Prepaid and other current assets

27,381

^[1]

6,018

Accounts receivable, net

152,560

143,772

365,792

222,999

^[2]

Deferred income taxes

23,931

25,754

Total current assets

4,742,036

836,477

PROPERTY AND EQUIPMENT, net

5,878,826

5,766,150

GOODWILL

2,815,271

2,842,717

^[3]

OTHER INTANGIBLE ASSETS, net

3,195,106

3,205,496

^[2]

DEFERRED INCOME TAXES

219,373

209,589

DEFERRED RENT ASSET

878,124

776,201

NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS

452,584

452,788

TOTAL

18,181,320

14,089,418

CURRENT LIABILITIES:

Accounts payable

90,845

89,578

Accrued expenses

331,311

286,962

Distributions payable

110,937

189

Accrued interest

84,528

71,271

Current portion of long-term obligations

67,276

60,031

Unearned revenue

138,422

124,147

Total current liabilities

823,319

632,178

LONG-TERM OBLIGATIONS

12,578,532

8,693,345

ASSET RETIREMENT OBLIGATIONS

461,586

435,613

OTHER NON-CURRENT LIABILITIES

705,966

644,101

Total liabilities

14,569,403

10,405,237

COMMITMENTS AND CONTINGENCIES

EQUITY:

Preferred stock: $.01 par value; 20,000,000 shares authorized; no shares issued or outstanding

Common stock: $.01 par value; 1,000,000,000 shares authorized; 397,345,022 and 395,963,218 shares issued; and 394,534,996 and 395,091,213 shares outstanding, respectively

3,973

3,959

Additional paid-in capital

5,097,325

5,012,124

Distributions in excess of earnings

(1,066,580)

(1,196,907)

Accumulated other comprehensive loss

(298,015)

(183,347)

Treasury stock (2,810,026 and 872,005 shares at cost, respectively)

(207,740)

(62,728)

Total American Tower Corporation equity

3,528,963

3,573,101

Noncontrolling interest

82,954

111,080

Total equity

3,611,917

3,684,181

TOTAL

$ 18,181,320

$ 14,089,418

[1]	Consists of highly liquid investments with original maturities in excess of three months.
[2]	December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.
[3]	Balances have been revised to reflect purchase accounting measurement period adjustments.

CONDENSED CONSOLIDATED BALANCE SHEETS-Unaudited (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
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	397,345,022	395,963,218
Common Stock, Shares, Outstanding	394,534,996	395,091,213
Treasury stock, shares	2,810,026	872,005

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS-Unaudited (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
REVENUES:
Rental and management	$ 796,575	$ 697,554	$ 2,363,207	$ 2,063,806
Network development services	11,305	15,781	56,231	43,780
Total operating revenues	807,880	713,335	2,419,438	2,107,586
OPERATING EXPENSES:
Rental and management (including stock-based compensation expense of $248, $195, $751 and $594, respectively)	195,953	177,336	585,465	506,120
Network development services (including stock-based compensation expense of $99, $245, $440 and $749, respectively)	4,876	7,568	22,839	22,153
Depreciation, amortization and accretion	184,922	144,061	555,334	465,788
Selling, general, administrative and development expense (including stock-based compensation expense of $14,711, $12,618, $51,964 and $38,311, respectively)	97,781	81,459	298,737	237,891
Other operating expenses	15,469	7,359	35,686	35,150
Total operating expenses	499,001	417,783	1,498,061	1,267,102
OPERATING INCOME	308,879	295,552	921,377	840,484
OTHER INCOME (EXPENSE):
Interest income, TV Azteca, net of interest expense of $371, $372, $1,113 and $1,114, respectively	3,544	3,586	10,673	10,715
Interest income	2,342	1,717	5,468	6,253
Interest expense	(106,335)	(102,272)	(318,916)	(297,622)
Loss on retirement of long-term obligations	0	0	(37,967)	(398)
Other (expense) income (including unrealized foreign currency (losses) gains of $(30,907), $46,191, $(151,673), and $(12,847), respectively)	(29,622)	46,294	(148,991)	(19,468)
Total other expense	(130,071)	(50,675)	(489,733)	(300,520)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND INCOME ON EQUITY METHOD INVESTMENTS	178,808	244,877	431,644	539,964
Income tax provision	(15,586)	(13,054)	(23,361)	(64,117)
Income on equity method investments	0	2	0	25
NET INCOME	163,222	231,825	408,283	475,872
Net loss attributable to noncontrolling interest	16,901	264	43,068	25,732
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION	$ 180,123	$ 232,089	$ 451,351	$ 501,604
NET INCOME PER COMMON SHARE AMOUNTS:
Basic net income attributable to American Tower Corporation (in dollars per share)	$ 0.46	$ 0.59	$ 1.14	$ 1.27
Diluted net income attributable to American Tower Corporation (in dollars per share)	$ 0.45	$ 0.58	$ 1.13	$ 1.26
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	394,759	395,244	395,138	394,626
Diluted (in shares)	398,348	399,487	399,275	399,084
DISTRIBUTIONS DECLARED, PER SHARE (in dollars per share)	$ 0.28	$ 0.23	$ 0.81	$ 0.66

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS-Unaudited (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock-based compensation expense	$ 15,058	$ 13,058	$ 53,155	$ 39,654
Unrealized foreign currency losses	(30,907)	46,191	(151,673)	(12,847)
Rental And Management [Member]
Stock-based compensation expense	248	195	751	594
Network Development Services [Member]
Stock-based compensation expense	99	245	440	749
Selling General Administrative And Development Expense [Member]
Stock-based compensation expense	14,711	12,618	51,964	38,311
TV Azteca [Member]
Net of interest expense	$ 371	$ 372	$ 1,113	$ 1,114

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME-Unaudited (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 163,222	$ 231,825	$ 408,283	$ 475,872
Other comprehensive (loss) income:
Changes in fair value of cash flow hedges, net of taxes of $(70), $0, $386 and $0, respectively	(1,334)	(955)	1,415	(2,483)
Reclassification of unrealized losses on cash flow hedges to net income, net of taxes of $58, $0, $176 and $0, respectively	683	199	1,877	397
Reclassification of unrealized losses on available-for-sale securities to net income	0	0	0	495
Foreign currency translation adjustments, net of taxes of $(2,329), $1,667, $4,254 and $7,764, respectively	(24,660)	38,782	(120,602)	(36,357)
Other comprehensive (loss) income	(25,311)	38,026	(117,310)	(37,948)
Comprehensive income	137,911	269,851	290,973	437,924
Comprehensive loss attributable to noncontrolling interest	18,453	1,460	45,710	42,216
Comprehensive income attributable to American Tower Corporation	$ 156,364	$ 271,311	$ 336,683	$ 480,140

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME-Unaudited (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Reclassification of unrealized losses on cash flow hedges to net income, tax	$ 58	$ 0	$ 176	$ 0
Foreign currency translation adjustments, tax	(2,329)	1,667	4,254	7,764
Net change in fair value of cash flow hedges, tax	$ (70)	$ 0	$ 386	$ 0

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS-Unaudited (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 408,283	$ 475,872
Adjustments to reconcile net income to cash provided by operating activities:
Stock-based compensation expense	53,155	39,654
Depreciation, amortization and accretion	555,334	465,788
Loss on early retirement of securitized debt	35,288	0
Other non-cash items reflected in statements of operations	164,406	79,655
Increase in net deferred rent asset	(83,694)	(92,296)
Increase in restricted cash	(62,703)	(693)
Increase in assets	(59,267)	(36,137)
Increase in liabilities	133,641	184,704
Cash provided by operating activities	1,144,443	1,116,547
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments for purchase of property and equipment and construction activities	(448,249)	(377,026)
Payments for acquisitions, net of cash acquired	(365,658)	(822,714)
Proceeds from sale of short-term investments and other non-current assets	27,889	358,707
Payments for short-term investments	(50,224)	(330,341)
Deposits, restricted cash, investments and other	(122,396)	(2,892)
Cash used for investing activities	(958,638)	(1,174,266)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from short-term borrowings, net	7,544	20,099
Borrowings under credit facilities	3,507,000	1,325,000
Proceeds from issuance of senior notes, net	2,221,792	698,670
Proceeds from issuance of Securities in securitization transaction, net	1,778,496	0
Proceeds from term loan credit facility	0	750,000
Proceeds from other long-term borrowings	27,971	99,132
Repayments of notes payable, credit facilities and capital leases	(3,705,454)	(2,655,367)
Contributions from noncontrolling interest holders, net	17,584	48,500
Purchases of common stock	(145,012)	(16,733)
Proceeds from stock options	32,973	42,825
Distributions	(209,711)	(169,816)
Payment for early retirement of securitized debt	(29,234)	0
Deferred financing costs and other financing activities	(9,190)	(30,215)
Cash provided by financing activities	3,494,759	112,095
Net effect of changes in foreign currency exchange rates on cash and cash equivalents	(8,829)	(2,255)
NET INCREASE IN CASH AND CASH EQUIVALENTS	3,671,735	52,121
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	368,618	330,191
CASH AND CASH EQUIVALENTS, END OF PERIOD	4,040,353	382,312
CASH PAID FOR INCOME TAXES (NET OF REFUNDS OF $17,336 AND $20,453, RESPECTIVELY)	23,172	28,465
CASH PAID FOR INTEREST	283,145	265,443
NON-CASH INVESTING AND FINANCING ACTIVITIES:
INCREASE (DECREASE) IN ACCOUNTS PAYABLE AND ACCRUED EXPENSES FOR PURCHASES OF PROPERTY AND EQUIPMENT AND CONSTRUCTION ACTIVITIES	17,208	(1,228)
PURCHASES OF PROPERTY AND EQUIPMENT UNDER CAPITAL LEASES	$ 16,199	$ 12,219

CONDENSED CONSOLIDATED STATEMENT OF EQUITY-Unaudited (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Other Comprehensive (Loss) Income	Earnings (Distributions) in Excess of Distributions (Earnings)	Noncontrolling Interest
BALANCE at Dec. 31, 2011	$ 3,410,142	$ 3,936		$ 4,903,800	$ (142,617)	$ (1,477,899)	$ 122,922
BALANCE (shares) at Dec. 31, 2011		393,642,079
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity (shares)		1,917,576
Stock-based compensation related activity	65,036	19		65,017
Issuance of common stock-Stock Purchase Plan (shares)		47,464
Issuance of common stock-Stock Purchase Plan	2,365	1		2,364
Treasury stock activity (shares)			(252,691)
Treasury stock activity	(16,733)		(16,733)
Change in fair value of cash flow hedges, net of tax	(2,483)				(1,862)		(621)
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	397				397
Reclassification of unrealized losses on available-for-sale securities to net income	495				495
Foreign currency translation adjustment, net of tax	(36,357)				(20,494)		(15,863)
Contributions from non-controlling interest	48,963						48,963
Distributions to non-controlling interest	(441)						(441)
Dividends/distributions declared	(261,274)					(261,274)
Net income (loss)	475,872					501,604	(25,732)
BALANCE at Sep. 30, 2012	3,685,982	3,956	(16,733)	4,971,181	(164,081)	(1,237,569)	129,228
BALANCE (shares) at Sep. 30, 2012		395,607,119	(252,691)
BALANCE at Dec. 31, 2012	3,684,181	3,959	(62,728)	5,012,124	(183,347)	(1,196,907)	111,080
BALANCE (shares) at Dec. 31, 2012	395,091,213	395,963,218	(872,005)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity (shares)		1,343,555
Stock-based compensation related activity	82,888	14		82,874
Issuance of common stock-Stock Purchase Plan (shares)		38,249
Issuance of common stock-Stock Purchase Plan	2,327			2,327
Treasury stock activity (shares)			(1,938,021)
Treasury stock activity	(145,012)		(145,012)
Change in fair value of cash flow hedges, net of tax	1,415				1,167		248
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	1,877				1,764		113
Reclassification of unrealized losses on available-for-sale securities to net income	0
Foreign currency translation adjustment, net of tax	(120,602)				(117,599)		(3,003)
Contributions from non-controlling interest	18,020						18,020
Distributions to non-controlling interest	(436)						(436)
Dividends/distributions declared	(321,024)					(321,024)
Net income (loss)	408,283					451,351	(43,068)
BALANCE at Sep. 30, 2013	$ 3,611,917	$ 3,973	$ (207,740)	$ 5,097,325	$ (298,015)	$ (1,066,580)	$ 82,954
BALANCE (shares) at Sep. 30, 2013	394,534,996	397,345,022	(2,810,026)

Description of Business, Basis of Presentation and Accounting Policies	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Basis of Presentation and Accounting Policies	Description of Business, Basis of Presentation and Accounting Policies American Tower Corporation is, through its various subsidiaries (collectively, “ATC” or the “Company”), an independent owner, operator and developer of wireless and broadcast communications real estate in the United States, Brazil, Chile, Colombia, Germany, Ghana, India, Mexico, Peru, South Africa and Uganda. In connection with its acquisition of MIP Tower Holdings LLC (“MIPT”) on October 1, 2013, the Company expanded its operations into two new markets, Costa Rica and Panama. The Company’s primary business is the leasing of antenna space on multi-tenant communications sites to wireless service providers, radio and television broadcast companies, wireless data and data providers, government agencies and municipalities and tenants in a number of other industries. The Company also manages rooftop and tower sites for property owners, operates in-building and outdoor distributed antenna system (“DAS”) networks, holds property interests under third-party communications sites and provides network development services that primarily support its rental and management operations and the addition of new tenants and equipment on its sites. Effective January 1, 2012, the Company reorganized to qualify as a real estate investment trust for federal income tax purposes (“REIT”). 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 through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international operating subsidiaries and joint ventures. The accompanying condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). The financial information included herein is unaudited; however, the Company believes that all adjustments (consisting primarily of normal recurring adjustments) considered necessary for a fair presentation of the Company’s financial position and results of operations for such periods have been included. These condensed consolidated financial statements and related notes should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. The Company believes that since January 1, 2012, it has been organized and has operated in a manner that enables it to qualify, and intends to continue to operate in a manner that will allow it to continue to qualify, as a REIT for federal income tax purposes. The Company filed an election to be taxed as a REIT effective as of January 1, 2012 on its U.S. federal income tax return for the 2012 taxable year. The Company holds and operates certain of its assets through one or more taxable REIT subsidiaries (“TRSs”). A TRS is a subsidiary of a REIT that is subject to applicable corporate income tax. The Company’s use of TRSs enables it to continue to engage in certain businesses while complying with REIT qualification requirements and also allows the Company to retain income generated by these businesses for reinvestment without the requirement of distributing those earnings. The non-REIT qualified businesses that the Company holds through TRSs include its network development services segment. In addition, the Company has included most of its international operations and DAS networks business within its TRSs. The Company changed the election for substantially all of its Mexican operations, all of which was previously designated as a TRS, to be treated as a qualified REIT subsidiary as of March 1, 2013. Although the election did not have a material effect on the Company’s deferred tax position, the Company recognized a one-time dividend from its Mexican operations, the income from which the Company may either offset with its net operating losses or distribute to its stockholders as part of its regular distributions. For all periods subsequent to March 1, 2013, the Company will be required to include the income from its Mexican operations as part of its REIT taxable income for the purpose of computing the Company’s REIT distribution requirements. The Company may, from time to time, change the election of other previously designated TRSs that hold certain of its other international operations to be treated as qualified REIT subsidiaries or other disregarded entities (collectively, “QRSs”), and may reorganize and transfer certain assets or operations from its TRSs to other subsidiaries, including QRSs. As a REIT, the Company generally is not subject to federal income taxes on its income and gains that the Company distributes to its stockholders, including the income derived from leasing towers. However, even as a REIT, the Company remains obligated to pay income taxes on earnings from its TRS assets. In addition, the Company’s international assets and operations continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted. Principles of Consolidation and Basis of Presentation—The accompanying condensed 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. 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 condensed consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying condensed consolidated financial statements. The significant estimates in the accompanying condensed 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. 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. Changes in Presentation—Changes have been made to the presentation of the Company’s condensed consolidated statements of cash flows for the nine months ended September 30, 2012 to be consistent with the current year presentation. Specifically, amounts surrendered for the satisfaction of employee tax obligations in connection with the vesting of restricted stock units of $16.7 million that were previously included in Purchases of common stock are now included in Deferred financing costs and other financing activities in the Company’s condensed consolidated statements of cash flows. Recently Adopted Accounting Standards—In February 2013, the Financial Accounting Standards Board (“FASB”) issued additional guidance on comprehensive income which adds new disclosure requirements for items reclassified out of accumulated other comprehensive income (“AOCI”) by component. This guidance enhances the transparency of changes in other comprehensive income (“OCI”) and items transferred out of AOCI in the financial statements and it does not amend any existing requirements for reporting net income or OCI in the financial statements. Since the guidance relates only to presentation and disclosure of information, the adoption did not have a material effect on the Company’s condensed consolidated financial condition or results of operations. In February 2013, the FASB issued guidance that clarifies the scope of transactions subject to disclosures about offsetting assets and liabilities. The guidance requires an entity to disclose information about offsetting and related arrangements to enable users of its financial statements to understand the effect of those arrangements on its financial position. This guidance is effective for annual and interim reporting periods beginning on or after January 1, 2013 on a retrospective basis. Since the guidance relates only to presentation and disclosure of information, the adoption did not have a material effect on the Company’s condensed consolidated financial condition or results of operations. In July 2013, the FASB issued guidance that permits the Fed Funds Effective Swap Rate (Overnight Index Swap Rate) to be used as a U.S. benchmark interest rate for hedge accounting purposes, in addition to U.S. Treasury rates and the London Interbank Offered Rate (“LIBOR”). The guidance also removed the restriction on using different benchmark rates for similar hedges. These amendments are effective prospectively for qualifying new or re-designated hedging relationships entered into on or after July 17, 2013. The adoption of this guidance did not have a material effect on the Company’s financial statements. In July 2013, the FASB issued guidance that requires an unrecognized tax benefit, or a portion of an unrecognized tax benefit, to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, with certain exceptions. The amendment is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted. The adoption of this guidance did not have a material effect on the Company’s financial statements.

Prepaid and Other Current Assets

9 Months Ended

Sep. 30, 2013

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid and Other Current Assets

Prepaid and other current assets consist of the following as of (in thousands):



	September 30, 2013		December 31, 2012 (1)
Acquisition deposit in escrow	$	120,000	$	—
Prepaid income tax	65,903		57,665
Prepaid operating ground leases	61,393		56,916
Unbilled receivables	27,922		32,588
Prepaid assets	34,260		19,037
Value added tax and other consumption tax receivables	16,771		22,443
Other miscellaneous current assets	39,543		34,350
Balance	$	365,792	$	222,999

(1) December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.

