notes	396,713			—			3.125	%	January 15, 2027
Total American Tower Corporation debt	14,418,624			13,498,902
Other debt, including capital lease obligations	135,849			110,876
Total	18,533,465			17,119,009
Less current portion long-term obligations	(238,806		)	(50,202		)
Long-term obligations	$	18,294,659		$	17,068,807

_______________


(1)	Represents the interest rate or maturity date as of December 31, 2016; interest rate does not reflect the impact of interest rate swap agreements.


(2)	Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2043.


(3)	Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048.


(4)	Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2045.


(5)	Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050.


(6)	Secured debt assumed by the Company in connection with its acquisition of MIP Tower Holdings LLC (“MIPT”). Maturity date represents anticipated repayment date; final legal maturity is March 15, 2042.


(7)	Debt was repaid in full subsequent to December 31, 2016. For more information see note 23.


(8)	Secured debt assumed in connection with the acquisition of certain legal entities holding a portfolio of property interests from Unison Holdings, LLC and Unison Site Management II, L.L.C. (together, “Unison”). Maturity date reflects the anticipated repayment date; final legal maturity is April 15, 2040.


(9)	Denominated in Indian Rupees (“INR”). Debt includes India working capital facility, remaining debt assumed by the Company in connection with the Viom Acquisition and debt that has been entered into by ATC TIPL.


(10)	Mandatorily redeemable preference shares (the “Preference Shares”) classified as debt, assumed by the Company in connection with the Viom Acquisition. The shares are to be redeemed in equal parts on March 26, 2017 and March 26, 2018.

(11)

(12)


(13)	Debt accrues interest at a variable rate.

Amounts outstanding and key terms of other subsidiary debt consisted of the following as of December 31, 2016 (in millions, except percentages):



	Amount Outstanding (Functional Currency)		Amount Outstanding (USD) (1)				Interest Rate		Maturity Date
	2016	2015	2016		2015
BR Towers Debentures (2)	329.3	332.8	$	101.0	$	85.2	7.400	%	October 15, 2023
South African Credit Facility (3)	1,164.0	830.0	$	84.3	$	53.2	9.308	%	December 17, 2020
Colombian Credit Facility (4)	170,000.0	190,000.0	$	56.1	$	59.6	10.920	%	April 24, 2021
Brazil Credit Facility (5)	147.7	85.4	$	44.6	$	21.9	Various		January 15, 2022

_______________


(1)	Includes applicable deferred financing costs.


(2)	Denominated in BRL, with an original principal amount of 300.0 million BRL. Debt accrues interest at a variable rate. The aggregate principal amount of the BR Towers Debentures may be adjusted periodically relative to changes in the National Extended Consumer Price Index.


(3)	Denominated in ZAR, with an original principal amount of 830.0 million ZAR. On December 23, 2016, the borrower borrowed an additional 500.0 million ZAR, with the ability to request an additional 330.0 million ZAR. Debt accrues interest at a variable rate.


(4)	Denominated in COP, with an original principal amount of 200.0 billion COP. Debt accrues interest at a variable rate. The loan agreement for the Colombian Credit Facility requires that the borrower manage exposure to variability in interest rates on certain of the amounts outstanding under the Colombian Credit Facility.


(5)	Denominated in BRL, with an original principal amount of 271.0 million BRL. Debt accrues interest at a variable rate. As of December 30, 2016, the borrower no longer maintains the ability to draw on the Brazil Credit Facility.

Schedule of India Indebtedness

indebtedness—Amounts outstanding and key terms of the India indebtedness consisted of the following as of December 31, 2016 (in millions, except percentages):



	Amount Outstanding (INR)	Amount Outstanding (USD)		Interest Rate (Range)		Maturity Date (Range)
Term loans	31,326	$	461.2	8.15% - 11.15%		March 31, 2017 - November 30, 2024
Debenture	6,000	$	88.3	9.90	%	April 28, 2020
Working capital facilities	0	$	0	8.70% - 11.70%		January 31, 2017 - October 23, 2017

Schedule of Shareholder Loans

Outstanding amounts under each of the Company’s shareholder loans consisted of the following as of December 31, (in thousands):



	2016		2015		Contractual Interest Rate		Maturity Date
Ghana loan (1)	$	71,047	$	70,314	21.87	%	December 31, 2019
Uganda loan (2)(3)	79,998		75,226		6.52	%	June 29, 2019

_______________


(1)	Denominated in GHS. As of December 31, 2016, the aggregate principal amount outstanding under the Ghana loan was 300.9 million GHS.


(2)	Interest accrues at a variable rate.


(3)	Includes $4.8 million of interest which was capitalized during the year ended December 31, 2016.

Schedule of Line of Credit Facilities

As of December 31, 2016, the key terms under the 2013 Credit Facility, the 2014 Credit Facility and the Term Loan were as follows:



	Outstanding Principal Balance (in millions)			Undrawn letters of credit (in millions)		Maturity Date		Current margin over LIBOR and base rate	Current commitment fee (1)
2013 Credit Facility	$	540.0	(2)	$	3.2	June 28, 2020	(3)	1.250% and 0.250%	0.150	%
2014 Credit Facility	$	1,385.0	(4)	$	7.3	January 31, 2022	(3)	1.250% and 0.250%	0.150	%
Term Loan	$	1,000.0	(2)	$	—	January 31, 2022		1.250% and 0.250%	N/A

_______________

(1) Fee on undrawn portion of each credit facility.

(2)

Schedule of Debt Discounts

The following table outlines key terms related to the Company’s outstanding senior notes as of December 31, 2016:



			Adjustments to Principal Amount (1)
	Aggregate Principal Amount		2016			2015			Semi-annual interest payments due	Issue Date	Par Call Date (2)
	(in thousands)
4.500% Notes	$	1,000,000	$	(1,324	)	$	(2,307	)	January 15 and July 15	December 7, 2010	N/A
3.40% Notes (3)	1,000,000		(284		)	(231		)	February 15 and August 15	August 19, 2013	N/A
7.25% Notes	300,000		(2,968		)	(3,758		)	May 15 and November 15	June 10, 2009	N/A
2.800% Notes	750,000		(5,083		)	(6,443		)	June 1 and December 1	May 7, 2015	May 1, 2020
5.050% Notes	700,000		(2,648		)	(2,784		)	March 1 and September 1	August 16, 2010	N/A
3.300% Notes	750,000		(5,238		)	—			February 15 and August 15	January 12, 2016	January 15, 2021
3.450% Notes	650,000		(6,152		)	(7,214		)	March 15 and September 15	August 7, 2014	N/A
5.900% Notes	500,000		(2,657		)	(2,812		)	May 1 and November 1	October 6, 2011	N/A
2.250% Notes (4)	600,000		(27,236		)	—			January 15 and July 15	September 30, 2016	N/A
4.70% Notes	700,000		(3,987		)	(4,626		)	March 15 and September 15	March 12, 2012	N/A
3.50% Notes	1,000,000		(10,731		)	(12,034		)	January 31 and July 31	January 8, 2013	N/A
5.00% Notes (3)	1,000,000		2,742			3,453			February 15 and August 15	August 19, 2013	N/A
4.000% Notes	750,000		(10,015		)	(10,943		)	June 1 and December 1	May 7, 2015	March 1, 2025
4.400% Notes	500,000		(4,788		)	—			February 15 and August 15	January 12, 2016	November 15, 2025
3.375% Notes	1,000,000		(16,631		)	—			April 15 and October 15	May 13, 2016	July 15, 2026
3.125% Notes	400,000		(3,287		)	—			January 15 and July 15	September 30, 2016	October 15, 2026

_______________


(1)	Includes unamortized discounts, premiums and debt issuance costs and fair value adjustments due to interest rate swaps.


(2)	The Company will not be required to pay a make-whole premium if redeemed on or after the par call date.


(3)	The original issue date for the 3.40% Notes and the 5.00% Notes was August 19, 2013. The issue date for the reopened 3.40% Notes and the reopened 5.00% Notes was January 10, 2014.


(4)	Includes $22.3 million fair value adjustment due to interest rate swaps.

Schedule of Maturities of Long-term Debt

ggregate principal maturities of long-term debt, including capital leases, for the next five years and thereafter are expected to be (in thousands):



Year Ending December 31,
2017	$	238,806
2018	1,649,137
2019	1,759,808
2020	2,677,594
2021	1,976,976
Thereafter	10,350,583

Total cash obligations	18,652,904
Unamortized discounts, premiums and debt issuance costs and fair value adjustments, net	(119,439		)

Balance as of December 31, 2016	$	18,533,465

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of fair value

The fair value of the Company’s financial assets and liabilities that are required to be measured on a recurring basis at fair value was as follows (in thousands):



	December 31, 2016						December 31, 2015
	Fair Value Measurements Using						Fair Value Measurements Using
	Level 1		Level 2		Level 3		Level 1	Level 2		Level 3
Assets:
Short-term investments (1)	$	4,026	—		—		—	—		—
Interest rate swap agreements	—		$	3	—		—	$	692	—
Embedded derivative in lease agreement	—		—		$	13,290	—	—		$	14,176
Liabilities:
Interest rate swap agreements	—		$	24,682	—		—	—		—
Acquisition-related contingent consideration	—		—		$	15,444	—	—		$	12,436

_______________


(1)	Consists of highly liquid investments with original maturities in excess of three months.

Schedule of derivative financial instruments

The notional amount and fair value of the Colombian interest rate swap agreements were as follows as of December 31, (in thousands):



	2016			2015
	Local	USD		Local	USD
Colombia (COP) (1)
Notional	85,000,000	$	28,327	95,000,000	$	30,164
Fair Value	8,763	3		2,179,374	692

_______________


(1)	As of December 31, 2016 and 2015, the interest rate swap agreement in Colombia was included in Notes receivable and other non-current assets on the consolidated balance sheet.

Schedule of contingent consideration changes

The changes in fair value of the contingent consideration were as follows during the years ended December 31, (in thousands):



	2016			2015
Balance as of January 1	$	12,436		$	28,524
Additions	8,811			1,626
Settlements	(306		)	(7,943		)
Change in fair value	(6,372		)	(4,781		)
Foreign currency translation adjustment	875			(4,990		)
Balance as of December 31	$	15,444		$	12,436

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income tax provision from continuing operations

The income tax provision from continuing operations consisted of the following for the years ended December 31, (in thousands):



	2016			2015			2014
Current:
Federal	$	(26,494	)	$	(73,930	)	$	(2,390	)
State	(1,976		)	(21,216		)	(797		)
Foreign	(100,074		)	(55,045		)	(57,934		)
Deferred:
Federal	(616		)	9,131			(4,180		)
State	(259		)	8			(973		)
Foreign	(26,082		)	(16,903		)	3,769
Income tax provision	$	(155,501	)	$	(157,955	)	$	(62,505	)

Reconciliation between the U.S. statutory rate and the effective rate from continuing operations

Reconciliation between the U.S. statutory rate and the effective rate from continuing operations is as follows for the years ended December 31:



	2016		2015		2014
Statutory tax rate	35	%	35	%	35	%
Adjustment to reflect REIT status (1)	(35	)	(35	)	(35	)
Foreign taxes	5		3		2
Foreign withholding taxes	4		3		3
Uncertain tax positions	5		—		—
Change in tax law	—		2		—
MIPT tax election (2)	—		11		—
Other	—		—		2
Effective tax rate	14	%	19	%	7	%

_______________

(1) Includes 29%, 36% and 24% from dividend paid deductions in 2016, 2015 and 2014, respectively.

(2) Includes federal and state taxes, net of federal benefit.

Components of income from continuing operations before income taxes and income on equity method investments

The domestic and foreign components of income from continuing operations before income taxes are as follows for the years ended December 31, (in thousands):



	2016		2015		2014
United States	$	882,552	$	785,201	$	857,457
Foreign	243,308		44,761		8,247
Total	$	1,125,860	$	829,962	$	865,704

Components of the net deferred tax asset and related valuation allowance

The components of the net deferred tax asset and liability and related valuation allowance were as follows as of December 31, (in thousands):



	2016			2015
Assets:
Net operating loss carryforwards	$	278,674		$	277,977
Accrued asset retirement obligations	130,014			92,295
Stock-based compensation	4,267			3,889
Unearned revenue	29,003			25,654
Unrealized loss on foreign currency	26,883			37,440
Other accruals and allowances	45,578			13,824
Items not currently deductible and other	26,886			17,608
Liabilities:
Depreciation and amortization	(942,409		)	(194,230		)
Deferred rent	(27,099		)	(20,720		)
Other	(9,294		)	(11,077		)
Subtotal	(437,497		)	242,660
Valuation allowance	(144,397		)	(136,952		)
Net deferred tax (liabilities) assets	$	(581,894	)	$	105,708

Summary of valuation allowance

A summary of the activity in the valuation allowance is as follows (in thousands):



	2016			2015			2014
Balance as of January 1,	$	136,952		$	141,241		$	136,006
Additions (1)	14,118			19,512			40,124
Reversals	—			—			(10,769		)
Foreign currency translation	(6,673		)	(23,801		)	(24,120		)
Balance as of December 31,	$	144,397		$	136,952		$	141,241

_______________

(1) Includes net charges to expense and allowances established through goodwill at acquisition.

Net operating loss carryforwards expire



Years ended December 31,	Federal		State		Foreign
2017 to 2021	$	—	$	59,213	$	8,950
2022 to 2026	—		388,695		184,611
2027 to 2031	146,763		98,538		—
2032 to 2036	16,604		32,345		—
Indefinite carryforward	—		—		831,185
Total	$	163,367	$	578,791	$	1,024,746

Change in unrecognized tax benefit

A reconciliation of the beginning and ending amount of unrecognized tax benefits are as follows for the years ended December 31, (in thousands):



	2016			2015			2014
Balance at January 1	$	28,114		$	31,947		$	32,545
Additions based on tax positions related to the current year	82,912			5,042			4,187
Additions for tax positions of prior years	—			—			3,780
Foreign currency	(307		)	(5,371		)	(3,216		)
Reduction as a result of the lapse of statute of limitations and effective settlements	(3,168		)	(3,504		)	(5,349		)
Balance at December 31	$	107,551		$	28,114		$	31,947

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock-based compensation expenses

During the years ended December 31, 2016, 2015 and 2014, the Company recorded and capitalized the following stock-based compensation expenses (in thousands):



	2016		2015		2014
Stock-based compensation expense	$	89,898	$	90,537	$	80,153
Stock-based compensation expense capitalized as property and equipment	1,443		2,052		1,589

Assumptions used to determine the grant date fair value for options granted

Key assumptions used to apply this pricing model were as follows:



	2016	2015	2014
Range of risk-free interest rate	1.00% - 1.73%	1.32% - 1.62%	1.46% - 1.74%
Weighted average risk-free interest rate	1.44%	1.61%	1.64%
Range of expected life of stock options	4.5 - 5.2 years	4.5 years	4.5 years
Range of expected volatility of the underlying stock price	20.59% - 21.45%	21.09% - 21.24%	21.94% - 23.35%
Weighted average expected volatility of underlying stock price	21.43%	21.09%	23.08%
Range of expected annual dividend yield	1.85% - 2.40%	1.50% - 1.85%	1.50%

Summary of the company's option activity

The Company’s option activity for the year ended December 31, 2016 was as follows:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Life (Years)	Aggregate Intrinsic Value (in millions)
Outstanding as of January 1, 2016	7,680,819			$71.10
Granted	1,161,370		95.16
Exercised	(1,520,541	)	55.86
Forfeited	(51,472	)	90.10
Expired	(800	)	33.96
Outstanding as of December 31, 2016	7,269,376			$78.00	6.73		$201.4
Exercisable as of December 31, 2016	3,519,976			$64.93	5.24		$143.4
Vested or expected to vest as of December 31, 2016	7,269,376			$78.00	6.73		$201.4

Schedule of options outstanding

The following table sets forth information regarding options outstanding at December 31, 2016:



Options Outstanding					Options Exercisable
Outstanding Number of Options	Range of Exercise Price Per Share	Weighted Average Exercise Price Per Share		Weighted Average Remaining Life (Years)	Options Exercisable	Weighted Average Exercise Price Per Share
733,732	$28.39 - $43.11	$	37.01	2.35	733,732	$	37.01
1,130,308	44.92 - 62.00	56.55		4.55	1,130,308	56.55
916,991	64.01 - 76.90	76.74		6.18	621,338	76.69
1,428,834	77.42- 81.18	81.12		7.14	589,547	81.13
1,900,077	81.46 - 94.57	94.35		8.15	441,405	94.34
1,159,434	94.71 - 113.60	95.21		9.19	3,646	99.14
7,269,376	$28.39 - $113.60	$	78.00	6.73	3,519,976	$	64.93

Summary of the company's restricted stock unit activity

The Company’s RSU and PSU activity for the year ended December 31, 2016 was as follows:



	RSUs		Weighted Average Grant Date Fair Value		PSUs	Weighted Average Grant Date Fair Value
Outstanding as of January 1, 2016 (1)	1,656,993		$	84.12	33,377	$	94.57
Granted (2)	784,178		95.15		209,380	93.81
Vested	(656,645	)	79.36		—	—
Forfeited	(120,783	)	90.18		—	—
Outstanding as of December 31, 2016	1,663,743		$	90.76	242,757	$	93.92
Expected to vest as of December 31, 2016	1,663,743		$	90.76	242,757	$	93.92

_______________


(1)	PSUs represent the shares issuable for the 2015 PSUs (as defined below) at the end of the three-year performance cycle based on exceeding the performance metric for the first year’s performance period.


