American Tower (AMT) 10-Q 1 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 22, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Entity Registrant Name	'AMERICAN TOWER CORP /MA/	'
Entity Central Index Key	'0001053507	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	395,745,715

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS-Unaudited (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
CURRENT ASSETS:	'		'
Cash and cash equivalents	$333,439		$293,576
Restricted cash	161,262		152,916
Short-term investments	34,430	[1]	18,612
Accounts receivable, net	227,155		151,084
Prepaid and other current assets	265,057		314,176	[2]
Deferred income taxes	21,638		22,401
Total current assets	1,042,981		952,765
PROPERTY AND EQUIPMENT, net	7,344,049		7,262,175
GOODWILL	3,737,681		3,729,792	[3]
OTHER INTANGIBLE ASSETS, net	6,617,524		6,701,459
DEFERRED INCOME TAXES	270,994		262,529
DEFERRED RENT ASSET	950,576		918,847
NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	453,602		445,004
TOTAL	20,417,407		20,272,571
CURRENT LIABILITIES:	'		'
Accounts payable	115,726		171,050
Accrued expenses	400,449		415,324
Distributions payable	127,286		575
Accrued interest	90,945		105,751
Current portion of long-term obligations	325,170		70,132
Unearned revenue	215,429		161,926
Total current liabilities	1,275,005		924,758
LONG-TERM OBLIGATIONS	14,009,007		14,408,146
ASSET RETIREMENT OBLIGATIONS	538,241		526,869
OTHER NON-CURRENT LIABILITIES	893,549		822,758
Total liabilities	16,715,802		16,682,531
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; 398,470,269 and 397,674,350 shares issued; and 395,660,243 and 394,864,324 shares outstanding, respectively	3,984		3,976
Additional paid-in capital	5,153,402		5,130,616
Distributions in excess of earnings	-1,006,058		-1,081,467
Accumulated other comprehensive loss	-272,410		-311,220
Treasury stock (2,810,026 and 2,810,026 shares at cost, respectively)	-207,740		-207,740
Total American Tower Corporation equity	3,671,178		3,534,165
Noncontrolling interest	30,427		55,875
Total equity	3,701,605		3,590,040
TOTAL	$20,417,407		$20,272,571
[1]	Consists of highly liquid investments with original maturities in excess of three months.
[2]	December 31, 2013 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_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS-Unaudited (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	398,470,269	397,674,350
Common Stock, Shares, Outstanding	395,660,243	394,864,324
Treasury stock, shares	2,810,026	2,810,026

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS-Unaudited (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
REVENUES:	'	'
Rental and management	$960,120	$777,433
Network development services	23,969	25,295
Total operating revenues	984,089	802,728
OPERATING EXPENSES:	'	'
Rental and management (including stock-based compensation expense of $372 and $246, respectively)	250,835	191,295
Network development services (including stock-based compensation expense of $132 and $192, respectively)	9,934	10,471
Depreciation, amortization and accretion	245,763	185,804
Selling, general, administrative and development expense (including stock-based compensation expense of $24,100 and $20,604, respectively)	110,029	101,153
Other operating expenses	13,891	14,319
Total operating expenses	630,452	503,042
OPERATING INCOME	353,637	299,686
OTHER INCOME (EXPENSE):	'	'
Interest income, TV Azteca, net of interest expense of $371 and $371, respectively	2,595	3,543
Interest income	2,018	1,714
Interest expense	-143,307	-111,766
Loss on retirement of long-term obligations	-238	-35,298
Other (expense) income (including unrealized foreign currency (losses) gains of ($2,005) and $22,143, respectively)	-3,743	22,291
Total other expense	-142,675	-119,516
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	210,962	180,170
Income tax provision	-17,649	-19,222
NET INCOME	193,313	160,948
Net loss attributable to noncontrolling interest	9,186	10,459
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION	$202,499	$171,407
NET INCOME PER COMMON SHARE AMOUNTS:	'	'
Basic net income attributable to American Tower Corporation (in dollars per share)	$0.51	$0.43
Diluted net income attributable to American Tower Corporation (in dollars per share)	$0.51	$0.43
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:	'	'
Basic (in shares)	395,146	395,239
Diluted (in shares)	399,120	399,659
DISTRIBUTIONS DECLARED, PER SHARE (in dollars per share)	$0.32	$0.26

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS-Unaudited (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Stock-based compensation expense	$24,604	$21,042
Unrealized foreign currency losses	-2,005	22,143
Rental And Management [Member]	'	'
Stock-based compensation expense	372	246
Network Development Services [Member]	'	'
Stock-based compensation expense	132	192
Selling General Administrative And Development Expense [Member]	'	'
Stock-based compensation expense	24,100	20,604
TV Azteca [Member]	'	'
Net of interest expense	$371	$371

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME-Unaudited (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$193,313	$160,948
Other comprehensive income (loss):	'	'
Changes in fair value of cash flow hedges, net of tax expense of $117 and $111, respectively	-704	-1,044
Reclassification of unrealized losses on cash flow hedges to net income, net of taxes of $55 and $59, respectively	914	549
Foreign currency translation adjustments, net of taxes of $1,056 and $13,732, respectively	22,492	27,427
Other comprehensive income	22,702	26,932
Comprehensive income	216,015	187,880
Comprehensive loss attributable to noncontrolling interest	25,294	8,831
Comprehensive income attributable to American Tower Corporation	$241,309	$196,711

CONDENSED_CONSOLIDATED_STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME-Unaudited (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net change in fair value of cash flow hedges, tax	$117	$111
Reclassification of unrealized losses on cash flow hedges to net income, tax	55	59
Foreign currency translation adjustments, tax	$1,056	$13,732

CONDENSED_CONSOLIDATED_STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS-Unaudited (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:	'	'
Net income	$193,313	$160,948
Adjustments to reconcile net income to cash provided by operating activities:	'	'
Stock-based compensation expense	24,604	21,042
Depreciation, amortization and accretion	245,763	185,804
Loss on early retirement of securitized debt	238	35,288
Other non-cash items reflected in statements of operations	5,060	-7,496
Increase in net deferred rent asset	-21,393	-26,806
(Increase) decrease in restricted cash	-8,347	22,583
Increase in assets	-43,449	-7,374
Increase in liabilities	80,793	10,047
Cash provided by operating activities	476,582	394,036
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Payments for purchase of property and equipment and construction activities	-213,891	-123,905
Payments for acquisitions, net of cash acquired	-62,761	-245,094
Proceeds from sale of short-term investments and other non-current assets	138,228	7,150
Payments for short-term investments	-151,263	-14,650
Deposits, restricted cash, investments and other	-1,369	-129
Cash used for investing activities	-291,056	-376,628
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Repayments of short-term borrowings	-172	0
Borrowings under credit facilities	0	249,000
Proceeds from issuance of senior notes, net	769,640	983,354
Proceeds from other long-term borrowings	3,033	0
Proceeds from issuance of Securities in securitization transaction, net	0	1,778,496
Repayments of notes payable, credit facilities and capital leases	-916,632	-2,937,744
(Distributions to) contributions from noncontrolling interest holders, net	-154	7,658
Purchases of common stock	0	-12,480
Proceeds from stock options	13,795	6,140
Payment for early retirement of securitized debt	0	-29,234
Deferred financing costs and other financing activities	-21,857	-10,561
Distributions	-554	0
Cash (used for) provided by financing activities	-152,901	34,629
Net effect of changes in foreign currency exchange rates on cash and cash equivalents	7,238	21,051
NET INCREASE IN CASH AND CASH EQUIVALENTS	39,863	73,088
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	293,576	368,618
CASH AND CASH EQUIVALENTS, END OF PERIOD	333,439	441,706
CASH PAID FOR INCOME TAXES (NET OF REFUNDS OF $738 AND $704, RESPECTIVELY)	19,094	13,543
CASH PAID FOR INTEREST	154,497	95,251
NON-CASH INVESTING AND FINANCING ACTIVITIES:	'	'
INCREASE IN ACCOUNTS PAYABLE AND ACCRUED EXPENSES FOR PURCHASES OF PROPERTY AND EQUIPMENT AND CONSTRUCTION ACTIVITIES	7,809	1,691
PURCHASES OF PROPERTY AND EQUIPMENT UNDER CAPITAL LEASES	$6,301	$4,495

CONDENSED_CONSOLIDATED_STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS-Unaudited (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Cash Flows [Abstract]	'	'
Proceeds from income tax refunds	$738	$704