Accrued Expenses

9 Months Ended

Sep. 30, 2013

Accrued Liabilities, Current [Abstract]

Accrued Expenses

Accrued expenses consist of the following as of (in thousands):



	September 30, 2013		December 31, 2012
Accrued property and real estate taxes	$	46,972	$	36,814
Payroll and related withholdings	38,359		37,586
Accrued construction costs	38,201		20,711
Accrued rent	23,485		24,394
Other accrued expenses	184,294		167,457
Balance	$	331,311	$	286,962

Goodwill and Other Intangible Assets

9 Months Ended

Sep. 30, 2013

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

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



	Rental and Management					Network Development Services		Total
	Domestic		International			Network Development Services		Total
Balance as of January 1, 2013 (1)	$	2,320,645	$	520,072		$	2,000	$	2,842,717
Additions	4,698		14,933			—		19,631
Effect of foreign currency translation	—		(47,077		)	—		(47,077		)
Balance as of September 30, 2013	$	2,325,343	$	487,928		$	2,000	$	2,815,271


(1)	Balances have been revised to reflect purchase accounting measurement period adjustments.

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



		September 30, 2013							December 31, 2012 (1)
	Estimated Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Book Value		Gross Carrying Value		Accumulated Amortization			Net Book Value
	(years)
Acquired network location (2)	Up to 20	$	1,731,664	$	(767,973	)	$	963,691	$	1,702,895	$	(721,135	)	$	981,760
Acquired customer-related intangibles	15-20	3,228,515		(1,093,481		)	2,135,034		3,133,166		(979,264		)	2,153,902
Acquired licenses and other intangibles	3-20	6,524		(2,087		)	4,437		26,079		(20,835		)	5,244
Economic Rights, TV Azteca	70	28,609		(14,037		)	14,572		28,954		(13,902		)	15,052
Total		4,995,312		(1,877,578		)	3,117,734		4,891,094		(1,735,136		)	3,155,958
Deferred financing costs, net (3)	N/A						77,372							49,538
Other intangible assets, net							$	3,195,106						$	3,205,496


(1)	December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.


(2)	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.


(3)	Deferred financing costs are amortized over the term of the respective debt instruments to which they relate using the effective interest method. This amortization is included in interest expense rather than in amortization expense.

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 customer-related intangibles typically represent the value to the Company of customer contracts and relationships in place at the time of an acquisition, including assumptions regarding estimated renewals. During the nine months ended September 30, 2013, the Company retired $19.6 million of intangible assets related to non-competition agreements that had expired and were fully amortized.

The Company amortizes these intangibles on a straight-line basis over their estimated useful lives. As of September 30, 2013, the remaining weighted average amortization period of the Company’s intangible assets, excluding deferred financing costs and the TV Azteca Economic Rights detailed in note 5 to the Company’s consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012, was approximately 13 years. Amortization of intangible assets for the three and nine months ended September 30, 2013 was approximately $57.7 million and $177.9 million (excluding amortization of deferred financing costs, which is included in interest expense), respectively. Amortization of intangible assets for the three and nine months ended September 30, 2012 was approximately $46.9 million and $154.3 million (excluding amortization of deferred financing costs, which is included in interest expense), respectively. The Company expects to record amortization expense (excluding amortization of deferred financing costs) as follows over the next five years (in millions):



Fiscal Year
2013 (remaining year)	$	61.5
2014	232.9
2015	214.5
2016	202.2
2017	195.7
2018	189.3

Financing Transactions	9 Months Ended
Financing Transactions	Sep. 30, 2013
Securities Financing Transactions [Abstract]
Financing Transactions	Financing Transactions Commercial Mortgage Pass-Through Certificates, Series 2007-1—During the year ended December 31, 2007, the Company completed a securitization transaction involving assets related to 5,295 broadcast and wireless communications towers owned by two special purpose subsidiaries of the Company through a private offering of $1.75 billion of Commercial Mortgage Pass-Through Certificates, Series 2007-1 (the “Certificates”). On March 15, 2013, the Company repaid all indebtedness outstanding under the Certificates ($1.75 billion in principal amount), plus prepayment consideration and accrued interest thereon and other costs and expenses related thereto, with proceeds from the offering of $1.8 billion of Secured Tower Revenue Securities, Series 2013-1A and Series 2013-2A, as described in more detail below (collectively, the “Securities”). The Company recorded a loss on retirement of long-term obligations in the accompanying condensed consolidated statements of operations of $35.3 million, consisting of prepayment consideration of $29.2 million and the expense of deferred financing costs of $6.1 million. Secured Tower Revenue Securities, Series 2013-1A and Series 2013-2A—On March 15, 2013, the Company completed a securitization transaction (the “Securitization”) involving assets related to 5,195 wireless and broadcast communications towers (the “Secured Towers”) owned by two special purpose subsidiaries of the Company, through a private offering of $1.8 billion of the Securities. The net proceeds of the transaction were $1.78 billion. The Securities were issued by American Tower Trust I (the “Trust”), a trust established by American Tower Depositor Sub, LLC (the “Depositor”), an indirect wholly owned special purpose subsidiary of the Company. 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 “Borrowers”), pursuant to a First Amended and Restated Loan and Security Agreement dated as of March 15, 2013 (the “Loan Agreement”). The Borrowers are special purpose entities formed solely for the purpose of holding the Secured Towers subject to a securitization. The Securities were issued in two separate series of the same class pursuant to a First Amended and Restated Trust and Servicing Agreement (the “Trust Agreement”), with terms identical to the Loan. The Series 2013-1A Securities have an expected life of five years with a final repayment date in March 2043 and an interest rate of 1.551%. The Series 2013-2A Securities have an expected life of ten years with a final repayment date in March 2048 and an interest rate of 3.070%. The effective weighted average life and interest rate of the Securities is 8.6 years and 2.648%, respectively. Amounts due under the Loan will be paid by the Borrowers solely from the cash flows generated by the Secured Towers. These funds in turn will be used by or on behalf of the Trust to service the payment of interest on the Securities and for any other payments required by the Loan Agreement or Trust Agreement. The Borrowers are required to make monthly payments of interest on the Loan. Subject to certain limited exceptions described below, no payments of principal will be required to be made prior to March 15, 2018, which is the anticipated repayment date for the component of the Loan associated with the Series 2013-1A Securities. On a monthly basis, after payment of all required amounts under the Loan Agreement and Trust Agreement, the excess cash flows generated from the operation of the Secured Towers are released to the Borrowers, and can then be distributed to, and used by, the Company. However, if the debt service coverage ratio (the “DSCR”), generally defined as the net cash flow divided by the amount of interest, servicing fees and trustee fees that the Borrowers will be required to pay over the succeeding 12 months on the principal amount of the Loan, as of the last day of any calendar quarter prior to the applicable anticipated repayment date, is 1.30x or less (the “Cash Trap DSCR”) for such quarter, and the DSCR continues to be equal to or below the Cash Trap DSCR for two consecutive calendar quarters, 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 loan documents, referred to as excess cash flow, will be deposited into a reserve account instead of being released to the Borrowers. The funds in the reserve account will not be released to the Borrowers unless the DSCR exceeds the Cash Trap DSCR for two consecutive calendar quarters. An “amortization period” commences if (i) as of the end of any calendar quarter the DSCR equals or falls below 1.15x (the “Minimum DSCR”) for such calendar quarter and such amortization period will continue to exist until the DSCR exceeds the Minimum DSCR for two consecutive calendar quarters or (ii) on the anticipated repayment date the component of the Loan corresponding to the applicable subclass of the 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. During an amortization period all excess cash is applied to payment of the principal on the Loan. The Borrowers may prepay the Loan in whole or in part at any time provided it is accompanied by applicable prepayment consideration. If the prepayment occurs within 12 months of the anticipated repayment date for the Series 2013-1A Securities or 18 months of the anticipated repayment date for the 2013-2A Securities, no prepayment consideration is due. The entire unpaid principal balance of the component of the Loan related to the Series 2013-1A Securities will be due in March 2043. The entire unpaid principal balance of the component of the Loan related to the Series 2013-2A Securities will be due in March 2048. 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 is secured by (1) mortgages, deeds of trust and deeds to secure debt on substantially all of the Secured Towers, (2) a pledge of the Borrowers’ operating cash flows from the Secured Towers, (3) a security interest in substantially all of the Borrowers’ personal property and fixtures and (4) the Borrowers’ rights under the tenant leases and the Management Agreement entered into in connection with the Securitization. American Tower Holding Sub, LLC, whose only material assets are its equity interests in each of the Borrowers, and American Tower Guarantor Sub, LLC, whose only material asset is its equity interest 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. American Tower Guarantor Sub, LLC, American Tower Holding Sub, LLC, the Depositor and the Borrowers each were formed as special purpose entities solely for purposes of entering a securitization transaction, and the assets and credit of these entities are not available to satisfy the debts and other obligations of the Company or any other person, except as set forth in the Loan Agreement. The Loan Agreement includes operating covenants and other restrictions customary for loans subject to rated securitizations. Among other things, the Borrowers are prohibited from incurring other indebtedness for borrowed money or further encumbering their assets subject to customary carveouts for ordinary course trade payables and permitted encumbrances (as defined in the Loan Agreement). The organizational documents of the Borrowers contain provisions consistent with rating agency securitization criteria for special purpose entities, including the requirement that the Borrowers maintain at least two independent directors. The Loan Agreement also contains certain covenants that require the Borrowers to provide the trustee with regular financial reports and operating budgets, promptly notify the trustee of events of default and material breaches under the Loan Agreement and other agreements related to the Secured Towers, and allow the trustee reasonable access to the Secured Towers, including the right to conduct site investigations. A failure to comply with the covenants in the Loan Agreement could prevent the Borrowers from taking certain actions with respect to the Secured Towers, and could prevent the Borrowers from distributing any excess cash from the operation of the Secured Towers to the Company. If the Borrowers were to default on the Loan, Midland Loan Services, a Division of PNC Bank, National Association, in its capacity as servicer on behalf of the trustee, could seek to foreclose upon or otherwise convert the ownership of the Secured Towers, in which case the Company could lose the Secured Towers and the revenue associated with the Secured Towers. Under the Loan Agreement, the Borrowers are required to maintain reserve accounts, including for ground rents, real estate and personal property taxes and insurance premiums, and to reserve a portion of advance rents from tenants on the Secured Towers. Based on the terms of the Loan Agreement, all rental cash receipts received for each month are reserved for the succeeding month and held in an account controlled by the trustee and then released. The $120.9 million held in the reserve accounts as of September 30, 2013 is classified as Restricted cash on the Company’s accompanying condensed consolidated balance sheet. 3.50% Senior Notes Offering—On January 8, 2013, the Company completed a registered public offering of $1.0 billion aggregate principal amount of 3.50% senior unsecured notes due 2023 (the “3.50% Notes”), which were issued at a price equal to 99.185% of their face value. The net proceeds to the Company from the offering were approximately $983.4 million, after deducting commissions and expenses. The Company used $265.0 million of the net proceeds to repay the outstanding indebtedness under its $1.0 billion senior unsecured revolving credit facility entered into in April 2011 (the “2011 Credit Facility”) and $718.4 million to repay a portion of the outstanding indebtedness incurred under its $1.0 billion senior unsecured revolving credit facility entered into in January 2012 (the “2012 Credit Facility”). The 3.50% Notes mature on January 31, 2023, and interest is payable semi-annually in arrears on January 31 and July 31 of each year, commencing on July 31, 2013. The Company may redeem the 3.50% Notes at any time at a redemption price equal to 100% of the principal amount, plus a make-whole premium, together with accrued interest to the redemption date. Interest on the notes began to accrue on January 8, 2013 and is computed on the basis of a 360-day year comprised of 12 30-day months. If the Company undergoes a change of control and ratings decline, each as defined in the supplemental indenture, the Company will be required to offer to repurchase all of the 3.50% Notes at a purchase price equal to 101% of the principal amount, plus accrued and unpaid interest (including additional interest, if any) up to but not including the repurchase date. The 3.50% 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. The supplemental indenture 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 supplemental indenture. 3.40% Senior Notes and 5.00% Senior Notes Offering—On August 19, 2013, the Company completed a registered public offering of $750 million aggregate principal amount of 3.40% senior unsecured notes due 2019 (the “3.40% Notes”) and $500 million aggregate principal amount of 5.00% senior unsecured notes due 2024 (the “5.00% Notes”). The net proceeds to the Company from the offering were approximately $1,238.7 million, after deducting commissions and estimated expenses. The Company used a portion of the proceeds to repay outstanding indebtedness under its $2.0 billion senior unsecured revolving credit facility (the “2013 Credit Facility”). The 3.40% Notes will mature on February 15, 2019 and bear interest at a rate of 3.40% per annum. The 5.00% Notes will mature on February 15, 2024 and bear interest at a rate of 5.00% per annum. Accrued and unpaid interest on the 3.40% Notes and the 5.00% Notes will be payable in U.S. Dollars semi-annually in arrears on February 15 and August 15 of each year, beginning on February 15, 2014. Interest on the 3.40% Notes and the 5.00% Notes will accrue from August 19, 2013 and will be computed on the basis of a 360-day year comprised of 12 30-day months. The Company may redeem the 3.40% Notes or the 5.00% Notes at any time at a redemption price equal to 100% of the principal amount, plus a make-whole premium, together with accrued interest to the redemption date. If the Company undergoes a change of control and ratings decline, each as defined in the supplemental indenture, the Company may be required to repurchase all of the 3.40% Notes and the 5.00% Notes at a purchase price equal to 101% of the principal amount of the 3.40% Notes and the 5.00% Notes, plus accrued and unpaid interest (including additional interest, if any), up to but not including the repurchase date. The 3.40% Notes and the 5.00% 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. The supplemental indenture 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 supplemental indenture. 2011 Credit Facility—On June 28, 2013, the Company terminated the 2011 Credit Facility upon entering into the 2013 Credit Facility. During the nine months ended September 30, 2013, the Company recorded a loss on retirement of long-term obligations in the accompanying condensed consolidated statements of operations of $2.7 million, related to the acceleration of the remaining deferred financing costs associated with the 2011 Credit Facility. The 2011 Credit Facility had a term of five years and a maturity date of April 8, 2016. The 2011 Credit Facility was terminated prior to maturity at the Company’s option without penalty or premium. The 2011 Credit Facility was undrawn at the time of termination. 2012 Credit Facility—As of September 30, 2013, the Company had $963.0 million outstanding under the 2012 Credit Facility, which was used to fund its acquisition of MIPT on October 1, 2013 (see note 14). The Company also had approximately $7.8 million of undrawn letters of credit. On October 29, 2013, the Company repaid $800 million under the 2012 Credit Facility with net proceeds from the $1.5 billion unsecured term loan entered into on October 29, 2013 (the “2013 Term Loan”) (see note 16) and cash on hand. The Company continues to maintain the ability to draw down and repay amounts under the 2012 Credit Facility in the ordinary course. The 2012 Credit Facility has a term of five years and matures on January 31, 2017. The 2012 Credit Facility does 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 current margin over LIBOR that the Company incurs on borrowings is 1.625%, which results in an interest rate of 1.81% as of September 30, 2013. The current commitment fee on the undrawn portion of the 2012 Credit Facility is 0.225%. On September 20, 2013, the Company entered into an amendment agreement with respect to the 2012 Credit Facility, which (i) amended the definition of “Total Debt” to be net of unrestricted domestic cash and cash equivalents and (ii) increased the permitted ratio of Total Debt to Adjusted EBITDA (as defined therein) from 6.00 to 1.00 to 6.50 to 1.00 from September 30, 2013 to September 30, 2014. 2013 Credit Facility—On June 28, 2013, the Company entered into the 2013 Credit Facility, which allowed the Company to borrow up to $1.5 billion, and includes a $1.0 billion sublimit for multicurrency borrowings, a $200.0 million sublimit for letters of credit, a $50.0 million sublimit for swingline loans and an expansion option allowing the Company to request additional commitments of up to $500.0 million, which the Company exercised on September 20, 2013. As a result, the Company may borrow up to $2.0 billion under the 2013 Credit Facility. The 2013 Credit Facility has a term of five years, matures on June 28, 2018 and includes two one-year renewal periods at the Company’s option. Any outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. The 2013 Credit Facility does 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 LIBOR as the applicable base rate for borrowings under the 2013 Credit Facility. The interest rate ranges between 1.125% to 2.000% above LIBOR for LIBOR-based borrowings, or between 0.125% to 1.000% above the defined base rate for base rate borrowings, in each case based upon the Company’s debt ratings. A quarterly commitment fee on the undrawn portion of the 2013 Credit Facility is required, ranging from 0.125% to 0.400% per annum, based upon the Company’s debt ratings. The current margin over LIBOR that the Company incurs on borrowings is 1.250%, which results in an interest rate of 1.43% as of September 30, 2013. The current commitment fee on the undrawn portion of the new credit facility is 0.150%. The loan agreement contains certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Any failure to comply with the financial and operating covenants of the loan agreement would not only prevent the Company from being able to borrow additional funds, but would constitute a default, which could result in, among other things, the amounts outstanding, including all accrued interest and unpaid fees, becoming immediately due and payable. On September 20, 2013, the Company entered into an amendment agreement with respect to the 2013 Credit Facility, which (i) amended the definition of “Total Debt” to be net of unrestricted domestic cash and cash equivalents, (ii) increased the permitted ratio of Total Debt to Adjusted EBITDA (as defined therein) from 6.00 to 1.00 to 6.50 to 1.00 from September 30, 2013 to September 30, 2014 and (iii) added an additional expansion feature permitting the Company to request an increase of the commitments under the 2013 Credit Facility from time to time up to an aggregate additional $750.0 million, including in the form of a term loan, from any of the lenders or other eligible lenders that elect to make such increases available, upon the satisfaction of certain conditions. As of September 30, 2013, the Company had $1,853.0 million outstanding under the 2013 Credit Facility, which was used to fund its acquisition of MIPT on October 1, 2013 (see note 14). The Company also had approximately $2.3 million of undrawn letters of credit. The Company continues to maintain the ability to draw down and repay amounts under the 2013 Credit Facility in the ordinary course. 2012 Term Loan—On June 29, 2012, the Company entered into a $750.0 million unsecured term loan (“2012 Term Loan”). The 2012 Term Loan has a term of five years and matures on June 29, 2017. The interest rate under the 2012 Term Loan is LIBOR plus 1.750%, or 1.93% as of September 30, 2013. On October 29, 2013, the Company repaid the 2012 Term Loan with net proceeds from the 2013 Term Loan (see note 16). On September 20, 2013, the Company entered into an amendment agreement with respect to the 2012 Term Loan, which (i) amended the definition of “Total Debt” to be net of unrestricted domestic cash and cash equivalents and (ii) increased the permitted ratio of Total Debt to Adjusted EBITDA (as defined therein) from 6.00 to 1.00 to 6.50 to 1.00 from September 30, 2013 to September 30, 2014. Short-Term Credit Facility—On September 20, 2013, the Company entered into a $1.0 billion senior unsecured revolving credit facility (the “Short-Term Credit Facility”). The Short-Term Credit Facility does not require amortization of payments and may be repaid prior to maturity in whole or in part at the Company’s option without penalty or premium. The unutilized portion of the commitments under the Short-Term Credit Facility may be irrevocably reduced or terminated by the Company in whole or in part without penalty. The Short-Term Credit Facility matures on September 19, 2014. Amounts borrowed under the Short-Term Credit Facility will bear interest, at the Company’s option, at a margin above LIBOR or the defined base rate. For LIBOR based borrowings, interest rates will range from 1.125% to 2.000% above LIBOR. For base rate borrowings, interest rates will range from 0.125% to 1.000% above the defined base rate. In each case, the applicable margin is based upon the Company’s debt ratings. In addition, the loan agreement provides for a quarterly commitment fee on the undrawn portion of the Short-Term Credit Facility ranging from 0.125% to 0.400% per annum, based upon the Company’s debt ratings. The current margin over LIBOR that the Company would incur (should it choose LIBOR) on borrowings is 1.250% and the current commitment fee on the undrawn portion is 0.150%. The loan agreement contains certain reporting, information, financial and operating covenants and other restrictions (including with respect to its real estate investment trust status, indebtedness, guaranties, mergers and asset sales, liens, dividends, corporate existence and financial reporting obligations) with which the Company must comply. Any failure to comply with the financial and operating covenants would not only prevent the Company from being able to borrow additional funds, but would constitute a default, which could result in, among other things, the amounts outstanding, including all accrued interest and unpaid fees, becoming immediately due and payable. As of September 30, 2013, the Company had no amounts outstanding under the Short-Term Credit Facility. The Company maintains the ability to draw down and repay amounts under the Short-Term Credit Facility in the ordinary course. Colombian Bridge Loans—In connection with the acquisition of communications sites from Colombia Movil S.A. E.S.P. (“Colombia Movil”) pursuant to an agreement dated July 17, 2011, one of the Company’s Colombian subsidiaries entered into five Colombian Peso (“COP”) denominated bridge loans for an aggregate principal amount outstanding of 94.0 billion COP (approximately $49.1 million) and an interest rate of 7.99%. On August 6, 2013, one of the Company’s Colombian subsidiaries entered into an additional 14.0 billion COP bridge loan (approximately $7.3 million) with an interest rate of 7.95%. As of September 30, 2013, the aggregate principal amount outstanding under the bridge loans was 108.0 billion COP (approximately $56.4 million) which mature on December 22, 2013. Indian Working Capital Facility—On April 29, 2013, one of the Company’s Indian subsidiaries (“ATC India”) entered into a working capital facility agreement (the “Indian Working Capital Facility”), which allows ATC India to borrow an amount not to exceed the Indian Rupee equivalent of $10.0 million. Any advances made pursuant to the Indian Working Capital Facility will be payable on the earlier of demand or six months following the borrowing date and the interest rate will be determined at the time of advance by the bank. As of September 30, 2013, ATC India had not drawn on the facility. South African Facility—The Company’s South African Facility was executed in November 2011 and generally matures on March 31, 2020. Principal and interest are payable quarterly in arrears with principal due in accordance with the repayment schedule. On September 30, 2013, the Company's ability to draw on the South African Facility expired. During the nine months ended September 30, 2013, the Company borrowed an additional 116.3 million South African Rand (“ZAR”) (approximately $11.6 million) to increase total borrowings under the South African Facility to 950.6 million ZAR (approximately $94.8 million) as of September 30, 2013.