(2)	PSUs represent the shares issuable for the 2015 PSUs at the end of the three-year performance cycle based on exceeding the performance metric for the second year’s performance period and the target number of shares issuable at the end of the three-year performance cycle for the 2016 PSUs (as defined below).

Redeemable Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2016

Temporary Equity Disclosure [Abstract]

Schedule of Redeemable Noncontrolling Interests

The following is a reconciliation of the changes in the Redeemable noncontrolling interests (in thousands):



Balance as of January 1, 2016	$	—
Fair value at acquisition	1,100,804
Net income attributable to noncontrolling interests	13,851
Foreign currency translation adjustment attributable to noncontrolling interests	(23,435		)
Balance as of December 31, 2016	$	1,091,220

Equity (Tables)

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Dividends Declared [Table Text Block]

Distributions—During the years ended December 31, 2016, 2015 and 2014, the Company declared the following cash distributions:



	For the year ended December 31,
	2016				2015				2014
	Distribution per share		Aggregate Payment Amount (in millions)		Distribution per share		Aggregate Payment Amount (in millions)		Distribution per share		Aggregate Payment Amount (in millions)
Common Stock	$	2.17	$	923.7	$	1.81	$	766.4	$	1.40	$	554.6
Series A Preferred Stock	$	5.25	$	31.5	$	3.94	$	23.7	$	3.98	$	23.9
Series B Preferred Stock	$	55.00	$	75.6	$	38.65	$	53.1	$	—	$	—

Schedule of Stock by Class

The following table characterizes the tax treatment of distributions declared per share of common stock and Mandatory Convertible Preferred Stock.



		For the year ended December 31,
		2016					2015					2014 (1)
		Per Share			%		Per Share			%		Per Share		%
Common Stock
	Ordinary dividend	$	2.1700	(2)	100.00	%	$	1.2694		70.13	%	$	1.4000	100.00	%
	Capital gains distribution	—			—		0.5406			29.87		—		—
	Total	$	2.1700		100.00	%	$	1.8100		100.00	%	$	1.4000	100.00	%
Series A Preferred Stock
	Ordinary dividend	$	6.4578	(3)	100.00	%	$	3.6818	(4)	70.13	%	$	2.6688	100.00	%
	Capital gains distribution	—			—		1.5682			29.87		—		—
	Total	$	6.4578		100.00	%	$	5.2500		100.00	%	$	2.6688	100.00	%
Series B Preferred Stock (5)
	Ordinary dividend	$	5.5000		100.00	%	$	2.7107		70.13	%	$	—	—	%
	Capital gains distribution	—			—		1.1546			29.87		—		—
	Total	$	5.5000		100.00	%	$	3.8653		100.00	%	$	—	—	%

_______________


(1)	The Company had no Series B Preferred Stock outstanding during the year ended December 31, 2014.


(2)	Includes dividend declared on December 14, 2016 of $0.58 per share, which was paid on January 13, 2017 to common stockholders of record at the close of business on December 28, 2016.


(3)	Includes a deemed distribution as a result of a conversion rate adjustment triggered on June 17, 2016.


(4)	Includes dividend declared on December 2, 2014 of $1.3125 per share, which was paid on February 16, 2015 to preferred stockholders of record at the close of business on February 1, 2015.


(5)	Represents the tax treatment on dividends per depositary share, each of which represents a 1/10th interest in a share of Series B Preferred Stock.

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 235
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-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
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-Section S99
-Paragraph 1
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21553-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 3
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Subparagraph (SX 210.5-02(27))
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

+ Details

Earnings Per Common Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of earnings per basic and diluted by common class

The following table sets forth basic and diluted net income per common share computational data for the years ended December 31, (in thousands, except per share data):



	2016			2015			2014
Net income attributable to American Tower Corporation stockholders	$	956,425		$	685,074		$	824,910
Dividends on preferred stock	(107,125		)	(90,163		)	(23,888		)
Net income attributable to American Tower Corporation common stockholders	849,300			594,911			801,022
Basic weighted average common shares outstanding	425,143			418,907			395,958
Dilutive securities	4,140			4,108			4,128
Diluted weighted average common shares outstanding	429,283			423,015			400,086
Basic net income attributable to American Tower Corporation common stockholders per common share	$	2.00		$	1.42		$	2.02
Diluted net income attributable to American Tower Corporation common stockholders per common share	$	1.98		$	1.41		$	2.00

Schedule of antidilutive securities excluded from computation of earnings per share



	2016	2015	2014
Restricted stock awards	6	—	5
Stock options	817	1,606	1,290
Preferred stock	17,509	15,408	4,303

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Future minimum rental payments under non-cancelable operating leases



Year Ending December 31,
2017	$	869
2018	846
2019	816
2020	776
2021	737
Thereafter	6,638
Total	$	10,682

Future minimum payments under capital leases

Future minimum payments under capital leases in effect at December 31, 2016 were as follows (in millions):



Year Ending December 31,
2017	$	28
2018	24
2019	22
2020	18
2021	14
Thereafter	163
Total minimum lease payments	269
Less amounts representing interest	(132		)
Present value of capital lease obligations	$	137

Future minimum rental receipts under operating lease agreements

Future minimum rental receipts expected from tenants under non-cancellable operating lease agreements in effect at December 31, 2016 were as follows (in millions):



Year Ending December 31,
2017	$	4,646
2018	4,502
2019	4,240
2020	3,905
2021	3,372
Thereafter	10,477
Total	$	31,142

- Definition

Tabular disclosure of a lessee's leasing arrangements including: (1) the basis on which contingent rental payments are determined, (2) the existence and terms of renewal or purchase options and escalation clauses, (3) restrictions imposed by lease arrangements, such as those concerning dividends, additional debt, and further leasing, (4) rent holidays, rent concessions, or leasehold improvement incentives and unusual provisions or conditions. Disclosure may also include the specific period used to amortize material leasehold improvements made at the inception of the lease or during the lease term. Additionally, for operating leases having initial or remaining noncancelable lease terms in excess of one year: (a) future minimum rental payments required as of the date of the latest balance sheet presented, in the aggregate and for each of the five succeeding fiscal years, (b) the total of minimum rentals to be received in the future under noncancelable subleases as of the date of the latest balance sheet presented, and (c) for all operating leases, rental expense for each period for which an income statement is presented, with separate amounts for minimum rentals, contingent rentals, and sublease rentals. Rental payments under leases with terms of a month or less that were not renewed need not be included.

+ References + Details

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2016

Supplemental Cash Flow Elements [Abstract]

Supplemental cash flow information and non-cash investing and financing activities

Supplemental cash flow information and non-cash investing and financing activities are as follows for the years ended December 31, (in thousands):



	2016			2015		2014
Supplemental cash flow information:
Cash paid for interest	$	645,092		$	577,952	$	548,089
Cash paid for income taxes (net of refunds of $19,554, $7,053 and $8,476, respectively)	96,241			157,058		69,212
Non-cash investing and financing activities:
(Decrease) increase in accounts payable and accrued expenses for purchases of property and equipment and construction activities	(18,973		)	2,780		1,121
Purchases of property and equipment under capital leases	55,635			36,851		36,486
Fair value of debt assumed through acquisitions	786,889			—		463,135
Exercise of purchase option for property and equipment for common shares issued	120,785			—		—
Settlement of accounts receivable related to acquisitions	—			899		31,849
Conversion of third-party debt to equity	—			—		111,181

Business Segments (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting, Measurement Disclosures [Abstract]

Summarized financial information concerning the company's reportable segments



	Property								Total Property		Services		Other		Total
Year ended December 31, 2016	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	3,370,033	$	827,627	$	529,531	$	985,935	$	5,713,126	$	72,542			$	5,785,668
Segment operating expenses (1)	733,403		465,938		223,716		337,887		1,760,944		27,007				1,787,951
Interest income, TV Azteca, net	—		—		—		10,960		10,960		—				10,960
Segment gross margin	2,636,630		361,689		305,815		659,008		3,963,142		45,535				4,008,677
Segment selling, general, administrative and development expense (1)	147,559		48,238		60,903		60,690		317,390		12,510				329,900
Segment operating profit	$	2,489,071	$	313,451	$	244,912	$	598,318	$	3,645,752	$	33,025			$	3,678,777
Stock-based compensation expense													$	89,898	89,898
Other selling, general, administrative and development expense													126,035		126,035
Depreciation, amortization and accretion													1,525,635		1,525,635
Other expense (2)													811,349		811,349
Income from continuing operations before income taxes															$	1,125,860
Capital expenditures (3)	$	310,744	$	115,508	$	86,128	$	172,568	$	684,948	$	—	$	16,439	$	701,387

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.4 million and $87.5 million, respectively.


(2)	Primarily includes interest expense.


(3)	Includes $18.9 million of capital lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes and capital leases in the cash flow from financing activities in our consolidated statement of cash flows.



	Property								Total Property		Services		Other		Total
Year ended December 31, 2015	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	3,157,501	$	242,223	$	395,092	$	885,572	$	4,680,388	$	91,128			$	4,771,516
Segment operating expenses (1)	678,499		126,874		163,820		304,629		1,273,822		32,993				1,306,815
Interest income, TV Azteca, net	—		—		—		11,209		11,209		—				11,209
Segment gross margin	2,479,002		115,349		231,272		592,152		3,417,775		58,135				3,475,910
Segment selling, general, administrative and development expense (1)	138,617		22,771		48,672		62,111		272,171		15,724				287,895
Segment operating profit	$	2,340,385	$	92,578	$	182,600	$	530,041	$	3,145,604	$	42,411			$	3,188,015
Stock-based compensation expense													$	90,537	90,537
Other selling, general, administrative and development expense													121,456		121,456
Depreciation, amortization and accretion													1,285,328		1,285,328
Other expense (2)													860,732		860,732
Income from continuing operations before income taxes															$	829,962
Capital expenditures	$	367,663	$	75,407	$	66,625	$	201,806	$	711,501	$	—	$	17,252	$	728,753

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.1 million and $88.5 million, respectively.


(2)	Primarily includes interest expense.



	Property								Total Property		Services		Other		Total
Year ended December 31, 2014	U.S.		Asia		EMEA		Latin America		Total Property		Services		Other		Total
	(in thousands)
Segment revenues	$	2,639,790	$	219,566	$	315,053	$	832,445	$	4,006,854	$	93,194			$	4,100,048
Segment operating expenses (1)	515,742		121,797		126,714		290,527		1,054,780		37,648				1,092,428
Interest income, TV Azteca, net	—		—		—		10,547		10,547		—				10,547
Segment gross margin	2,124,048		97,769		188,339		552,465		2,962,621		55,546				3,018,167
Segment selling, general, administrative and development expense (1)	124,944		19,632		39,553		66,890		251,019		12,469				263,488
Segment operating profit	$	1,999,104	$	78,137	$	148,786	$	485,575	$	2,711,602	$	43,077			$	2,754,679
Stock-based compensation expense													$	80,153	80,153
Other selling, general, administrative and development expense (2)													104,738		104,738
Depreciation, amortization and accretion													1,003,802		1,003,802
Other expense (3)													700,282		700,282
Income from continuing operations before income taxes															$	865,704
Capital expenditures	$	576,153	$	74,334	$	70,126	$	229,645	$	950,258	$	—	$	24,146	$	974,404

_______________


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.8 million and $78.3 million, respectively.


(2)	Includes $7.9 million of expense previously recorded as segment selling, general, administrative and development expense.


(3)	Primarily includes interest expense.

Reconciliation of assets from segments to consolidated

Additional information relating to the total assets of the Company’s operating segments is as follows for the years ended December 31, (in thousands):



	2016		2015		2014
U.S. property	$	18,846,941	$	19,286,465	$	14,335,731
Asia property (1)	4,535,293		736,149		738,290
EMEA property (1)	2,062,399		2,249,634		1,275,253
Latin America property (1)	4,938,064		4,401,258		4,700,357
Services	48,327		68,388		57,367
Other (2)	448,126		162,378		156,567
Total assets	$	30,879,150	$	26,904,272	$	21,263,565

_______________


(1)	Balances are translated at the applicable period end exchange rate, which may impact comparability between periods.


(2)	Balances include corporate assets such as cash and cash equivalents, certain tangible and intangible assets and income tax accounts that have not been allocated to specific segments.

Schedule of disclosure on geographic areas, long-lived assets



	2016		2015		2014
Operating Revenues:
United States	$	3,442,575	$	3,248,629	$	2,732,984
Asia (1):
India	827,627		242,223		219,566
EMEA (1):
Germany	60,163		55,965		64,946
Ghana	116,219		94,549		95,486
Nigeria	215,402		109,701		—
South Africa	80,006		80,510		98,334
Uganda	57,741		54,367		56,287
Latin America (1):
Argentina	1,065		—		—
Brazil	506,182		408,644		331,089
Chile	33,831		29,650		31,756
Colombia	79,755		78,351		89,421
Costa Rica	18,968		17,244		16,742
Mexico	331,173		340,461		354,116
Panama (2)	—		—		1,243
Peru	14,961		11,222		8,078
Total International	2,343,093		1,522,887		1,367,064
Total operating revenues	$	5,785,668	$	4,771,516	$	4,100,048

_______________


(1)	Balances are translated at the applicable exchange rate, which may impact comparability between periods.


(2)	In September 2014, the Company completed the sale of its operations in Panama.



	2016		2015
Long-Lived Assets (1):
United States	$	16,969,558	$	17,516,535
Asia (2):
India	4,094,190		619,370
EMEA (2):
Germany	397,317		388,727
Ghana	192,158		217,530
Nigeria	640,634		1,018,980
South Africa	271,760		133,088
Uganda	141,533		162,346
Latin America (2):
Argentina	137,588		—
Brazil	2,626,431		2,204,494
Chile	137,170		121,938
Colombia	272,338		256,892
Costa Rica	117,481		120,292
Mexico	797,798		976,707
Peru	66,593		59,206
Total International	9,892,991		6,279,570
Total long-lived assets	$	26,862,549	$	23,796,105

_______________


(1)	Includes Property and equipment, net, Goodwill and Other intangible assets, net.


(2)	Balances are translated at the applicable period end exchange rate, which may impact comparability between periods.