CONDENSED_CONSOLIDATED_STATEME6

CONDENSED CONSOLIDATED STATEMENT OF EQUITY-Unaudited (USD $)	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Other Comprehensive (Loss) Income	Earnings (Distributions) in Excess of Distributions (Earnings)	Noncontrolling Interest
In Thousands, except Share data, unless otherwise specified
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	'	395,963,218	-872,005	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Stock-based compensation related activity (shares)	'	660,809	'	'	'	'	'
Stock-based compensation related activity	17,144	7	'	17,137	'	'	'
Treasury stock activity (shares)	'	'	-164,120	'	'	'	'
Treasury stock activity	-12,480	'	-12,480	'	'	'	'
Change in fair value of cash flow hedges, net of tax	-1,044	'	'	'	-1,115	'	71
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	549	'	'	'	511	'	38
Foreign currency translation adjustment, net of tax	27,427	'	'	'	25,908	'	1,519
Contributions from non-controlling interest	7,820	'	'	'	'	'	7,820
Distributions to non-controlling interest	-162	'	'	'	'	'	-162
Dividends/distributions declared	-102,861	'	'	'	'	-102,861	'
Net income (loss)	160,948	'	'	'	'	171,407	-10,459
BALANCE at Mar. 31, 2013	3,781,522	3,966	-75,208	5,029,261	-158,043	-1,128,361	109,907
BALANCE (shares) at Mar. 31, 2013	'	396,624,027	-1,036,125	'	'	'	'
BALANCE at Dec. 31, 2013	3,590,040	3,976	-207,740	5,130,616	-311,220	-1,081,467	55,875
BALANCE (shares) at Dec. 31, 2013	394,864,324	397,674,350	-2,810,026	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Stock-based compensation related activity (shares)	'	795,919	'	'	'	'	'
Stock-based compensation related activity	22,794	8	'	22,786	'	'	'
Change in fair value of cash flow hedges, net of tax	-704	'	'	'	-780	'	76
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	914	'	'	'	879	'	35
Foreign currency translation adjustment, net of tax	22,492	'	'	'	38,711	'	-16,219
Distributions to non-controlling interest	-154	'	'	'	'	'	-154
Dividends/distributions declared	-127,090	'	'	'	'	-127,090	'
Net income (loss)	193,313	'	'	'	'	202,499	-9,186
BALANCE at Mar. 31, 2014	$3,701,605	$3,984	($207,740)	$5,153,402	($272,410)	($1,006,058)	$30,427
BALANCE (shares) at Mar. 31, 2014	395,660,243	398,470,269	-2,810,026	'	'	'	'

Description_of_Business_Basis_

Description of Business, Basis of Presentation and Accounting Policies	3 Months Ended
	Mar. 31, 2014
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, Costa Rica, Germany, Ghana, India, Mexico, Panama, Peru, South Africa and Uganda. 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. Since January 1, 2012, the Company has been organized and has qualified as a real estate investment trust (“REIT”) for U.S. federal income tax purposes.
	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 holding and operating subsidiaries and joint ventures.
	The Company holds and operates certain of its assets through one or more taxable REIT subsidiaries (“TRSs”). 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 businesses that the Company holds through its TRSs primarily include certain of its international operations and a portion of our managed network business.
	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 space on its towers. However, even as a REIT, the Company remains obligated to pay income taxes on earnings from its TRS operations. In addition, the Company’s international assets and operations, including those designated as direct or indirect qualified REIT subsidiaries or other disregarded entities of a REIT (collectively, “QRSs”), continue to be subject to taxation in the foreign jurisdictions where those assets are held or those operations are conducted.
	The Company may, from time to time, change the election of previously designated TRSs that hold certain of its operations to be treated as QRSs, and may reorganize and transfer certain assets or operations from its TRSs to other subsidiaries, including QRSs. For all periods subsequent to the conversion from a TRS to a QRS, the Company includes the income from the QRSs as part of its REIT taxable income for the purpose of computing the Company’s REIT distribution requirements. During the quarter ended March 31, 2014, the Company restructured certain of its domestic TRSs, which included a portion of its network development services segment and indoor DAS networks business, to be treated as QRSs. As of March 31, 2014, in addition to these businesses, the Company’s QRSs include its domestic tower leasing business and most of its operations in Costa Rica, Mexico and Panama. The Company changed the previous TRS election for certain of its German subsidiaries to be treated as QRSs as of April 1, 2014.
	The accompanying condensed consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission. 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, 2013.
	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 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.
	Functional Currency—The functional currency of the Company’s foreign operating subsidiaries is the respective local currency, except for Costa Rica and Panama, where the functional currency is the U.S. Dollar.  All foreign currency assets and liabilities held by the subsidiaries are translated into U.S. Dollars at the exchange rate in effect at the end of the applicable fiscal reporting period and all foreign currency revenues and expenses are translated at the average monthly exchange rates. Translation adjustments are reflected in equity as a component of Accumulated other comprehensive income (loss) (“AOCI”) in the condensed consolidated balance sheet.
	Transactional gains and losses on foreign currency transactions are reflected in Other expense (income) in the condensed consolidated statements of operations.  However, the effect from fluctuations in foreign currency exchange rates on intercompany notes whose payment is not planned or anticipated in the foreseeable future, is reflected in AOCI in the condensed consolidated balance sheet.  During the three months ended March 31, 2014, the Company recorded unrealized foreign currency losses of $15.5 million, of which $13.5 million was recorded in AOCI and $2.0 million was recorded in Other expense (income).
	Accounting Standards Updates—In April 2014, the Financial Accounting Standards Board (the “FASB”) issued additional guidance on reporting discontinued operations. Under this guidance, only disposals representing a strategic shift in operations would be presented as discontinued operations. This guidance would require expanded disclosures about discontinued operations that would provide information about the assets, liabilities, income and expenses of discontinued operations. Additionally, the guidance would require disclosure of the pre-tax income attributable to a disposal of a significant part of an entity that does not qualify for discontinued operations reporting. This guidance will be effective for reporting periods beginning on or after December 15, 2014. The FASB permits early adoption of this standard, but only for disposals or classifications as held for sale that have not been reported in financial statements previously issued or available for issuance. The impact of the adoption of this accounting standard update on the Company’s statements of operations, balance sheet, cash flows and disclosures will be based on the Company’s future disposal activity.

Prepaid_and_Other_Current_Asse

Prepaid and Other Current Assets	3 Months Ended
	Mar. 31, 2014
Prepaid Expense and Other Assets, Current [Abstract]	'
Prepaid and Other Current Assets	'
	Prepaid and Other Current Assets
	Prepaid and other current assets consists of the following as of (in thousands):
		31-Mar-14		December 31, 2013 (1)
	Prepaid operating ground leases	$	74,013	$	82,950
	Prepaid income tax	56,674		52,612
	Unbilled receivables	37,115		25,412
	Prepaid assets	34,865		34,243
	Value added tax and other consumption tax receivables	17,647		78,262
	Other miscellaneous current assets	44,743		40,697
	Balance	$	265,057	$	314,176
	(1) December 31, 2013 balances have been revised to reflect purchase accounting measurement period adjustments.

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Other Intangible Assets	'
	Goodwill and Other Intangible Assets
	The changes in the carrying value of goodwill for the Company’s business segments are as follows (in thousands):
			Rental and Management						Network			Total
									Development
			Domestic			International			Services
	Balance as of January 1, 2014 (1)		$	3,132,553		$	595,239		$	2,000		$	3,729,792
	Additions		—			40			—			40
	Effect of foreign currency translation		—			7,849			—			7,849
	Balance as of March 31, 2014		$	3,132,553		$	603,128		$	2,000		$	3,737,681
	-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):
					31-Mar-14									December 31, 2013
			Estimated		Gross			Accumulated			Net Book			Gross		Accumulated			Net Book
			Useful		Carrying			Amortization			Value			Carrying		Amortization			Value
			Lives		Value									Value
			(years)
	Acquired network location (1)		Up to 20		$	2,368,782		$	(827,571	)	$	1,541,211		$	2,365,474	$	(791,359	)	$	1,574,115
	Acquired customer-related intangibles		15-20		6,216,899			(1,238,111		)	4,978,788			6,201,868		(1,170,239		)	5,031,629
	Acquired licenses and other intangibles		20-Mar		6,688			(2,470		)	4,218			6,583		(2,297		)	4,286
	Economic Rights, TV Azteca		70		28,742			(14,342		)	14,400			28,783		(14,229		)	14,554
	Total				$	8,621,111		$	(2,082,494	)	$	6,538,617		$	8,602,708	$	(1,978,124	)	$	6,624,584
	Deferred financing  costs, net (2)		N/A								78,907								76,875
	Other intangible assets, net										$	6,617,524							$	6,701,459
	-1	Acquired network location intangibles are amortized over the shorter of the term of the corresponding ground lease taking into consideration lease renewal options and residual value or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.
	-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 Depreciation, amortization and accretion 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.
	The Company amortizes its acquired network intangibles and customer-related intangibles on a straight-line basis over their estimated useful lives. As of March 31, 2014, 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 its Annual Report on Form 10-K for the year ended December 31, 2013, is approximately 16 years. Amortization of intangible assets for the three months ended March 31, 2014 and 2013 was approximately $102.6 million and $60.5 million (excluding amortization of deferred financing costs, which is included in Interest expense), respectively. Based on current exchange rates, the Company expects to record amortization expense (excluding amortization of deferred financing costs) as follows over the remaining current year and the next five subsequent years (in millions):
	Fiscal Year
	2014 (remaining year)	$	308.1
	2015	408.2
	2016	405.5
	2017	403.2
	2018	401.1
	2019	399

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2014
Accrued Liabilities, Current [Abstract]	'
Accrued Expenses	'
	Accrued Expenses
	Accrued expenses consists of the following as of (in thousands):
		31-Mar-14		31-Dec-13
	Accrued construction costs	$	65,363	$	52,446
	Accrued property and real estate taxes	57,944		54,529
	Payroll and related withholdings	33,164		50,843
	Accrued rent	31,846		28,456
	Other accrued expenses	212,132		229,050
	Balance	$	400,449	$	415,324