Derivative Financial Instruments

9 Months Ended

Sep. 30, 2013

Summary of Derivative Instruments [Abstract]

Derivative Financial Instruments

The Company is exposed to certain risks related to its ongoing business operations. The primary risk managed through the use of derivative instruments is interest rate risk. From time to time, the Company enters into interest rate protection agreements to manage exposure to variability in cash flows relating to forecasted interest payments. Under these agreements, the Company is exposed to credit risk to the extent that a counterparty fails to meet the terms of a contract. The Company’s credit risk exposure is limited to the current value of the contract at the time the counterparty fails to perform.

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 accumulated other comprehensive income (loss) and are recognized in the results of operations when the hedged item affects earnings. Ineffective portions of changes in the fair value of cash flow hedges are recognized immediately in the results of operations. For derivative instruments not designated as hedging instruments, changes in fair value are recognized in the results of operations in the period in which the change occurs.

The Company, through certain of its foreign subsidiaries, has entered into interest rate swap agreements to manage its exposure to variability in interest rates on debt in South Africa and Colombia. As of December 31, 2012, the Company had nine interest rate swap agreements outstanding in South Africa and one interest rate swap agreement outstanding in Colombia. During the three months ended September 30, 2013, the Company entered into three additional interest rate swaps agreements in South Africa with an aggregate notional value of 24.6 million ZAR (approximately $2.5 million). As a result, as of September 30, 2013, the Company had 12 interest rate swap agreements outstanding in South Africa with an aggregate notional value of 442.7 million ZAR (approximately $44.1 million), which notional value is reduced in accordance with the repayment schedule under the South African Facility, and one interest rate swap agreement outstanding in Colombia with a notional value of 101.3 billion COP (approximately $52.9 million).

The Company’s South African interest rate swap agreements accrue interest based on Johannesburg Interbank Agreed Rate (“JIBAR”), have been designated as cash flow hedges, have fixed interest rates ranging from 6.09% to 7.83% and expire on March 31, 2020. The Company’s Colombian interest rate swap agreement accrues interest based on the Inter-bank Rate (“IBR”), has been designated as a cash flow hedge, has a fixed interest rate of 5.78% and expires on November 30, 2020.

As of September 30, 2013 and December 31, 2012, the notional amount and fair value of the Company’s interest rate swap agreements (expressed in their respective currency units), which are recorded in Other non-current liabilities, are as follows (in thousands):



	September 30, 2013 (1)	December 31, 2012 (2)
ZAR
Notional	442,655	423,634
Carrying Amount/Fair Value	909	20,441
COP
Notional	101,250,000	101,250,000
Carrying Amount/Fair Value	2,869,430	5,356,377


(1)	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $97.0 million and $1.6 million, respectively, as of September 30, 2013.


(2)	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $107.3 million and $5.4 million, respectively, as of December 31, 2012.

During the three months ended September 30, 2013 and 2012, the interest rate swap agreements held by the Company had the following impact on OCI included in the condensed consolidated balance sheets and in the condensed consolidated statements of operations (in thousands):



Three Months Ended September 30, 2013
Amount of Gain/(Loss) Recognized in OCI on Derivatives (Effective Portion)			Location of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
$	(1,404	)	Interest expense	$	(741	)	N/A	N/A
Three Months Ended September 30, 2012
Amount of Gain/(Loss) Recognized in OCI on Derivatives (Effective Portion)			Location of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
$	(1,135	)	Interest expense	$	(181	)	N/A	N/A

During the nine months ended September 30, 2013 and 2012, the interest rate swap agreements held by the Company had the following impact on OCI included in the condensed consolidated balance sheets and in the condensed consolidated statements of operations (in thousands):

Nine Months Ended September 30, 2013

Amount of Gain/(Loss)

Recognized in OCI on

Derivatives (Effective

Portion)

Location of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Amount of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective Portion)

Location of Gain/(Loss)

Recognized in Income on

Derivative (Ineffective

Portion and Amount

Excluded from

Effectiveness Testing)

Gain/(Loss) Recognized in

Income on Derivative

(Ineffective Portion and

Amount Excluded from

Effectiveness Testing)

1,801

Interest expense

(2,053

)

N/A

Nine Months Ended September 30, 2012

Amount of Gain/(Loss)

Recognized in OCI on

Derivatives (Effective

Portion)

Location of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Amount of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Location of Gain/(Loss)

Recognized in Income on

Derivative (Ineffective

Portion and Amount

Excluded from

Effectiveness Testing)

Gain/(Loss) Recognized in

Income on Derivative

(Ineffective Portion and

Amount Excluded from

Effectiveness Testing)

(2,985

)

Interest expense

(502

)

N/A

As of September 30, 2013, approximately $1.4 million related to derivatives designated as cash flow hedges is expected to be reclassified from Accumulated other comprehensive loss into earnings in the next twelve months.

Fair Value Measurements

9 Months Ended

Sep. 30, 2013

Fair Value Disclosures [Abstract]

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 is as follows (in thousands):



	September 30, 2013
	Fair Value Measurements Using					Assets/Liabilities at Fair Value
	Level 1	Level 2		Level 3		Assets/Liabilities at Fair Value
Assets:
Short-term investments (1)		$	27,381			$	27,381
Liabilities:
Acquisition-related contingent consideration				$	22,409	$	22,409
Interest rate swap agreements (2)		$	1,589			$	1,589



	December 31, 2012
	Fair Value Measurements Using						Assets/Liabilities at Fair Value
	Level 1		Level 2		Level 3		Assets/Liabilities at Fair Value
Assets:
Short-term investments (1)	$	6,018					$	6,018
Liabilities:
Acquisition-related contingent consideration					$	23,711	$	23,711
Interest rate swap agreements (2)			$	5,442			$	5,442


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


(2)	Consists of interest rate swap agreements based on JIBAR and IBR whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data.

Cash and cash equivalents include short-term investments, including money market funds, with original maturities of three months or less whose fair value approximated cost at September 30, 2013 and December 31, 2012.

The fair value of the Company’s interest rate swap agreements recorded as net liabilities is included in Other non-current liabilities in the accompanying condensed consolidated balance sheets. Fair valuations of the Company’s interest rate swap agreements reflect the value of the instrument including the values associated with counterparty risk and the Company’s own credit standing. The Company includes in the valuation of the derivative instrument the value of the net credit differential between the counterparties to the derivative contract.

The Company may be required to pay additional consideration under certain agreements for the acquisition of communications sites in Colombia and Ghana if certain barter agreements with other wireless carriers are converted to cash-paying master lease agreements (see note 14).

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 condensed consolidated statements of operations. The Company determines the fair value of acquisition-related contingent consideration, and any subsequent changes in fair value using a discounted probability-weighted approach. This approach takes into consideration Level 3 unobservable inputs including probability 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 these unobservable inputs could significantly impact the fair value of the liabilities recorded in the accompanying condensed consolidated balance sheets and operating expenses in the condensed consolidated statements of operations.

As of September 30, 2013, the Company estimates that the value of all potential acquisition-related contingent consideration required payments to be between zero and $37.8 million. During the three months ended September 30, 2013 and 2012, the fair value of the contingent consideration changed as follows (in thousands):



	2013			2012
Balance as of July 1	$	21,218		$	29,897
Additions	3,599			1,180
Payments	(3,729		)	(3,951		)
Change in fair value	1,303			325
Foreign currency translation adjustment	18			(242		)
Balance as of September 30	$	22,409		$	27,209

During the nine months ended September 30, 2013 and 2012, the fair value of the contingent consideration changed as follows (in thousands):



	2013			2012
Balance as of January 1	$	23,711		$	25,617
Additions	4,087			1,533
Payments	(7,952		)	(4,397		)
Change in fair value	4,610			3,791
Foreign currency translation adjustment	(2,047		)	665
Balance as of September 30	$	22,409		$	27,209

Items Measured at Fair Value on a Nonrecurring Basis—During the nine months ended September 30, 2013, certain long-lived assets held and used were written down to their net realizable value of $4.0 billion, resulting in an asset impairment charge of $2.0 million, which was recorded in Other operating expenses in the accompanying condensed consolidated statements of operations. During the nine months ended September 30, 2012, certain long-lived assets held and used with a carrying value of $299.9 million were written down to their net realizable value of $289.2 million, resulting in an asset impairment charge of $10.7 million, which was recorded in Other operating expenses in the accompanying condensed consolidated statements of operations. These adjustments were determined by comparing the estimated proceeds from sale of assets or the projected future discounted cash flows to be provided from the long-lived assets (calculated using Level 3 inputs) to the asset’s carrying value when indications of impairment exist. There were no other items measured at fair value on a nonrecurring basis during the nine months ended September 30, 2013.

Fair Value of Financial Instruments—The carrying value of the Company’s financial instruments, with the exception of long-term obligations, including the current portion, reasonably approximate the related fair value as of September 30, 2013 and December 31, 2012. 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 was estimated using a discounted cash flow analysis using rates for debt with similar terms and maturities. As of September 30, 2013, the carrying value and fair value of long-term obligations, including the current portion, were $12.6 billion and $12.7 billion, respectively, of which $8.4 billion was measured using Level 1 inputs and $4.3 billion was measured using Level 2 inputs. As of December 31, 2012, the carrying value and fair value of long-term obligations, including the current portion, were $8.8 billion and $9.4 billion, respectively, of which $4.9 billion was measured using Level 1 inputs and $4.5 billion was measured using Level 2 inputs.

Accumulated Other Comprehensive Loss

9 Months Ended

Sep. 30, 2013

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Loss

The changes in Accumulated other comprehensive loss for the three months ended September 30, 2013 are as follows (in thousands):



	Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign Currency Items			Total
Balance as of July 1, 2013	$	(1,182	)	$	(3,427	)	$	(269,647	)	$	(274,256	)
Other comprehensive loss before reclassifications, net of tax	(1,289		)	—			(23,114		)	(24,403		)
Amounts reclassified from accumulated other comprehensive loss, net of tax	445			199			—			644
Net current-period other comprehensive income (loss)	(844		)	199			(23,114		)	(23,759		)
Balance as of September 30, 2013	$	(2,026	)	$	(3,228	)	$	(292,761	)	$	(298,015	)

(1) Losses on cash flow hedges have been reclassified into interest expense in the accompanying condensed consolidated statements of operations. The tax effect of less than $0.1 million is included in income tax expense for the three months ended September 30, 2013.

The changes in Accumulated other comprehensive loss for the nine months ended September 30, 2013 are as follows (in thousands):



	Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign Currency Items			Total
Balance as of January 1, 2013	$	(4,358	)	$	(3,827	)	$	(175,162	)	$	(183,347	)
Other comprehensive loss before reclassifications, net of tax	1,167			—			(117,599		)	(116,432		)
Amounts reclassified from accumulated other comprehensive loss, net of tax	1,165			599			—			1,764
Net current-period other comprehensive income (loss)	2,332			599			(117,599		)	(114,668		)
Balance as of September 30, 2013	$	(2,026	)	$	(3,228	)	$	(292,761	)	$	(298,015	)


(1)	Losses on cash flow hedges have been reclassified into interest expense in the accompanying condensed consolidated statements of operations. The tax effect of $0.1 million is included in income tax expense for the nine months ended September 30, 2013.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2013
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Taxes	Income Taxes The Company provides for income taxes at the end of each interim period based on the estimated effective tax rate for the full fiscal year. Cumulative adjustments to the Company’s estimate are recorded in the interim period in which a change in the estimated annual effective tax rate is determined. As described in note 1, the Company reorganized to qualify as a REIT for the taxable year commencing January 1, 2012. As a REIT, the Company will continue to be subject to income taxes on the income of its TRSs, and taxation in foreign jurisdictions where it conducts international operations. Under the provisions of the Internal Revenue Code of 1986, as amended, (the “Code”) the Company may deduct amounts distributed to stockholders against the income generated in its QRSs. Additionally, the Company is able to offset income in both its TRSs and QRSs by utilizing their respective net operating losses. The Company 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. As of September 30, 2013 and December 31, 2012, the total amount of unrecognized tax benefits that would impact the effective tax rate, if recognized, was approximately $31.2 million and $30.6 million, respectively. The increase in the amount of unrecognized tax benefits during the three and nine months ended September 30, 2013 is primarily attributable to the additions to the Company’s existing tax positions partially offset by fluctuations in foreign currency exchange rates and the closure of certain tax years. 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, as described in note 13 to the Company’s consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2012. The impact of the amount of such changes to previously recorded uncertain tax positions could range from zero to $1.3 million. The Company recorded penalties and income tax-related interest expense during the three and nine months ended September 30, 2013 of $0.9 million and $3.5 million, respectively, and during the three and nine months ended September 30, 2012 of $1.3 million and $3.9 million, 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 three and nine months ended September 30, 2013 by $0.8 million and $1.4 million, respectively. As of September 30, 2013 and December 31, 2012, the total amount of accrued penalties and income tax-related interest included in Other non-current liabilities in the condensed consolidated balance sheets was $29.8 million and $28.7 million, respectively. In September 2013, the Internal Revenue Service released final Tangible Property Regulations (the “Final Regulations”). The Final Regulations provide guidance on applying Section 263(a) of the Code to amounts paid to acquire, produce or improve tangible property, as well as rules for materials and supplies (Code Section 162). These regulations contain certain changes from the temporary and proposed tangible property regulations that were issued on December 27, 2011. The Final Regulations are generally effective for taxable years beginning on or after January 1, 2014. In addition, taxpayers are permitted to early adopt the Final Regulations for taxable years beginning on or after January 1, 2012. The Company does not expect the Final Regulations to have a material effect on its results of operations. The Company is currently evaluating the impact on its financial condition.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2013

Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]

Stock-Based Compensation

The Company recognized stock-based compensation expense during the three and nine months ended September 30, 2013 of $15.1 million and $53.2 million, respectively, and stock-based compensation expense during the three and nine months ended September 30, 2012 of $13.1 million and $39.7 million, respectively. Stock-based compensation expense for the nine months ended September 30, 2013 included $1.1 million related to the modification of the vesting and exercise terms for certain employees’ equity awards. The Company capitalized $0.4 million and $1.2 million of stock-based compensation expense as property and equipment during the three and nine months ended September 30, 2013, respectively, and capitalized $0.5 million and $1.6 million of stock-based compensation expense as property and equipment during the three and nine months ended September 30, 2012, respectively.

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 (“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 over various periods, generally four years, and stock options generally expire ten years from the date of grant. As of September 30, 2013, the Company had the ability to grant stock-based awards with respect to an aggregate of 16.6 million shares of common stock under the 2007 Plan.

Effective January 1, 2013, the Company’s Compensation Committee adopted a death, disability and retirement benefits program in connection with equity awards that provides for accelerated vesting and extended exercise periods of stock options and restricted stock units granted on or after January 1, 2013 upon an employee’s death or permanent disability, or upon an employee’s qualified retirement, provided certain eligibility criteria are met. Accordingly, for grants made after January 1, 2013, the Company recognizes compensation expense for all stock-based compensation 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. Due to the accelerated recognition of stock-based compensation expense related to awards granted to retirement eligible employees, the Company recognized an additional $7.5 million of stock-based compensation expense during the nine months ended September 30, 2013.

Stock Options—The Company’s option activity for the nine months ended September 30, 2013 is as follows:



	Number of Options
Outstanding as of January 1, 2013	5,829,945
Granted	1,420,206
Exercised	(799,233	)
Forfeited	(53,245	)
Expired	—
Outstanding as of September 30, 2013	6,397,673

The Company estimates the fair value of each option grant on the date of grant using the Black-Scholes pricing model. The following assumptions were used to determine the grant date fair value for options granted during the nine months ended September 30, 2013:



Range of risk-free interest rate	0.75% - 1.03%
Weighted average risk-free interest rate	0.90	%
Expected life of option grants	4.4 years
Range of expected volatility of underlying stock price	26.60% - 36.09%
Weighted average expected volatility of underlying stock price	33.56	%
Expected annual dividend yield	1.50	%

The weighted average grant date fair value per share during the nine months ended September 30, 2013 was $19.15. As of September 30, 2013, total unrecognized compensation expense related to unvested stock options was $39.3 million and is expected to be recognized over a weighted average period of approximately two years.