Schedule of revenue by major customers



	2016		2015		2014
AT&T	21	%	24	%	20	%
Verizon Wireless	15	%	16	%	11	%
Sprint	11	%	13	%	15	%
T-Mobile	9	%	10	%	10	%

Selected Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Information [Abstract]

Schedule of quarterly financial information

Selected quarterly financial data for the years ended December 31, 2016 and 2015 is as follows (in thousands, except per share data):



	Three Months Ended												Year Ended December 31,
	March 31,			June 30,			September 30,			December 31,			Year Ended December 31,
2016:
Operating revenues	$	1,289,047		$	1,442,227		$	1,514,845		$	1,539,549		$	5,785,668
Costs of operations (1)	351,445			459,711			491,237			487,996			1,790,389
Operating income	451,853			432,806			479,074			489,296			1,853,029
Net income	281,307			192,464			263,735			232,853			970,359
Net income attributable to American Tower Corporation stockholders	275,159			187,550			264,509			229,207			956,425
Dividends on preferred stock	(26,781		)	(26,782		)	(26,781		)	(26,781		)	(107,125		)
Net income attributable to American Tower Corporation common stockholders	248,378			160,768			237,728			202,426			849,300
Basic net income per share attributable to American Tower Corporation common stockholders	0.59			0.38			0.56			0.48			2.00
Diluted net income per share attributable to American Tower Corporation common stockholders	0.58			0.37			0.55			0.47			1.98



	Three Months Ended												Year Ended December 31,
	March 31,			June 30,			September 30,			December 31,			Year Ended December 31,
2015:
Operating revenues	$	1,079,190		$	1,174,375		$	1,237,910		$	1,280,041		$	4,771,516
Costs of operations (1)	264,640			322,458			365,389			356,381			1,308,868
Operating income	419,966			389,774			400,925			402,124			1,612,789
Net income	195,492			157,180			97,740			221,595			672,007
Net income attributable to American Tower Corporation stockholders	193,317			156,056			102,999			232,702			685,074
Dividends on preferred stock	(9,819		)	(26,782		)	(26,781		)	(26,781		)	(90,163		)
Net income attributable to American Tower Corporation common stockholders	183,498			129,274			76,218			205,921			594,911
Basic net income per share attributable to American Tower Corporation common stockholders	0.45			0.31			0.18			0.49			1.42
Diluted net income per share attributable to American Tower Corporation common stockholders	0.45			0.30			0.18			0.48			1.41

_______________


(1)	Represents Operating expenses, exclusive of Depreciation, amortization and accretion, Selling, general, administrative and development expense, and Other operating expenses.

Business and Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) customers joint_venture shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Principles of Consolidation and Basis of Presentation:
Number of joint ventures with controlling interests \| joint_venture	2
Accounts Receivable and Deferred Rent Asset:
Number of customers, concentration of credit risk \| customers	4
Functional Currency:
Foreign currency transaction gain (loss), in AOCI and Income Statement	$ (153,900)
Foreign currency transaction gain (loss), reclassified as AOCI	105,000
Foreign currency transaction loss	(48,900)
Property and Equipment:
Labor costs capitalized	47,700	$ 44,700	$ 48,500
Interest costs capitalized	1,500	1,800	2,800
Other Comprehensive Income (Loss):
Accumulated other comprehensive loss	(1,999,332)	(1,836,996)
Revenue Recognition:
Straight line revenue	131,700	155,000	123,700
Rent Expense:
Straight-line ground rent expense	$ 67,800	$ 56,100	$ 38,400
Share-based Compensation:
Shares paid for tax withholding for share based compensation \| shares	1,219,755
Retirement Plan:
Employers percentage of employees first 6 percent	75.00%	75.00%	75.00%
Employee maximum annual contribution eligible for match	6.00%	6.00%	6.00%
Company's contribution	$ 9,100	$ 7,400	$ 6,500
New accounting pronouncement, percent of revenues effected	12.00%
Performance Shares
Share-based Compensation:
Vesting period	3 years
Performance Shares \| 2007 Plan
Share-based Compensation:
Vesting period	3 years
Restricted Stock
Share-based Compensation:
Shares paid for tax withholding for share based compensation \| shares	218,063
Restricted Stock \| 2007 Plan
Share-based Compensation:
Vesting period	4 years
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
Principles of Consolidation and Basis of Presentation:
Reclassification from accumulated other comprehensive income	$ (9,100)
Foreign Currency Items
Other Comprehensive Income (Loss):
Accumulated other comprehensive loss	$ 2,000,000	$ 1,800,000	$ 800,000
Maximum
Goodwill and Other Intangible Assets:
Estimated useful life of respective assets	20 years
Maximum \| Performance Shares
Share-based Compensation:
Percentage of potential target shares	200.00%
Minimum
Goodwill and Other Intangible Assets:
Estimated useful life of respective assets	3 years
Minimum \| Performance Shares
Share-based Compensation:
Percentage of potential target shares	0.00%
Sales Revenue, Net \| Customer Concentration Risk
Accounts Receivable and Deferred Rent Asset:
Concentration risk, percentage	10.00%	10.00%	10.00%
Uganda \| Corporate Joint Venture
Principles of Consolidation and Basis of Presentation:
Company's ownership percentage	51.00%
Noncontrolling owners, ownership percentage	49.00%
Ghana \| Corporate Joint Venture
Principles of Consolidation and Basis of Presentation:
Company's ownership percentage	51.00%
Noncontrolling owners, ownership percentage	49.00%
South Africa \| Corporate Joint Venture
Principles of Consolidation and Basis of Presentation:
Company's ownership percentage	75.00%
Noncontrolling owners, ownership percentage	25.00%
ATC Europe
Principles of Consolidation and Basis of Presentation:
Noncontrolling owners, ownership percentage	49.00%
Company's ownership percentage	51.00%
ATC, TIPL
Principles of Consolidation and Basis of Presentation:
Company's ownership percentage	51.00%
Other Acquisition 2016
Principles of Consolidation and Basis of Presentation:
Company's ownership percentage	49.00%
Four Customers \| Sales Revenue, Net \| Customer Concentration Risk
Accounts Receivable and Deferred Rent Asset:
Concentration risk, percentage	56.00%

Business and Summary of Significant Accounting Policies (Changes in Allowances) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance as of January 1	$ 23,096	$ 17,306	$ 19,895
Current year increases	49,966	19,878	8,243
Write-offs, net of recoveries and other	(27,174)	(14,088)	(10,832)
Balance as of December 31	$ 45,888	$ 23,096	$ 17,306

Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid operating ground leases	$ 134,167	$ 128,542
Prepaid income tax	127,142	45,056
Unbilled receivables	57,661	34,173
Prepaid assets	36,300	32,892
Value added tax and other consumption tax receivables	31,570	30,239
Other miscellaneous current assets	54,193	35,333
Prepaids and other current assets	$ 441,033	$ 306,235

Property and Equipment (Property and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Towers	$ 11,740,479	$ 10,726,656
Equipment	1,176,260	1,095,906
Buildings and improvements	621,874	607,661
Land and improvements	1,909,732	1,728,115
Construction-in-progress	203,411	238,960
Total	15,651,756	14,397,298
Less accumulated depreciation	(5,134,498)	(4,530,874)
Property and equipment, net	$ 10,517,258	$ 9,866,424
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Tower \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Buildings and Improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Buildings and Improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	32 years
Land and Improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years

Property and Equipment (Narrative) (Details) $ in Millions		12 Months Ended
Property and Equipment (Narrative) (Details) $ in Millions	Dec. 08, 2016 tower	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Depreciation expense		$ 758.9	$ 661.4	$ 551.8
Capital Leased Assets, Number of Units Acquired Through Purchase Option \| tower	1,523
Assets Held under Capital Leases
Property, Plant and Equipment [Line Items]
Capital leases, which are primarily classified as towers or land and improvements		4,735.3	5,112.4
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation		$ 1,198.0	$ 1,414.6

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 699.8	$ 568.3	$ 411.7
Weighted Average
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, remaining amortization period	16 years

Goodwill and Other Intangible Assets (Rollforward) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 4,091,805	$ 4,032,174
Additions	975,744	214,685
Effect of foreign currency translation	3,131	(155,054)
Goodwill, ending balance	5,070,680	4,091,805
Services
Goodwill [Roll Forward]
Goodwill, beginning balance	1,988	1,988
Additions	0	0
Effect of foreign currency translation	0	0
Goodwill, ending balance	1,988	1,988
United States \| Property
Goodwill [Roll Forward]
Goodwill, beginning balance	3,379,163	3,356,096
Additions	0	23,067
Effect of foreign currency translation	0	0
Goodwill, ending balance	3,379,163	3,379,163
Asia \| Property
Goodwill [Roll Forward]
Goodwill, beginning balance	170,719	178,521
Additions	881,783	610
Effect of foreign currency translation	(23,189)	(8,412)
Goodwill, ending balance	1,029,313	170,719
EMEA \| Property
Goodwill [Roll Forward]
Goodwill, beginning balance	132,570	78,647
Additions	40,386	68,663
Effect of foreign currency translation	(22,445)	(14,740)
Goodwill, ending balance	150,511	132,570
Latin America \| Property
Goodwill [Roll Forward]
Goodwill, beginning balance	407,365	416,922
Additions	53,575	122,345
Effect of foreign currency translation	48,765	(131,902)
Goodwill, ending balance	509,705	$ 407,365
Additions 2016
Goodwill [Roll Forward]
Additions	975,600
Goodwill, Impaired, Adjustment to Initial Estimate Amount	$ 100

Goodwill and Other Intangible Assets (Changes in the Carrying Value of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 14,794,815	$ 12,670,816
Accumulated Amortization	(3,520,204)	(2,832,940)
Net Book Value	11,274,611	9,837,876
Acquired network location intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	4,622,316	3,980,281
Accumulated Amortization	(1,280,284)	(1,052,393)
Net Book Value	$ 3,342,032	$ 2,927,888
Acquired network location intangibles \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	20 years	20 years
Acquired tenant-related intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 10,130,466	$ 8,640,554
Accumulated Amortization	(2,224,119)	(1,763,853)
Net Book Value	$ 7,906,347	6,876,701
Acquired tenant-related intangibles \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	15 years
Acquired tenant-related intangibles \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	20 years
Acquired licenses and other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 28,140	28,293
Accumulated Amortization	(4,827)	(5,486)
Net Book Value	$ 23,313	22,807
Acquired licenses and other intangibles \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	3 years
Acquired licenses and other intangibles \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	20 years
Economic Rights, TV Azteca
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 13,893	21,688
Accumulated Amortization	(10,974)	(11,208)
Net Book Value	$ 2,919	$ 10,480
Finite-lived intangible asset, useful life	70 years

Goodwill and Other Intangible Assets (Expected Future Amortization Expenses) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2017	$ 710.5
2018	707.8
2019	705.1
2020	686.3
2021	$ 676.8

Notes Receivable and Other Non-Current Assets (Narrative) (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2000 USD ($)	Dec. 31, 2000 USD ($) communications_site	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Economic Rights, TV Azteca
Notes Receivable And Other NonCurrent Assets [Line Items]
Term of the loan, years		70 years
Loan prepayment without penalty, period, years	50 years
Number of broadcast towers \| communications_site		190
Commercial rights, annual payment	$ 1,500,000	$ 1,500,000
Percentage of the revenues from leasing of towers		100.00%
Capital lease, liability	18,600,000	$ 18,600,000
Capital lease, asset	18,600,000	18,600,000
Capital lease asset and discount on note	30,200,000	30,200,000
TV Azteca
Notes Receivable And Other NonCurrent Assets [Line Items]
Loans receivable	$ 119,800,000	$ 119,800,000	$ 91,800,000	$ 91,800,000
Loan interest rate		13.11%
Term of the loan, years		70 years
Loan prepayment without penalty, period, years		50 years
Loans receivable, net of discount			82,900,000	$ 82,900,000
Repayment of Principal \| TV Azteca
Notes Receivable And Other NonCurrent Assets [Line Items]
Loans receivable			$ 28,000,000

Notes Receivable and Other Non-Current Assets (Notes Receivable and Other Non-Current Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Notes Receivable And Other Long Term Assets [Abstract]
Long-term prepaid ground rent	$ 467,781	$ 388,790
Notes receivable	83,736	83,658
Other miscellaneous assets	290,006	260,455
Notes receivable and other non-current assets	$ 841,523	$ 732,903

Acquisitions (Narrative) (Details) € in Millions, ₨ in Billions											9 Months Ended	12 Months Ended
	Feb. 15, 2017 USD ($) communications_site	Feb. 15, 2017 EUR (€) communications_site	Apr. 21, 2016 USD ($) site system	Apr. 21, 2016 INR (₨)	Mar. 17, 2016 USD ($) site	Dec. 16, 2015 USD ($) communications_site	Sep. 30, 2015 USD ($) communications_site	Jul. 01, 2015 USD ($)	Apr. 29, 2015 USD ($) communications_site	Mar. 27, 2015 USD ($) yr	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) site	Dec. 31, 2015 USD ($) communications_site	Dec. 31, 2014 USD ($)	Apr. 21, 2016 INR (₨) site system	Mar. 27, 2015 communications_site	Mar. 27, 2015 site	Mar. 27, 2015 Rate
Business Acquisition [Line Items]
Business combination, pro forma information, revenue of acquiree since acquisition date, actual											$ 567,900,000
Business combination pro forma information gross margin of acquiree since acquisition date actual											241,100,000
Initial lease term												10 years
Contingent consideration												$ 15,444,000	$ 12,436,000	$ 28,524,000
Value added tax and other consumption tax receivables												31,570,000	30,239,000
Fair value of debt assumed through acquisitions												786,889,000	0	463,135,000
Redeemable noncontrolling interest												1,091,220,000	0
Accounts payable												118,666,000	$ 96,714,000
Verizon Transaction
Business Acquisition [Line Items]
Number of communications sites acquired																11,449	163
Aggregate purchase price										$ 5,066,000,000
Verizon Transaction \| Leased Sites
Business Acquisition [Line Items]
Capital leased assets, number of units \| communications_site																11,286
Right to lease, weighted average term										28 years
Initial lease term										10 years
Successive terms to renew lease \| yr										8
Renewal term										5 years
Future monthly sublease rent per tower										$ 1,900
Fixed annual rent escalation percentage \| Rate																		2.00%
Verizon Transaction \| Owned Sites
Business Acquisition [Line Items]
Number of communications sites acquired \| communications_site																163
Airtel Acquisition
Business Acquisition [Line Items]
Number of communications sites acquired \| communications_site													4,716
Airtel Acquisition \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price								$ 1,112,000,000
TIM Acquisition
Business Acquisition [Line Items]
Number of communications sites acquired \| communications_site						182	1,125		4,176
Adjustment, consideration transferred											$ (800,000)
Preferred stock assumed through acquisitions												796,048,000
Noncash or part noncash acquisition, value of liabilities assumed													$ 0
TIM Acquisition \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price						$ 21,700,000	$ 130,900,000		$ 644,300,000
Preferred stock assumed through acquisitions														796,867,000
Noncash or part noncash acquisition, value of liabilities assumed													$ 0
Other International Acquisitions 2015
Business Acquisition [Line Items]
Number of communications sites acquired \| communications_site													439
Contingent consideration													$ 300,000
Other Acquisition 2015 \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price													22,500,000
Preferred stock assumed through acquisitions														$ 164,875,000
Noncash or part noncash acquisition, value of liabilities assumed													0
Other Acquisition 2015 \| Adjusted Purchase Price Allocation
Business Acquisition [Line Items]
Adjustment, consideration transferred												(200,000)
Preferred stock assumed through acquisitions													164,706,000
Noncash or part noncash acquisition, value of liabilities assumed													$ 0
Other Us Acquisition 2015
Business Acquisition [Line Items]
Number of communications sites acquired \| communications_site													210
Aggregate purchase price													$ 142,400,000
Contingent consideration													$ 1,300,000
Number of property interests acquired \| communications_site													4
Viom Transaction
Business Acquisition [Line Items]
Number of communications sites acquired \| site			42,000												42,000
Distributed antenna systems acquired \| system			200												200
Percentage of voting interest acquired			51.00%												51.00%
Fair value of debt assumed through acquisitions			$ 800,000,000	₨ 52.3
Viom Transaction \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price			1,100,000,000	₨ 76.4
Fair value of debt assumed through acquisitions												$ 786,889,000
Viom Transaction \| Mandatorily Redeemable Preferred Stock
Business Acquisition [Line Items]
Redeemable noncontrolling interest			$ 25,100,000												₨ 1.7
Other Acquisition 2016
Business Acquisition [Line Items]
Number of communications sites acquired \| site												891
Aggregate purchase price												$ 304,400,000
Contingent consideration, liability, noncurrent												8,800,000
Accounts payable												12,100,000
Other Acquisition 2016 \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Fair value of debt assumed through acquisitions												$ 0
Airtel Tanzania
Business Acquisition [Line Items]
Number of communications sites acquired \| site					1,350
Airtel Tanzania \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price					$ 179,000,000
Additional sites to be acquired \| site					100
Acquired Network Location \| Maximum
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life												20 years	20 years
Subsequent Event \| FPS Towers [Member]
Business Acquisition [Line Items]
Percentage of voting interest acquired	100.00%	100.00%
Subsequent Event \| FPS Towers [Member] \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price	$ 757,100,000	€ 713.9
Additional sites to be acquired \| communications_site	2,400	2,400