Longterm_Obligations

Long-term Obligations	3 Months Ended
	Mar. 31, 2014
Securities Financing Transactions [Abstract]	'
Financing Transactions	'
	Long-Term Obligations
	Current portion of long-term obligations—In connection with its acquisition of MIP Tower Holdings LLC (“MIPT”) (see note 14) on October 1, 2013, the Company assumed approximately $1.49 billion principal amount of existing indebtedness under six series, consisting of eleven separate classes, of Secured Tower Revenue Notes issued by certain subsidiaries of Global Tower Partners (“GTP”) in several securitization transactions (the “GTP Notes”). The Series 2010-1 Class C Notes and the Series 2010-1 Class F Notes (together, the “Series 2010-1 Notes”) have an aggregate principal amount of $250.0 million and an anticipated repayment date of February 15, 2015. As a result, the aggregate principal balance of $250.0 million and the unamortized premium of $4.7 million of the Series 2010-1 Notes is reflected in Current portion of long-term obligations on the condensed consolidated balance sheet.
	Subsidiary Debt
	Costa Rica Loan—In connection with its acquisition of MIPT (see note 14), the Company assumed $32.6 million of secured debt in Costa Rica (the “Costa Rica Loan”), which was repaid in full on February 12, 2014.
	Colombian Bridge Loans—In connection with the acquisition of communications sites in Colombia, one of the Company’s Colombian subsidiaries entered into six Colombian Pesos (“COP”) denominated bridge loans for an aggregate principal amount of 108.0 billion COP (approximately $55.0 million as of March 31, 2014). In April 2014, the maturity date of the loans was extended to June 22, 2014 and the interest rate decreased from 7.94% to 7.89%.
	Mexican Loan—In connection with the acquisition of towers in Mexico from NII Holdings, Inc. (“NII”) during the fourth quarter of 2013, one of the Company’s Mexican subsidiaries entered into a 5.2 billion Mexican Pesos (“MXN”) denominated unsecured bridge loan (the “Mexican Loan”) and subsequently borrowed approximately 4.9 billion MXN (approximately $376.9 million as of March 31, 2014). On March 31, 2014, the Mexican subsidiary repaid 1.1 billion MXN (approximately $80.3 million) of the outstanding indebtedness with cash on hand. The Mexican subsidiary’s ability to draw down the remaining 0.3 billion MXN under the Mexican Loan expired on February 28, 2014.
	Colombian Loan—In connection with the establishment of the Company’s joint venture with Millicom International Cellular SA (“Millicom”) and the acquisition of certain communications sites in Colombia, ATC Colombia B.V., a majority owned subsidiary of the Company, entered into a U.S. Dollar-denominated shareholder loan agreement (the “Colombian Loan”), as the borrower, with the Company’s wholly owned subsidiary (the “ATC Colombian Subsidiary”), and a wholly owned subsidiary of Millicom (the “Millicom Subsidiary”), as the lenders. Pursuant to the loan agreement, accrued interest is periodically capitalized and added to the principal amount outstanding. The portion of the Colombian Loan made by the ATC Colombian Subsidiary is eliminated in consolidation, and the portion of the Colombian Loan made by the Millicom Subsidiary is reported as outstanding debt of the Company. During the three months ended March 31, 2014, the joint venture borrowed an additional $3.0 million under the Colombian Loan, resulting in $38.7 million outstanding at March 31, 2014. Borrowings subsequent to the initial loan mature approximately ten years from the date of such borrowing.
	Credit Facilities
	2012 Credit Facility—In January 2014, the Company repaid $88.0 million of outstanding indebtedness under its $1.0 billion senior unsecured revolving credit facility (the “2012 Credit Facility”) with net proceeds from a registered public offering of $250.0 million aggregate principal amount of reopened 3.40% senior unsecured notes due 2019 and $500.0 million aggregate principal amount of reopened 5.00% senior unsecured notes due 2024. As of March 31, 2014, the Company has no amounts outstanding under the 2012 Credit Facility and approximately $7.5 million of undrawn letters of credit. The Company maintains 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 the London Interbank Offered Rate (“LIBOR”) that the Company would incur (should it choose LIBOR) on borrowings is 1.625%, and the current commitment fee on the undrawn portion of the 2012 Credit Facility is 0.225%.
	2013 Credit Facility—In January 2014, the Company repaid $710.0 million of outstanding indebtedness under its $2.0 billion multi-currency senior unsecured revolving credit facility (the “2013 Credit Facility”) with net proceeds from a registered public offering of $250.0 million aggregate principal amount of reopened 3.40% senior unsecured notes due 2019 and $500.0 million aggregate principal amount of reopened 5.00% senior unsecured notes due 2024 and cash on hand. As of March 31, 2014, the Company has $1.1 billion outstanding under the 2013 Credit Facility and approximately $3.2 million of undrawn letters of credit. On April 1, 2014, the Company borrowed an additional $165.0 million to fund an acquisition in the United States (see note 16). The Company maintains the ability to draw down and repay amounts under the 2013 Credit Facility in the ordinary course. The 2013 Credit Facility includes an expansion option allowing the Company to request additional commitments of up to $750.0 million, including in the form of a term loan.
	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. 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 current margin over LIBOR that the Company incurs on borrowings is 1.250%, and the current commitment fee on the undrawn portion of the 2013 Credit Facility is 0.150%.
	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 principal and may be repaid prior to maturity in whole or in part at the Company’s option without penalty or premium. The Company may reduce or terminate the unutilized portion of the commitments under the Short-Term Credit Facility in whole or in part without penalty.
	The Short-Term Credit Facility matures on September 19, 2014. 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%.
	As of March 31, 2014, the Company has no amounts outstanding under the Short-Term Credit Facility and maintains the ability to draw down and repay amounts under the Short-Term Credit Facility in the ordinary course.
	2013 Term Loan—On October 29, 2013, the Company entered into a $1.5 billion unsecured term loan (the “2013 Term Loan”), which includes an expansion option allowing the Company to request additional commitments of up to $500.0 million. The 2013 Term Loan matures on January 3, 2019. The current interest rate under the 2013 Term Loan is LIBOR plus 1.250%.
	Senior Notes
	Senior Notes Offering—On January 10, 2014, the Company completed a registered public offering through a reopening of its (i) 3.40% senior unsecured notes due 2019 (the “3.40% Notes”), in an aggregate principal amount of $250.0 million and (ii) 5.00% senior unsecured notes due 2024 (the “5.00% Notes”), in an aggregate principal amount of $500.0 million. The net proceeds from the offering were approximately $763.8 million, after deducting commissions and estimated expenses. As of March 31, 2014, the aggregate outstanding principal amount of each of the 3.40% Notes and the 5.00% Notes is $1.0 billion.
	The Company used a portion of the proceeds, together with cash on hand, to repay $88.0 million of outstanding indebtedness under the 2012 Credit Facility and $710.0 million of outstanding indebtedness under the 2013 Credit Facility.
	The reopened 3.40% Notes issued on January 10, 2014 have identical terms as, are fungible with and are part of a single series of senior debt securities with the 3.40% Notes issued on August 19, 2013. The reopened 5.00% Notes issued on January 10, 2014 have identical terms as, are fungible with and are part of a single series of senior debt securities with the 5.00% Notes issued on August 19, 2013.
	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 is 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 accrues from August 19, 2013 and is computed on the basis of a 360-day year comprised of twelve 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.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2014
Summary of Derivative Instruments [Abstract]	'
Derivative Financial Instruments	'
	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 portion of changes in the fair value of the derivative is recorded in AOCI and is recognized in the results of operations when the hedged item affects earnings. The ineffective portion of changes in the fair value of cash flow hedges is 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 Colombia and South Africa and these interest rate swap agreements have been designated as cash flow hedges.
	South Africa
	One of the Company's South African subsidiaries has fifteen interest rate swap agreements outstanding in South Africa, which mature on the earlier of termination of the underlying debt or March 31, 2020. The interest rate swap agreements provide that the Company pay a fixed interest rate ranging from 6.09% to 7.83% and receive variable interest at the three-month Johannesburg Interbank Agreed Rate (“JIBAR”) over the term of the interest rate swap agreements. The notional value is reduced in accordance with the repayment schedule under the related credit agreement.
	Colombia
	One of the Company's Colombian subsidiaries has an interest rate swap agreement outstanding in Colombia, which matures on the earlier of termination of the underlying debt or November 30, 2020. The interest rate swap agreement provides that the Company pay a fixed interest rate of 5.78% and receive variable interest at the three-month Inter-bank Rate (“IBR”) over the term of the interest rate swap agreement. The notional value is reduced in accordance with the repayment schedule under the related credit agreement.
	Costa Rica
	One of the Company's Costa Rican subsidiaries had three interest rate swaps agreements in Costa Rica, which were terminated upon repayment of the Costa Rica Loan on February 12, 2014.
	The notional amount and fair value of the interest rate swap agreements are as follows (in thousands):
		31-Mar-14					31-Dec-13
		Local		USD			Local		USD
	South Africa (ZAR)
	Notional	463,337		43,994			469,354		44,732
	Fair Value	7,577		719			939		90
	Colombia (COP)
	Notional	100,996,875		51,390			101,250,000		52,547
	Fair Value	(3,616,412	)	(1,840	)		(3,000,236	)	(1,557	)
	Costa Rica (USD)
	Notional			—					42,000
	Fair Value			—					(628	)
	As of March 31, 2014 and December 31, 2013, the South African interest rate swap agreements were in an asset position and were included in Notes receivable and other non-current assets on the condensed consolidated balance sheets. The Colombian interest rate swap agreement is in a liability position and is included in Other non-current liabilities on the condensed consolidated balance sheets.
	During the three months ended March 31, 2014 and 2013, the interest rate swap agreements had the following impact on the Company’s condensed consolidated financial statements (in thousands):
	Three Months Ended March 31,	Gain(Loss) Recognized in Other Comprehensive Income - Effective Portion		Gain(Loss)		Location of Gain(Loss) Reclassified from AOCI into Income- Effective Portion		Gain(Loss) Recognized		Location of Gain(Loss) Recognized in Income -
				Reclassified from				in Income - Ineffective Portion		Ineffective Portion
				AOCI into