Restricted Stock Units—The Company’s restricted stock unit activity during the nine months ended September 30, 2013 is as follows:



	Number of Units
Outstanding as of January 1, 2013	1,968,553
Granted	803,561
Vested	(806,868	)
Forfeited	(106,658	)
Outstanding as of September 30, 2013	1,858,588

As of September 30, 2013, total unrecognized compensation expense related to unvested restricted stock units granted under the 2007 Plan was $86.7 million and is expected to be recognized over a weighted average period of approximately two years. Distributions accrue with each unvested restricted stock unit award granted subsequent to January 1, 2012, which are payable upon vesting.

Employee Stock Purchase Plan—The Company maintains an employee stock purchase plan (the “ESPP”) for all eligible employees as described in note 14 to the Company’s consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2012. Under the ESPP, shares of the Company’s common stock may be purchased on the last day of each bi-annual offering period at 85% of the lower of the fair market value on the first or the 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 nine months ended September 30, 2013, employee contributions were accumulated to purchase an estimated 57,000 shares under the ESPP.

Key assumptions used to apply the Black-Scholes pricing model for shares purchased through the ESPP during the nine months ended September 30, 2013, which resulted in a fair value per share of $13.41, are as follows:



Approximate risk-free interest rate	0.07%-0.13%
Expected life of shares	6 months
Expected volatility of underlying stock price over the option period	12.21%-13.57%
Expected annual dividend yield	1.50%

Equity

9 Months Ended

Sep. 30, 2013

Stockholders' Equity Note [Abstract]

Equity

Stock Repurchase Program—In March 2011, the Board of Directors approved a stock repurchase program, pursuant to which the Company is authorized to purchase up to $1.5 billion of its common stock (“2011 Buyback”).

During the nine months ended September 30, 2013, the Company repurchased 1,938,021 shares of its common stock for an aggregate of $145.0 million, including commissions and fees, pursuant to the 2011 Buyback. On September 6, 2013, the Company temporarily suspended repurchases following the signing of its agreement to acquire MIPT.

As of September 30, 2013, the Company had repurchased a total of approximately 6.3 million shares of its common stock under the 2011 Buyback for an aggregate of $389.0 million, including commissions and fees.

Under the 2011 Buyback, the Company is authorized to purchase shares from time to time through open market purchases or privately negotiated transactions at prevailing prices in accordance with securities laws and other legal requirements, and subject to market conditions and other factors. To facilitate repurchases, the Company makes purchases pursuant to trading plans under Rule 10b5-1 of the Securities Exchange Act of 1934, as amended, which allows the Company to repurchase shares during periods when it otherwise might be prevented from doing so under insider trading laws or because of self-imposed trading blackout periods.

The Company continues to manage the pacing of the remaining $1.1 billion under the 2011 Buyback in response to general market conditions and other relevant factors. The Company expects to fund any further repurchases of its common stock through a combination of cash on hand, cash generated by operations and borrowings under its credit facilities. Purchases under the 2011 Buyback are subject to the Company having available cash to fund repurchases.

Distributions—During the nine months ended September 30, 2013, the Company declared the following regular cash distributions to its stockholders:



Declaration Date	Payment Date	Record Date	Distribution per share	Aggregate Payment Amount (in millions)
March 12, 2013	April 25, 2013	April 10, 2013	$0.26	$102.8
May 22, 2013	July 16, 2013	June 17, 2013	$0.27	$106.7
September 12, 2013	October 7, 2013	September 23, 2013	$0.28	$110.5

The Company accrues distributions on unvested restricted stock unit awards granted subsequent to January 1, 2012, which are payable upon vesting. As of September 30, 2013, the Company had accrued $1.6 million of distributions payable related to unvested restricted stock units. During the nine months ended September 30, 2013, the Company paid $0.2 million of distributions payable upon the vesting of restricted stock units.

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

Earnings Per Common Share

9 Months Ended

Sep. 30, 2013

Earnings Per Share [Abstract]

Earnings Per Common Share

Basic income from continuing operations per common share represents income from continuing operations attributable to American Tower Corporation divided by the weighted average number of common shares outstanding during the period. Diluted income from continuing operations per common share represents income from continuing operations attributable to American Tower Corporation divided by the weighted average number of common shares outstanding during the period and any dilutive common share equivalents, including unvested restricted stock and shares issuable upon exercise of stock options as determined under the treasury stock method. Dilutive common share equivalents also include the dilutive impact of the Verizon transaction (see note 13).

The following table sets forth basic and diluted income from continuing operations per common share computational data for the three and nine months ended September 30, 2013 and 2012 (in thousands, except per share data):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012
Income from continuing operations attributable to American Tower Corporation	$	180,123	$	232,089	$	451,351	$	501,604
Basic weighted average common shares outstanding	394,759		395,244		395,138		394,626
Dilutive securities	3,589		4,243		4,137		4,458
Diluted weighted average common shares outstanding	398,348		399,487		399,275		399,084
Basic income from continuing operations attributable to American Tower Corporation per common share	$	0.46	$	0.59	$	1.14	$	1.27
Diluted income from continuing operations attributable to American Tower Corporation per common share	$	0.45	$	0.58	$	1.13	$	1.26

For the three and nine months ended September 30, 2013, the diluted weighted average number of common shares outstanding excluded shares issuable upon exercise of the Company’s stock options and stock-based awards of 2.5 million and 1.1 million, respectively, as the effect would be anti-dilutive. For the three and nine months ended September 30, 2012, the diluted weighted average number of common shares outstanding excluded shares issuable upon exercise of the Company’s stock options and stock-based awards of 1.2 million and 1.0 million, respectively, as the effect would be anti-dilutive.

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2013
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, other than the legal proceedings discussed below, 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. TriStar Litigation—The Company is involved in several lawsuits against TriStar Investors LLP and its affiliates (“TriStar”) in various states regarding single tower sites where TriStar has taken land interests under the Company’s owned or managed sites and the Company believes TriStar has induced the landowner to breach obligations to the Company. In addition, on February 16, 2012, TriStar brought a federal action against the Company in the United States District Court for the Northern District of Texas, in which TriStar principally alleges that the Company made misrepresentations to landowners when competing with TriStar for land under the Company’s owned or managed sites. On January 22, 2013, the Company filed an amended answer and counterclaim against TriStar and certain of its employees, denying Tristar’s claims and asserting that TriStar has engaged in a pattern of unlawful activity, including: (i) entering into agreements not to compete for land under certain towers; and (ii) making widespread misrepresentations to landowners regarding both TriStar and the Company. TriStar and the Company are seeking injunctive relief that would prohibit the other party from making certain statements when interacting with landowners, as well as damages. Commitments AT&T Transaction—The Company has an agreement with SBC Communications Inc., a predecessor entity to AT&T Inc. (“AT&T”), for the lease or sublease of approximately 2,450 towers from AT&T commencing between December 2000 and August 2004. Substantially all of the towers are part of the 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 sublease for that site plus the fair market value of certain alterations made to the related tower by AT&T. The aggregate purchase option price for the towers leased and subleased was approximately $585.3 million as of September 30, 2013, and will accrete at a rate of 10% per year to 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 Consumer Price Index. Verizon Transaction—In December 2000, the Company entered into an agreement with ALLTEL, a predecessor entity to Verizon Wireless (“Verizon”), to acquire towers through a 15-year sublease agreement. Pursuant to the agreement, as amended, with Verizon, the Company acquired rights to a total of 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, which will occur in tranches between April 2016 and March 2017 based on the original closing date for such tranche of towers. The purchase price per tower as of the original closing date was $27,500 and will accrete at a rate of 3% per annum through the expiration of the applicable sublease. The aggregate purchase option price for the subleased towers was approximately $70.7 million as of September 30, 2013. At Verizon’s option, at the expiration of the sublease, the purchase price would be payable in cash or with 769 shares of the Company’s common stock per tower, which at September 30, 2013 would be valued at approximately $101.2 million. 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. During the nine months ended September 30, 2013, the Company received notices from the Indian tax authorities of their intent to challenge the transfer pricing related to taxes arising out of transactions of Essar Telecom Infrastructure Private Limited (“ETIPL”) in 2008, prior to the Company’s acquisition of ETIPL in August 2010. Pursuant to the Company’s definitive acquisition agreement, 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. Since no formal assessment has been issued and the Company believes ETIPL’s tax position will be sustained, the Company has not accounted for any potential impact of this notification.

Acquisitions

9 Months Ended

Sep. 30, 2013

Business Combination, Description [Abstract]

Acquisitions

All of the acquisitions described below are being accounted for as business combinations and are consistent with the Company’s strategy to expand in selected geographic areas.

The estimates of the fair value of the assets 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 preliminary purchase price allocations that are not yet finalized relate to the fair value of certain tangible and intangible assets acquired and liabilities assumed, including contingent consideration, and residual goodwill and any related tax impact. The fair values 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. During the measurement period, the Company will adjust assets and/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 and/or liabilities as of that date. The effect of measurement period adjustments to the estimated fair values is reflected as if the adjustments had been completed on the acquisition date. The impact of all changes that do not qualify as measurement period adjustments are included in current period earnings. If the actual results differ from the estimates and judgments used in these fair values, the amounts recorded in the condensed consolidated financial statements could be subject to a possible impairment of the intangible assets and/or goodwill, or require acceleration of the amortization expense of intangible assets in subsequent periods. During the nine months ended September 30, 2013, the Company made certain purchase accounting measurement period adjustments related to several acquisitions and therefore retrospectively adjusted the fair value of the assets acquired and liabilities assumed in the condensed consolidated balance sheet as of December 31, 2012.

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 condensed consolidated statements of operations for the nine months ended September 30, 2013 from the date of respective acquisition. The date of acquisition, and by extension the point at which the Company begins to recognize the results of an acquisition may be dependent 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. For sites acquired from communication service providers, these sites may never have been operated as a business and were utilized solely by the seller as a component of their network infrastructure. An acquisition, depending on its size and nature, may or may not involve the transfer of business operations or employees.

The Company expenses acquisition and merger related costs in the period in which they are incurred and services are received. Acquisition and merger related costs may include finder’s fees, advisory, legal, accounting, valuation and other professional or consulting fees and general administrative costs, and are included in Other operating expenses. During the three and nine months ended September 30, 2013, the Company recognized acquisition and merger related expenses of $8.9 million and $25.8 million, respectively. During the three and nine months ended September 30, 2012, the Company recognized acquisition and merger related expenses of $5.2 million and $14.8 million, respectively.

2013 Acquisitions

Mexico Axtel Acquisition—On January 23, 2013, the Company entered into a definitive agreement to purchase communications sites from Axtel, S.A.B. de C.V. (“Axtel”). Pursuant to the definitive agreement, on January 31, 2013, the Company acquired 883 communications sites from Axtel for an aggregate purchase price of $248.5 million, subject to post-closing adjustments and value added tax.

Other International Acquisitions—During the nine months ended September 30, 2013, the Company acquired a total of 644 additional communications sites and equipment in the Company’s international markets, including Brazil, Colombia, Ghana, Mexico, and South Africa, for an aggregate purchase price of $80.5 million (including contingent consideration of $4.1 million and value added tax of $3.7 million), subject to post-closing adjustments.

Other U.S. Acquisitions—During the nine months ended September 30, 2013, the Company acquired a total of 41 additional communications sites and equipment, as well as 19 property interests, in the United States for an aggregate purchase price of $52.7 million, including cash paid of approximately $52.3 million and net liabilities assumed of approximately $0.4 million, subject to post-closing adjustments.

The following table summarizes the preliminary allocation of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed for the fiscal year 2013 acquisitions based upon their estimated fair value at the date of acquisition (in thousands). Balances are reflected in the accompanying condensed consolidated balance sheets as of September 30, 2013.



	Mexico Axtel			Other International			Other U.S.
Current assets	$	—		$	3,688		$	1,433
Non-current assets	4,032			1,835			44
Property and equipment	86,100			39,693			17,493
Intangible assets (1):
Customer-related intangible assets	115,700			18,401			24,296
Network location intangible assets	41,700			19,984			5,605
Current liabilities	—			—			(440		)
Other non-current liabilities	(9,377		)	(7,653		)	(786		)
Fair value of net assets acquired	$	238,155		$	75,948		$	47,645
Goodwill (2)	10,368			4,565			4,698


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


(2)	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for South Africa where goodwill is expected to be partially deductible.

2012 Acquisitions

Brazil-Vivo Acquisition—On March 30, 2012, the Company entered into a definitive agreement to purchase up to 1,500 communications sites from Vivo S.A. (“Vivo”). Pursuant to the agreement, on March 30, 2012, the Company purchased 800 communications sites for an aggregate purchase price of $151.7 million. On June 30, 2012, the Company purchased the remaining 700 communications sites for an aggregate purchase price of $126.3 million, subject to post-closing adjustments. In addition, the Company and Vivo amended the asset purchase agreement to allow for the acquisition of up to an additional 300 communications sites by the Company, subject to regulatory approval. On August 31, 2012, the Company purchased an additional 192 communications sites from Vivo for an aggregate purchase price of $32.7 million, subject to post-closing adjustments.

Diamond Acquisition (United States)—On December 28, 2012, the Company acquired Diamond Communications Trust and its subsidiary New Towers LLC, which held a portfolio of 316 communications sites and 24 property interests under third-party communications sites, for an aggregate purchase price of $322.5 million, including cash paid of $320.1 million and net liabilities assumed of $2.4 million.

Germany Acquisition—On November 14, 2012, the Company entered into a definitive agreement to purchase communications sites from E-Plus Mobilfunk GmbH & Co. KG (“E-Plus”). On December 4, 2012, the Company completed the purchase of 2,031 communications sites from E-Plus, for an aggregate purchase price of $525.7 million.

Skyway Acquisition (United States)—On December 20, 2012, the Company acquired an entity holding a portfolio of 318 communications sites from Skyway Towers Holdings, LLC (“Skyway”) for an aggregate purchase price of $169.6 million, including cash paid of approximately $169.5 million and net liabilities assumed of approximately $0.1 million. The aggregate purchase price was subsequently decreased to $166.3 million, including cash paid of approximately $166.2 million and net liabilities assumed of approximately $0.1 million, primarily due to the return of 11 communications sites to Skyway pursuant to the terms of the purchase agreement.

Uganda Acquisition—On December 8, 2011, the Company entered into a definitive agreement with MTN Group Limited (“MTN Group”) to establish a joint venture in Uganda. The joint venture is controlled by a holding company of which a wholly owned subsidiary of the Company holds a 51% interest and a wholly owned subsidiary of MTN Group holds a 49% interest. The joint venture owns a tower operations company in Uganda and is managed and controlled by the Company.

Pursuant to the agreement, the joint venture agreed to purchase a total of up to 1,000 existing communications sites from MTN Group’s operating subsidiary in Uganda, subject to customary closing conditions. On June 29, 2012, the joint venture acquired 962 communications sites for an aggregate purchase price of $171.5 million, subject to post-closing adjustments. As a result of post-closing adjustments, the aggregate purchase price was adjusted from $171.5 million to $173.2 million during the year ended December 31, 2012, and further adjusted to $169.2 million during the nine months ended September 30, 2013.

On August 15, 2013, the Company returned seven communications sites to MTN Group pursuant to the terms of the agreement.

Other International Acquisitions—During the year ended December 31, 2012, the Company acquired a total of 705 additional communications sites and equipment in the Company’s international markets, including Mexico and South Africa, for an aggregate purchase price of $162.7 million (including value added tax of $21.9 million), subject to post-closing adjustments.

Other United States Acquisitions—During the year ended December 31, 2012, the Company acquired a total of 128 additional communications sites and equipment in the United States for an aggregate purchase price of $146.2 million, subject to post-closing adjustments. The purchase price was subsequently reduced to $146.1 million during nine months ended September 30, 2013.

The following table summarizes the updated allocation of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed based upon their estimated fair value at the date of acquisition (in thousands). Balances are reflected in the accompanying condensed consolidated balance sheets as of September 30, 2013.



	Brazil Vivo (1)			Diamond (U.S.)			Germany			Skyway (U.S.)			Uganda (1)			Other International			Other U.S.
Current assets	$	—		$	842		$	14,043		$	740		$	—		$	21,911		$	—
Non-current assets	22,418			—			—			—			2,258			2,309			153
Property and equipment	138,959			72,447			203,494			58,913			102,366			66,073			61,091
Intangible assets (2):
Customer-related intangible assets	83,012			184,200			288,330			64,400			30,500			52,911			61,266
Network location intangible assets	40,983			32,000			21,997			20,500			26,000			15,935			16,133
Current liabilities	—			(3,216		)	(2,988		)	(454		)	—			—			—
Other non-current liabilities	(18,195		)	(3,423		)	(23,243		)	(3,222		)	(7,528		)	(6,294		)	(1,310		)
Fair value of net assets acquired	$	267,177		$	282,850		$	501,633		$	140,877		$	153,596		$	152,845		$	137,333
Goodwill (3)	43,518			37,276			24,020			25,308			15,644			9,844			8,724

(1) The allocation of the purchase price was finalized during the nine months ended September 30, 2013.


(2)	Customer-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 domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for Uganda where goodwill is not expected to be deductible and South Africa where goodwill is expected to be partially deductible.

The following table summarizes the preliminary allocation of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed based upon their estimated fair value at the date of acquisition (in thousands). Balances are reflected in the consolidated balance sheets in the Annual Report on Form 10-K for the year ended December 31, 2012.



	Brazil Vivo			Diamond (U.S.)			Germany			Skyway (U.S.)			Uganda			Other International			Other U.S.
Current assets	$	—		$	842		$	14,483		$	740		$	—		$	21,911		$	—
Non-current assets	24,460			—			—			—			2,258			4,196			153
Property and equipment	138,959			69,045			233,073			60,671			102,366			61,080			61,995
Intangible assets (1):
Customer-related intangible assets	80,010			171,300			218,146			63,000			36,500			49,227			61,966
Network location intangible assets	37,980			28,400			20,819			20,700			27,000			16,442			16,233
Current liabilities	—			(3,216		)	(2,990		)	(454		)	—			—			—
Other non-current liabilities	(18,195		)	(3,423		)	(23,243		)	(3,333		)	(7,528		)	(5,893		)	(1,310		)
Fair value of net assets acquired	$	263,214		$	262,948		$	460,288		$	141,324		$	160,596		$	146,963		$	139,037
Goodwill (2)	47,481			57,178			65,365			28,224			12,564			15,726			7,124


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


(2)	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for Uganda where goodwill is not expected to be deductible and South Africa where goodwill is expected to be partially deductible.

Contingent Consideration

The Company may be required to pay additional consideration under certain agreements related to acquisitions in Colombia and Ghana if certain barter agreements with other wireless carriers are converted to cash-paying master lease agreements.