Acquisitions (Merger and Integration Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Acquisition and merger related expenses	$ 15,875	$ 18,799	$ 26,969
Integration costs	$ 9,901	$ 18,097	$ 13,057

Acquisitions (Schedule of Aggregate Purchase Consideration Paid and the Amount of Assets Acquired) (Details) $ in Thousands, ₨ in Billions								12 Months Ended
	Apr. 21, 2016 USD ($)	Apr. 21, 2016 INR (₨)	Dec. 16, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jul. 01, 2015 USD ($)	Apr. 29, 2015 USD ($)	Mar. 27, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Goodwill								$ 5,070,680	$ 4,091,805	$ 4,032,174
Debt assumed								$ (786,889)	$ 0	(463,135)
Maximum \| Acquired Network Location
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life								20 years	20 years
Maximum \| Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life								20 years
Viom Transaction
Business Acquisition [Line Items]
Debt assumed	$ (800,000)	₨ (52.3)
Viom Transaction \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price	$ 1,100,000	₨ 76.4
Current assets								$ 276,560
Non-current assets								57,645
Property and equipment								701,988
Current liabilities								(195,900)
Deferred tax liability								(619,070)
Other non-current liabilities								(102,751)
Net assets acquired								2,154,416
Goodwill								881,783
Fair value of net assets acquired								3,036,199
Debt assumed								(786,889)
Redeemable noncontrolling interests								(1,100,804)
Purchase Price								1,148,506
Viom Transaction \| Preliminary Purchase Price Allocation \| Tenant-related intangible assets
Business Acquisition [Line Items]
Customer-related intangible assets								1,369,580
Viom Transaction \| Preliminary Purchase Price Allocation \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets								666,364
Verizon Transaction
Business Acquisition [Line Items]
Aggregate purchase price							$ 5,066,000
Airtel Acquisition \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price					$ 1,112,000
TIM Acquisition
Business Acquisition [Line Items]
Current assets								0
Non-current assets								0
Property and equipment								274,530
Current liabilities								(3,192)
Other non-current liabilities								(74,966)
Net assets acquired								673,932
Goodwill								122,116
Fair value of net assets acquired								796,048
Noncash or part noncash acquisition, value of liabilities assumed									$ 0
Preferred stock assumed through acquisitions								(796,048)
TIM Acquisition \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets								115,795
TIM Acquisition \| Customer Relationships
Business Acquisition [Line Items]
Customer-related intangible assets								361,765
TIM Acquisition \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price			$ 21,700	$ 130,900		$ 644,300
Current assets										0
Non-current assets										0
Property and equipment										275,630
Current liabilities										(3,192)
Other non-current liabilities										(74,966)
Net assets acquired										674,856
Goodwill										122,011
Fair value of net assets acquired										796,867
Noncash or part noncash acquisition, value of liabilities assumed									0
Preferred stock assumed through acquisitions										(796,867)
TIM Acquisition \| Preliminary Purchase Price Allocation \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets										115,562
TIM Acquisition \| Preliminary Purchase Price Allocation \| Customer Relationships
Business Acquisition [Line Items]
Customer-related intangible assets										361,822
Other Acquisition 2016
Business Acquisition [Line Items]
Aggregate purchase price								304,400
Other Acquisition 2016 \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Current assets								25,477
Non-current assets								2,336
Property and equipment								81,521
Current liabilities								(14,782)
Deferred tax liability								(43,756)
Other non-current liabilities								(29,472)
Net assets acquired								210,526
Goodwill								93,856
Fair value of net assets acquired								304,382
Debt assumed								0
Redeemable noncontrolling interests								0
Purchase Price								304,382
Other Acquisition 2016 \| Preliminary Purchase Price Allocation \| Tenant-related intangible assets
Business Acquisition [Line Items]
Customer-related intangible assets								105,557
Other Acquisition 2016 \| Preliminary Purchase Price Allocation \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets								$ 83,645
Other Acquisition 2015 \| Preliminary Purchase Price Allocation
Business Acquisition [Line Items]
Aggregate purchase price									22,500
Current assets										1,113
Non-current assets										995
Property and equipment										42,716
Current liabilities										(624)
Other non-current liabilities										(4,028)
Net assets acquired										140,864
Goodwill										24,011
Fair value of net assets acquired										164,875
Noncash or part noncash acquisition, value of liabilities assumed									0
Preferred stock assumed through acquisitions										(164,875)
Other Acquisition 2015 \| Preliminary Purchase Price Allocation \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets										37,691
Other Acquisition 2015 \| Preliminary Purchase Price Allocation \| Customer Relationships
Business Acquisition [Line Items]
Customer-related intangible assets										$ 63,001
Other Acquisition 2015 \| Adjusted Purchase Price Allocation
Business Acquisition [Line Items]
Current assets									1,113
Non-current assets									995
Property and equipment									42,716
Current liabilities									(624)
Other non-current liabilities									(4,028)
Net assets acquired									140,695
Goodwill									24,011
Fair value of net assets acquired									164,706
Noncash or part noncash acquisition, value of liabilities assumed									0
Preferred stock assumed through acquisitions									(164,706)
Other Acquisition 2015 \| Adjusted Purchase Price Allocation \| Acquired Network Location
Business Acquisition [Line Items]
Customer-related intangible assets									37,691
Other Acquisition 2015 \| Adjusted Purchase Price Allocation \| Customer Relationships
Business Acquisition [Line Items]
Customer-related intangible assets									$ 62,832

Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2016
Business Combinations [Abstract]
Business Acquisition, Pro Forma Revenue	$ 6,055,187	$ 5,886,691
Business Acquisition, Pro Forma Net Income (Loss)	$ 847,738	$ 544,641
Business Acquisition, Pro Forma Information [Abstract]
Basic net income attributable to American Tower Corporation (in dollars per share)	$ 1.99	$ 1.29
Diluted net income attributable to American Tower Corporation (in dollars per share)	$ 1.97	$ 1.27

Acquisitions - Schedule Of Business Acquisitions By Acquisition Contingent Consideration (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Fair value of debt assumed through acquisitions	$ 786,889,000	$ 0	$ 463,135,000
Contingent consideration, maximum potential value	46,795,987
Contingent consideration	15,444,000	12,436,000	$ 28,524,000
Contingent consideration, additions	8,811,000
Contingent consideration, settlements	(306,000)
Change in fair value	(6,372,000)	$ (4,781,000)
Colombia
Business Acquisition [Line Items]
Contingent consideration, maximum potential value	23,557,000
Contingent consideration	5,342,000
Contingent consideration, additions	0
Contingent consideration, settlements	0
Change in fair value	(4,964,000)
Ghana
Business Acquisition [Line Items]
Contingent consideration, maximum potential value	555,000
Contingent consideration	555,000
Contingent consideration, additions	0
Contingent consideration, settlements	0
Change in fair value	47,000
India
Business Acquisition [Line Items]
Contingent consideration, maximum potential value	0
Contingent consideration	0
Contingent consideration, additions	0
Contingent consideration, settlements	0
Change in fair value	(161,000)
Costa Rica
Business Acquisition [Line Items]
Contingent consideration, maximum potential value	22,291,000
Contingent consideration	9,154,000
Contingent consideration, settlements	0
South Africa
Business Acquisition [Line Items]
Contingent consideration, additions	8,692,000
United States
Business Acquisition [Line Items]
Contingent consideration, maximum potential value	393,000
Contingent consideration	393,000
Contingent consideration, additions	119,000
Contingent consideration, settlements	(306,000)
Change in fair value	$ (1,294,000)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities, Current [Abstract]
Accrued property and real estate taxes	$ 138,361	$ 75,827
Payroll and related withholdings	76,141	62,334
Accrued rent	50,951	54,732
Amounts payable to tenants	32,326	58,683
Accrued construction costs	28,587	19,857
Accrued income tax payable	11,551	11,704
Other accrued expenses	282,646	233,276
Accrued expenses	$ 620,563	$ 516,413

Long-Term Obligations (Narrative) (Details) ₨ / shares in Units, ₨ in Millions, BRL in Millions, COP in Billions							1 Months Ended		12 Months Ended
	Feb. 15, 2017 USD ($)	Dec. 23, 2016 ZAR	Sep. 30, 2016 USD ($)	May 13, 2016 USD ($)	Jan. 12, 2016 USD ($)	May 29, 2015 USD ($) tower	Oct. 28, 2016 USD ($)	Mar. 31, 2013 USD ($) tower	Dec. 31, 2016 USD ($) installment quarter renewal_period Class shares	Dec. 31, 2015 USD ($) quarter renewal_period	Dec. 31, 2014 USD ($)	Jan. 01, 2017 USD ($)	Dec. 31, 2016 INR (₨) quarter ₨ / shares shares	Dec. 31, 2016 COP quarter shares	Dec. 31, 2016 BRL quarter shares	Dec. 31, 2016 ZAR quarter shares	Dec. 31, 2015 BRL quarter	Dec. 31, 2015 ZAR quarter	Jan. 23, 2015 ZAR	Nov. 30, 2014 BRL	Jan. 10, 2014	Dec. 31, 2013 USD ($)	Aug. 19, 2013
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 18,533,465,000
Valuation allowance									144,397,000	$ 136,952,000	$ 141,241,000											$ 136,006,000
Proceeds from issuance of senior notes, net									3,236,383,000	1,492,298,000	1,415,844,000
Fair value of debt assumed through acquisitions									786,889,000	0	463,135,000
Interest costs capitalized									1,500,000	1,800,000	2,800,000
Borrowings under credit facilities									$ 2,446,845,000	6,126,618,000	2,187,000,000
Annual renewal periods, number \| renewal_period									2
Extinguishment of Debt, Gain (Loss), Net of Tax									$ 1,168,000	(79,750,000)	(3,379,000)
Accrued interest									157,297,000	115,672,000
Gain (loss) on retirement of long-term obligations									$ 1,168,000	(79,606,000)	$ (3,473,000)
Capital lease obligation and notes payable, interest rate, maximum									9.50%				9.50%	9.50%	9.50%	9.50%
Capital Lease Obligation And Notes Payable Interest Mature In Periods Minimum									1 year
Capital lease obligation and notes payable, maturity, maximum									70 years
Capital Lease Obligations									$ 135,800,000	110,900,000
Capital Lease Obligation And Notes Payable Interest Rates Ranging Minimum									2.40%				2.40%	2.40%	2.40%	2.40%
Third measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA									6.00				6.00	6.00	6.00	6.00
Fourth measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA									7.00				7.00	7.00	7.00	7.00
Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Borrowing Capacity of EBITDA									50.00%				50.00%	50.00%	50.00%	50.00%
Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 286,009,000	219,902,000
Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage									100.00%
Maximum Adjusted EBITDA									3.5				3.5	3.5	3.5	3.5
Repurchase price as a percentage of principal									101.00%				101.00%	101.00%	101.00%	101.00%
BR Towers Debentures
Debt Instrument [Line Items]
Debt Instrument, Issuer Shares Used In Securitization, Percent									100.00%
BR Towers Debentures \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 101,000,000	85,200,000					BRL 329.3		BRL 332.8
Long-term debt, stated interest rate									7.40%				7.40%	7.40%	7.40%	7.40%
BR Towers Debentures \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016 \| BRL																				BRL 300.0
Uganda Loan \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 79,998,000	$ 75,226,000
Long-term debt, stated interest rate									16.60%				16.60%	16.60%	16.60%	16.60%
Interest costs capitalized									$ 4,800,000
Debt instrument, interest rate, effective Percentage									6.52%				6.52%	6.52%	6.52%	6.52%
Viom Debenture \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 88,300,000				₨ 6,000
Long-term debt, stated interest rate									9.90%				9.90%	9.90%	9.90%	9.90%
Viom Debenture \| Secured Debt \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate									0.60%
Debt Instrument, Basis Spread On Variable Rate, Reset Rate									10.00%
Debt Instrument, Basis Spread On Variable Rate, Reset Period One									36 months
Debt Instrument, Basis Spread On Variable Rate, Reset Period Two									48 months
Viom Debenture \| Secured Debt \| Minimum \| Base Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread On Variable Rate, Reset Threshold									9.75%
Viom Debenture \| Secured Debt \| Maximum \| Base Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread On Variable Rate, Reset Threshold									10.25%
Commercial Mortgage Pass Through Certificates Series 2013 \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016								$ 1,800,000,000
Number of broadcast and wireless communications towers \| tower								5,181
Weighted average life, years								8 years 7 months 6 days
Debt, weighted average interest rate								2.648%
Cash trap debt service credit ratio									1.30	1.3			1.30	1.30	1.30	1.30	1.3	1.3
Number of consecutive quarters required for release of funds \| quarter									2	2			2	2	2	2	2	2
Minimum, DSCR									1.15	1.15			1.15	1.15	1.15	1.15	1.15	1.15
Threshold for majority of holders in event of default									50.00%
Restricted cash									$ 82,700,000
Proceeds from issuance of senior notes, net								$ 1,780,000,000
Secured Tower Revenue Securities, Series 2013-1A
Debt Instrument [Line Items]
Period during which no prepayment consideration is due, period									12 months
Secured Tower Revenue Securities, Series 2013-2A
Debt Instrument [Line Items]
Period during which no prepayment consideration is due, period									18 months
Series 2015-1 Class A \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016						$ 350,000,000			$ 347,108,000	$ 346,262,000
Long-term debt, stated interest rate									2.35%				2.35%	2.35%	2.35%	2.35%
Series 2015-2 Class A \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016						$ 525,000,000			$ 519,437,000	518,776,000
Long-term debt, stated interest rate									3.482%				3.482%	3.482%	3.482%	3.482%
Commercial Mortgage Pass Through Certificates Series 2015 \| Secured Debt
Debt Instrument [Line Items]
Number of broadcast and wireless communications towers \| tower						3,596
Weighted average life, years						8 years 1 month 6 days
Debt, weighted average interest rate						3.029%
Restricted cash									$ 16,800,000
Series 2012-1 Class A Notes \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt									$ 94,100,000
GTP Notes
Debt Instrument [Line Items]
Long-term Debt, Repayment Terms, Number of Site Released Upon Repayment \| Class									472
GTP Notes \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 179,459,000	281,902,000
Principal amount									173,700,000
Debt instrument, unamortized premium									$ 5,700,000
GTP Notes \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									4.336%				4.336%	4.336%	4.336%	4.336%
GTP Notes \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									7.358%				7.358%	7.358%	7.358%	7.358%
Secured Cellular Site Revenue Notes \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 132,960,000	201,930,000
Principal amount									129,000,000
Debt instrument, unamortized premium									$ 4,000,000
Secured Cellular Site Revenue Notes \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									6.392%				6.392%	6.392%	6.392%	6.392%
Secured Cellular Site Revenue Notes \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									9.522%				9.522%	9.522%	9.522%	9.522%
Viom Term Loan \| Secured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 461,200,000				₨ 31,326
Viom Term Loan \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Debt Instrument, Term									1 year
Long-term debt, stated interest rate									8.15%				8.15%	8.15%	8.15%	8.15%
Debt Instrument, Prepayment Penalty, Percent Of Principal									1.00%
Debt Instrument, Payment Terms, Repayment Period									6 months
Viom Term Loan \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Debt Instrument, Term									10 years
Long-term debt, stated interest rate									11.15%				11.15%	11.15%	11.15%	11.15%
Debt Instrument, Prepayment Penalty, Percent Of Principal									2.00%
Debt Instrument, Payment Terms, Repayment Period									36 months
Series 2010-1 Class C \| Secured Debt
Debt Instrument [Line Items]
Repayments of senior debt							$ 67,000,000
Viom preferred shares \| Mandatorily Redeemable Preferred Stock
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 24,537,000
Long-term debt, stated interest rate									13.50%				13.50%	13.50%	13.50%	13.50%
Debt Instrument, Redemption Price, Percentage									2.00%
Preferred stock, shares outstanding \| shares									166,666,666				166,666,666	166,666,666	166,666,666	166,666,666
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Maximum Amount									$ 24,500,000				₨ 1,670
Preferred Stock, Number Of Redemption Installments \| installment									2
Preferred Stock, Redemption Price Per Share \| ₨ / shares													₨ 10
Preferred Stock, Dividend Rate, Percentage									13.50%
South African Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Balance as of December 31, 2016 \| ZAR																			ZAR 830,000,000
Long-term debt, stated interest rate									9.308%				9.308%	9.308%	9.308%	9.308%
Long-term line of credit									$ 84,300,000	53,200,000						ZAR 1,164,000,000		ZAR 830,000,000
South African Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Borrowings under credit facilities \| ZAR		ZAR 500,000,000
South African Facility \| Unsecured Debt
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity \| ZAR																ZAR 330,000,000.0
Ghana Loan \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 71,047,000	70,314,000
Long-term debt, stated interest rate									21.87%				21.87%	21.87%	21.87%	21.87%
Line of credit facility, maximum borrowing capacity									$ 300,900,000
2014 Colombian Long Term Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Balance as of December 31, 2016 \| COP														COP 200.0
Credit Facility 2014 \| Swingline Loan
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity									50,000,000
Credit Facility 2014 \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity									2,000,000,000
Principal amount									1,385,000,000
Long-term line of credit									1,385,000,000	$ 1,980,000,000
Borrowings under credit facilities									245,000,000
Line of credit facility, maximum borrowing capacity									3,000,000,000.00
Repayment of indebtedness under credit facility									840,000,000
Letters of credit, amount outstanding									$ 7,300,000
Annual renewal periods, number \| renewal_period										2
Line of credit facility, commitment fee percentage									0.15%	0.15%
Debt instrument, interest rate, effective Percentage									2.432%				2.432%	2.432%	2.432%	2.432%
Credit Facility 2014 \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Principal amount									$ 1,095,000,000
Basis spread on variable rate									1.25%
Credit Facility 2014 \| Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Principal amount									$ 290,000,000
Basis spread on variable rate									0.25%
Credit Facility 2014 \| Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage										0.10%
Credit Facility 2014 \| Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage										0.40%
Credit Facility 2014 \| Unsecured Debt \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate										1.00%
Credit Facility 2014 \| Unsecured Debt \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate										2.00%
Credit Facility 2014 \| Unsecured Debt \| Maximum \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate										1.00%
India Indebtedness \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									8.15%				8.15%	8.15%	8.15%	8.15%
India Indebtedness \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Long-term debt, stated interest rate									11.70%				11.70%	11.70%	11.70%	11.70%
India Indebtedness \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 549,528,000	$ 8,752,000
Term Loan 2013 \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate									1.25%
Term Loan 2013 \| Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate									0.25%
Term Loan 2013 \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 993,936,000	$ 1,993,601,000
Principal amount									1,000,000,000
Letters of credit, amount outstanding									$ 0
Debt instrument, interest rate, effective Percentage									2.02%				2.02%	2.02%	2.02%	2.02%
Repayments of Long-term Debt									$ 1,000,000,000
Term Loan 2013 \| Unsecured Debt \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Basis for Effective Rate									0.01
Term Loan 2013 \| Unsecured Debt \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Basis for Effective Rate									0.02
Term Loan 2013 \| Unsecured Debt \| Maximum \| Base Rate
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Basis for Effective Rate									0.01
Term Loan 2013 \| Unsecured Debt \| Third measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA										7.00							7.00	7.00
Term Loan 2013 \| Unsecured Debt \| Fourth measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA										6.00							6.00	6.00
Credit Facility 2013 \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity									$ 2,750,000,000
Principal amount									540,000,000
Long-term line of credit									539,975,000	$ 1,225,000,000
Borrowings under credit facilities									1,900,000,000
Line of credit facility, maximum borrowing capacity									4,250,000,000.00
Repayment of indebtedness under credit facility									2,600,000,000
Letters of credit, amount outstanding									$ 3,200,000
Line of credit facility, commitment fee percentage									0.15%
Debt instrument, interest rate, effective Percentage									1.963%				1.963%	1.963%	1.963%	1.963%
Credit Facility 2013 \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate									1.25%
Credit Facility 2013 \| Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate									0.25%
Credit Facility 2013 \| Revolving Credit Facility \| Third measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA										7.00							7.00	7.00
Credit Facility 2013 \| Revolving Credit Facility \| Fourth measurement period
Debt Instrument [Line Items]
Ratio of total debt to EBITDA										6.00							6.00	6.00
Credit Facility 2013 \| Unsecured Debt \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate										1.00%
Credit Facility 2013 \| Unsecured Debt \| Maximum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate										2.00%
Credit Facility 2013 \| Unsecured Debt \| Maximum \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate										1.00%
3.300% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 744,762,000	$ 0
Long-term debt, stated interest rate					3.30%				3.30%				3.30%	3.30%	3.30%	3.30%
Principal amount					$ 750,000,000					750,000,000
4.400% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 495,212,000	0
Long-term debt, stated interest rate					4.40%				4.40%				4.40%	4.40%	4.40%	4.40%
Principal amount					$ 500,000,000					750,000,000
Three point three zero and four point four zero percent senior notes [Member] \| Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of senior notes, net					$ 1,237,200,000
2.800% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 744,917,000	743,557,000
Long-term debt, stated interest rate									2.80%				2.80%	2.80%	2.80%	2.80%
Principal amount										750,000,000
4.000% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 739,985,000	739,057,000
Long-term debt, stated interest rate									4.00%				4.00%	4.00%	4.00%	4.00%
Principal amount										500,000,000
3.40% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 999,716,000	999,769,000
Long-term debt, stated interest rate									3.40%				3.40%	3.40%	3.40%	3.40%					3.40%		3.40%
Principal amount										1,000,000,000
5.00% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 1,002,742,000	1,003,453,000
Long-term debt, stated interest rate									5.00%				5.00%	5.00%	5.00%	5.00%					5.00%		5.00%
Principal amount										1,000,000,000
3.375% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 983,369,000	0
Long-term debt, stated interest rate				3.375%					3.375%				3.375%	3.375%	3.375%	3.375%
Proceeds from issuance of senior notes, net				$ 981,500,000
Principal amount				$ 1,000,000,000						1,000,000,000
2.250% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 572,764,000	0
Long-term debt, stated interest rate			2.25%						2.25%				2.25%	2.25%	2.25%	2.25%
Interest rate swap agreements									$ 22,300,000
Principal amount			$ 600,000,000							600,000,000
Debt instrument, interest rate, effective Percentage									1.97%				1.97%	1.97%	1.97%	1.97%
3.125% senior notes \| Senior Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 396,713,000	0
Long-term debt, stated interest rate			3.125%						3.125%				3.125%	3.125%	3.125%	3.125%
Proceeds from issuance of senior notes, net			$ 990,600,000
Principal amount			$ 400,000,000							400,000,000
Subsidiaries
Debt Instrument [Line Items]
Balance as of December 31, 2016									$ 3,978,992,000	$ 3,509,231,000
Subsidiaries \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity									2,250,000,000
Multicurrency Borrowings \| Credit Facility 2013 \| Revolving Credit Facility
Debt Instrument [Line Items]
Capacity available for specific purpose other than for trade purchases									1,000,000,000
Letter of Credit \| Credit Facility 2014 \| Revolving Credit Facility
Debt Instrument [Line Items]
Capacity available for specific purpose other than for trade purchases									200,000,000
Letter of Credit \| Credit Facility 2013 \| Revolving Credit Facility
Debt Instrument [Line Items]
Capacity available for specific purpose other than for trade purchases									200,000,000
Swingline Loan \| Credit Facility 2013 \| Revolving Credit Facility
Debt Instrument [Line Items]
Capacity available for specific purpose other than for trade purchases									50,000,000
Unison \| Secured Cellular Site Revenue Notes \| Secured Debt
Debt Instrument [Line Items]
Principal amount									$ 196,000,000
Subsequent Event \| Uganda Loan \| Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016												$ 31,800,000
Subsequent Event \| GTP Notes \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt	$ 173,500,000
Gain (loss) on retirement of long-term obligations	1,800,000
Subsequent Event \| Secured Cellular Site Revenue Notes \| Secured Debt
Debt Instrument [Line Items]
Repayments of secured debt	129,000,000
Gain (loss) on retirement of long-term obligations	$ 14,500,000