				Income -
				Effective Portion
	2014	($587)		($969)		Interest Expense		N/A		N/A
	2013	($933)		($608)		Interest Expense		N/A		N/A
	As of March 31, 2014, approximately $0.3 million related to derivatives designated as cash flow hedges and recorded in AOCI is expected to be reclassified into earnings in the next twelve months.
	For additional information on the Company’s interest rate swap agreements, see notes 7 and 8.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Below are the three levels of inputs that may be used to measure fair value:
	Level 1		Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2		Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3		Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	Items Measured at Fair Value on a Recurring Basis—The fair value of the Company’s financial assets and liabilities that are required to be measured on a recurring basis at fair value is as follows (in thousands):
		March 31, 2014
		Fair Value Measurements Using								Assets/Liabilities
		Level 1		Level 2				Level 3		at Fair Value
	Assets:
	Short-term investments (1)			$	34,430					$	34,430
	Interest rate swap agreements			$	719					$	719
	Liabilities:
	Acquisition-related contingent consideration							$	31,342	$	31,342
	Interest rate swap agreements			$	1,840					$	1,840
		31-Dec-13
		Fair Value Measurements Using								Assets/Liabilities
		Level 1		Level 2				Level 3		at Fair Value
	Assets:
	Short-term investments (1)			$	18,612					$	18,612
	Interest rate swap agreements			$	90					$	90
	Liabilities:
	Acquisition-related contingent consideration							$	31,890	$	31,890
	Interest rate swap agreements			$	2,185					$	2,185
	-1	Consists of highly liquid investments with original maturities in excess of three months.
	Interest Rate Swap Agreements
	The fair value of the Company’s interest rate swap agreements is determined using pricing models with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data. Fair valuations of the interest rate swap agreements reflect the value of the instrument including the values associated with counterparty risk, the Company’s own credit standing and the value of the net credit differential between the counterparties to the derivative contract.
	Acquisition-Related Contingent Consideration
	The Company may be required to pay additional consideration under certain agreements for the acquisition of communications sites if specific conditions are met or events occur. In Colombia and Ghana, the Company may be required to pay additional consideration upon the conversion of certain barter agreements with other wireless carriers to cash-paying lease agreements. In addition, in Costa Rica, Panama and the United States, the Company may be required to pay additional consideration if certain pre-designated tenant leases commence during a specified period of time.
	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 consolidated balance sheets and Operating expenses in the condensed consolidated statements of operations.
	As of March 31, 2014, the Company estimates that the value of all potential acquisition-related contingent consideration required payments to be between zero and $48.8 million. During the three months ended March 31, 2014 and 2013, the fair value of the contingent consideration changed as follows (in thousands):
		2014				2013
	Balance as of January 1	$	31,890			$	23,711
	Additions	—				165
	Payments	(615		)		(3,189		)
	Change in fair value	582				5,255
	Foreign currency translation adjustment	(515		)		(741		)
	Balance as of March 31	$	31,342			$	25,201
	Items Measured at Fair Value on a Nonrecurring Basis—The Company’s long-lived assets are measured at fair value on a nonrecurring basis using Level 3 inputs. During the three months ended March 31, 2014 and 2013, the Company did not record any asset impairment charges and there were no other items measured at fair value on a nonrecurring basis during the three months ended March 31, 2014.
	Fair Value of Financial Instruments—The carrying value of the Company’s financial instruments that reasonably approximate fair value at March 31, 2014 and December 31, 2013 includes cash and cash equivalents, restricted cash, accounts receivable and accounts payable. The Company’s estimates of fair value of its long-term obligations, including the current portion, are based primarily upon reported market values. For long-term debt not actively traded, fair value was estimated using either indicative price quotes or a discounted cash flow analysis using rates for debt with similar terms and maturities. As of March 31, 2014, the carrying value and fair value of long-term obligations, including the current portion, are $14.3 billion and $14.7 billion, respectively, of which $9.0 billion was measured using Level 1 inputs and $5.7 billion was measured using Level 2 inputs. As of December 31, 2013, the carrying value and fair value of long-term obligations, including the current portion, were $14.5 billion and $14.7 billion, respectively, of which $8.6 billion was measured using Level 1 inputs and $6.1 billion was measured using Level 2 inputs.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Accumulated Other Comprehensive Loss	'
	Accumulated Other Comprehensive Loss
	The changes in Accumulated other comprehensive loss for the three months ended March 31, 2014 and 2013 are as follows (in thousands):
		Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign			Total
								Currency
								Items
	Balance as of January 1, 2014	$	(1,869	)	$	(3,029	)	$	(306,322	)	$	(311,220	)
	Other comprehensive loss before reclassifications, net of tax	(780		)	—			38,711			37,931
	Amounts reclassified from accumulated other comprehensive loss, net of tax	679			200			—			879
	Net current-period other comprehensive (loss) income	(101		)	200			38,711			38,810
	Balance as of March 31, 2014	$	(1,970	)	$	(2,829	)	$	(267,611	)	$	(272,410	)
	(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 March 31, 2014.
		Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign			Total
								Currency
								Items
	Balance as of January 1, 2013	$	(4,780	)	$	(3,827	)	$	(202,509	)	$	(211,116	)
	Other comprehensive loss before reclassifications, net of tax	(1,044		)	—			27,427			26,383
	Amounts reclassified from accumulated other comprehensive loss, net of tax	350			199			—			549
	Net current-period other comprehensive (loss) income	(694		)	199			27,427			26,932
	Balance as of March 31, 2013	$	(5,474	)	$	(3,628	)	$	(175,082	)	$	(184,184	)
	(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 three months ended March 31, 2013.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
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. The Company reorganized to qualify as a REIT for the taxable year commencing January 1, 2012. As a REIT, the Company continues 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 Company may deduct amounts distributed to stockholders against the income generated in its QRSs. The Company is able to offset income in both its TRSs and QRSs by utilizing their respective net operating losses. In addition, MIPT has been organized and has qualified as a REIT. It is independently subject to, and must comply with, the same REIT requirements that the Company must satisfy in order to qualify as a REIT, together with all other rules applicable to REITs.
	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 March 31, 2014 and December 31, 2013, the total amount of unrecognized tax benefits that would impact the effective tax rate, if recognized, was approximately $33.4 million and $31.1 million, respectively. The increase in the amount of unrecognized tax benefits during the three months ended March 31, 2014 is primarily attributable to the additions to the Company’s existing tax positions and fluctuations in foreign currency exchange rates. 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 14 to the Company’s consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2013. The impact of the amount of such changes to previously recorded uncertain tax positions could range from zero to $10.8 million.
	The Company recorded penalties and income tax-related interest expense during the three months ended March 31, 2014 and 2013 of $1.3 million and $1.4 million, respectively. As of March 31, 2014 and December 31, 2013, the total amount of accrued penalties and income tax-related interest included in Other non-current liabilities in the condensed consolidated balance sheets was $32.4 million and $30.9 million, respectively.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]	'
Stock-Based Compensation	'
	Stock-Based Compensation
	The Company recognized stock-based compensation expense during the three months ended March 31, 2014 and 2013 of $24.6 million and $21.0 million, respectively. The Company capitalized $0.4 million of stock-based compensation expense as property and equipment during each of the three months ended March 31, 2014 and 2013.
	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 March 31, 2014, the Company has the ability to grant stock-based awards with respect to an aggregate of 14.0 million shares of common stock under the 2007 Plan.
	The Company’s Compensation Committee adopted a death, disability and retirement benefits program in connection with equity awards granted on or after January 1, 2013, which provides for accelerated vesting and extended exercise periods of stock options and restricted stock units upon an employee’s death or permanent disability, or upon an employee’s qualified retirement, provided certain eligibility criteria are met. Due to the accelerated recognition of stock-based compensation expense related to awards granted to retirement eligible employees, the Company recognized an incremental $8.5 million and $6.7 million of stock-based compensation expense during the three months ended March 31, 2014 and 2013, respectively.
	Stock Options—The Company’s option activity for the three months ended March 31, 2014 is as follows:
		Number of
		Options
	Outstanding as of January 1, 2014	6,106,171
	Granted	1,855,366
	Exercised	(343,863	)
	Forfeited	(18,741	)
	Expired	(32,888	)
	Outstanding as of March 31, 2014	7,566,045
	The fair value of each option granted during the three months ended March 31, 2014 is estimated on the date of grant using the Black-Scholes option pricing model based on the assumptions noted in the table below:
	Range of risk-free interest rate		1.46% - 1.72%
	Weighted average risk-free interest rate		1.64	%
	Expected life of option grants		4.5 years
	Range of expected volatility of underlying stock price		23.09% - 23.35%
	Weighted average expected volatility of underlying stock price		23.09	%
	Expected annual dividend yield		1.5	%
	The weighted average grant date fair value per share during the three months ended March 31, 2014 was $14.84. As of March 31, 2014, total unrecognized compensation expense related to unvested stock options is $52.7 million and is expected to be recognized over a weighted average period of approximately three years.
	Restricted Stock Units—The following table summarizes the Company’s restricted stock unit activity during the three months ended March 31, 2014:
		Number of
		Units
	Outstanding as of January 1, 2014	1,840,137
	Granted	775,197
	Vested	(669,501	)
	Forfeited	(25,062	)
	Outstanding as of March 31, 2014	1,920,771
	As of March 31, 2014, total unrecognized compensation expense related to unvested restricted stock units granted under the 2007 Plan is $117.9 million and is expected to be recognized over a weighted average period of approximately three years.