Colombia—Under the terms of the agreement with Colombia Movil, the Company is required to make additional payments upon the conversion of certain barter agreements with other wireless carriers to cash paying lease agreements. Based on current estimates, the Company expected the value of potential contingent consideration payments required to be made under the amended agreement to be between zero and $36.9 million and estimated it to be $21.5 million using a probability weighted average of the expected outcomes at September 30, 2013. During the three and nine months ended September 30, 2013, the Company recorded additional contingent consideration of $3.6 million and $4.1 million, respectively, related to acquisitions during the period. In addition, during the three and nine months ended September 30, 2013, the Company recorded an increase in fair value of $0.5 million and $1.5 million, respectively, in Other operating expenses in the accompanying condensed consolidated statements of operations.

South Africa—Under the terms of the agreement with Cell C (Pty) Limited (“Cell C”) dated November 4, 2010, pursuant to which the Company agreed to purchase up to 1,400 existing communications sites and additional communications sites in South Africa, the Company was required to make periodic payments for each collocation of a specific wireless carrier installed on the acquired communications sites occurring within a four-year period after the initial closing date. During the three months ended September 30, 2013, the Company amended its agreement with Cell C whereby the Company made a one-time payment of $2.5 million, which satisfied its remaining contingent consideration obligations. During the three months ended September 30, 2013, no further adjustments to the fair value of the contingent consideration were required. During the nine months ended September 30, 2013, the Company recorded a net increase in fair value of $3.4 million in Other operating expenses in the accompanying condensed consolidated statements of operations.

Other—Certain agreements in Brazil, Ghana and the United States include provisions that provide for contingent consideration.

During the three and nine months ended September 30, 2013, the Company recorded an increase in fair value of $0.8 million and a net decrease in fair value of $0.3 million, respectively, related to the contingent consideration liability for the acquisitions of communications sites in Brazil, Ghana and the United States. The change in fair value was recorded in Other operating expenses in the accompanying condensed consolidated statements of operations.

During the three months ended September 30, 2013, the Company paid an additional $1.0 million and satisfied the remaining obligation associated with the acquisition in Brazil. In addition, during the nine months ended September 30, 2013, the Company reduced the obligation associated with the acquisition in the United States to zero. The Company recorded an increase in the fair value of the contingent consideration liability as a result of the conversion of certain barter agreements in Ghana to cash-paying master lease agreements. Based on current estimates, the Company expects the value of potential contingent consideration payments required to be made under the agreement to be between zero and $0.9 million and estimated it to be $0.9 million using a probability weighted average of the expected outcomes at September 30, 2013.

For more information regarding contingent consideration, see note 7 to the accompanying condensed consolidated financial statements.

Other Signed Acquisitions

NII Holdings Acquisition—On August 8, 2013, the Company entered into an agreement with NII Holdings, Inc. to acquire up to 2,790 communications sites in Brazil and 1,666 communications sites in Mexico in two separate transactions, for approximately 945 million Brazilian Reais (“BRL”) (approximately $423.8 million) and 5,025 million Mexican Pesos (approximately $382.3 million), respectively. The Company paid $120.0 million into escrow for this transaction which is reflected in Prepaid and other current assets in the condensed consolidated balance sheets as of September 30, 2013.

Brazil-Z Sites Acquisition—On September 26, 2013, the Company entered into an agreement with Z-Sites Locação de Imóveis Ltda. to acquire up to 236 communications sites in Brazil for an aggregate purchase price of up to approximately 283 million BRL (approximately $127.1 million).

Subsequently Closed Acquisition

MIPT Acquisition—On October 1, 2013, the Company, through its wholly-owned subsidiary American Tower Investments LLC, acquired 100% of the outstanding common membership interests of MIPT, a private REIT, which is the parent company of Global Tower Partners, and related companies, for a total purchase price of approximately $4.8 billion, subject to customary post-closing purchase price adjustments.

The purchase price was satisfied with approximately $3.3 billion in cash, including an aggregate of approximately $2.8 billion from borrowings under the 2012 Credit Facility and the 2013 Credit Facility, and the assumption of approximately $1.5 billion of MIPT’s existing indebtedness. MIPT's existing indebtedness included $1.49 billion of securitized indebtedness under eleven separate classes of Secured Tower Revenue Notes and $32.6 million of secured debt in Costa Rica.

The following table reflects the preliminary allocation of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed for MIPT based upon the estimated fair value at the date of acquisition. The primary areas of the preliminary purchase price allocations that are not yet finalized relate to the fair value of property and equipment, intangible assets and goodwill. The valuations consist of a discounted cash flow analysis or other appropriate valuation techniques to determine the fair value of the assets acquired and liabilities assumed.



	MIPT
Current assets	$	104,044
Non-current assets	627
Property, equipment and easements	1,290,143
Intangible assets (1):
Customer-related intangible assets	2,536,700
Network location intangible assets	338,600
Current liabilities	(88,497		)
Long-term obligations (2)	(1,573,366		)
Other non-current liabilities	(49,158		)
Fair value of net assets acquired	$	2,559,093
Goodwill (3)	756,833

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


(2)	Long-term obligations included $1.5 billion of MIPT's existing indebtedness and a fair value adjustment of $53.0 million.

(3) Goodwill will be allocated to the Company’s domestic and international rental and management segments, as applicable. The Company expects goodwill recorded to its domestic rental and management segment will be deductible for tax purposes and goodwill recorded to its international segment will not be deductible for tax purposes.

MIPT Acquisition—Pro Forma Consolidated Results

The following pro forma information presents the financial results as if the acquisition of MIPT had occurred on January 1, 2012. The pro forma results do not include any anticipated cost synergies, costs or other effects of the planned integration of MIPT. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the acquisition been completed on the dates indicated, nor are they indicative of the future operating results of the combined company.



	Three months ended September 30,				Nine months ended September 30,
	2013		2012		2013		2012
Operating revenues	$	888,432	$	788,623	$	2,659,294	$	2,326,753
Net income attributable to American Tower Corporation	$	142,357	$	195,647	$	343,992	$	392,156
Net income per common share amounts:
Basic net income attributable to American Tower Corporation	$	0.36	$	0.50	$	0.87	$	0.99
Diluted net income attributable to American Tower Corporation	$	0.36	$	0.49	$	0.86	$	0.98

Business Segments

9 Months Ended

Sep. 30, 2013

Segment Reporting, Measurement Disclosures [Abstract]

Business Segments

The Company operates in three business segments: domestic rental and management, international rental and management and network development services. The Company’s primary business is leasing antenna space on multi-tenant communications sites to wireless service providers, radio and television broadcast companies, wireless data and data providers, government agencies and municipalities and tenants in a number of other industries. This business is referred to as the Company’s rental and management operations and is comprised of domestic and international segments, which consist of the following as of September 30, 2013:


•	Domestic: rental and management operations in the United States; and


•	International: rental and management operations in Brazil, Chile, Colombia, Germany, Ghana, India, Mexico, Peru, South Africa and Uganda.

The Company has applied the aggregation criteria to operations within the international rental and management operating segments on a basis consistent with management’s review of information and performance evaluation.

The Company’s network development 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 and the addition of new tenants and equipment on its sites. The network development services segment is a strategic business unit that offers different services from the rental and management operating segments and requires different resources, skill sets and marketing strategies.

The accounting policies applied in compiling segment information below are similar to those described in note 1 to the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. 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 international rental and management 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, Loss on retirement of long-term obligations, Other income (expense), Net income (loss) attributable to noncontrolling interest, Income (loss) on equity method investments and Income tax provision (benefit). 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 condensed consolidated statements of operations and condensed consolidated balance sheets.

Summarized financial information concerning the Company’s reportable segments for the three and nine months ended September 30, 2013 and 2012 is shown in the following tables. The “Other” column 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 expense; interest income; interest expense; loss on retirement of long-term obligations; and other income (expense), as well as reconciles segment operating profit to income from continuing operations before income taxes and income on equity method investments, as these amounts are not utilized in assessing each segment’s performance.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Three months ended September 30, 2013	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	529,941	$	266,634	$	796,575	$	11,305			$	807,880
Segment operating expenses (1)	95,232		100,473		195,705		4,777				200,482
Interest income, TV Azteca, net	—		3,544		3,544		—				3,544
Segment gross margin	434,709		169,705		604,414		6,528				610,942
Segment selling, general, administrative and development expense (1)	24,523		31,728		56,251		1,880				58,131
Segment operating profit	$	410,186	$	137,977	$	548,163	$	4,648			$	552,811
Stock-based compensation expense									$	15,058	15,058
Other selling, general, administrative and development expense									24,939		24,939
Depreciation, amortization and accretion									184,922		184,922
Other expense (principally interest expense and other (expense) income)									149,084		149,084
Income from continuing operations before income taxes and income on equity method investments											$	178,808
Total assets	$	12,037,318	$	5,427,416	$	17,464,734	$	49,973	$	666,613	$	18,181,320


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.3 million and $14.7 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Three months ended September 30, 2012	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	480,351	$	217,203	$	697,554	$	15,781			$	713,335
Segment operating expenses (1)	92,072		85,069		177,141		7,323				184,464
Interest income, TV Azteca, net	—		3,586		3,586		—				3,586
Segment gross margin	388,279		135,720		523,999		8,458				532,457
Segment selling, general, administrative and development expense (1)	20,141		25,057		45,198		2,127				47,325
Segment operating profit	$	368,138	$	110,663	$	478,801	$	6,331			$	485,132
Stock-based compensation expense									$	13,058	13,058
Other selling, general, administrative and development expense									21,516		21,516
Depreciation, amortization and accretion									144,061		144,061
Other expense (principally interest expense and other (expense) income)									61,620		61,620
Income from continuing operations before income taxes and income on equity method investments											$	244,877


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.4 million and $12.6 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Nine months ended September 30, 2013	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	1,566,660	$	796,547	$	2,363,207	$	56,231			$	2,419,438
Segment operating expenses (1)	282,273		302,441		584,714		22,399				607,113
Interest income, TV Azteca, net	—		10,673		10,673		—				10,673
Segment gross margin	1,284,387		504,779		1,789,166		33,832				1,822,998
Segment selling, general, administrative and development expense (1)	71,664		93,753		165,417		7,105				172,522
Segment operating profit	$	1,212,723	$	411,026	$	1,623,749	$	26,727			$	1,650,476
Stock-based compensation expense									$	53,155	53,155
Other selling, general, administrative and development expense									74,251		74,251
Depreciation, amortization and accretion									555,334		555,334
Other expense (principally interest expense and other (expense) income)									536,092		536,092
Income from continuing operations before income taxes and income on equity method investments											$	431,644


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.2 million and $52.0 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Nine months ended September 30, 2012	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	1,440,824	$	622,982	$	2,063,806	$	43,780			$	2,107,586
Segment operating expenses (1)	273,188		232,338		505,526		21,404				526,930
Interest income, TV Azteca, net	—		10,715		10,715		—				10,715
Segment gross margin	1,167,636		401,359		1,568,995		22,376				1,591,371
Segment selling, general, administrative and development expense (1)	60,638		68,433		129,071		4,410				133,481
Segment operating profit	$	1,106,998	$	332,926	$	1,439,924	$	17,966			$	1,457,890
Stock-based compensation expense									$	39,654	39,654
Other selling, general, administrative and development expense									66,099		66,099
Depreciation, amortization and accretion									465,788		465,788
Other expense (principally interest expense and other (expense) income)									346,385		346,385
Income from continuing operations before income taxes and income on equity method investments											$	539,964


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.3 million and $38.3 million, respectively.

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2013
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events 2013 Term Loan—On October 29, 2013, the Company entered into the 2013 Term Loan of $1.5 billion. The Company used the net proceeds from the 2013 Term Loan and cash on hand to repay the 2012 Term Loan and $800 million of outstanding indebtedness under the 2012 Credit Facility. The 2013 Term Loan matures on January 3, 2019. Any outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. The 2013 Term Loan may be paid prior to maturity in whole or in part at our option without penalty or premium. The Company has the option of choosing either a defined base rate or LIBOR as the applicable base rate. The interest rate ranges between 1.125% to 2.250% above LIBOR for LIBOR based borrowings or between 0.125% to 1.250% above the defined base rate for base rate borrowings, in each case based upon our debt ratings. The current margin over LIBOR that the Company would incur (should it choose LIBOR) on borrowings is 1.25%. The loan agreement contains certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Any failure to comply with the financial and operating covenants of the loan agreement would constitute a default, which could result in, among other things, the amounts outstanding, including all accrued interest and unpaid fees, becoming immediately due and payable.

Description of Business, Basis of Presentation and Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation—The accompanying condensed 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.
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 condensed consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying condensed consolidated financial statements. The significant estimates in the accompanying condensed 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. 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.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards—In February 2013, the Financial Accounting Standards Board (“FASB”) issued additional guidance on comprehensive income which adds new disclosure requirements for items reclassified out of accumulated other comprehensive income (“AOCI”) by component. This guidance enhances the transparency of changes in other comprehensive income (“OCI”) and items transferred out of AOCI in the financial statements and it does not amend any existing requirements for reporting net income or OCI in the financial statements. Since the guidance relates only to presentation and disclosure of information, the adoption did not have a material effect on the Company’s condensed consolidated financial condition or results of operations. In February 2013, the FASB issued guidance that clarifies the scope of transactions subject to disclosures about offsetting assets and liabilities. The guidance requires an entity to disclose information about offsetting and related arrangements to enable users of its financial statements to understand the effect of those arrangements on its financial position. This guidance is effective for annual and interim reporting periods beginning on or after January 1, 2013 on a retrospective basis. Since the guidance relates only to presentation and disclosure of information, the adoption did not have a material effect on the Company’s condensed consolidated financial condition or results of operations. In July 2013, the FASB issued guidance that permits the Fed Funds Effective Swap Rate (Overnight Index Swap Rate) to be used as a U.S. benchmark interest rate for hedge accounting purposes, in addition to U.S. Treasury rates and the London Interbank Offered Rate (“LIBOR”). The guidance also removed the restriction on using different benchmark rates for similar hedges. These amendments are effective prospectively for qualifying new or re-designated hedging relationships entered into on or after July 17, 2013. The adoption of this guidance did not have a material effect on the Company’s financial statements. In July 2013, the FASB issued guidance that requires an unrecognized tax benefit, or a portion of an unrecognized tax benefit, to be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, with certain exceptions. The amendment is effective for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted. The adoption of this guidance did not have a material effect on the Company’s financial statements.
Comparability of Prior Year Financial Data, Policy	Changes in Presentation—Changes have been made to the presentation of the Company’s condensed consolidated statements of cash flows for the nine months ended September 30, 2012 to be consistent with the current year presentation. Specifically, amounts surrendered for the satisfaction of employee tax obligations in connection with the vesting of restricted stock units of $16.7 million that were previously included in Purchases of common stock are now included in Deferred financing costs and other financing activities in the Company’s condensed consolidated statements of cash flows.

Prepaid and Other Current Assets (Tables)

9 Months Ended

Sep. 30, 2013

Prepaid Expense and Other Assets, Current [Abstract]

Prepaid expense and other current assets

Prepaid and other current assets consist of the following as of (in thousands):



	September 30, 2013		December 31, 2012 (1)
Acquisition deposit in escrow	$	120,000	$	—
Prepaid income tax	65,903		57,665
Prepaid operating ground leases	61,393		56,916
Unbilled receivables	27,922		32,588
Prepaid assets	34,260		19,037
Value added tax and other consumption tax receivables	16,771		22,443
Other miscellaneous current assets	39,543		34,350
Balance	$	365,792	$	222,999

(1) December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2013

Accrued Liabilities, Current [Abstract]

Schedule of accrued liabilities

Accrued expenses consist of the following as of (in thousands):



	September 30, 2013		December 31, 2012
Accrued property and real estate taxes	$	46,972	$	36,814
Payroll and related withholdings	38,359		37,586
Accrued construction costs	38,201		20,711
Accrued rent	23,485		24,394
Other accrued expenses	184,294		167,457
Balance	$	331,311	$	286,962

Goodwill and Other Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2013

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 are as follows (in thousands):



	Rental and Management					Network Development Services		Total
	Domestic		International			Network Development Services		Total
Balance as of January 1, 2013 (1)	$	2,320,645	$	520,072		$	2,000	$	2,842,717
Additions	4,698		14,933			—		19,631
Effect of foreign currency translation	—		(47,077		)	—		(47,077		)
Balance as of September 30, 2013	$	2,325,343	$	487,928		$	2,000	$	2,815,271


(1)	Balances have been revised to reflect purchase accounting measurement period adjustments.

Schedule of finite-lived intangible assets

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



		September 30, 2013							December 31, 2012 (1)
	Estimated Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Book Value		Gross Carrying Value		Accumulated Amortization			Net Book Value
	(years)
Acquired network location (2)	Up to 20	$	1,731,664	$	(767,973	)	$	963,691	$	1,702,895	$	(721,135	)	$	981,760
Acquired customer-related intangibles	15-20	3,228,515		(1,093,481		)	2,135,034		3,133,166		(979,264		)	2,153,902
Acquired licenses and other intangibles	3-20	6,524		(2,087		)	4,437		26,079		(20,835		)	5,244
Economic Rights, TV Azteca	70	28,609		(14,037		)	14,572		28,954		(13,902		)	15,052
Total		4,995,312		(1,877,578		)	3,117,734		4,891,094		(1,735,136		)	3,155,958
Deferred financing costs, net (3)	N/A						77,372							49,538
Other intangible assets, net							$	3,195,106						$	3,205,496


(1)	December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.


(2)	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.


(3)	Deferred financing costs are amortized over the term of the respective debt instruments to which they relate using the effective interest method. This amortization is included in interest expense rather than in amortization expense.

Expected future amortization expenses

The Company expects to record amortization expense (excluding amortization of deferred financing costs) as follows over the next five years (in millions):



Fiscal Year
2013 (remaining year)	$	61.5
2014	232.9
2015	214.5
2016	202.2
2017	195.7
2018	189.3

Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2013

Summary of Derivative Instruments [Abstract]

Schedule of derivative financial instruments



	September 30, 2013 (1)	December 31, 2012 (2)
ZAR
Notional	442,655	423,634
Carrying Amount/Fair Value	909	20,441
COP
Notional	101,250,000	101,250,000
Carrying Amount/Fair Value	2,869,430	5,356,377


(1)	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $97.0 million and $1.6 million, respectively, as of September 30, 2013.


(2)	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $107.3 million and $5.4 million, respectively, as of December 31, 2012.