Long-Term Obligations (Long-Term Financing Arrangements) (Details) $ in Thousands			1 Months Ended	12 Months Ended
	Feb. 15, 2017 USD ($)	Feb. 10, 2017 USD ($)	Oct. 28, 2016 USD ($)	Dec. 31, 2016 USD ($) Class	Jan. 01, 2017 USD ($)	Sep. 30, 2016	May 13, 2016	Jan. 12, 2016	Dec. 31, 2015 USD ($)	May 29, 2015 USD ($)	Jan. 10, 2014	Aug. 19, 2013	Mar. 31, 2013 USD ($)
Debt Instrument [Line Items]
Debt, long-term and short-term, combined amount				$ 18,533,465					$ 17,119,009
Less current portion long-term obligations				(238,806)					(50,202)
Balance as of December 31, 2016				18,533,465
Other long-term debt				135,849					110,876
Long-term debt, excluding current maturities				18,294,659					17,068,807
Parent
Debt Instrument [Line Items]
Balance as of December 31, 2016				14,418,624					13,498,902
Subsidiaries
Debt Instrument [Line Items]
Balance as of December 31, 2016				$ 3,978,992					3,509,231
GTP Notes
Debt Instrument [Line Items]
Long-term Debt, Repayment Terms, Number of Site Released Upon Repayment \| Class				472
Credit Facility 2013 \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term line of credit				$ 539,975					1,225,000
Debt instrument, interest rate, effective Percentage				1.963%
Credit Facility 2014 \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term line of credit				$ 1,385,000					1,980,000
Debt instrument, interest rate, effective Percentage				2.432%
Secured Debt \| Series 2010-1 Class C
Debt Instrument [Line Items]
Repayments of senior debt			$ 67,000
Secured Debt \| Series 2012-1 Class A Notes
Debt Instrument [Line Items]
Repayments of secured debt				$ 94,100
Secured Debt \| Commercial Mortgage Pass Through Certificates Series 2013
Debt Instrument [Line Items]
Balance as of December 31, 2016													$ 1,800,000
Secured Debt \| Commercial Mortgage Pass Through Certificates Series 2013 \| Secured Tower Revenue Securities, Series 2013-1A
Debt Instrument [Line Items]
Long-term debt, stated interest rate				1.551%
Balance as of December 31, 2016				$ 498,642					497,478
Secured Debt \| Commercial Mortgage Pass Through Certificates Series 2013 \| Secured Tower Revenue Securities, Series 2013-2A
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.07%
Balance as of December 31, 2016				$ 1,290,267					1,288,689
Secured Debt \| Series 2015-2 Class A
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.482%
Balance as of December 31, 2016				$ 519,437					518,776	$ 525,000
Secured Debt \| GTP Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016				179,459					281,902
Secured Debt \| Secured Cellular Site Revenue Notes
Debt Instrument [Line Items]
Balance as of December 31, 2016				$ 132,960					201,930
Secured Debt \| Series 2015-1 Class A
Debt Instrument [Line Items]
Long-term debt, stated interest rate				2.35%
Balance as of December 31, 2016				$ 347,108					346,262	$ 350,000
Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016				286,009					219,902
Unsecured Debt \| Uganda Replacement Loan
Debt Instrument [Line Items]
Balance as of December 31, 2016				$ 80,000
Unsecured Debt \| Uganda Loan
Debt Instrument [Line Items]
Debt instrument, interest rate, effective Percentage				6.52%
Long-term debt, stated interest rate				16.60%
Balance as of December 31, 2016				$ 79,998					75,226
Unsecured Debt \| India Indebtedness
Debt Instrument [Line Items]
Balance as of December 31, 2016				549,528					8,752
Unsecured Debt \| Shareholder Loans
Debt Instrument [Line Items]
Balance as of December 31, 2016				$ 151,045					145,540
Unsecured Debt \| Term Loan 2013
Debt Instrument [Line Items]
Debt instrument, interest rate, effective Percentage				2.02%
Balance as of December 31, 2016				$ 993,936					1,993,601
Mandatorily Redeemable Preferred Stock \| Viom preferred shares
Debt Instrument [Line Items]
Long-term debt, stated interest rate				13.50%
Balance as of December 31, 2016				$ 24,537
Senior Notes \| 4.500% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				4.50%
Balance as of December 31, 2016				$ 998,676					997,693
Senior Notes \| 3.40% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.40%							3.40%	3.40%
Balance as of December 31, 2016				$ 999,716					999,769
Senior Notes \| 7.25% Senior Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				7.25%
Balance as of December 31, 2016				$ 297,032					296,242
Senior Notes \| 2.800% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				2.80%
Balance as of December 31, 2016				$ 744,917					743,557
Senior Notes \| 5.05% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				5.05%
Balance as of December 31, 2016				$ 697,352					697,216
Senior Notes \| 3.300% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.30%				3.30%
Balance as of December 31, 2016				$ 744,762					0
Senior Notes \| 3.450% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.45%
Balance as of December 31, 2016				$ 643,848					642,786
Senior Notes \| 5.900% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				5.90%
Balance as of December 31, 2016				$ 497,343					497,188
Senior Notes \| 2.250% senior notes
Debt Instrument [Line Items]
Debt instrument, interest rate, effective Percentage				1.97%
Long-term debt, stated interest rate				2.25%		2.25%
Balance as of December 31, 2016				$ 572,764					0
Senior Notes \| 4.000% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				4.00%
Balance as of December 31, 2016				$ 739,985					739,057
Senior Notes \| 4.400% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				4.40%				4.40%
Balance as of December 31, 2016				$ 495,212					0
Senior Notes \| 3.375% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.375%			3.375%
Balance as of December 31, 2016				$ 983,369					0
Senior Notes \| 3.125% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.125%		3.125%
Balance as of December 31, 2016				$ 396,713					0
Senior Notes \| 4.70% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				4.70%
Balance as of December 31, 2016				$ 696,013					695,374
Senior Notes \| 3.50% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				3.50%
Balance as of December 31, 2016				$ 989,269					987,966
Senior Notes \| 5.00% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate				5.00%							5.00%	5.00%
Balance as of December 31, 2016				$ 1,002,742					$ 1,003,453
Subsequent Event \| Secured Debt \| GTP Notes
Debt Instrument [Line Items]
Repayments of secured debt	$ 173,500
Subsequent Event \| Secured Debt \| Secured Cellular Site Revenue Notes
Debt Instrument [Line Items]
Repayments of secured debt	$ 129,000
Subsequent Event \| Unsecured Debt \| Uganda Loan
Debt Instrument [Line Items]
Balance as of December 31, 2016					$ 31,800
Subsequent Event \| Senior Notes \| 7.25% Senior Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate		7.25%
Repayments of senior debt		$ 341,400

Long-Term Obligations Long-Term Obligations (India Indebtedness) (Details)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 INR (₨)
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 18,533,465,000
Secured Debt \| Viom Term Loan
Debt Instrument [Line Items]
Balance as of December 31, 2016	461,200,000	₨ 31,326,000,000
Secured Debt \| Viom Debenture
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 88,300,000	₨ 6,000,000,000
Debt Instrument, Interest Rate, Stated Percentage	9.90%	9.90%
Line of Credit \| Viom Working Capital Facilities
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 0	₨ 0
Minimum \| Secured Debt \| Viom Term Loan
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.15%	8.15%
Minimum \| Line of Credit \| Viom Working Capital Facilities
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.70%	8.70%
Maximum \| Secured Debt \| Viom Term Loan
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	11.15%	11.15%
Maximum \| Line of Credit \| Viom Working Capital Facilities
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	11.70%	11.70%