Equity

Equity	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Equity	'
	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 (the “2011 Buyback”). On September 6, 2013, the Company temporarily suspended repurchases in connection with its acquisition of MIPT.
	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, including its financial policies. 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.
	Sales of Equity Securities—The Company receives proceeds from sales of its equity securities pursuant to its employee stock purchase plan and upon exercise of stock options granted under its equity incentive plans. During the three months ended March 31, 2014, the Company received an aggregate of $13.8 million in proceeds upon exercises of stock options.
	Distributions—During the three months ended March 31, 2014, 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)
	6-Mar-14	25-Apr-14	10-Apr-14	$0.32	$126.60
	The Company accrues distributions on unvested restricted stock unit awards granted subsequent to January 1, 2012, which are payable upon vesting. As of March 31, 2014, the amount accrued for distributions payable related to unvested restricted stock units was $1.8 million. During the three months ended March 31, 2014, the Company paid $0.6 million of distributions 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

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Common Share	'
	Earnings Per Common Share
	Basic net income from continuing operations per common share represents net income from continuing operations attributable to American Tower Corporation divided by the weighted average number of common shares outstanding during the period. Diluted net income from continuing operations per common share represents net 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 net income from continuing operations per common share computational data for the three months ended March 31, 2014 and 2013 (in thousands, except per share data):
		Three Months Ended March 31,
		2014			2013
	Net income from continuing operations attributable to American Tower Corporation	$	202,499		$	171,407
	Basic weighted average common shares outstanding	395,146			395,239
	Dilutive securities	3,974			4,420
	Diluted weighted average common shares outstanding	399,120		399,659	399,659
	Basic net income from continuing operations attributable to American Tower Corporation per common share	$	0.51		$	0.43
	Diluted net income from continuing operations attributable to American Tower Corporation per common share	$	0.51		$	0.43
	For the three months ended March 31, 2014 and 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 1.7 million and 0.4 million, respectively, as the effect would be anti-dilutive.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
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 (the “District Court”), 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.  Both parties are seeking injunctive relief that would prohibit the other party from making certain statements when interacting with landowners, as well as significant damages. On April 3, 2014, the District Court ruled on the parties’ cross-motions for summary judgment, permitting both parties’ claims of misrepresentation to proceed to trial, as well as related state law actions, and dismissing certain of the parties’ other claims.
	Commitments
	AT&T Transaction—The Company has an agreement with SBC Communications Inc., a predecessor entity to AT&T Inc. (“AT&T”), that initially provided 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 Company’s securitization transaction completed in March 2013. 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. As of March 31, 2014, the Company has purchased four of the subleased towers upon expiration of the applicable agreement. The aggregate purchase option price for the remaining towers leased and subleased is approximately $611.2 million as of March 31, 2014, 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 is approximately $71.7 million as of March 31, 2014. 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 March 31, 2014, would be valued at approximately $111.8 million in the aggregate.
	Other Contingencies—The Company is subject to income tax and other taxes in the geographic areas where it operates, and periodically receives notifications of audits, assessments or other actions by taxing authorities. The Company evaluates the circumstances of each notification based on the information available, and records a liability for any potential outcome that is probable or more likely than not unfavorable, if the liability is also reasonably estimable. On January 21, 2014, the Company received an income tax assessment in the amount of 22.6 billion Indian Rupees (approximately $369.0 million on the date of assessment), asserting tax liabilities arising out of a transfer pricing review of transactions by Essar Telecom Infrastructure Private Limited (“ETIPL”), and more specifically involving the issuance of share capital and the determination by the tax authority that an income tax obligation arose as a result of such issuance. The assessment was made with respect to transactions that took place in the tax year commencing in 2008, prior to the Company’s acquisition of ETIPL. Under the Company’s definitive acquisition agreement of ETIPL, the seller is obligated to indemnify and defend the Company with respect to any tax-related liability that may arise from activities prior to March 31, 2010. The Company believes that there is no basis upon which the tax assessment can be enforced under existing tax law and accordingly has not recorded an obligation in the consolidated financial statements. The assessment is being challenged with the appellate authorities.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2014
Business Combination, Description [Abstract]	'
Acquisitions	'
	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 value of these net assets acquired are based on management’s estimates and assumptions, as well as other information compiled by management, including valuations that utilize customary valuation procedures and techniques. While the Company believes that such preliminary estimates provide a reasonable basis for estimating the fair value of assets acquired and liabilities assumed, it will evaluate any necessary information prior to finalization of the fair value. During the measurement period, the Company will adjust assets or liabilities if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in the revised estimated values of those assets or liabilities as of that date. 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 or goodwill, or require acceleration of the amortization expense of intangible assets in subsequent periods.
	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 three months ended March 31, 2014 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 recognizes 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 months ended March 31, 2014 and 2013, the Company recognized acquisition and merger related expenses, including the fair value adjustments to contingent consideration, of $9.8 million and $13.6 million, respectively. In addition, during the three months ended March 31, 2014, the Company recorded $2.5 million of integration costs related to recently closed acquisitions.
	2014 Acquisitions
	International Acquisitions—During the three months ended March 31, 2014, the Company acquired a total of twelve communications sites and equipment in Ghana, for an aggregate purchase price of $3.1 million (including value added tax of $0.4 million), and $0.1 million of assets acquired for total consideration of approximately $3.2 million. The purchase price is subject to post-closing adjustments.
	U.S. Acquisitions—During the three months ended March 31, 2014, the Company acquired a total of three communications sites and equipment, as well as four property interests, for an aggregate purchase price of $3.1 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 2014 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 March 31, 2014.
			International			U.S.
	Current assets		$	505		$	13
	Property and equipment		1,964			1,916
	Intangible assets (1):
	Customer-related intangible assets		395			1,087
	Network location intangible assets		369			301
	Current liabilities		—			(172		)
	Other non-current liabilities		(28		)	(37		)
	Fair value of net assets acquired		$	3,205		$	3,108
	Goodwill (2)		40			—
	-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 international rental and management segment and the Company expects goodwill recorded will be deductible for tax purposes.
	2013 Acquisitions
	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 and the parent company of GTP, an owner and operator, through its various operating subsidiaries, of approximately 4,860 communications sites in the United States and approximately 510 communications sites in Costa Rica and Panama. GTP also manages rooftops and holds property interests that it leases to communications service providers and third-party tower operators.
	The preliminary purchase price of $4.9 billion was satisfied with approximately $3.3 billion in cash, including an aggregate of approximately $2.8 billion from borrowings under the Company’s credit facilities, and the assumption of approximately $1.5 billion of MIPT’s existing indebtedness.
	The consideration consisted of the following (in thousands):
	Cash consideration (1)	$	3,330,462
	Assumption of existing indebtedness at historical cost	1,527,621
	Estimated total purchase price	$	4,858,083
	-1	Cash consideration includes $14.5 million of an additional purchase price adjustment which was paid to the sellers during the three months ended March 31, 2014 and is reflected in Accrued expenses on the consolidated balance sheet included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
	The following table summarizes the updated allocation of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed for the MIPT acquisition based upon the estimated fair value at the date of acquisition (in thousands). During the three months ended March 31, 2014, the Company made certain purchase accounting measurement period adjustments of approximately $0.1 million to Prepaid and other current assets and Goodwill. As a result, the Company retrospectively adjusted the fair value of the assets acquired and liabilities assumed in the condensed consolidated balance sheet as of December 31, 2013. Other than Prepaid and other current assets and Goodwill, the balances in the table below as of March 31, 2014 remain unchanged from the balances reflected in the consolidated balance sheets in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
			Updated Purchase Price Allocation
	Cash and cash equivalents		$	35,967
	Restricted cash		30,883
	Accounts receivable, net		10,021
	Prepaid and other current assets		22,984
	Property and equipment		996,901
	Intangible assets (1):
	Customer-related intangible assets		2,629,188
	Network location intangible assets		467,300
	Notes receivable and other non-current assets		4,220
	Accounts payable		(9,249		)
	Accrued expenses		(37,004		)
	Accrued interest		(3,253		)
	Current portion of long-term obligations		(2,820		)
	Unearned revenue		(35,753		)
	Long-term obligations (2)		(1,573,366		)
	Asset retirement obligations		(43,089		)
	Other non-current liabilities		(37,326		)
	Fair value of net assets acquired		$	2,455,604
	Goodwill (3)		874,858
	-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. The fair value adjustment was based primarily on reported market values using Level 2 inputs.
	-3	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will not be deductible for tax purposes.
	Other 2013 Acquisitions
	Axtel Mexico Acquisition—On January 31, 2013, the Company acquired 883 communications sites from Axtel, S.A.B. de C.V. for an aggregate purchase price of $248.5 million.
	NII Acquisition—On August 8, 2013, the Company entered into an agreement with NII to acquire up to 1,666 communications sites in Mexico and 2,790 communications sites in Brazil in two separate transactions, subject to due diligence and customary closing conditions.
	On November 8, 2013, the Company acquired 1,483 communications sites in Mexico from NII for an aggregate purchase price of approximately $436.0 million (including value added tax of approximately $60.3 million) and net assets of approximately $0.9 million for total cash consideration of approximately $436.9 million. The aggregate purchase price is subject to post-closing adjustments.
	On December 6, 2013, the Company acquired 1,940 communications sites in Brazil from NII for an aggregate purchase price of approximately $349.0 million, subject to post-closing adjustments.
	Z Sites Acquisition—On November 29, 2013, the Company acquired 238 communications sites from Z-Sites Locação de Imóveis Ltda for an aggregate purchase price of approximately $122.8 million, subject to post-closing adjustments.
	Other International Acquisitions—During the year ended December 31, 2013, the Company acquired a total of 714 additional communications sites in Brazil, Chile, Colombia, Ghana, Mexico and South Africa, for an aggregate purchase price of $89.8 million (including contingent consideration of $4.1 million and value added tax of $4.9 million).
	Other U.S. Acquisitions—During the year ended December 31, 2013, the Company acquired a total of 55 additional communications sites and 23 property interests in the United States for an aggregate purchase price of $65.6 million, subject to post-closing adjustments. The purchase price included cash paid of approximately $65.2 million and net liabilities assumed of approximately $0.4 million.
	The following table summarizes the preliminary allocation, unless otherwise noted, of the aggregate purchase price paid and the amounts of assets acquired and liabilities assumed for the fiscal year 2013 acquisitions. The allocation is based upon the estimated fair value at the date of acquisition (in thousands). Balances as of March 31, 2014 are unchanged from the balances reflected in the consolidated balance sheets in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
		Axtel Mexico (1)			NII Mexico (2)			NII Brazil			Z Sites			Other International			Other U.S.
Current assets		$	—		$	61,183		$	—		$	—		$	4,863		$	1,220
Non-current assets		2,626			11,969			4,484			6,157			1,991			44
Property and equipment		86,100			147,364			105,784			24,832			44,844			23,803
Intangible assets (3):
Customer-related intangible assets		119,392			135,175			149,333			64,213			20,590			29,325
Network location intangible assets		43,031			63,791			93,867			17,123			20,727			7,607
Current liabilities		—			—			—			—			—			(454		)
Other non-current liabilities		(9,377		)	(10,478		)	(13,188		)	(1,502		)	(8,168		)	(786		)
Fair value of net assets acquired		$	241,772		$	409,004		$	340,280		$	110,823		$	84,847		$	60,759
Goodwill (4)		6,751			27,928			8,704			11,953			4,970			4,403
-1	The allocation of the purchase price was finalized during the year ended December 31, 2013.
-2	Current assets includes approximately $60.3 million of value added tax.
-3	Customer-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.
-4	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.
Pro Forma Consolidated Results
The following unaudited pro forma information presents the financial results as if the 2013 acquisitions had occurred on January 1, 2012 (in thousands, except per share data). Management relied on various estimates and assumptions due to the fact that some of the 2013 acquisitions never operated as a business and were utilized solely by the seller as a component of their network infrastructure. As a result, historical operating results for these acquisitions are not available. The pro forma results do not include any anticipated cost synergies, costs or other effects of the planned integration of the 2013 acquisitions. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the acquisitions been completed on the dates indicated, nor are they indicative of the future operating results of the Company.
		Three Months Ended March 31, 2013
Pro forma operating revenues		$	924,821
Pro forma net income attributable to American Tower Corporation		$	136,355
Pro forma net income per common share amounts:
Basic net income attributable to American Tower Corporation		$	0.34
Diluted net income attributable to American Tower Corporation		$	0.34
Acquisition-Related Contingent Consideration
The Company may be required to pay additional consideration under certain agreements for the acquisition of communications sites if specific conditions are met or events occur.
Colombia—Under the terms of the agreement with Colombia Movil S.A. E.S.P., 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 expects the value of potential contingent consideration payments required to be made under the agreement to be between zero and $36.0 million and estimates it to be $23.1 million using a probability weighted average of the expected outcomes at March 31, 2014. During the three months ended March 31, 2014, the Company recorded an increase in fair value of $0.5 million in Other operating expenses in the accompanying condensed consolidated statements of operations.
Ghana—Under the terms of the agreement, as amended, with MTN Group Limited, 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 expects the value of potential contingent consideration payments required to be made under the amended agreement to be between zero and $0.7 million and estimates it to be $0.7 million using a probability weighted average of the expected outcomes at March 31, 2014.
MIPT—In connection with the acquisition of MIPT, the Company assumed additional contingent consideration liability related to previously closed acquisitions in Costa Rica, Panama and the United States. The Company is required to make additional payments to the sellers if certain pre-designated tenant leases commence during a limited specified period of time after the applicable acquisition was completed, generally one year or less. The Company initially recorded $9.3 million of contingent consideration liability as part of the preliminary purchase price allocation upon closing of the acquisition. Based on current estimates, the Company expects the value of potential contingent consideration payments required to be made under these agreements to be between zero and $12.1 million and estimates it to be $7.5 million using a probability weighted average of the expected outcomes at March 31, 2014. During the three months ended March 31, 2014, the Company made payments under these agreements of $0.6 million.
For more information regarding contingent consideration, see note 7.