Schedule of interest rate swap agreements' impact on other comprehensive income

Nine Months Ended September 30, 2013

Amount of Gain/(Loss)

Recognized in OCI on

Derivatives (Effective

Portion)

Location of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Amount of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective Portion)

Location of Gain/(Loss)

Recognized in Income on

Derivative (Ineffective

Portion and Amount

Excluded from

Effectiveness Testing)

Gain/(Loss) Recognized in

Income on Derivative

(Ineffective Portion and

Amount Excluded from

Effectiveness Testing)

1,801

Interest expense

(2,053

)

N/A

Nine Months Ended September 30, 2012

Amount of Gain/(Loss)

Recognized in OCI on

Derivatives (Effective

Portion)

Location of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Amount of Gain/(Loss)

Reclassified from

Accumulated OCI into

Income (Effective

Portion)

Location of Gain/(Loss)

Recognized in Income on

Derivative (Ineffective

Portion and Amount

Excluded from

Effectiveness Testing)

Gain/(Loss) Recognized in

Income on Derivative

(Ineffective Portion and

Amount Excluded from

Effectiveness Testing)

(2,985

)

Interest expense

(502

)

N/A



Three Months Ended September 30, 2013
Amount of Gain/(Loss) Recognized in OCI on Derivatives (Effective Portion)			Location of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
$	(1,404	)	Interest expense	$	(741	)	N/A	N/A
Three Months Ended September 30, 2012
Amount of Gain/(Loss) Recognized in OCI on Derivatives (Effective Portion)			Location of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
$	(1,135	)	Interest expense	$	(181	)	N/A	N/A

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2013

Fair Value Disclosures [Abstract]

Schedule of fair value, assets and liabilities measured on 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 is as follows (in thousands):



	September 30, 2013
	Fair Value Measurements Using					Assets/Liabilities at Fair Value
	Level 1	Level 2		Level 3		Assets/Liabilities at Fair Value
Assets:
Short-term investments (1)		$	27,381			$	27,381
Liabilities:
Acquisition-related contingent consideration				$	22,409	$	22,409
Interest rate swap agreements (2)		$	1,589			$	1,589



	December 31, 2012
	Fair Value Measurements Using						Assets/Liabilities at Fair Value
	Level 1		Level 2		Level 3		Assets/Liabilities at Fair Value
Assets:
Short-term investments (1)	$	6,018					$	6,018
Liabilities:
Acquisition-related contingent consideration					$	23,711	$	23,711
Interest rate swap agreements (2)			$	5,442			$	5,442


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


(2)	Consists of interest rate swap agreements based on JIBAR and IBR whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data.

Schedule of business acquisitions by acquisition, contingent consideration

During the nine months ended September 30, 2013 and 2012, the fair value of the contingent consideration changed as follows (in thousands):



	2013			2012
Balance as of January 1	$	23,711		$	25,617
Additions	4,087			1,533
Payments	(7,952		)	(4,397		)
Change in fair value	4,610			3,791
Foreign currency translation adjustment	(2,047		)	665
Balance as of September 30	$	22,409		$	27,209

During the three months ended September 30, 2013 and 2012, the fair value of the contingent consideration changed as follows (in thousands):



	2013			2012
Balance as of July 1	$	21,218		$	29,897
Additions	3,599			1,180
Payments	(3,729		)	(3,951		)
Change in fair value	1,303			325
Foreign currency translation adjustment	18			(242		)
Balance as of September 30	$	22,409		$	27,209

Accumulated Other Comprehensive Loss (Tables)

9 Months Ended

Sep. 30, 2013

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of accumulated other comprehensive income (loss)

The changes in Accumulated other comprehensive loss for the three months ended September 30, 2013 are as follows (in thousands):



	Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign Currency Items			Total
Balance as of July 1, 2013	$	(1,182	)	$	(3,427	)	$	(269,647	)	$	(274,256	)
Other comprehensive loss before reclassifications, net of tax	(1,289		)	—			(23,114		)	(24,403		)
Amounts reclassified from accumulated other comprehensive loss, net of tax	445			199			—			644
Net current-period other comprehensive income (loss)	(844		)	199			(23,114		)	(23,759		)
Balance as of September 30, 2013	$	(2,026	)	$	(3,228	)	$	(292,761	)	$	(298,015	)

The changes in Accumulated other comprehensive loss for the nine months ended September 30, 2013 are as follows (in thousands):



	Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign Currency Items			Total
Balance as of January 1, 2013	$	(4,358	)	$	(3,827	)	$	(175,162	)	$	(183,347	)
Other comprehensive loss before reclassifications, net of tax	1,167			—			(117,599		)	(116,432		)
Amounts reclassified from accumulated other comprehensive loss, net of tax	1,165			599			—			1,764
Net current-period other comprehensive income (loss)	2,332			599			(117,599		)	(114,668		)
Balance as of September 30, 2013	$	(2,026	)	$	(3,228	)	$	(292,761	)	$	(298,015	)


(1)	Losses on cash flow hedges have been reclassified into interest expense in the accompanying condensed consolidated statements of operations. The tax effect of $0.1 million is included in income tax expense for the nine months ended September 30, 2013.

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2013

Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]

Summary of the company's option activity

The Company’s option activity for the nine months ended September 30, 2013 is as follows:



	Number of Options
Outstanding as of January 1, 2013	5,829,945
Granted	1,420,206
Exercised	(799,233	)
Forfeited	(53,245	)
Expired	—
Outstanding as of September 30, 2013	6,397,673

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

The following assumptions were used to determine the grant date fair value for options granted during the nine months ended September 30, 2013:



Range of risk-free interest rate	0.75% - 1.03%
Weighted average risk-free interest rate	0.90	%
Expected life of option grants	4.4 years
Range of expected volatility of underlying stock price	26.60% - 36.09%
Weighted average expected volatility of underlying stock price	33.56	%
Expected annual dividend yield	1.50	%



Approximate risk-free interest rate	0.07%-0.13%
Expected life of shares	6 months
Expected volatility of underlying stock price over the option period	12.21%-13.57%
Expected annual dividend yield	1.50%

Summary of the company's restricted stock unit activity

The Company’s restricted stock unit activity during the nine months ended September 30, 2013 is as follows:



	Number of Units
Outstanding as of January 1, 2013	1,968,553
Granted	803,561
Vested	(806,868	)
Forfeited	(106,658	)
Outstanding as of September 30, 2013	1,858,588

Equity (Tables)

9 Months Ended

Sep. 30, 2013

Equity [Abstract]

Schedule of dividends payable

During the nine months ended September 30, 2013, the Company declared the following regular cash distributions to its stockholders:



Declaration Date	Payment Date	Record Date	Distribution per share	Aggregate Payment Amount (in millions)
March 12, 2013	April 25, 2013	April 10, 2013	$0.26	$102.8
May 22, 2013	July 16, 2013	June 17, 2013	$0.27	$106.7
September 12, 2013	October 7, 2013	September 23, 2013	$0.28	$110.5

Earnings Per Common Share (Tables)

9 Months Ended

Sep. 30, 2013

Earnings Per Share [Abstract]

Schedule of earnings per basic and diluted by common class



	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012
Income from continuing operations attributable to American Tower Corporation	$	180,123	$	232,089	$	451,351	$	501,604
Basic weighted average common shares outstanding	394,759		395,244		395,138		394,626
Dilutive securities	3,589		4,243		4,137		4,458
Diluted weighted average common shares outstanding	398,348		399,487		399,275		399,084
Basic income from continuing operations attributable to American Tower Corporation per common share	$	0.46	$	0.59	$	1.14	$	1.27
Diluted income from continuing operations attributable to American Tower Corporation per common share	$	0.45	$	0.58	$	1.13	$	1.26

Acquisitions (Tables)

9 Months Ended

Sep. 30, 2013

Business Combination, Description [Abstract]

Schedule of recognized identified assets acquired and liabilities assumed



	Mexico Axtel			Other International			Other U.S.
Current assets	$	—		$	3,688		$	1,433
Non-current assets	4,032			1,835			44
Property and equipment	86,100			39,693			17,493
Intangible assets (1):
Customer-related intangible assets	115,700			18,401			24,296
Network location intangible assets	41,700			19,984			5,605
Current liabilities	—			—			(440		)
Other non-current liabilities	(9,377		)	(7,653		)	(786		)
Fair value of net assets acquired	$	238,155		$	75,948		$	47,645
Goodwill (2)	10,368			4,565			4,698


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


(2)	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for South Africa where goodwill is expected to be partially deductible.



	MIPT
Current assets	$	104,044
Non-current assets	627
Property, equipment and easements	1,290,143
Intangible assets (1):
Customer-related intangible assets	2,536,700
Network location intangible assets	338,600
Current liabilities	(88,497		)
Long-term obligations (2)	(1,573,366		)
Other non-current liabilities	(49,158		)
Fair value of net assets acquired	$	2,559,093
Goodwill (3)	756,833

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


(2)	Long-term obligations included $1.5 billion of MIPT's existing indebtedness and a fair value adjustment of $53.0 million.



	Brazil Vivo			Diamond (U.S.)			Germany			Skyway (U.S.)			Uganda			Other International			Other U.S.
Current assets	$	—		$	842		$	14,483		$	740		$	—		$	21,911		$	—
Non-current assets	24,460			—			—			—			2,258			4,196			153
Property and equipment	138,959			69,045			233,073			60,671			102,366			61,080			61,995
Intangible assets (1):
Customer-related intangible assets	80,010			171,300			218,146			63,000			36,500			49,227			61,966
Network location intangible assets	37,980			28,400			20,819			20,700			27,000			16,442			16,233
Current liabilities	—			(3,216		)	(2,990		)	(454		)	—			—			—
Other non-current liabilities	(18,195		)	(3,423		)	(23,243		)	(3,333		)	(7,528		)	(5,893		)	(1,310		)
Fair value of net assets acquired	$	263,214		$	262,948		$	460,288		$	141,324		$	160,596		$	146,963		$	139,037
Goodwill (2)	47,481			57,178			65,365			28,224			12,564			15,726			7,124


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


(2)	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for Uganda where goodwill is not expected to be deductible and South Africa where goodwill is expected to be partially deductible.



	Brazil Vivo (1)			Diamond (U.S.)			Germany			Skyway (U.S.)			Uganda (1)			Other International			Other U.S.
Current assets	$	—		$	842		$	14,043		$	740		$	—		$	21,911		$	—
Non-current assets	22,418			—			—			—			2,258			2,309			153
Property and equipment	138,959			72,447			203,494			58,913			102,366			66,073			61,091
Intangible assets (2):
Customer-related intangible assets	83,012			184,200			288,330			64,400			30,500			52,911			61,266
Network location intangible assets	40,983			32,000			21,997			20,500			26,000			15,935			16,133
Current liabilities	—			(3,216		)	(2,988		)	(454		)	—			—			—
Other non-current liabilities	(18,195		)	(3,423		)	(23,243		)	(3,222		)	(7,528		)	(6,294		)	(1,310		)
Fair value of net assets acquired	$	267,177		$	282,850		$	501,633		$	140,877		$	153,596		$	152,845		$	137,333
Goodwill (3)	43,518			37,276			24,020			25,308			15,644			9,844			8,724

(1) The allocation of the purchase price was finalized during the nine months ended September 30, 2013.


(2)	Customer-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 domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for Uganda where goodwill is not expected to be deductible and South Africa where goodwill is expected to be partially deductible.

Business acquisition, pro forma information

he following pro forma information presents the financial results as if the acquisition of MIPT had occurred on January 1, 2012. The pro forma results do not include any anticipated cost synergies, costs or other effects of the planned integration of MIPT. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the acquisition been completed on the dates indicated, nor are they indicative of the future operating results of the combined company.



	Three months ended September 30,				Nine months ended September 30,
	2013		2012		2013		2012
Operating revenues	$	888,432	$	788,623	$	2,659,294	$	2,326,753
Net income attributable to American Tower Corporation	$	142,357	$	195,647	$	343,992	$	392,156
Net income per common share amounts:
Basic net income attributable to American Tower Corporation	$	0.36	$	0.50	$	0.87	$	0.99
Diluted net income attributable to American Tower Corporation	$	0.36	$	0.49	$	0.86	$	0.98

Business Segments (Tables)

9 Months Ended

Sep. 30, 2013

Segment Reporting, Measurement Disclosures [Abstract]

Summarized financial information concerning the company's reportable segments



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Three months ended September 30, 2013	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	529,941	$	266,634	$	796,575	$	11,305			$	807,880
Segment operating expenses (1)	95,232		100,473		195,705		4,777				200,482
Interest income, TV Azteca, net	—		3,544		3,544		—				3,544
Segment gross margin	434,709		169,705		604,414		6,528				610,942
Segment selling, general, administrative and development expense (1)	24,523		31,728		56,251		1,880				58,131
Segment operating profit	$	410,186	$	137,977	$	548,163	$	4,648			$	552,811
Stock-based compensation expense									$	15,058	15,058
Other selling, general, administrative and development expense									24,939		24,939
Depreciation, amortization and accretion									184,922		184,922
Other expense (principally interest expense and other (expense) income)									149,084		149,084
Income from continuing operations before income taxes and income on equity method investments											$	178,808
Total assets	$	12,037,318	$	5,427,416	$	17,464,734	$	49,973	$	666,613	$	18,181,320


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.3 million and $14.7 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Nine months ended September 30, 2012	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	1,440,824	$	622,982	$	2,063,806	$	43,780			$	2,107,586
Segment operating expenses (1)	273,188		232,338		505,526		21,404				526,930
Interest income, TV Azteca, net	—		10,715		10,715		—				10,715
Segment gross margin	1,167,636		401,359		1,568,995		22,376				1,591,371
Segment selling, general, administrative and development expense (1)	60,638		68,433		129,071		4,410				133,481
Segment operating profit	$	1,106,998	$	332,926	$	1,439,924	$	17,966			$	1,457,890
Stock-based compensation expense									$	39,654	39,654
Other selling, general, administrative and development expense									66,099		66,099
Depreciation, amortization and accretion									465,788		465,788
Other expense (principally interest expense and other (expense) income)									346,385		346,385
Income from continuing operations before income taxes and income on equity method investments											$	539,964


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.3 million and $38.3 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Nine months ended September 30, 2013	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	1,566,660	$	796,547	$	2,363,207	$	56,231			$	2,419,438
Segment operating expenses (1)	282,273		302,441		584,714		22,399				607,113
Interest income, TV Azteca, net	—		10,673		10,673		—				10,673
Segment gross margin	1,284,387		504,779		1,789,166		33,832				1,822,998
Segment selling, general, administrative and development expense (1)	71,664		93,753		165,417		7,105				172,522
Segment operating profit	$	1,212,723	$	411,026	$	1,623,749	$	26,727			$	1,650,476
Stock-based compensation expense									$	53,155	53,155
Other selling, general, administrative and development expense									74,251		74,251
Depreciation, amortization and accretion									555,334		555,334
Other expense (principally interest expense and other (expense) income)									536,092		536,092
Income from continuing operations before income taxes and income on equity method investments											$	431,644


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $1.2 million and $52.0 million, respectively.



	Rental and Management				Total Rental and Management		Network Development Services		Other		Total
Three months ended September 30, 2012	Domestic		International		Total Rental and Management		Network Development Services		Other		Total
	(in thousands)
Segment revenues	$	480,351	$	217,203	$	697,554	$	15,781			$	713,335
Segment operating expenses (1)	92,072		85,069		177,141		7,323				184,464
Interest income, TV Azteca, net	—		3,586		3,586		—				3,586
Segment gross margin	388,279		135,720		523,999		8,458				532,457
Segment selling, general, administrative and development expense (1)	20,141		25,057		45,198		2,127				47,325
Segment operating profit	$	368,138	$	110,663	$	478,801	$	6,331			$	485,132
Stock-based compensation expense									$	13,058	13,058
Other selling, general, administrative and development expense									21,516		21,516
Depreciation, amortization and accretion									144,061		144,061
Other expense (principally interest expense and other (expense) income)									61,620		61,620
Income from continuing operations before income taxes and income on equity method investments											$	244,877


(1)	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.4 million and $12.6 million, respectively.

Description of Business, Basis of Presentation and Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payments Related to Tax Withholding for Share-based Compensation	$ 16.7

Prepaid and Other Current Assets (Details) (USD $)
In Thousands, unless otherwise specified

Sep. 30, 2013

Dec. 31, 2012

Prepaid Expense and Other Assets, Current [Abstract]

Acquisition deposit in escrow

$ 120,000

$ 0

Prepaid income tax

65,903

57,665

^[1]

Prepaid operating ground leases

61,393

56,916

^[1]

Unbilled receivables

27,922

32,588

^[1]

Prepaid assets

34,260

19,037

^[1]

Value added tax and other consumption tax receivables

16,771

22,443

^[1]

Other miscellaneous current assets

39,543

34,350

^[1]

Balance

$ 365,792

$ 222,999

^[1]

[1]	December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.

Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accrued Liabilities, Current [Abstract]
Accrued property and real estate taxes	$ 46,972	$ 36,814
Payroll and related withholdings	38,359	37,586
Accrued construction costs	38,201	20,711
Accrued rent	23,485	24,394
Other accrued expenses	184,294	167,457
Balance	$ 331,311	$ 286,962

Goodwill and Other Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period of intangible assets, years			13 years
Amortization of intangible assets	$ 57.7	$ 46.9	$ 177.9	$ 154.3
Noncompete Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, fully amortized retired intangible assets			$ 19.6

Goodwill and Other Intangible Assets (Rollforward) (Details) (USD $)
In Thousands, unless otherwise specified

9 Months Ended

Sep. 30, 2013

$ 2,842,717

^[1]

19,631

(47,077)

2,815,271

Rental And Management [Member] | Domestic [Member]

2,320,645

^[1]

4,698

2,325,343

Rental And Management [Member] | International [Member]

520,072

^[1]

14,933

(47,077)

487,928

Network Development Services [Member]

2,000

^[1]

$ 2,000

[1]	Balances have been revised to reflect purchase accounting measurement period adjustments.

Goodwill and Other Intangible Assets (Changes in the Carrying Value of Goodwill) (Details) (USD $)
In Thousands, unless otherwise specified

9 Months Ended

Sep. 30, 2013

Dec. 31, 2012

$ 4,995,312

$ 4,891,094

^[1]

(1,877,578)

(1,735,136)

^[1]

Deferred financing costs, net

3,117,734

3,155,958

^[1]

77,372

^[2]

49,538

^[1],[2]

Other intangible assets, net

3,195,106

3,205,496

^[1]

Acquired Network Location [Member]

1,731,664

^[3]

1,702,895

^[1],[3]

(767,973)

^[3]

(721,135)

^[1],[3]

963,691

^[3]

981,760

^[1],[3]

Acquired Network Location [Member] | Maximum [Member]

20 years

Acquired Customer Relationships [Member]

3,228,515

3,133,166

^[1]

(1,093,481)

(979,264)

^[1]

2,135,034

2,153,902

^[1]

Acquired Customer Relationships [Member] | Minimum [Member]

15 years

Acquired Customer Relationships [Member] | Maximum [Member]

20 years

Acquired Licenses And Other Intangibles [Member]

6,524

26,079

^[1]

(2,087)

(20,835)

^[1]

4,437

5,244

^[1]

Acquired Licenses And Other Intangibles [Member] | Minimum [Member]

3 years

Acquired Licenses And Other Intangibles [Member] | Maximum [Member]

20 years

Economic Rights, TV Azteca [Member]

28,609

28,954

^[1]

(14,037)

(13,902)

^[1]

$ 14,572

$ 15,052

^[1]

Number of interest rate swap agreements

70 years

[1]	December 31, 2012 balances have been revised to reflect purchase accounting measurement period adjustments.
[2]	Deferred financing costs are amortized over the term of the respective debt instruments to which they relate using the effective interest method. This amortization is included in interest expense rather than in amortization expense.
[3]	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.