Long-Term Obligations Long-Term Obligations (Other Subsidiary Debt) (Details) COP in Millions, BRL in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 INR (₨)	Dec. 31, 2016 COP	Dec. 31, 2016 BRL	Dec. 31, 2016 ZAR	Dec. 31, 2015 COP	Dec. 31, 2015 BRL	Dec. 31, 2015 ZAR	Jan. 23, 2015 ZAR	Dec. 31, 2014 BRL	Nov. 30, 2014 BRL
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 18,533,465,000
Proceeds from Lines of Credit	2,446,845,000	$ 6,126,618,000	$ 2,187,000,000
Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016	286,009,000	219,902,000
Unsecured Debt \| BR Towers Debentures
Debt Instrument [Line Items]
Balance as of December 31, 2016 \| BRL													BRL 300.0
Unsecured Debt \| South African Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity \| ZAR							ZAR 330,000,000.0
Unsecured Debt \| Brazil Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity \| BRL												BRL 271.0
Secured Debt \| Viom Term Loan
Debt Instrument [Line Items]
Balance as of December 31, 2016	461,200,000			₨ 31,326,000,000
Secured Debt \| BR Towers Debentures
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 101,000,000	85,200,000				BRL 329.3			BRL 332.8
Long-term debt, stated interest rate	7.40%			7.40%	7.40%	7.40%	7.40%
Secured Debt \| Viom Debenture
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 88,300,000			₨ 6,000,000,000
Long-term debt, stated interest rate	9.90%			9.90%	9.90%	9.90%	9.90%
Line of Credit \| Viom Working Capital Facilities
Debt Instrument [Line Items]
Balance as of December 31, 2016	$ 0			₨ 0
Revolving Credit Facility \| South African Facility
Debt Instrument [Line Items]
Balance as of December 31, 2016 \| ZAR											ZAR 830,000,000
Long-term debt, stated interest rate	9.308%			9.308%	9.308%	9.308%	9.308%
Long-term line of credit	$ 84,300,000	53,200,000					ZAR 1,164,000,000			ZAR 830,000,000
Revolving Credit Facility \| Colombian Credit Facility
Debt Instrument [Line Items]
Long-term debt, stated interest rate	10.92%			10.92%	10.92%	10.92%	10.92%
Long-term line of credit	$ 56,100,000	59,600,000			COP 170,000.0			COP 190,000.0
Revolving Credit Facility \| Brazil Credit Facility
Debt Instrument [Line Items]
Long-term line of credit	$ 44,600,000	$ 21,900,000				BRL 147.7			BRL 85.4

Long-Term Obligations (Schedule of Shareholder Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Interest costs capitalized	$ 1,500	$ 1,800	$ 2,800
Balance as of December 31, 2016	18,533,465
Unsecured Debt
Debt Instrument [Line Items]
Balance as of December 31, 2016	286,009	219,902
Unsecured Debt \| Ghana Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	300,900
Balance as of December 31, 2016	$ 71,047	70,314
Long-term debt, stated interest rate	21.87%
Unsecured Debt \| Uganda Loan
Debt Instrument [Line Items]
Interest costs capitalized	$ 4,800
Balance as of December 31, 2016	$ 79,998	$ 75,226
Long-term debt, stated interest rate	16.60%
Debt instrument, interest rate, effective Percentage	6.52%

Long-Term Obligations Long-Term Obligations (Schedule of Term Loans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Credit Facility 2013 \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Principal amount	$ 540.0
Letters of credit, amount outstanding	$ 3.2
Line of credit facility, commitment fee percentage	0.15%
Credit Facility 2014 \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Principal amount	$ 1,385.0
Letters of credit, amount outstanding	$ 7.3
Line of credit facility, commitment fee percentage	0.15%	0.15%
London Interbank Offered Rate (LIBOR) \| Credit Facility 2013 \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
London Interbank Offered Rate (LIBOR) \| Credit Facility 2014 \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Principal amount	$ 1,095.0
Basis spread on variable rate	1.25%
London Interbank Offered Rate (LIBOR) \| Term Loan 2013 \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Unsecured Debt \| Term Loan 2013
Line of Credit Facility [Line Items]
Principal amount	$ 1,000.0
Letters of credit, amount outstanding	$ 0.0

Long-Term Obligations (Schedule of Debt Discounts) (Details) - Senior Notes - USD ($)	Dec. 31, 2016	Sep. 30, 2016	May 13, 2016	Jan. 12, 2016	Dec. 31, 2015
4.500% senior notes
Debt Instrument [Line Items]
Principal amount					$ 1,000,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	$ (1,324,000)				(2,307,000)
2.250% senior notes
Debt Instrument [Line Items]
Principal amount		$ 600,000,000			600,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(27,236,000)				0
3.125% senior notes
Debt Instrument [Line Items]
Principal amount		$ 400,000,000			400,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(3,287,000)				0
3.40% senior notes
Debt Instrument [Line Items]
Principal amount					1,000,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(284,000)				(231,000)
7.25% Senior Notes
Debt Instrument [Line Items]
Principal amount					300,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(2,968,000)				(3,758,000)
2.800% senior notes
Debt Instrument [Line Items]
Principal amount					750,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(5,083,000)				(6,443,000)
5.05% senior notes
Debt Instrument [Line Items]
Principal amount					700,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(2,648,000)				(2,784,000)
3.300% senior notes
Debt Instrument [Line Items]
Principal amount				$ 750,000,000	750,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(5,238,000)				0
3.450% senior notes
Debt Instrument [Line Items]
Principal amount					650,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(6,152,000)				(7,214,000)
5.900% senior notes
Debt Instrument [Line Items]
Principal amount					500,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(2,657,000)				(2,812,000)
4.70% senior notes
Debt Instrument [Line Items]
Principal amount					700,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(3,987,000)				(4,626,000)
3.50% senior notes
Debt Instrument [Line Items]
Principal amount					1,000,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(10,731,000)				(12,034,000)
5.00% senior notes
Debt Instrument [Line Items]
Principal amount					1,000,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	2,742,000				3,453,000
4.000% senior notes
Debt Instrument [Line Items]
Principal amount					500,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(10,015,000)				(10,943,000)
4.400% senior notes
Debt Instrument [Line Items]
Principal amount				$ 500,000,000	750,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	(4,788,000)				0
3.375% senior notes
Debt Instrument [Line Items]
Principal amount			$ 1,000,000,000		1,000,000,000
Debt Instrument, unamortized discount (premium) and debt issuance costs, net	$ (16,631,000)				$ 0

Long-Term Obligations (Aggregate Carrying Value of Long-Term Debt) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Debt Disclosure [Abstract]
2017	$ 238,806
2018	1,649,137
2019	1,759,808
2020	2,677,594
2021	1,976,976
Thereafter	10,350,583
Total cash obligations	18,652,904
Unamortized discounts, premiums and debt issuance costs and fair value adjustments, net	119,439
Balance as of December 31, 2016	$ 18,533,465

Other Non-Current Liabilities (Other Non-Current Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other Liabilities, Noncurrent [Abstract]
Unearned revenue	$ 457,272	$ 451,844
Deferred rent liability	407,157	348,532
Other miscellaneous liabilities	278,294	158,973
Other non-current liabilities	$ 1,142,723	$ 959,349

- Definition

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References + Details

Asset Retirement Obligations (Carrying Value of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance as of January 1,	$ 856,936	$ 609,035
Asset retirement obligation, foreign currency translation	(9,600)	81,700
Additions	64,092	277,982
Accretion expense	67,010	55,592
Revisions in estimates	(21,130)	(83,636)
Settlements	(1,401)	(2,037)
Balance as of December 31,	$ 965,507	$ 856,936

Fair Value Measurements (Narrative) (Details) COP in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) interest_rate_swap	Dec. 31, 2015 USD ($)	Dec. 31, 2016 COP interest_rate_swap	Sep. 30, 2016 USD ($)	Dec. 31, 2015 COP	Jul. 01, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of embedded derivative asset						$ 14,600,000
Business combination, contingent consideration arrangements, range of outcomes, value, low	$ 0
Business combination, contingent consideration arrangements, range of outcomes, value, high	46,795,987
Impairment of long-lived assets held for use	28,500,000	$ 15,100,000
Assets held and used, original carrying value	12,700,000,000	12,600,000,000
Debt, long-term and short-term, combined amount	18,533,465,000	17,119,009,000
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value gain (loss) recognized in other income	(900,000)
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	18,800,000,000	17,400,000,000
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	11,800,000,000	8,700,000,000
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	7,000,000,000	8,700,000,000
Interest Rate Swap \| Colombian Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount	$ 28,327,000	30,164,000	COP 85,000,000		COP 95,000,000
Interest Rate Swap \| Senior Notes \| 2.250% senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps entered into \| interest_rate_swap	3		3
Fair value gain (loss) recognized in other income	$ 2,400,000.0
Derivative, Notional Amount				$ 600,000,000
Interest Rate Swap \| Revolving Credit Facility \| Colombian Credit Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount		$ 33,300,000			COP 100,000,000
Derivative, fixed interest rate		5.74%			5.74%

Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) COP in Thousands, $ in Thousands	Dec. 31, 2016 USD ($)	Dec. 31, 2016 COP	Dec. 31, 2015 USD ($)	Dec. 31, 2015 COP	Jul. 01, 2015 USD ($)	Dec. 31, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 4,026		$ 0
Fair value of embedded derivative asset					$ 14,600
Acquisition-related contingent consideration	15,444		12,436			$ 28,524
Colombian Credit Facility \| Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset	3	COP 8,763	692	COP 2,179,374
Fair Value, Inputs, Level 1 \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	4,026
Fair Value, Inputs, Level 2 \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements	24,682
Fair Value, Inputs, Level 2 \| Fair Value, Measurements, Recurring [Member] \| Colombian Credit Facility \| Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value, gross asset	3		692
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquisition-related contingent consideration			12,436
Fair Value, Inputs, Level 3 \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of embedded derivative asset	13,290		14,176
Acquisition-related contingent consideration	$ 15,444		$ 12,436

Fair Value Measurements (Schedule of derivative financial instruments) (Details) - Interest Rate Swap - Colombian Credit Facility COP in Thousands, $ in Thousands	Dec. 31, 2016 USD ($)	Dec. 31, 2016 COP	Dec. 31, 2015 USD ($)	Dec. 31, 2015 COP
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount	$ 28,327	COP 85,000,000	$ 30,164	COP 95,000,000
Derivative asset, fair value, gross asset	$ 3	COP 8,763	$ 692	COP 2,179,374

Fair Value Measurements (Contingent Consideration) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1	$ 12,436	$ 28,524
Additions	8,811	1,626
Settlements	(306)	(7,943)
Change in fair value	(6,372)	(4,781)
Foreign currency translation adjustment	875	(4,990)
Balance as of December 31	15,444	12,436
Fair Value, Inputs, Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1	$ 12,436
Balance as of December 31		$ 12,436

Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Contingency [Line Items]
Valuation allowance	$ 144,397,000	$ 136,952,000	$ 141,241,000	$ 136,006,000
Undistributed earnings of foreign subsidiaries	648,700,000
Unrecognized tax benefits that would impact the ETR	102,900,000	28,100,000
Additions based on tax positions related to the current year	82,912,000	5,042,000	4,187,000
Deferred Taxes, Business Combination, Valuation Allowance, Available to Reduce Goodwill	23,800,000
Decrease in unrecognized tax benefits, lapse of applicable statute of limitations	3,168,000	3,504,000	5,349,000
Unrecognized tax benefits, income tax penalties and interest	9,200,000	3,200,000	6,500,000
Unrecognized Tax Benefits, Decrease In Income Tax Penalties And Interest Expense Resulting From Expiration Of Applicable Statute Of Limitations	3,400,000	3,100,000	$ 9,900,000
Unrecognized tax benefits, income tax penalties and interest accrued	24,300,000	$ 20,200,000
Minimum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	0
Maximum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	10,800,000
Mexican Tax Authority
Income Tax Contingency [Line Items]
Tax credit carryforward	$ 900,000

Income Taxes (Income Tax Provision from Continuing Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ (26,494)	$ (73,930)	$ (2,390)
State	(1,976)	(21,216)	(797)
Foreign	(100,074)	(55,045)	(57,934)
Deferred:
Federal	(616)	9,131	(4,180)
State	(259)	8	(973)
Foreign	(26,082)	(16,903)	3,769
Income tax provision	$ (155,501)	$ (157,955)	$ (62,505)

Income Taxes (Reconciliation Between the U.S. Statutory Rate and the Effective Rate from Continuing Operations) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory tax rate	35.00%	35.00%	35.00%
Tax adjustment related to REIT	(35.00%)	(35.00%)	(35.00%)
Foreign taxes	5.00%	3.00%	2.00%
Foreign withholding taxes	4.00%	3.00%	3.00%
Uncertain tax positions	5.00%	0.00%	0.00%
Change in tax law	0.00%	2.00%	0.00%
MIPT tax election	0.00%	11.00%	0.00%
Other	0.00%	0.00%	2.00%
Effective tax rate	14.00%	19.00%	7.00%
Dividend paid deduction, percentage	29.00%	36.00%	24.00%

Income Taxes (Components of Income from Continuing Operations Before Income Taxes and Income on Equity Method Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
United States	$ 882,552	$ 785,201	$ 857,457
Foreign	243,308	44,761	8,247
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	$ 1,125,860	$ 829,962	$ 865,704

Income Taxes (Components of the Net Deferred Tax Asset and Related Valuation Allowance) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 278,674	$ 277,977
Accrued asset retirement obligations	130,014	92,295
Stock-based compensation	4,267	3,889
Unearned revenue	29,003	25,654
Unrealized loss on foreign currency	26,883	37,440
Other accruals and allowances	45,578	13,824
Items not currently deductible and other	26,886	17,608
Depreciation and amortization	(942,409)	(194,230)
Deferred rent	(27,099)	(20,720)
Other	(9,294)	(11,077)
Deferred Tax Liabilities, Gross, Noncurrent	437,497
Subtotal		242,660
Valuation allowance	(144,397)	(136,952)
Net deferred tax (liabilities) assets	$ (581,894)
Net deferred tax (liabilities) assets		$ 105,708

Income Taxes (Valuation Allowance Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of January 1,	$ 136,952	$ 141,241	$ 136,006
Additions	14,118	19,512	40,124
Reversals	0	0	(10,769)
Foreign currency translation	(6,673)	(23,801)	(24,120)
Balance as of December 31,	$ 144,397	$ 136,952	$ 141,241

Income Taxes (Net Operating Loss Carryforwards Expire) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Federal
Operating Loss Carryforwards [Line Items]
2017 to 2021	$ 0
2022 to 2026	0
2027 to 2031	146,763
2032 to 2036	16,604
Indefinite carryforward	0
Total	163,367
State
Operating Loss Carryforwards [Line Items]
2017 to 2021	59,213
2022 to 2026	388,695
2027 to 2031	98,538
2032 to 2036	32,345
Indefinite carryforward	0
Total	578,791
Foreign
Operating Loss Carryforwards [Line Items]
2017 to 2021	8,950
2022 to 2026	184,611
2027 to 2031	0
2032 to 2036	0
Indefinite carryforward	831,185
Total	$ 1,024,746

Income Taxes (Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 28,114	$ 31,947	$ 32,545
Additions based on tax positions related to the current year	82,912	5,042	4,187
Additions for tax positions of prior years	0	0	3,780
Foreign currency	(307)	(5,371)	(3,216)
Reduction as a result of the lapse of statute of limitations and effective settlements	(3,168)	(3,504)	(5,349)
Balance at December 31	$ 107,551	$ 28,114	$ 31,947

Stock-Based Compensation (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 89,898,000	$ 90,537,000	$ 80,153,000.000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Total unrecognized compensation expense	$ 12,000,000
Expected recognition of stock award compensation expense weighted average period in years	2 years
Three Year Performance Grant, Shares Granted	169,340	70,135
Shares granted, grant date fair value not yet established	23,377
Stock-based compensation expense	$ 8,400,000
Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	0.00%
Performance Shares \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	200.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 14.60	$ 15.06	$ 14.86
Intrinsic value of stock options exercised	$ 77,600,000	$ 32,100,000	$ 58,000,000
Total unrecognized compensation expense	$ 25,600,000
Expected recognition of stock award compensation expense weighted average period in years	2 years
Employee service share-based compensation, cash received from exercise of stock options	$ 84,900,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	$ 86,100,000
Expected recognition of stock award compensation expense weighted average period in years	2 years
Total fair value of restricted stock units vested during period	$ 63,800,000
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issuable under stock incentive plan	9,500,000
2007 Plan \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
2007 Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
2007 Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

Stock-Based Compensation Stock-Based Compensation (Summary of Stock-Based Compensation Expenses) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	$ 89,898,000	$ 90,537,000	$ 80,153,000.000
Stock-based compensation expense capitalized as property and equipment	$ 1,443,000	$ 2,052,000,000	$ 1,589,000,000