Business_Segments

Business Segments	3 Months Ended
	Mar. 31, 2014
Segment Reporting, Measurement Disclosures [Abstract]	'
Business Segments	'
	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, as of March 31, 2014, consist of the following:
	•	Domestic: rental and management operations in the United States; and
	•	International: rental and management operations in Brazil, Chile, Colombia, Costa Rica, Germany, Ghana, India, Mexico, Panama, 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, 2013. 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 months ended March 31, 2014 and 2013 is shown in the following tables. The “Other” column (i) represents amounts excluded from specific segments, such as business development operations, stock-based compensation expense and corporate expenses included in Selling, general, administrative and development expense; Other operating expenses; Interest income; Interest expense; Loss on retirement of long-term obligations; and Other income (expense), and (ii) reconciles segment operating profit to Income from continuing operations before income taxes, as these amounts are not utilized in assessing each segment’s performance.
		Rental and Management				Total Rental and		Network		Other		Total
						Management		Development
	Three months ended March 31, 2014	Domestic		International				Services
		(in thousands)
	Segment revenues	$	635,779	$	324,341	$	960,120	$	23,969			$	984,089
	Segment operating expenses (1)	121,509		128,954		250,463		9,802				260,265
	Interest income, TV Azteca, net	—		2,595		2,595		—				2,595
	Segment gross margin	514,270		197,982		712,252		14,167				726,419
	Segment selling, general, administrative and development expense (1)	27,409		29,216		56,625		2,530				59,155
	Segment operating profit	$	486,861	$	168,766	$	655,627	$	11,637			$	667,264
	Stock-based compensation expense									$	24,604	24,604
	Other selling, general, administrative and development expense									26,774		26,774
	Depreciation, amortization and accretion									245,763		245,763
	Other expense (principally interest expense and other operating expenses)									159,161		159,161
	Income from continuing operations before income taxes											$	210,962
	Total assets	$	13,527,578	$	6,622,829	$	20,150,407	$	65,417	$	201,583	$	20,417,407
	-1	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.5 million and $24.1 million, respectively.
		Rental and Management				Total Rental and		Network		Other		Total
						Management		Development
	Three months ended March 31, 2013	Domestic		International				Services
		(in thousands)
	Segment revenues	$	515,676	$	261,757	$	777,433	$	25,295			$	802,728
	Segment operating expenses (1)	91,833		99,216		191,049		10,279				201,328
	Interest income, TV Azteca, net	—		3,543		3,543		—				3,543
	Segment gross margin	423,843		166,084		589,927		15,016				604,943
	Segment selling, general, administrative and development expense (1)	22,898		29,535		52,433		2,901				55,334
	Segment operating profit	$	400,945	$	136,549	$	537,494	$	12,115			$	549,609
	Stock-based compensation expense									$	21,042	21,042
	Other selling, general, administrative and development expense									25,215		25,215
	Depreciation, amortization and accretion									185,804		185,804
	Other expense (principally interest expense and other (expense) income)									137,378		137,378
	Income from continuing operations before income taxes											$	180,170
	Total assets	$	8,477,955	$	5,564,160	$	14,042,115	$	66,857	$	354,768	$	14,463,740
	-1	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.4 million and $20.6 million, respectively.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Richland Acquisition—On April 3, 2014, the Company, through its wholly-owned subsidiary, acquired entities holding a portfolio of 60 communications sites, which at the time of acquisition were leased primarily to radio and television broadcast tenants, and four property interests in the United States from Richland Properties LLC and other related entities for an aggregate purchase price of $381.1 million and approximately $4.8 million of additional net assets for total consideration of approximately $385.9 million. The total consideration of approximately $385.9 million was satisfied with approximately $182.9 million in cash, approximately $6.5 million payable to the seller upon satisfaction of certain closing conditions and the assumption of approximately $196.5 million of existing indebtedness.

Description_of_Business_Basis_1

Description of Business, Basis of Presentation and Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
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 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.
Functional Currency	'
	Functional Currency—The functional currency of the Company’s foreign operating subsidiaries is the respective local currency, except for Costa Rica and Panama, where the functional currency is the U.S. Dollar.  All foreign currency assets and liabilities held by the subsidiaries are translated into U.S. Dollars at the exchange rate in effect at the end of the applicable fiscal reporting period and all foreign currency revenues and expenses are translated at the average monthly exchange rates. Translation adjustments are reflected in equity as a component of Accumulated other comprehensive income (loss) (“AOCI”) in the condensed consolidated balance sheet.
	Transactional gains and losses on foreign currency transactions are reflected in Other expense (income) in the condensed consolidated statements of operations.  However, the effect from fluctuations in foreign currency exchange rates on intercompany notes whose payment is not planned or anticipated in the foreseeable future, is reflected in AOCI in the condensed consolidated balance sheet.  During the three months ended March 31, 2014, the Company recorded unrealized foreign currency losses of $15.5 million, of which $13.5 million was recorded in AOCI and $2.0 million was recorded in Other expense (income).
Accounting Standards Updates	'
	Accounting Standards Updates—In April 2014, the Financial Accounting Standards Board (the “FASB”) issued additional guidance on reporting discontinued operations. Under this guidance, only disposals representing a strategic shift in operations would be presented as discontinued operations. This guidance would require expanded disclosures about discontinued operations that would provide information about the assets, liabilities, income and expenses of discontinued operations. Additionally, the guidance would require disclosure of the pre-tax income attributable to a disposal of a significant part of an entity that does not qualify for discontinued operations reporting. This guidance will be effective for reporting periods beginning on or after December 15, 2014. The FASB permits early adoption of this standard, but only for disposals or classifications as held for sale that have not been reported in financial statements previously issued or available for issuance. The impact of the adoption of this accounting standard update on the Company’s statements of operations, balance sheet, cash flows and disclosures will be based on the Company’s future disposal activity.