Goodwill and Other Intangible Assets (Expected Future Amortization Expenses) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
2013 (remaining year)	$ 61.5
2014	232.9
2015	214.5
2016	202.2
2017	195.7
2018	$ 189.3

Financing Transactions (Narrative) (Details)	3 Months Ended		9 Months Ended					0 Months Ended	3 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended								9 Months Ended								9 Months Ended					0 Months Ended								9 Months Ended	0 Months Ended				0 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended			0 Months Ended				0 Months Ended		0 Months Ended			0 Months Ended	9 Months Ended		9 Months Ended
Financing Transactions (Narrative) (Details)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 Revolving Credit Facility [Member] Short Term Credit Facility [Member] LIBOR Based Borrowings [Member] Minimum [Member]	Sep. 30, 2013 Revolving Credit Facility [Member] Short Term Credit Facility [Member] LIBOR Based Borrowings [Member] Maximum [Member]	Sep. 30, 2013 Revolving Credit Facility [Member] Credit Facility 2013 [Member] LIBOR Based Borrowings [Member] Minimum [Member]	Jan. 08, 2013 Credit Facility 2011 [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Credit Facility 2011 [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Credit Facility 2011 [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Credit Facility 2012 [Member] Revolving Credit Facility [Member] USD ($)	Oct. 29, 2013 Credit Facility 2012 [Member] Revolving Credit Facility [Member] Subsequent Event [Member] USD ($)	Sep. 30, 2013 Credit Facility 2012 [Member] Revolving Credit Facility [Member] LIBOR Based Borrowings [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] USD ($) renewal_periods	Jun. 28, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] USD ($)	Jun. 28, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Multicurrency Borrowings [Member] USD ($)	Jun. 28, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Letter of Credit [Member] USD ($)	Jun. 28, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Swingline Loan [Member] USD ($)	Sep. 20, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Additional Commitments [Member] USD ($)	Jun. 28, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Additional Commitments [Member] USD ($)	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Minimum [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Maximum [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] LIBOR Based Borrowings [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] LIBOR Based Borrowings [Member] Maximum [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Based Rate Borrowings [Member] Minimum [Member]	Sep. 30, 2013 Credit Facility 2013 [Member] Revolving Credit Facility [Member] Based Rate Borrowings [Member] Maximum [Member]	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member]	Sep. 20, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] Minimum [Member]	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] Maximum [Member]	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] LIBOR Based Borrowings [Member]	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] Based Rate Borrowings [Member] Minimum [Member]	Sep. 30, 2013 Short Term Credit Facility [Member] Revolving Credit Facility [Member] Based Rate Borrowings [Member] Maximum [Member]	Jun. 30, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] USD ($) Loan	Jun. 30, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] COP Loan	Sep. 30, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] USD ($)	Sep. 30, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] COP	Aug. 06, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] USD ($)	Aug. 06, 2013 Colombian Bridge Loan [Member] Short-term Debt [Member] COP	Sep. 30, 2013 Colombian Bridge Loan [Member] Revolving Credit Facility [Member]	Aug. 06, 2013 Colombian Bridge Loan [Member] Revolving Credit Facility [Member]	Sep. 30, 2013 Indian Facility [Member] Revolving Credit Facility [Member] USD ($)	Aug. 28, 2013 South African Facility [Member] Revolving Credit Facility [Member] USD ($)	Aug. 28, 2013 South African Facility [Member] Revolving Credit Facility [Member] ZAR	Sep. 30, 2013 South African Facility [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 South African Facility [Member] Revolving Credit Facility [Member] ZAR	Mar. 15, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2007 [Member] USD ($)	Sep. 30, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2007 [Member] USD ($)	Dec. 31, 2007 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2007 [Member] USD ($) towers	Mar. 15, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2013 [Member] USD ($) towers	Sep. 30, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2013 [Member] USD ($) Series subsidiary	Sep. 30, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2013 [Member] Series 2013-1 [Member]	Sep. 30, 2013 Secured Debt [Member] Commercial Mortgage Pass Through Certificates Series 2013 [Member] Series 2013-2 [Member]	Jan. 08, 2013 Senior Notes [Member] 3.50% Senior Notes [Member] USD ($)	Sep. 30, 2013 Senior Notes [Member] 3.50% Senior Notes [Member]	Aug. 19, 2013 Senior Notes [Member] Three Point Four Zero Percent Senior Notes [Member] USD ($)	Aug. 19, 2013 Senior Notes [Member] Five Point Zero Percent Senior Notes [Member] USD ($)	Aug. 19, 2013 Senior Notes [Member] Three Point Four Zero and Five Point Zero Percent Senior Notes [Member] [Member] USD ($)	Sep. 30, 2013 Senior Notes [Member] Three Point Four Zero and Five Point Zero Percent Senior Notes [Member] [Member]	Jan. 08, 2013 Credit Facility 2012 [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Oct. 29, 2013 Unsecured Debt [Member] Term Loan 2013 [Member] USD ($)	Sep. 30, 2013 Unsecured Debt [Member] Term Loan 2012 [Member]	Jun. 29, 2012 Unsecured Debt [Member] Term Loan 2012 [Member] USD ($)	Sep. 30, 2013 Unsecured Debt [Member] Term Loan 2012 [Member] LIBOR Based Borrowings [Member] Minimum [Member]	Sep. 30, 2013 Unsecured Debt [Member] Term Loan 2012 [Member] LIBOR Based Borrowings [Member] Maximum [Member]
Debt Instrument [Line Items]
Number of broadcast and wireless communications towers																																																	5,295	5,195
Number of subsidiaries																																																			2
Long-term debt																																																	$ 1,750,000,000	$ 1,800,000,000															$ 750,000,000
Repayment of indebtedness								265,000,000				800,000,000																																			1,750,000,000													718,400,000
Loss on retirement of long-term obligations	0	0	(37,967,000)	(398,000)																																												35,300,000
Payments of debt extinguishment costs			29,234,000	0																																												29,200,000
Write off of deferred debt issuance cost									2,700,000																																							6,100,000
Proceeds from the issuance of debt																																																		1,780,000,000				983,400,000				1,238,700,000
Series of securities																																																			2
Weighted average interest rate																																																			2.648%
Cash Trap Debt Service Credit Ratio																																																			1.30
Debt instrument, term										5 years	5 years			5 years																												0 years 6 months										5 years	10 years											5 years
Weighted average life																																																			8 years 7 months 6 days
Maximum debt service credit ratio																																																			1.15
Restricted cash and cash equivalents																																																			120,900,000
Stated percentage interest rate											1.81%			1.43%																										7.99%	7.95%											1.551%	3.07%	3.50%		3.40%	5.00%
Long-term debt, gross																																																						1,000,000,000.0		750,000,000	500,000,000
Debt issuance cost percentage																																																						99.185%
Line of credit facility, maximum borrowing capacity									1,000,000,000.0	1,000,000,000.0	1,000,000,000.0			2,000,000,000.0	1,500,000,000.0													1,000,000,000.0						49,100,000.0	94,000,000,000.0			7,300,000.0	14,000,000,000.0			10,000,000.0
Redemption price as a percentage of principal																																																							100.00%
Repurchase price as percentage of principal																																																							101.00%				101.00%
Maximum adjusted EBITDA (in times)																																																							3.5
Credit facility, outstanding											963,000,000																																		94,800,000	950,600,000
Letters of credit outstanding											7,800,000			2,300,000
Borrowings under credit facilities			3,507,000,000	1,325,000,000										1,853,000,000																													11,600,000	116,300,000																			1,500,000,000
Basis spread on variable rate					1.125%	2.00%	1.125%						1.625%										1.25%	2.00%	0.125%	1.00%					1.25%	0.125%	1.00%																																	1.75%	1.93%
Commitment fee percentage											0.225%			0.15%							0.125%	0.40%					0.15%		0.125%	0.40%
Line of credit facility, capacity available for specific purposes																1,000,000,000.0	200,000,000.0	50,000,000.0	750,000,000	500,000,000.0
Number of annual renewal periods														2
Ratio of total debt to EBITDA																																																													6.50	6.00
Number of bridge loans																																		5	5
Short term debt outstanding																																				$ 56,400,000	108,000,000,000					$ 0

Derivative Financial Instruments (Narrative) (Details)

Sep. 30, 2013

USD ($)

Dec. 31, 2012

USD ($)

Sep. 30, 2013

South African Facility [Member]

USD ($)

interest_rate_swap

Sep. 30, 2013

South African Facility [Member]

ZAR

Dec. 31, 2012

South African Facility [Member]

ZAR

Sep. 30, 2013

Colombian Long Term Credit Facility [Member]

USD ($)

interest_rate_swap

Sep. 30, 2013

Colombian Long Term Credit Facility [Member]

COP

Dec. 31, 2012

Colombian Long Term Credit Facility [Member]

COP

Aug. 26, 2013

Three Interest Swap Agreements [Member]

South African Facility [Member]

USD ($)

interest_rate_swap

Aug. 26, 2013

Three Interest Swap Agreements [Member]

South African Facility [Member]

ZAR

Derivative [Line Items]

Derivative, lower fixed interest rate range

6.09%

Derivative, higher fixed interest rate range

7.83%

Derivative, notional amount

$ 97,000,000

$ 107,300,000

$ 44,100,000

442,655,000

^[1]

423,634,000

^[2]

$ 52,900,000

101,250,000,000

^[1]

101,250,000,000

^[2]

$ 2,500,000

24,600,000

Derivative, fixed interest rate

5.78%

Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net

$ 1,400,000

[1]	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $97.0 million and $1.6 million, respectively, as of September 30, 2013.
[2]	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $107.3 million and $5.4 million, respectively, as of December 31, 2012.

Derivative Financial Instruments (Schedule of Interest Rate Swap Agreements) (Details)
In Thousands, unless otherwise specified

Sep. 30, 2013

USD ($)

Dec. 31, 2012

USD ($)

Sep. 30, 2013

South African Facility [Member]

USD ($)

Sep. 30, 2013

South African Facility [Member]

ZAR

Dec. 31, 2012

South African Facility [Member]

ZAR

Sep. 30, 2013

Colombian Long Term Credit Facility [Member]

USD ($)

Sep. 30, 2013

Colombian Long Term Credit Facility [Member]

COP

Dec. 31, 2012

Colombian Long Term Credit Facility [Member]

COP

Derivative [Line Items]

Notional

$ 97,000

$ 107,300

$ 44,100

442,655

^[1]

423,634

^[2]

$ 52,900

101,250,000

^[1]

101,250,000

^[2]

Carrying Amount/Fair Value

909

^[1]

20,441

^[2]

2,869,430

^[1]

5,356,377

^[2]

Aggregate fair value

$ 1,589

^[3]

$ 5,442

^[3]

[1]	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $97.0 million and $1.6 million, respectively, as of September 30, 2013.
[2]	The interest rate swap agreements are denominated in ZAR and COP and have an aggregate notional amount and fair value of $107.3 million and $5.4 million, respectively, as of December 31, 2012.
[3]	Consists of interest rate swap agreements based on JIBAR and IBR whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data.

Derivative Financial Instruments (Schedule of Interest Rate Swap Agreements Impact on Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of Derivative Instruments [Abstract]
Amount of gain/(loss) recognized in OCI on derivatives (effective portion)	$ (1,404)	$ (1,135)	$ 1,801	$ (2,985)
Amount of gain/(loss) reclassified from accumulated OCI into income (effective portion)	$ (741)	$ (181)	$ (2,053)	$ (502)

Fair Value Measurements (Narrative) (Details) (USD $)	9 Months Ended
Fair Value Measurements (Narrative) (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business combination, contingent consideration arrangements, range of outcomes, value, low	$ 0
Business combination, contingent consideration arrangements, range of outcomes, value, high	37,800,000
Assets held and used, long-lived, carrying value		299,900,000
Impairment charges to write down certain assets to net realizable value	2,000,000	10,700,000
Assets held and used, long-lived fair value, carrying value after impairment, Net Realizable Value	4,000,000,000	289,200,000
Carrying value of long-term obligations, including current portion	12,600,000,000		8,800,000,000
Fair value of long-term obligations, including current portion	12,700,000,000		9,400,000,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-term obligations, including current portion	8,400,000,000		4,900,000,000
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-term obligations, including current portion	$ 4,300,000,000		$ 4,500,000,000

Fair Value Measurement (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $)
In Thousands, unless otherwise specified

Sep. 30, 2013

Jun. 30, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Dec. 31, 2011

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Interest rate swap agreements

$ 27,381

^[1]

$ 6,018

22,409

21,218

23,711

27,209

29,897

25,617

1,589

^[2]

5,442

^[2]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

6,018

^[1]

Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]

Interest rate swap agreements

27,381

^[1]

1,589

^[2]

5,442

^[2]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

22,409

Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

$ 23,711

[1]	Consists of highly liquid investments with original maturities in excess of three months.
[2]	Consists of interest rate swap agreements based on JIBAR and IBR whose value is determined using a pricing model with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data.

Fair Value Measurement (Contingent Consideration Change) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance	$ 21,218	$ 29,897	$ 23,711	$ 25,617
Additions	3,599	1,180	4,087	1,533
Payments	(3,729)	(3,951)	(7,952)	(4,397)
Change in fair value	1,303	325	4,610	3,791
Foreign currency translation adjustment	18	(242)	(2,047)	665
Balance	$ 22,409	$ 27,209	$ 22,409	$ 27,209

Accumulated Other Comprehensive Loss (Details) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Accumulated Other Comprehensive Income (Loss) [Line Items]

Income tax expense

$ 15,586

$ 13,054

$ 23,361

$ 64,117

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

Other comprehensive loss before reclassifications, net of tax

(274,256)

(183,347)

(24,403)

(116,432)

Amounts reclassified from accumulated other comprehensive loss, net of tax

644

1,764

Net current-period other comprehensive income (loss)

(23,759)

(114,668)

Accumulated Other Comprehensive Income (Loss) [Line Items]

(298,015)

Unrealized Losses on Cash Flow Hedges [Member]

Income tax expense

100

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

Other comprehensive loss before reclassifications, net of tax

(1,182)

^[1]

(4,358)

^[2]

(1,289)

^[1]

1,167

^[2]

Amounts reclassified from accumulated other comprehensive loss, net of tax

445

^[1]

1,165

^[2]

Net current-period other comprehensive income (loss)

(844)

^[1]

2,332

^[2]

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

(2,026)

^[1],[2]

(2,026)

^[1],[2]

Treasury Lock [Member]

Other comprehensive loss before reclassifications, net of tax

(3,427)

(3,827)

Amounts reclassified from accumulated other comprehensive loss, net of tax

199

599

Net current-period other comprehensive income (loss)

199

599

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

(3,228)

Foreign Currency Items [Member]

Other comprehensive loss before reclassifications, net of tax

(269,647)

(175,162)

(23,114)

(117,599)

Amounts reclassified from accumulated other comprehensive loss, net of tax

Net current-period other comprehensive income (loss)

(23,114)

(117,599)

Customer-related intangible

$ (292,761)

[1]	Losses on cash flow hedges have been reclassified into interest expense in the accompanying condensed consolidated statements of operations. The tax effect of less than $0.1 million is included in income tax expense for the three months ended September 30, 2013.
[2]	Losses on cash flow hedges have been reclassified into interest expense in the accompanying condensed consolidated statements of operations. The tax effect of $0.1 million is included in income tax expense for the nine months ended September 30, 2013.

Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Unrecognized tax benefits that would impact effective tax rate	$ 31.2		$ 31.2		$ 30.6
Impact of change in unrecognized tax benefit, lower	0		0
Impact of change in unrecognized tax benefits, upper	1.3		1.3
Penalties and tax-related interest expense during period	0.9	1.3	3.5	3.9
Decrease in liability for uncertain tax positions	0.8		1.4
Unrecognized tax benefits, income tax penalties and interest accrued	$ 29.8		$ 29.8		$ 28.7

Stock-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
Stock-Based Compensation (Narrative) (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 15,058,000	$ 13,058,000	$ 53,155,000	$ 39,654,000
Stock-based compensation expense related to modification of the vesting and exercise terms for a certain employee's equity awards	0		1,100,000
Capitalized stock-based compensation expense	400,000	500,000	1,200,000	1,600,000
Vesting period			4 years
Accelerated recognition of stock-based compensation expense related to awards granted to retirement eligible employees, additional expense recognized			7,500,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)			$ 19.15
Total unrecognized compensation expense	39,300,000		39,300,000
Total compensation cost not yet recognized, period for recognition			2 years
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	$ 86,700,000		$ 86,700,000
Total compensation cost not yet recognized, period for recognition			2 years
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchased during bi-annual offer			85.00%
Number of shares purchased by employees under the Employee Stock Purchase Plan			57,000
Employee stock purchase plan, fair value per share (in dollars per share)			$ 13.41
2007 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Expiration period			10 years
Number of shares issuable under stock incentive plan	16,600,000		16,600,000

Stock-Based Compensation (Summary of the Company's Option Activity) (Details)	9 Months Ended
	Sep. 30, 2013
Options Activity, Outstanding [Roll Forward]
Outstanding	5,829,945
Granted	1,420,206
Exercised	(799,233)
Forfeited	(53,245)
Expired	0
Outstanding	6,397,673

Stock-Based Compensation (Assumptions Used to Determine the Grant Date Fair Value for Options Granted) (Details) (Employee Stock Option [Member])	9 Months Ended
	Sep. 30, 2013
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum range of risk-free interest rate	0.75%
Maximum range of risk-free interest rate	1.03%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.90%
Expected life of option grants	4 years 4 months 24 days
Minimum range of expected volatility of underlying stock price	26.60%
Maximum range of expected volatility of underlying stock price	36.09%
Expected volatility of underlying stock price over the option period	33.56%
Expected annual dividend yield	1.50%

Stock-Based Compensation (Summary of the Company's Restricted Stock Unit Activity) (Details) (Restricted Stock Units [Member])	9 Months Ended
	Sep. 30, 2013
Restricted Stock Units [Member]
Restricted Stock Unit Activity, Outstanding [Roll Forward]
Outstanding	1,968,553
Granted	803,561
Vested	(806,868)
Forfeited	(106,658)
Outstanding	1,858,588

Stock-Based Compensation ESPP (Details) (Employee Stock Purchase Plan [Member])	9 Months Ended
	Sep. 30, 2013
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum range of risk-free interest rate	0.07%
Maximum range of risk-free interest rate	0.13%
Minimum range of expected volatility of underlying stock price	12.21%
Maximum range of expected volatility of underlying stock price	13.57%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of shares	6 months
Expected annual dividend yield	1.50%

Equity (Narrative) (Details) (USD $)	9 Months Ended		1 Months Ended	9 Months Ended	31 Months Ended
Equity (Narrative) (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2011 Common Stock	Sep. 30, 2013 Treasury Stock	Sep. 30, 2013 Treasury Stock
Equity, Class of Treasury Stock [Line Items]
Authorized repurchase of common stock			$ 1,500,000,000
Treasury stock, shares, acquired				1,938,021	6,300,000
Treasury stock, value, acquired, cost method	145,012,000	16,733,000		145,000,000	389,000,000
Remaining stock value of buyback				1,100,000,000
Accrued dividend, restricted stock units	1,600,000
Paid dividend, restricted stock units	$ 200,000