Stock-Based Compensation (Assumptions Used to Determine the Grant Date Fair Value for Options Granted) (Details) - Employee Stock Option	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum range of risk-free interest rate	1.00%	1.32%	1.46%
Maximum range of risk-free interest rate	1.73%	1.62%	1.74%
Weighted average risk-free interest rate	1.44%	1.61%	1.64%
Expected life of stock options		4 years 4 months 52 days	4 years 6 months
Minimum range of expected volatility of underlying stock price	20.59%	21.09%	21.94%
Maximum range of expected volatility of underlying stock price	21.45%	21.24%	23.35%
Weighted average expected volatility of underlying stock price	21.43%	21.09%	23.08%
Range of expected annual dividend yield			1.50%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of stock options	4 years 6 months
Range of expected annual dividend yield	1.85%	1.50%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of stock options	5 years 2 months 12 days
Range of expected annual dividend yield	2.40%	1.85%

Stock-Based Compensation (Summary of the Company's Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 8 months 23 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	5 years 2 months 27 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	6 years 8 months 23 days
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding as of January 1, 2016 (in shares) \| shares	7,680,819
Granted (in shares) \| shares	1,161,370
Exercised (in shares) \| shares	(1,520,541)
Forfeited (in shares) \| shares	(51,472)
Expired (in shares) \| shares	(800)
Outstanding as of December 31, 2016 (in shares) \| shares	7,269,376
Exercisable as of December 31, 2016 (in shares) \| shares	3,519,976
Vested or expected to vest as of December 31, 2016 (in shares) \| shares	7,269,376
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding as of January 1, 2016 (in dollars per share) \| $ / shares	$ 71.10
Granted (in dollars per share) \| $ / shares	95.16
Exercised (in dollars per share) \| $ / shares	55.86
Forfeited (in dollars per share) \| $ / shares	90.10
Expired (in dollars per share) \| $ / shares	33.96
Outstanding as of December 31, 2016 (in dollars per share) \| $ / shares	78.00
Exercisable as of December 31, 2016 (in dollars per share) \| $ / shares	64.93
Vested or expected to vest as of December 31, 2016 (in dollars per share) \| $ / shares	$ 78.00
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Aggregate intrinsic value, outstanding \| $	$ 201.4
Aggregate intrinsic value, exercisable \| $	143.4
Aggregate intrinsic value, vested or expected to vest \| $	$ 201.4

Stock-Based Compensation (Schedule of Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	7,269,376
Exercise price per share, minimum	$ 28.39
Exercise price per share, maximum	$ 113.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	6 years 8 months 23 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 78.00
Options Exercisable (in shares) \| shares	3,519,976
Weighted Average Exercise Price Per Share (in dollars per share)	$ 64.93
$28.39 - $43.11
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	733,732
Exercise price per share, minimum	$ 28.39
Exercise price per share, maximum	$ 43.11
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 4 months 6 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 37.01
Options Exercisable (in shares) \| shares	733,732
Weighted Average Exercise Price Per Share (in dollars per share)	$ 37.01
44.92 - 62.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	1,130,308
Exercise price per share, minimum	$ 44.92
Exercise price per share, maximum	$ 62
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	4 years 6 months 18 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 56.55
Options Exercisable (in shares) \| shares	1,130,308
Weighted Average Exercise Price Per Share (in dollars per share)	$ 56.55
64.01 - 76.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	916,991
Exercise price per share, minimum	$ 64.01
Exercise price per share, maximum	$ 76.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	6 years 2 months 5 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 76.74
Options Exercisable (in shares) \| shares	621,338
Weighted Average Exercise Price Per Share (in dollars per share)	$ 76.69
77.42- 81.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	1,428,834
Exercise price per share, minimum	$ 77.42
Exercise price per share, maximum	$ 81.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	7 years 1 month 21 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 81.12
Options Exercisable (in shares) \| shares	589,547
Weighted Average Exercise Price Per Share (in dollars per share)	$ 81.13
81.46 - 94.57
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	1,900,077
Exercise price per share, minimum	$ 81.46
Exercise price per share, maximum	$ 94.57
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	8 years 1 month 24 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 94.35
Options Exercisable (in shares) \| shares	441,405
Weighted Average Exercise Price Per Share (in dollars per share)	$ 94.34
94.71 - 113.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Number of Options (in shares) \| shares	1,159,434
Exercise price per share, minimum	$ 94.71
Exercise price per share, maximum	$ 113.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	9 years 2 months 9 days
Weighted Average Exercise Price Per Share (in dollars per share)	$ 95.21
Options Exercisable (in shares) \| shares	3,646
Weighted Average Exercise Price Per Share (in dollars per share)	$ 99.14

Stock-Based Compensation (Summary of the Company's Restricted Stock Unit Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding as of January 1, 2016 (in shares)	1,656,993
Granted (in shares)	784,178
Vested (in shares)	(656,645)
Forfeited (in shares)	(120,783)
Outstanding as of December 31, 2016 (in shares)	1,656,993	1,663,743
Expected to vest, net of estimated forfeitures, as of December 31, 2016 (in shares)		1,663,743
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding as of January 1, 2016 (in dollars per share)	$ 84.12
Granted (in dollars per share)	95.15
Vested (in dollars per share)	79.36
Forfeitures (in dollars per share)	90.18
Outstanding as of December 31, 2016 (in dollars per share)	$ 90.76
Expected to vest, net of estimated forfeitures, as of December 31, 2016 (in dollars per share)		$ 90.76
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding as of January 1, 2016 (in shares)	33,377
Granted (in shares)	209,380
Vested (in shares)	0
Forfeited (in shares)	0
Outstanding as of December 31, 2016 (in shares)	33,377	242,757
Expected to vest, net of estimated forfeitures, as of December 31, 2016 (in shares)		242,757
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding as of January 1, 2016 (in dollars per share)	$ 94.57
Granted (in dollars per share)	93.81
Vested (in dollars per share)	0.00
Forfeitures (in dollars per share)	0.00
Outstanding as of December 31, 2016 (in dollars per share)	$ 93.92
Expected to vest, net of estimated forfeitures, as of December 31, 2016 (in dollars per share)		$ 93.92

Redeemable Noncontrolling Interests (Details) - 12 months ended Dec. 31, 2016 $ in Thousands	USD ($)	₨ / shares
Temporary Equity Disclosure [Abstract]
Temporary equity redemption price per share (in INR per share) \| ₨ / shares		₨ 216
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance as of January 1, 2016	$ 0
Fair value at acquisition	1,100,804
Net income attributable to noncontrolling interests	13,851
Foreign currency translation adjustment attributable to noncontrolling interests	(23,435)
Balance as of December 31, 2016	$ 1,091,220

Equity (Narrative) (Details)				12 Months Ended
Equity (Narrative) (Details)	Dec. 14, 2016 $ / shares	Dec. 08, 2016 tower shares	Dec. 02, 2016 $ / shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Mar. 31, 2011 USD ($)
Class of Stock [Line Items]
Issuance of stock (shares) \| shares		1,171,187
Capital Leased Assets, Number of Units Acquired Through Purchase Option \| tower		1,523
Authorized repurchase of common stock \| $							$ 1,500,000,000.0
Remaining stock value of buyback \| $				$ 1,100,000,000
Proceeds from stock options and stock purchase plan \| $				92,473,000	$ 50,716,000	$ 62,276,000
Distributions paid on common stock \| $				886,116,000	710,852,000	404,631,000
Preferred stock dividends declared \| $				107,125,000	$ 76,772,000	$ 23,888,000
Accrued dividend RSU \| $				$ 6,700,000
Common Stock
Class of Stock [Line Items]
Common stock, dividends declared per share (in dollars per share) \| $ / shares	$ 0.58			$ 2.1700	$ 1.8100	$ 1.4000
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, depositary shares, percentage of preferred shares \| shares				0.1
Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, liquidation preference per share \| $ / shares				$ 1,000.00
Shares issued, price per share \| $ / shares				100.00
Preferred stock, dividends per share, declared (in dollars per share) \| $ / shares				$ 5.5000	3.8653	0.00
Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock \| Minimum
Class of Stock [Line Items]
Conversion factor, preferred stock \| shares				8.5911
Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock \| Maximum
Class of Stock [Line Items]
Conversion factor, preferred stock \| shares				10.3093
Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, dividends per share, declared (in dollars per share) \| $ / shares			$ 1.3125	$ 6.4578	$ 5.2500	$ 2.6688
Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock \| Minimum
Class of Stock [Line Items]
Conversion factor, preferred stock \| shares				0.9272
Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock \| Maximum
Class of Stock [Line Items]
Conversion factor, preferred stock \| shares				1.1591
Dividends Declared and Paid
Class of Stock [Line Items]
Paid dividend RSU \| $				$ 2,400,000
Dividends Declared and Paid \| Common Stock
Class of Stock [Line Items]
Distributions paid on common stock \| $				923,700,000	$ 766,400,000	$ 554,600,000
Dividends Declared and Paid \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared \| $				$ 75,600,000	$ 53,100,000
Preferred stock, dividends per share, declared (in dollars per share) \| $ / shares				$ 55.00	$ 38.65
Dividends Declared and Paid \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock dividends declared \| $				$ 31,500,000	$ 23,700,000	$ 23,900,000
Preferred stock, dividends per share, declared (in dollars per share) \| $ / shares				$ 5.25	$ 3.94	$ 3.98
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Class of Stock [Line Items]
Preferred stock, par value \| $ / shares				$ 0.01	$ 0.01
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series B Preferred Stock
Class of Stock [Line Items]
Issuance of stock (shares) \| shares					1,375,000
Preferred stock, shares issued \| shares				1,375,000
Preferred stock, dividend rate, percentage				5.50%
Preferred stock, par value \| $ / shares				$ 0.01
Preferred stock, depositary shares \| shares				13,750,000
Preferred stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Series A Preferred Stock
Class of Stock [Line Items]
Issuance of stock (shares) \| shares						6,000,000
Preferred stock, shares issued \| shares				6,000,000	6,000,000
Preferred stock, dividend rate, percentage				5.25%	5.25%
Preferred stock, par value \| $ / shares				$ 0.01
Preferred stock, liquidation preference per share \| $ / shares				$ 100.00

Equity (Distributions) (Detail) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Dec. 14, 2016	Dec. 02, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Dividends Payable [Line Items]
Payments of ordinary dividends, common Stock			$ 886,116	$ 710,852	$ 404,631
Dividends, Preferred Stock, Cash			$ 107,125	$ 76,772	$ 23,888
Common Stock
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)	$ 0.58		$ 2.1700	$ 1.8100	$ 1.4000
Dividends declared, common stock, percent of total			100.00%	100.00%	100.00%
Common Stock \| Ordinary Income
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)			$ 2.1700	$ 1.2694	$ 1.4000
Dividends declared, common stock, percent of total			100.00%	70.13%	100.00%
Common Stock \| Capital Gain
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)			$ 0	$ 0.5406	$ 0.00
Dividends declared, common stock, percent of total			0.00%	29.87%	0.00%
Common Stock \| Dividends Declared and Paid
Dividends Payable [Line Items]
Payments of ordinary dividends, common Stock			$ 923,700	$ 766,400	$ 554,600
Series A Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)		$ 1.3125	$ 6.4578	$ 5.2500	$ 2.6688
Dividends declared, preferred stock, declared			100.00%	100.00%	100.00%
Series A Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Ordinary Income
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 6.4578	$ 3.6818	$ 2.6688
Dividends declared, preferred stock, declared			100.00%	70.13%	100.00%
Series A Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Capital Gain
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 0.0000	$ 1.5682	$ 0.00
Dividends declared, preferred stock, declared			0.00%	29.87%	0.00%
Series A Preferred Stock \| Dividends Declared and Paid \| Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 5.25	$ 3.94	$ 3.98
Dividends, Preferred Stock, Cash			$ 31,500	$ 23,700	$ 23,900
Series B Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 5.5000	$ 3.8653	$ 0.00
Dividends declared, preferred stock, declared			100.00%	100.00%	0.00%
Series B Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Ordinary Income
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 5.5000	$ 2.7107	$ 0.0000
Dividends declared, preferred stock, declared			100.00%	70.13%	0.00%
Series B Preferred Stock \| Convertible Preferred Stock Subject to Mandatory Redemption \| Capital Gain
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 0.0000	$ 1.1546	$ 0.00
Dividends declared, preferred stock, declared			0.00%	29.87%	0.00%
Series B Preferred Stock \| Dividends Declared and Paid \| Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)			$ 55.00	$ 38.65
Dividends, Preferred Stock, Cash			$ 75,600	$ 53,100

Impairments, Net Loss on Sale of Long-Lived Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment Impairment or Disposal [Abstract]
Impairment charges and net losses on sales or disposals of long-lived assets	$ 53.6	$ 29.8	$ 28.5
Impairment charges	28.5	15.1	15.3
Losses associated with the sale or disposal of certain non-core towers, other assets and other miscellaneous items	$ 25.1	$ 14.7	$ 13.2

Earnings Per Common Share (Schedule of Earnings Per Basic And Diluted by Common Class) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	$ 229,207	$ 264,509	$ 187,550	$ 275,159	$ 232,702	$ 102,999	$ 156,056	$ 193,317	$ 956,425	$ 685,074	$ 824,910
Dividends on preferred stock	(26,781)	(26,781)	(26,782)	(26,781)	(26,781)	(26,781)	(26,782)	(9,819)	(107,125)	(90,163)	(23,888)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 202,426	$ 237,728	$ 160,768	$ 248,378	$ 205,921	$ 76,218	$ 129,274	$ 183,498	$ 849,300	$ 594,911	$ 801,022
Basic weighted average common shares outstanding									425,143	419	395,958
Dilutive securities									4,140	4	4,128
Diluted weighted average common shares outstanding									429,283	423	400,086
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.48	$ 0.56	$ 0.38	$ 0.59	$ 0.49	$ 0.18	$ 0.31	$ 0.45	$ 2.00	$ 1.42	$ 2.02
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.47	$ 0.55	$ 0.37	$ 0.58	$ 0.48	$ 0.18	$ 0.30	$ 0.45	$ 1.98	$ 1.41	$ 2.00

Earnings Per Common Share (Schedule of Shares Excluded From Computation of Earnings Per Share) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable upon conversion of the stock-based awards and convertible notes	6	0	5
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable upon conversion of the stock-based awards and convertible notes	817	1,606	1,290
Preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable upon conversion of the stock-based awards and convertible notes	17,509	15,408	4,303

Commitments And Contingencies (Narrative) (Details) ₨ in Millions					1 Months Ended	12 Months Ended
	Dec. 08, 2016 tower	Dec. 05, 2016 USD ($)	Dec. 05, 2016 INR (₨)	Mar. 27, 2015 USD ($) communications_site renewal_period	Dec. 31, 2000 tower	Dec. 31, 2016 USD ($) tower renewal_period shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Initial lease term						10 years
Aggregate rent expense \| $						$ 986,200,000	$ 804,800,000	$ 655,000,000
Capital Leased Assets, Number of Units Acquired Through Purchase Option	1,523
Loss Contingency, Foreign Income Tax Assessment		$ 69,800,000	₨ 4,750
Verizon Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units \| communications_site				11,286
Right to lease, weighted average term				28 years
Aggregate purchase option price for towers \| $				$ 5,000,000,000
Customer lease, initial term				10 years
Successive terms to renew lease \| renewal_period				8
Renewal term				5 years
At T Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units						2,350
Aggregate purchase option price for towers \| $						$ 760,100,000
Successive terms to renew lease \| renewal_period						4
Renewal term						5 years
Operating lease, term of contract						27 years
Number of communications sites acquired						77
Purchase price accretion rate (per year)						10.00%
At T Transaction \| Commitments subsequent to June 30, 2020
Loss Contingencies [Line Items]
Renewal term						1 year
ALLTEL Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units					1,800
Capital Leased Assets, Number of Units Acquired Through Purchase Option	1,523
Capital Lease Obligation, Number of Unit With Intent to Exercise Purchase Option						243
Aggregate purchase option price for towers \| $						$ 10,400,000
Average lease term (in years)					15 years
Cash purchase price per tower \| $						$ 42,844
Purchase price of tower in shares of common stock \| shares						769

Commitments and Contingencies (Future Minimum Rental Payments Under Non-Cancelable Operating Leases) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	$ 869
2018	846
2019	816
2020	776
2021	737
Thereafter	6,638
Total	$ 10,682

Commitments and Contingencies (Future Minimum Payments Under Capital Leases) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	$ 28
2018	24
2019	22
2020	18
2021	14
Thereafter	163
Total minimum lease payments	269
Less amounts representing interest	(132)
Present value of capital lease obligations	$ 137