Prepaid_and_Other_Current_Asse1

Prepaid and Other Current Assets (Tables)	3 Months Ended
	Mar. 31, 2014
Prepaid Expense and Other Assets, Current [Abstract]	'
Prepaid expense and other current assets	'
	Prepaid and other current assets consists of the following as of (in thousands):
		31-Mar-14		December 31, 2013 (1)
	Prepaid operating ground leases	$	74,013	$	82,950
	Prepaid income tax	56,674		52,612
	Unbilled receivables	37,115		25,412
	Prepaid assets	34,865		34,243
	Value added tax and other consumption tax receivables	17,647		78,262
	Other miscellaneous current assets	44,743		40,697
	Balance	$	265,057	$	314,176
	(1) December 31, 2013 balances have been revised to reflect purchase accounting measurement period adjustments.

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2014
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			Total
									Development
			Domestic			International			Services
	Balance as of January 1, 2014 (1)		$	3,132,553		$	595,239		$	2,000		$	3,729,792
	Additions		—			40			—			40
	Effect of foreign currency translation		—			7,849			—			7,849
	Balance as of March 31, 2014		$	3,132,553		$	603,128		$	2,000		$	3,737,681
	-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):
					31-Mar-14									December 31, 2013
			Estimated		Gross			Accumulated			Net Book			Gross		Accumulated			Net Book
			Useful		Carrying			Amortization			Value			Carrying		Amortization			Value
			Lives		Value									Value
			(years)
	Acquired network location (1)		Up to 20		$	2,368,782		$	(827,571	)	$	1,541,211		$	2,365,474	$	(791,359	)	$	1,574,115
	Acquired customer-related intangibles		15-20		6,216,899			(1,238,111		)	4,978,788			6,201,868		(1,170,239		)	5,031,629
	Acquired licenses and other intangibles		20-Mar		6,688			(2,470		)	4,218			6,583		(2,297		)	4,286
	Economic Rights, TV Azteca		70		28,742			(14,342		)	14,400			28,783		(14,229		)	14,554
	Total				$	8,621,111		$	(2,082,494	)	$	6,538,617		$	8,602,708	$	(1,978,124	)	$	6,624,584
	Deferred financing  costs, net (2)		N/A								78,907								76,875
	Other intangible assets, net										$	6,617,524							$	6,701,459
	-1	Acquired network location intangibles are amortized over the shorter of the term of the corresponding ground lease taking into consideration lease renewal options and residual value or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.
	-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 Depreciation, amortization and accretion expense.
Expected future amortization expenses	'
	Based on current exchange rates, the Company expects to record amortization expense (excluding amortization of deferred financing costs) as follows over the remaining current year and the next five subsequent years (in millions):
	Fiscal Year
	2014 (remaining year)	$	308.1
	2015	408.2
	2016	405.5
	2017	403.2
	2018	401.1
	2019	399

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Liabilities, Current [Abstract]	'
Schedule of accrued liabilities	'
	Accrued expenses consists of the following as of (in thousands):
		31-Mar-14		31-Dec-13
	Accrued construction costs	$	65,363	$	52,446
	Accrued property and real estate taxes	57,944		54,529
	Payroll and related withholdings	33,164		50,843
	Accrued rent	31,846		28,456
	Other accrued expenses	212,132		229,050
	Balance	$	400,449	$	415,324

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Derivative Instruments [Abstract]	'
Schedule of derivative financial instruments	'
	The notional amount and fair value of the interest rate swap agreements are as follows (in thousands):
		31-Mar-14					31-Dec-13
		Local		USD			Local		USD
	South Africa (ZAR)
	Notional	463,337		43,994			469,354		44,732
	Fair Value	7,577		719			939		90
	Colombia (COP)
	Notional	100,996,875		51,390			101,250,000		52,547
	Fair Value	(3,616,412	)	(1,840	)		(3,000,236	)	(1,557	)
	Costa Rica (USD)
	Notional			—					42,000
	Fair Value			—					(628	)
Schedule of interest rate swap agreements' impact on other comprehensive income	'
	During the three months ended March 31, 2014 and 2013, the interest rate swap agreements had the following impact on the Company’s condensed consolidated financial statements (in thousands):
	Three Months Ended March 31,	Gain(Loss) Recognized in Other Comprehensive Income - Effective Portion		Gain(Loss)		Location of Gain(Loss) Reclassified from AOCI into Income- Effective Portion		Gain(Loss) Recognized		Location of Gain(Loss) Recognized in Income -
				Reclassified from				in Income - Ineffective Portion		Ineffective Portion
				AOCI into
				Income -
				Effective Portion
	2014	($587)		($969)		Interest Expense		N/A		N/A
	2013	($933)		($608)		Interest Expense		N/A		N/A

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
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):
		March 31, 2014
		Fair Value Measurements Using								Assets/Liabilities
		Level 1		Level 2				Level 3		at Fair Value
	Assets:
	Short-term investments (1)			$	34,430					$	34,430
	Interest rate swap agreements			$	719					$	719
	Liabilities:
	Acquisition-related contingent consideration							$	31,342	$	31,342
	Interest rate swap agreements			$	1,840					$	1,840
		31-Dec-13
		Fair Value Measurements Using								Assets/Liabilities
		Level 1		Level 2				Level 3		at Fair Value
	Assets:
	Short-term investments (1)			$	18,612					$	18,612
	Interest rate swap agreements			$	90					$	90
	Liabilities:
	Acquisition-related contingent consideration							$	31,890	$	31,890
	Interest rate swap agreements			$	2,185					$	2,185
	-1	Consists of highly liquid investments with original maturities in excess of three months.
Schedule of business acquisitions by acquisition, contingent consideration	'
	During the three months ended March 31, 2014 and 2013, the fair value of the contingent consideration changed as follows (in thousands):
		2014				2013
	Balance as of January 1	$	31,890			$	23,711
	Additions	—				165
	Payments	(615		)		(3,189		)
	Change in fair value	582				5,255
	Foreign currency translation adjustment	(515		)		(741		)
	Balance as of March 31	$	31,342			$	25,201

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2014
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 March 31, 2014 and 2013 are as follows (in thousands):
		Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign			Total
								Currency
								Items
	Balance as of January 1, 2014	$	(1,869	)	$	(3,029	)	$	(306,322	)	$	(311,220	)
	Other comprehensive loss before reclassifications, net of tax	(780		)	—			38,711			37,931
	Amounts reclassified from accumulated other comprehensive loss, net of tax	679			200			—			879
	Net current-period other comprehensive (loss) income	(101		)	200			38,711			38,810
	Balance as of March 31, 2014	$	(1,970	)	$	(2,829	)	$	(267,611	)	$	(272,410	)
	(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 March 31, 2014.
		Unrealized Losses on Cash Flow Hedges (1)			Deferred Loss on the Settlement of the Treasury Rate Lock			Foreign			Total
								Currency
								Items
	Balance as of January 1, 2013	$	(4,780	)	$	(3,827	)	$	(202,509	)	$	(211,116	)
	Other comprehensive loss before reclassifications, net of tax	(1,044		)	—			27,427			26,383
	Amounts reclassified from accumulated other comprehensive loss, net of tax	350			199			—			549
	Net current-period other comprehensive (loss) income	(694		)	199			27,427			26,932
	Balance as of March 31, 2013	$	(5,474	)	$	(3,628	)	$	(175,082	)	$	(184,184	)
	(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 three months ended March 31, 2013.