Equity (Schedule Of Dividends) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Dividends Payable [Line Items]
Distribution per share (in dollars per share)	$ 0.28	$ 0.23	$ 0.81	$ 0.66
Aggregate Payment Amount			$ 209,711	$ 169,816
First Quarter [Member]
Dividends Payable [Line Items]
Declaration Date			Mar. 12, 2013
Payment Date			Apr. 25, 2013
Record Date			Apr. 10, 2013
Distribution per share (in dollars per share)			$ 0.26
Aggregate Payment Amount			102,800
Second Quarter [Member]
Dividends Payable [Line Items]
Declaration Date			May 22, 2013
Payment Date			Jul. 16, 2013
Record Date			Jun. 17, 2013
Distribution per share (in dollars per share)			$ 0.27
Aggregate Payment Amount			106,700
Third Quarter [Member]
Dividends Payable [Line Items]
Declaration Date			Sep. 12, 2013
Payment Date			Oct. 07, 2013
Record Date			Sep. 23, 2013
Distribution per share (in dollars per share)			$ 0.28
Aggregate Payment Amount			$ 110,500

Earnings Per Common Share (Narrative) (Details) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Shares issuable upon conversion of the stock-based awards	2.5	1.2	1.1	1.0

Earnings Per Common Share (Schedule of Earnings Per Basic And Diluted by Common Class) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Income from continuing operations attributable to American Tower Corporation	$ 180,123	$ 232,089	$ 451,351	$ 501,604
Basic weighted average common shares outstanding (in shares)	394,759	395,244	395,138	394,626
Dilutive securities (in shares)	3,589	4,243	4,137	4,458
Diluted weighted average common shares outstanding (in shares)	398,348	399,487	399,275	399,084
Basic income attributable to American Tower Corporation per common share (in dollars per share)	$ 0.46	$ 0.59	$ 1.14	$ 1.27
Diluted income attributable to American Tower Corporation per common share (in dollars per share)	$ 0.45	$ 0.58	$ 1.13	$ 1.26

Commitments And Contingencies (Narrative) (Details) (USD $)	1 Months Ended	9 Months Ended
	Dec. 31, 2000 towers	Sep. 30, 2013
AT&T Transaction [Member]
Long-term Purchase Commitment [Line Items]
Number of towers leased or subleased		2,450
Lessee leasing arrangements, operating leases, term of contract		27 years
Aggregate purchase option price for towers		$ 585,300,000
Purchase price accretion rate (per year)		10.00%
Right to continue to lease space, number of terms		4
Lessee leasing arrangements, operating leases, renewal term		5 years
ALLTEL Transaction [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase option price for towers		70,700,000
Purchase price accretion rate (per year)		3.00%
Long-term purchase commitment, time period	P15Y
Capital leased assets, number of units	1,800
Cash purchase price per tower	27,500
Purchase price of tower in shares of common stock		769
Value of potential shares payable		$ 101,200,000

Acquisitions (Narrative) (Details)	3 Months Ended		9 Months Ended			0 Months Ended	9 Months Ended		0 Months Ended				0 Months Ended			9 Months Ended	0 Months Ended		9 Months Ended	12 Months Ended		12 Months Ended	9 Months Ended	12 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended			0 Months Ended			0 Months Ended			0 Months Ended
Acquisitions (Narrative) (Details)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)	Jan. 31, 2013 Mexico Axtel Acquisition [Member] USD ($) sites	Sep. 30, 2013 Other International Acquisition 2013 [Member] USD ($) sites	Sep. 30, 2013 Other US Acquisition 2013 [Member] USD ($) sites propertyinterests	Aug. 31, 2012 Brazil-Vivo Acquisition [Member] USD ($) sites	Jun. 30, 2012 Brazil-Vivo Acquisition [Member] USD ($) sites	Mar. 30, 2012 Brazil-Vivo Acquisition [Member] USD ($) sites	Sep. 30, 2012 Brazil-Vivo Acquisition [Member] sites	Dec. 28, 2012 Diamond Acquisition [Member] USD ($) propertyinterests sites	Dec. 04, 2012 Germany Acquisition [Member] USD ($) sites	Dec. 20, 2012 Skyway Acquisition [Member] USD ($) sites	Sep. 30, 2013 Skyway Acquisition [Member] USD ($) sites	Jun. 29, 2012 Uganda Acquisition [Member] USD ($) sites	Dec. 08, 2011 Uganda Acquisition [Member] sites	Sep. 30, 2013 Uganda Acquisition [Member] USD ($)	Dec. 31, 2012 Uganda Acquisition [Member] USD ($)	Aug. 15, 2013 Uganda Acquisition [Member] sites	Dec. 31, 2012 Other International Acquisition 2012 [Member] USD ($) sites	Sep. 30, 2013 Other US Acquisition 2012 [Member] USD ($)	Dec. 31, 2012 Other US Acquisition 2012 [Member] USD ($) sites	Sep. 30, 2013 Colombia Movil Acquisition [Member] USD ($)	Sep. 30, 2013 Colombia Movil Acquisition [Member] USD ($)	Nov. 04, 2010 Cell C Acquisition [Member] sites	Sep. 30, 2013 Cell C Acquisition [Member] USD ($)	Sep. 30, 2013 Cell C Acquisition [Member] USD ($)	Sep. 30, 2013 Other Contingent Consideration [Member] USD ($)	Sep. 30, 2013 Other Contingent Consideration [Member] USD ($)	Sep. 30, 2013 Other Contingent Consideration [Member] UNITED STATES USD ($)	Sep. 30, 2013 NII Holdings Acquisition [Member] USD ($)	Aug. 09, 2013 NII Holdings Acquisition [Member] Brazil [Member] USD ($)	Aug. 09, 2013 NII Holdings Acquisition [Member] Brazil [Member] BRL	Aug. 07, 2013 NII Holdings Acquisition [Member] Brazil [Member] sites	Aug. 09, 2013 NII Holdings Acquisition [Member] Mexico [Member] USD ($)	Aug. 09, 2013 NII Holdings Acquisition [Member] Mexico [Member] MXN	Aug. 07, 2013 NII Holdings Acquisition [Member] Mexico [Member] sites	Sep. 26, 2013 Z-Sites Acquisition [Member] USD ($) sites	Sep. 26, 2013 Z-Sites Acquisition [Member] BRL sites	Oct. 02, 2013 MIPT Acquisition [Member] Subsequent Event [Member] USD ($)	Oct. 02, 2013 Secured Debt [Member] MIPT Acquisition [Member] Subsequent Event [Member] USD ($)	Oct. 02, 2013 MIPT Costa Rica Debt [Member] MIPT Acquisition [Member] Subsequent Event [Member] USD ($)
Business Acquisition [Line Items]
Business combination, acquisition and merger related expenses	$ 8,900,000	$ 5,200,000	$ 25,800,000	$ 14,800,000																																						$ 4,800,000,000
Number of communications sites acquired						883	644	41	192		800	700	316	2,031	318		962					705		128												2,790			1,666	236	236
Aggregate purchase price						248,500,000	80,500,000	52,700,000	32,700,000	126,300,000	151,700,000		322,500,000	525,700,000	169,600,000	166,300,000	171,500,000		169,200,000	173,200,000		162,700,000	146,100,000	146,200,000										423,800,000	945,000,000		382,300,000	5,025,000,000		127,100,000	283,000,000
Acquisition deposit in escrow	120,000,000		120,000,000		0																												120,000,000
Estimated contingent consideration fair value							4,100,000																		21,500,000	21,500,000				900,000	900,000	0
Value added tax receivable							3,700,000															21,900,000
Number of property interests acquired								19
Business acquisition, cost of acquired entity, cash paid								52,300,000					320,100,000		169,500,000	166,200,000																										3,300,000,000
Noncash or part noncash acquisition, value of liabilities assumed								400,000					2,400,000		100,000	100,000																										1,500,000,000
Long-term debt																																											1,490,000,000	0
Maximum number of communications sites to be acquired											1,500							1,000									1,400
Additional communications sites to be acquired										300
Number of property interests acquired under third party sites													24
Contingent consideration term																													P4Y
Number of sites returned																11					7
Equity method investment, ownership percentage																		51.00%																								100.00%
Percentage of minority investors																		49.00%
Business combination, contingent consideration arrangements, range of outcomes, value, low	0		0																						0	0				0	0
Business combination, contingent consideration arrangements, range of outcomes, value, high	37,800,000		37,800,000																						36,900,000	36,900,000				900,000	900,000
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability, purchases	3,599,000	1,180,000	4,087,000	1,533,000																					3,600,000	4,100,000
Business combination, contingent consideration arrangements, change in amount of contingent consideration, liability																									500,000	1,500,000			3,400,000	800,000	300,000
Business acquisition, contingent consideration, actual cash payment																												2,500,000		1,000,000
Borrowings under credit facilities			$ 3,507,000,000	$ 1,325,000,000																																						$ 2,800,000,000

Acquisitions (Schedule of Aggregate Purchase Consideration Paid and the Amount of Assets Acquired) (Details) (USD $)

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

0 Months Ended

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Mexico Axtel Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Sep. 30, 2013

Mexico Axtel Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Other International Acquisition 2013 [Member]

Preliminary Purchase Price Allocation [Member]

Sep. 30, 2013

Other International Acquisition 2013 [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Other US Acquisition 2013 [Member]

Sep. 30, 2013

Other US Acquisition 2013 [Member]

Preliminary Purchase Price Allocation [Member]

Sep. 30, 2013

Other US Acquisition 2013 [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 31, 2012

Brazil-Vivo Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Brazil-Vivo Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Brazil-Vivo Acquisition [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Brazil-Vivo Acquisition [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 28, 2012

Diamond Acquisition [Member]

Dec. 31, 2012

Diamond Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Diamond Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Diamond Acquisition [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Diamond Acquisition [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 31, 2012

Germany Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Germany Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Germany Acquisition [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Germany Acquisition [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 20, 2012

Skyway Acquisition [Member]

Sep. 30, 2013

Skyway Acquisition [Member]

Dec. 31, 2012

Skyway Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Skyway Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Skyway Acquisition [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Skyway Acquisition [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 31, 2012

Uganda Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Uganda Acquisition [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Uganda Acquisition [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Uganda Acquisition [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 31, 2012

Other International Acquisition 2012 [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Other International Acquisition 2012 [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Other International Acquisition 2012 [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Other International Acquisition 2012 [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Dec. 31, 2012

Other US Acquisition 2012 [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Other US Acquisition 2012 [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Sep. 30, 2013

Other US Acquisition 2012 [Member]

Purchase Price Allocation [Member]

Sep. 30, 2013

Other US Acquisition 2012 [Member]

Purchase Price Allocation [Member]

Acquired Network Location [Member]

Oct. 02, 2013

Maximum [Member]

Preliminary Purchase Price Allocation [Member]

Sep. 30, 2013

Maximum [Member]

Preliminary Purchase Price Allocation [Member]

Dec. 31, 2012

Maximum [Member]

Preliminary Purchase Price Allocation [Member]

Sep. 30, 2013

Maximum [Member]

Purchase Price Allocation [Member]

Oct. 02, 2013

Subsequent Event [Member]

MIPT Acquisition [Member]

Oct. 02, 2013

Subsequent Event [Member]

MIPT Acquisition [Member]

Acquired Network Location [Member]

Business Acquisition [Line Items]

Current assets

$ 0

$ 3,688,000

$ 1,433,000

$ 0

^[1]

$ 842,000

$ 14,483,000

$ 14,043,000

$ 740,000

$ 0

^[1]

$ 21,911,000

$ 0

$ 104,044,000

Non-current assets

4,032,000

1,835,000

44,000

24,460,000

22,418,000

^[1]

2,258,000

^[1]

4,196,000

2,309,000

153,000

627,000

Property and equipment

86,100,000

39,693,000

17,493,000

138,959,000

69,045,000

72,447,000

233,073,000

203,494,000

60,671,000

58,913,000

102,366,000

61,080,000

66,073,000

61,995,000

61,091,000

1,290,143,000

Intangible assets:

115,700,000

^[2]

18,401,000

^[2]

24,296,000

^[2]

80,010,000

^[2]

83,012,000

^[1],[2]

171,300,000

^[2]

184,200,000

^[2]

218,146,000

^[2]

288,330,000

^[2]

63,000,000

^[2]

64,400,000

^[2]

36,500,000

^[2]

30,500,000

^[1],[2]

49,227,000

^[2]

52,911,000

^[2]

61,966,000

^[2]

61,266,000

^[2]

2,536,700,000

^[2]

Network location intangibles

41,700,000

^[2]

19,984,000

^[2]

5,605,000

^[2]

37,980,000

^[2]

40,983,000

^[1],[2]

28,400,000

^[2]

32,000,000

^[2]

20,819,000

^[2]

21,997,000

^[2]

20,700,000

^[2]

20,500,000

^[2]

27,000,000

^[2]

26,000,000

^[1],[2]

16,442,000

^[2]

15,935,000

^[2]

16,233,000

^[2]

16,133,000

^[2]

338,600,000

^[2]

Current liabilities

(440,000)

^[1]

(3,216,000)

(2,990,000)

(2,988,000)

(454,000)

^[1]

(88,497,000)

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt

(1,573,366,000)

^[3]

Other non-current liabilities

(9,377,000)

(7,653,000)

(786,000)

(18,195,000)

(3,423,000)

(23,243,000)

(3,333,000)

(3,222,000)

(7,528,000)

(5,893,000)

(6,294,000)

(1,310,000)

(49,158,000)

Fair value of net assets acquired

238,155,000

75,948,000

47,645,000

263,214,000

267,177,000

^[1]

262,948,000

282,850,000

460,288,000

501,633,000

141,324,000

140,877,000

160,596,000

153,596,000

^[1]

146,963,000

152,845,000

139,037,000

137,333,000

2,559,093,000

Goodwill

2,815,271,000

2,842,717,000

^[4]

10,368,000

^[5]

4,565,000

^[5]

4,698,000

^[5]

47,481,000

^[6]

43,518,000

57,178,000

^[6]

37,276,000

65,365,000

^[6]

24,020,000

28,224,000

^[6]

25,308,000

12,564,000

^[6]

15,644,000

15,726,000

^[6]

9,844,000

7,124,000

^[6]

8,724,000

756,833,000

^[7]

Acquired finite-live intangible assets, weighted average useful life

20 years

Noncash or part noncash acquisition, value of liabilities assumed

400,000

2,400,000

100,000

1,500,000,000

Liabilities, Fair Value Adjustment

$ 53,000,000

[1]	The allocation of the purchase price was finalized during the nine months ended September 30, 2013.
[2]	Customer-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.
[3]	Long-term obligations included $1.5 billion of MIPT's existing indebtedness and a fair value adjustment of $53.0 million.
[4]	Balances have been revised to reflect purchase accounting measurement period adjustments.
[5]	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for South Africa where goodwill is expected to be partially deductible. .
[6]	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will be deductible for tax purposes, except for Uganda where goodwill is not expected to be deductible and South Africa where goodwill is expected to be partially deductible.
[7]	Goodwill will be allocated to the Company’s domestic and international rental and management segments, as applicable. The Company expects goodwill recorded to its domestic rental and management segment will be deductible for tax purposes and goodwill recorded to its international segment will not be deductible for tax purposes.

Acquisitions (Pro Forma Information) (Details) (Subsequent Event [Member], MIPT Acquisition [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Subsequent Event [Member] \| MIPT Acquisition [Member]
Business Acquisition [Line Items]
Operating revenues	$ 888,432	$ 788,623	$ 2,659,294	$ 2,326,753
Net income attributable to American Tower Corporation	$ 142,357	$ 195,647	$ 343,992	$ 392,156
Basic earnings per share (in dollars per share)	$ 360	$ 500	$ 870	$ 990
Diluted earnings per share (in dollars per share)	$ 360	$ 490	$ 860	$ 980

Business Segments (Summarized Financial Information Concerning the Company's Reportable Segments) (Details) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

$ 807,880

$ 713,335

$ 2,419,438

$ 2,107,586

200,482

^[1]

184,464

^[2]

607,113

^[3]

526,930

^[4]

3,544

3,586

10,673

10,715

Segment selling, general, administrative and development expense

610,942

532,457

1,822,998

1,591,371

58,131

^[1]

47,325

^[2]

172,522

^[3]

133,481

^[4]

552,811

485,132

1,650,476

1,457,890

Other selling, general, administrative and development expense

15,058

13,058

53,155

39,654

24,939

21,516

74,251

66,099

Depreciation, amortization and accretion

184,922

144,061

555,334

465,788

Other expense (principally interest expense and other (expense) income)

149,084

61,620

536,092

346,385

INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND INCOME ON EQUITY METHOD INVESTMENTS

178,808

244,877

431,644

539,964

18,181,320

14,089,418

Operating Expense [Member]

300

400

1,200

1,300

Selling General Administrative And Development Expense [Member]

14,700

12,600

52,000

38,300

Operating Segments [Member] | Rental And Management [Member]

796,575

697,554

2,363,207

2,063,806

195,705

^[1]

177,141

^[2]

584,714

^[3]

505,526

^[4]

3,544

3,586

10,673

10,715

Segment selling, general, administrative and development expense

604,414

523,999

1,789,166

1,568,995

56,251

^[1]

45,198

^[2]

165,417

^[3]

129,071

^[4]

548,163

478,801

1,623,749

1,439,924

17,464,734

Operating Segments [Member] | Rental And Management [Member] | Domestic [Member]

529,941

480,351

1,566,660

1,440,824

95,232

^[1]

92,072

^[2]

282,273

^[3]

273,188

^[4]

Segment selling, general, administrative and development expense

434,709

388,279

1,284,387

1,167,636

24,523

^[1]

20,141

^[2]

71,664

^[3]

60,638

^[4]

410,186

368,138

1,212,723

1,106,998

12,037,318

Operating Segments [Member] | Rental And Management [Member] | International [Member]

266,634

217,203

796,547

622,982

100,473

^[1]

85,069

^[2]

302,441

^[3]

232,338

^[4]

3,544

3,586

10,673

10,715

Segment selling, general, administrative and development expense

169,705

135,720

504,779

401,359

31,728

^[1]

25,057

^[2]

93,753

^[3]

68,433

^[4]

137,977

110,663

411,026

332,926

5,427,416

Operating Segments [Member] | Network Development Services [Member]

11,305

15,781

56,231

43,780

4,777

^[1]

7,323

^[2]

22,399

^[3]

21,404

^[4]

Segment selling, general, administrative and development expense

6,528

8,458

33,832

22,376

1,880

^[1]

2,127

^[2]

7,105

^[3]

4,410

^[4]

4,648

6,331

26,727

17,966

49,973

Operating Segments [Member] | All Other Segments [Member]

Other selling, general, administrative and development expense

15,058

13,058

53,155

39,654

24,939

21,516

74,251

66,099

Depreciation, amortization and accretion

184,922

144,061

555,334

465,788

Other expense (principally interest expense and other (expense) income)

149,084

61,620

536,092

346,385