Commitments and Contingencies (Future Minimum Rental Receipts Under Operating Lease Agreements) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2017	$ 4,646
2018	4,502
2019	4,240
2020	3,905
2021	3,372
Thereafter	10,477
Total	$ 31,142

Supplemental Cash Flow Information (Supplemental Cash Flow Information and Non-Cash Investing and Financing Activities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental cash flow information:
Cash paid for interest	$ 645,092	$ 577,952	$ 548,089
Cash paid for income taxes (net of refunds of $19,554, $7,053 and $8,476, respectively)	96,241	157,058	69,212
Non-cash investing and financing activities:
(Decrease) increase in accounts payable and accrued expenses for purchases of property and equipment and construction activities	(18,973)	(2,780)	(1,121)
Purchases of property and equipment under capital leases	55,635	36,851	36,486
Fair value of debt assumed through acquisitions	786,889	0	463,135
Exercise of purchase option for property and equipment for common shares issued	120,785	0	0
Settlement of accounts receivable related to acquisitions	0	899	31,849
Conversion of third-party debt to equity	0	0	111,181
Proceeds from income tax refunds	$ 19,554	$ 7,053	$ 8,476

Business Segments (Summarized Financial Information Concerning the Company's Reportable Segments) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Segment revenues	$ 1,539,549,000	$ 1,514,845,000	$ 1,442,227,000	$ 1,289,047,000	$ 1,280,041,000	$ 1,237,910,000	$ 1,174,375,000	$ 1,079,190,000	$ 5,785,668,000	$ 4,771,516,000	$ 4,100,048,000
Segment operating expenses									1,787,951,000	1,306,815,000	1,092,428,000
Segment gross margin									4,008,677,000	3,475,910,000	3,018,167,000
Segment selling, general, administrative and development expense									329,900,000	287,895,000	263,488,000
Segment operating profit									3,678,777,000	3,188,015,000	2,754,679,000
Stock-based compensation expense									89,898,000	90,537,000	80,153,000.000
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities									5,093,747,000	6,393,405,000	3,903,144,000
Other selling, general, administrative and development expense									126,035,000	121,456,000	104,738,000
Depreciation, amortization and accretion									1,525,635,000	1,285,328,000	1,003,802,000
Other expense									811,349,000	860,732,000	700,282,000
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									1,125,860,000	829,962,000	865,704,000
Amount previously recorded as segment selling, general and administrative expense											7,900,000
Capital expenditures									701,387,000	728,753,000	974,404,000
Repayment of capital lease for capital expenditures									18,900,000
United States
Segment Reporting Information [Line Items]
Segment revenues									3,442,575,000	3,248,629,000	2,732,984,000
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Stock-based compensation expense											80,153,000
Other selling, general, administrative and development expense											104,738,000
Depreciation, amortization and accretion											1,003,802,000
Other expense											700,282,000
Capital expenditures									16,439,000	17,252,000	24,146,000
Operating Segments \| Property
Segment Reporting Information [Line Items]
Segment revenues									5,713,126,000	4,680,388,000	4,006,854,000
Segment operating expenses									1,760,944,000	1,273,822,000	1,054,780,000
Segment gross margin									3,963,142,000	3,417,775,000	2,962,621,000
Segment selling, general, administrative and development expense									317,390,000	272,171,000	251,019,000
Segment operating profit									3,645,752,000	3,145,604,000	2,711,602,000
Capital expenditures									684,948,000	711,501,000	950,258,000
Operating Segments \| Property \| United States
Segment Reporting Information [Line Items]
Segment revenues									3,370,033,000	3,157,501,000	2,639,790,000
Segment operating expenses									733,403,000	678,499,000	515,742,000
Segment gross margin									2,636,630,000	2,479,002,000	2,124,048,000
Segment selling, general, administrative and development expense									147,559,000	138,617,000	124,944,000
Segment operating profit									2,489,071,000	2,340,385,000	1,999,104,000
Capital expenditures									310,744,000	367,663,000	576,153,000
Operating Segments \| Property \| Asia
Segment Reporting Information [Line Items]
Segment revenues									827,627,000	242,223,000	219,566,000
Segment operating expenses									465,938,000	126,874,000	121,797,000
Segment gross margin									361,689,000	115,349,000	97,769,000
Segment selling, general, administrative and development expense									48,238,000	22,771,000	19,632,000
Segment operating profit									313,451,000	92,578,000	78,137,000
Capital expenditures									115,508,000	75,407,000	74,334,000
Operating Segments \| Property \| EMEA
Segment Reporting Information [Line Items]
Segment revenues									529,531,000	395,092,000	315,053,000
Segment operating expenses									223,716,000	163,820,000	126,714,000
Segment gross margin									305,815,000	231,272,000	188,339,000
Segment selling, general, administrative and development expense									60,903,000	48,672,000	39,553,000
Segment operating profit									244,912,000	182,600,000	148,786,000
Capital expenditures									86,128,000	66,625,000	70,126,000
Operating Segments \| Property \| Latin America
Segment Reporting Information [Line Items]
Segment revenues									985,935,000	885,572,000	832,445,000
Segment operating expenses									337,887,000	304,629,000	290,527,000
Segment gross margin									659,008,000	592,152,000	552,465,000
Segment selling, general, administrative and development expense									60,690,000	62,111,000	66,890,000
Segment operating profit									598,318,000	530,041,000	485,575,000
Capital expenditures									172,568,000	201,806,000	229,645,000
Operating Segments \| Services
Segment Reporting Information [Line Items]
Segment revenues									72,542,000	91,128,000	93,194,000
Segment operating expenses									27,007,000	32,993,000	37,648,000
Segment gross margin									45,535,000	58,135,000	55,546,000
Segment selling, general, administrative and development expense									12,510,000	15,724,000	12,469,000
Segment operating profit									33,025,000	42,411,000	43,077,000
Capital expenditures									0	0	0
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Stock-based compensation expense									89,898,000	90,537,000
Other selling, general, administrative and development expense									126,035,000	121,456,000
Depreciation, amortization and accretion									1,525,635,000	1,285,328,000
Other expense									811,349,000	860,732,000
Selling General Administrative And Development Expense
Segment Reporting Information [Line Items]
Stock-based compensation expense									87,460,000	88,484,000	78,316,000
Operating Expense
Segment Reporting Information [Line Items]
Stock-based compensation expense									2,400,000	2,100,000	1,800,000
TV Azteca
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									10,960,000	11,209,000	10,547,000
TV Azteca \| Operating Segments \| Property
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									10,960,000	11,209,000	10,547,000
TV Azteca \| Operating Segments \| Property \| United States
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									0	0	0
TV Azteca \| Operating Segments \| Property \| Asia
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									0	0	0
TV Azteca \| Operating Segments \| Property \| EMEA
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									0	0	0
TV Azteca \| Operating Segments \| Property \| Latin America
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									10,960,000	11,209,000	10,547,000
TV Azteca \| Operating Segments \| Services
Segment Reporting Information [Line Items]
Interest income, TV Azteca, net of interest expense of $1,163, $820 and $1,482, respectively									$ 0	$ 0	$ 0

Business Segments (Additional Information Relating to the Company's Operating Segments) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 30,879,150	$ 26,904,272	$ 21,263,565
Corporate, Non-Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Assets			156,567
Operating Segments \| Property \| United States
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,846,941	19,286,465	14,335,731
Operating Segments \| Property \| Asia
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,535,293	736,149	738,290
Operating Segments \| Property \| EMEA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,062,399	2,249,634	1,275,253
Operating Segments \| Property \| Latin America
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,938,064	4,401,258	4,700,357
Operating Segments \| Services
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	48,327	68,388	$ 57,367
Corporate, Non-Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 448,126	$ 162,378

Business Segments (Summarized Geographic Information Related to the Company's Operating Revenues and Long-Lived Assets) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues	$ 1,539,549	$ 1,514,845	$ 1,442,227	$ 1,289,047	$ 1,280,041	$ 1,237,910	$ 1,174,375	$ 1,079,190	$ 5,785,668	$ 4,771,516	$ 4,100,048
Long-Lived Assets	26,862,549				23,796,105				26,862,549	23,796,105
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									3,442,575	3,248,629	2,732,984
Long-Lived Assets	16,969,558				17,516,535				16,969,558	17,516,535
India
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									827,627	242,223	219,566
Long-Lived Assets	4,094,190				619,370				4,094,190	619,370
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									60,163	55,965	64,946
Long-Lived Assets	397,317				388,727				397,317	388,727
Ghana
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									116,219	94,549	95,486
Long-Lived Assets	192,158				217,530				192,158	217,530
Nigeria
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									215,402	109,701	0
Long-Lived Assets	640,634				1,018,980				640,634	1,018,980
South Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									80,006	80,510	98,334
Long-Lived Assets	271,760				133,088				271,760	133,088
Uganda
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									57,741	54,367	56,287
Long-Lived Assets	141,533				162,346				141,533	162,346
Argentina
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									1,065	0	0
Long-Lived Assets	137,588				0				137,588	0
Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									506,182	408,644	331,089
Long-Lived Assets	2,626,431				2,204,494				2,626,431	2,204,494
Chile
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									33,831	29,650	31,756
Long-Lived Assets	137,170				121,938				137,170	121,938
Colombia
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									79,755	78,351	89,421
Long-Lived Assets	272,338				256,892				272,338	256,892
Costa Rica
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									18,968	17,244	16,742
Long-Lived Assets	117,481				120,292				117,481	120,292
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									331,173	340,461	354,116
Long-Lived Assets	797,798				976,707				797,798	976,707
Panama
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									0	0	1,243
Peru
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									14,961	11,222	8,078
Long-Lived Assets	66,593				59,206				66,593	59,206
Total International
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment revenues									2,343,093	1,522,887	$ 1,367,064
Long-Lived Assets	$ 9,892,991				$ 6,279,570				$ 9,892,991	$ 6,279,570

Business Segments (Major Customers) (Details) - Customer Concentration Risk - Sales Revenue, Net	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%
AT&T Mobility
Revenue, Major Customer [Line Items]
Concentration risk, percentage	21.00%	24.00%	20.00%
Verizon Wireless
Revenue, Major Customer [Line Items]
Concentration risk, percentage	15.00%	16.00%	11.00%
Sprint Nextel
Revenue, Major Customer [Line Items]
Concentration risk, percentage	11.00%	13.00%	15.00%
T-Mobile
Revenue, Major Customer [Line Items]
Concentration risk, percentage	9.00%	10.00%	10.00%

Selected Quarterly Financial Data (Schedule Of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Operating revenues	$ 1,539,549	$ 1,514,845	$ 1,442,227	$ 1,289,047	$ 1,280,041	$ 1,237,910	$ 1,174,375	$ 1,079,190	$ 5,785,668	$ 4,771,516	$ 4,100,048
Cost of operations	487,996	491,237	459,711	351,445	356,381	365,389	322,458	264,640	1,790,389	1,308,868
Operating income	489,296	479,074	432,806	451,853	402,124	400,925	389,774	419,966	1,853,029	1,612,789	1,486,922
Net income	232,853	263,735	192,464	281,307	221,595	97,740	157,180	195,492	970,359	672,007	803,199
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	229,207	264,509	187,550	275,159	232,702	102,999	156,056	193,317	956,425	685,074	824,910
Dividends on preferred stock	(26,781)	(26,781)	(26,782)	(26,781)	(26,781)	(26,781)	(26,782)	(9,819)	(107,125)	(90,163)	(23,888)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 202,426	$ 237,728	$ 160,768	$ 248,378	$ 205,921	$ 76,218	$ 129,274	$ 183,498	$ 849,300	$ 594,911	$ 801,022
Basic net income per common share (in dollars per share)	$ 0.48	$ 0.56	$ 0.38	$ 0.59	$ 0.49	$ 0.18	$ 0.31	$ 0.45	$ 2.00	$ 1.42	$ 2.02
Diluted net income per common share (in dollars per share)	$ 0.47	$ 0.55	$ 0.37	$ 0.58	$ 0.48	$ 0.18	$ 0.30	$ 0.45	$ 1.98	$ 1.41	$ 2.00

Subsequent Events (Details) $ in Thousands, € in Millions				12 Months Ended
Subsequent Events (Details) $ in Thousands, € in Millions	Feb. 15, 2017 USD ($)	Feb. 15, 2017 EUR (€)	Feb. 10, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Feb. 15, 2017 EUR (€)
Subsequent Event [Line Items]
Accrued interest				$ 157,297	$ 115,672
Gain (loss) on retirement of long-term obligations				1,168	(79,606)	$ (3,473)
Prepayment consideration				$ 86	$ 85,672	$ 11,593
Secured Debt \| GTP Notes \| Subsequent Event
Subsequent Event [Line Items]
Repayments of secured debt	$ 173,500
Gain (loss) on retirement of long-term obligations	1,800
Prepayment consideration	7,200
Secured Debt \| Secured Cellular Site Revenue Notes \| Subsequent Event
Subsequent Event [Line Items]
Repayments of secured debt	129,000
Gain (loss) on retirement of long-term obligations	14,500
Prepayment consideration	$ 18,300
Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Redemption Price, Percentage				100.00%
Senior Notes \| 7.25% Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				7.25%
Senior Notes \| 7.25% Senior Notes \| Subsequent Event
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			7.25%
Debt Instrument, Redemption Price, Percentage			112.0854%
Repayments of senior debt			$ 341,400
Accrued interest			5,100
Gain (loss) on retirement of long-term obligations			39,100
Prepayment consideration			$ 36,300
FPS Towers [Member] \| Subsequent Event
Subsequent Event [Line Items]
Percentage of voting interest acquired	100.00%						100.00%
FPS Towers [Member] \| Preliminary Purchase Price Allocation \| Subsequent Event
Subsequent Event [Line Items]
Business Combination, Consideration Transferred	$ 757,100	€ 713.9
Subsidiary of Common Parent [Member] \| FPS Towers [Member] \| Subsequent Event
Subsequent Event [Line Items]
Loan to an affiliated entity	$ 238,600						€ 225.0

Schedule III - Real Estate And Accumulated Depreciation (Schedule Of Real Estate And Accumulated Depreciation) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) site	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Number of units \| site	144,119
Encumbrances	$ 3,815,002
Gross amount carried at close of current period	14,276,973	$ 13,046,291	$ 10,469,207
Accumulated depreciation at close of current period	$ (4,548,096)	$ (3,994,874)	$ (3,613,078)	$ (3,297,033)
Date of construction	Various
Date acquired	Various
Percentage Of Gross Amounts Maximum	5.00%
Maximum
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statements is computed	20 years

Schedule III - Real Estate And Accumulated Depreciation (Activity Of Real Estate And Accumulated Depreciation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Adjusted Real Estate Gross At Carrying Value			$ 10,434,326	$ 9,921,276
SEC Schedule III, Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Gross amount at beginning	$ 13,046,291	$ 10,469,207
Acquisitions	787,206	2,620,778	397,837
Discretionary capital projects	105,279	210,421	437,720
Discretionary ground lease purchases	168,133	144,695	159,637
Redevelopment capital expenditures	136,821	114,089	96,782
Capital improvements	81,790	42,417	41,967
Start-up capital expenditures	128,707	35,561	21,173
Other additions	139,356	201,118	22,069
Total additions	1,547,292	3,369,079	1,177,185
Cost of real estate sold or disposed	(85,789)	(60,975)	(60,147)
Other deductions	(230,821)	(696,139)	(569,107)
Total deductions	(316,610)	(757,114)	(629,254)
Balance at end	14,276,973	13,046,291	10,469,207
SEC Schedule III, Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Gross amount of accumulated depreciation at beginning	(3,994,874)	(3,613,078)	(3,297,033)
Depreciation	(647,910)	(557,052)	(457,135)
Other additions	0	0	(761)
Total additions	(647,910)	(557,052)	(457,896)
Amount of accumulated depreciation for assets sold or disposed	24,911	30,083	20,953
Other deductions	69,777	145,173	120,898
Total deductions	94,688	175,256	141,851
Balance at end	$ (4,548,096)	$ (3,994,874)	$ (3,613,078)

Asset Retirement Obligations (Narrative) (Details) $ in Billions	Dec. 31, 2016 USD ($)
Asset Retirement Obligation [Abstract]
Estimated undiscounted future cash outlay for asset retirement obligations	$ 2.5