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]	'
Summary of the company's option activity	'
	The Company’s option activity for the three months ended March 31, 2014 is as follows:
		Number of
		Options
	Outstanding as of January 1, 2014	6,106,171
	Granted	1,855,366
	Exercised	(343,863	)
	Forfeited	(18,741	)
	Expired	(32,888	)
	Outstanding as of March 31, 2014	7,566,045
Assumptions used to determine the grant date fair value for options granted	'
	The fair value of each option granted during the three months ended March 31, 2014 is estimated on the date of grant using the Black-Scholes option pricing model based on the assumptions noted in the table below:
	Range of risk-free interest rate		1.46% - 1.72%
	Weighted average risk-free interest rate		1.64	%
	Expected life of option grants		4.5 years
	Range of expected volatility of underlying stock price		23.09% - 23.35%
	Weighted average expected volatility of underlying stock price		23.09	%
	Expected annual dividend yield		1.5	%
Summary of the company's restricted stock unit activity	'
	The following table summarizes the Company’s restricted stock unit activity during the three months ended March 31, 2014:
		Number of
		Units
	Outstanding as of January 1, 2014	1,840,137
	Granted	775,197
	Vested	(669,501	)
	Forfeited	(25,062	)
	Outstanding as of March 31, 2014	1,920,771

Equity_Tables

Equity (Tables)	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Schedule of dividends payable	'
	During the three months ended March 31, 2014, 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)
	6-Mar-14	25-Apr-14	10-Apr-14	$0.32	$126.60

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Schedule of earnings per basic and diluted by common class	'
	The following table sets forth basic and diluted net income from continuing operations per common share computational data for the three months ended March 31, 2014 and 2013 (in thousands, except per share data):
		Three Months Ended March 31,
		2014			2013
	Net income from continuing operations attributable to American Tower Corporation	$	202,499		$	171,407
	Basic weighted average common shares outstanding	395,146			395,239
	Dilutive securities	3,974			4,420
	Diluted weighted average common shares outstanding	399,120		399,659	399,659
	Basic net income from continuing operations attributable to American Tower Corporation per common share	$	0.51		$	0.43
	Diluted net income from continuing operations attributable to American Tower Corporation per common share	$	0.51		$	0.43

Acquisitions_Tables

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2014
Business Combination, Description [Abstract]	'
Schedule of recognized identified assets acquired and liabilities assumed	'
	Balances as of March 31, 2014 are unchanged from the balances reflected in the consolidated balance sheets in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
			Axtel Mexico (1)			NII Mexico (2)			NII Brazil			Z Sites			Other International			Other U.S.
	Current assets		$	—		$	61,183		$	—		$	—		$	4,863		$	1,220
	Non-current assets		2,626			11,969			4,484			6,157			1,991			44
	Property and equipment		86,100			147,364			105,784			24,832			44,844			23,803
	Intangible assets (3):
	Customer-related intangible assets		119,392			135,175			149,333			64,213			20,590			29,325
	Network location intangible assets		43,031			63,791			93,867			17,123			20,727			7,607
	Current liabilities		—			—			—			—			—			(454		)
	Other non-current liabilities		(9,377		)	(10,478		)	(13,188		)	(1,502		)	(8,168		)	(786		)
	Fair value of net assets acquired		$	241,772		$	409,004		$	340,280		$	110,823		$	84,847		$	60,759
	Goodwill (4)		6,751			27,928			8,704			11,953			4,970			4,403
	-1	The allocation of the purchase price was finalized during the year ended December 31, 2013.
	-2	Current assets includes approximately $60.3 million of value added tax.
	-3	Customer-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years.
	-4	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.
	Other than Prepaid and other current assets and Goodwill, the balances in the table below as of March 31, 2014 remain unchanged from the balances reflected in the consolidated balance sheets in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
			Updated Purchase Price Allocation
	Cash and cash equivalents		$	35,967
	Restricted cash		30,883
	Accounts receivable, net		10,021
	Prepaid and other current assets		22,984
	Property and equipment		996,901
	Intangible assets (1):
	Customer-related intangible assets		2,629,188
	Network location intangible assets		467,300
	Notes receivable and other non-current assets		4,220
	Accounts payable		(9,249		)
	Accrued expenses		(37,004		)
	Accrued interest		(3,253		)
	Current portion of long-term obligations		(2,820		)
	Unearned revenue		(35,753		)
	Long-term obligations (2)		(1,573,366		)
	Asset retirement obligations		(43,089		)
	Other non-current liabilities		(37,326		)
	Fair value of net assets acquired		$	2,455,604
	Goodwill (3)		874,858
	-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. The fair value adjustment was based primarily on reported market values using Level 2 inputs.
	-3	Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will not be deductible for tax purposes.
	Balances are reflected in the accompanying condensed consolidated balance sheets as of March 31, 2014.
			International			U.S.
	Current assets		$	505		$	13
	Property and equipment		1,964			1,916
	Intangible assets (1):
	Customer-related intangible assets		395			1,087
	Network location intangible assets		369			301
	Current liabilities		—			(172		)
	Other non-current liabilities		(28		)	(37		)
	Fair value of net assets acquired		$	3,205		$	3,108
	Goodwill (2)		40			—
	-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 international rental and management segment and the Company expects goodwill recorded will be deductible for tax purposes.
Fair value of consideration transferred	'
	The consideration consisted of the following (in thousands):
	Cash consideration (1)	$	3,330,462
	Assumption of existing indebtedness at historical cost	1,527,621
	Estimated total purchase price	$	4,858,083
	-1	Cash consideration includes $14.5 million of an additional purchase price adjustment which was paid to the sellers during the three months ended March 31, 2014 and is reflected in Accrued expenses on the consolidated balance sheet included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
Business acquisition, pro forma information	'
	Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the acquisitions been completed on the dates indicated, nor are they indicative of the future operating results of the Company.
			Three Months Ended March 31, 2013
	Pro forma operating revenues		$	924,821
	Pro forma net income attributable to American Tower Corporation		$	136,355
	Pro forma net income per common share amounts:
	Basic net income attributable to American Tower Corporation		$	0.34
	Diluted net income attributable to American Tower Corporation		$	0.34

Business_Segments_Tables

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting, Measurement Disclosures [Abstract]	'
Summarized financial information concerning the company's reportable segments	'
		Rental and Management				Total Rental and		Network		Other		Total
						Management		Development
	Three months ended March 31, 2014	Domestic		International				Services
		(in thousands)
	Segment revenues	$	635,779	$	324,341	$	960,120	$	23,969			$	984,089
	Segment operating expenses (1)	121,509		128,954		250,463		9,802				260,265
	Interest income, TV Azteca, net	—		2,595		2,595		—				2,595
	Segment gross margin	514,270		197,982		712,252		14,167				726,419
	Segment selling, general, administrative and development expense (1)	27,409		29,216		56,625		2,530				59,155
	Segment operating profit	$	486,861	$	168,766	$	655,627	$	11,637			$	667,264
	Stock-based compensation expense									$	24,604	24,604
	Other selling, general, administrative and development expense									26,774		26,774
	Depreciation, amortization and accretion									245,763		245,763
	Other expense (principally interest expense and other operating expenses)									159,161		159,161
	Income from continuing operations before income taxes											$	210,962
	Total assets	$	13,527,578	$	6,622,829	$	20,150,407	$	65,417	$	201,583	$	20,417,407
	-1	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.5 million and $24.1 million, respectively.
		Rental and Management				Total Rental and		Network		Other		Total
						Management		Development
	Three months ended March 31, 2013	Domestic		International				Services
		(in thousands)
	Segment revenues	$	515,676	$	261,757	$	777,433	$	25,295			$	802,728
	Segment operating expenses (1)	91,833		99,216		191,049		10,279				201,328
	Interest income, TV Azteca, net	—		3,543		3,543		—				3,543
	Segment gross margin	423,843		166,084		589,927		15,016				604,943
	Segment selling, general, administrative and development expense (1)	22,898		29,535		52,433		2,901				55,334
	Segment operating profit	$	400,945	$	136,549	$	537,494	$	12,115			$	549,609
	Stock-based compensation expense									$	21,042	21,042
	Other selling, general, administrative and development expense									25,215		25,215
	Depreciation, amortization and accretion									185,804		185,804
	Other expense (principally interest expense and other (expense) income)									137,378		137,378
	Income from continuing operations before income taxes											$	180,170
	Total assets	$	8,477,955	$	5,564,160	$	14,042,115	$	66,857	$	354,768	$	14,463,740
	-1	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.4 million and $20.6 million, respectively.

Description_of_Business_Basis_2

Description of Business, Basis of Presentation and Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Gain (Loss) on Investments [Line Items]	'	'
Foreign currency transaction gain (loss), in AOCI and Income Statement	$15,500,000	'
Unrealized foreign currency losses	-2,005,000	22,143,000
Reclassified to AOCI [Member]	'	'
Gain (Loss) on Investments [Line Items]	'	'
Foreign currency transaction gain (loss), reclassified as AOCI	13,500,000	'
Recorded in Other expense (income) [Member]	'	'
Gain (Loss) on Investments [Line Items]	'	'
Unrealized foreign currency losses	$2,000,000	'

Prepaid_and_Other_Current_Asse2

Prepaid and Other Current Assets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Prepaid Expense and Other Assets, Current [Abstract]	'	'
Prepaid operating ground leases	$74,013	$82,950	[1]
Prepaid income tax	56,674	52,612	[1]
Unbilled receivables	37,115	25,412	[1]
Prepaid assets	34,865	34,243	[1]
Value added tax and other consumption tax receivables	17,647	78,262	[1]
Other miscellaneous current assets	44,743	40,697	[1]
Balance	$265,057	$314,176	[1]
[1]	December 31, 2013 balances have been revised to reflect purchase accounting measurement period adjustments.

Goodwill_and_Other_Intangible_2

Goodwill and Other Intangible Assets (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Weighted average amortization period of intangible assets, years	'16 years	'
Amortization of intangible assets	$102.60	$60.50

Goodwill_and_Other_Intangible_3

Goodwill and Other Intangible Assets (Rollforward) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Goodwill [Roll Forward]	'
Balance as of January 1, 2014 (1)	$3,729,792	[1]
Additions	40
Effect of foreign currency translation	7,849
Balance as of March 31, 2014	3,737,681
Rental And Management [Member] | Domestic [Member]	'
Goodwill [Roll Forward]	'
Balance as of January 1, 2014 (1)	3,132,553	[1]
Additions	0
Effect of foreign currency translation	0
Balance as of March 31, 2014	3,132,553
Rental And Management [Member] | International [Member]	'
Goodwill [Roll Forward]	'
Balance as of January 1, 2014 (1)	595,239	[1]
Additions	40
Effect of foreign currency translation	7,849
Balance as of March 31, 2014	603,128
Network Development Services [Member]	'
Goodwill [Roll Forward]	'
Balance as of January 1, 2014 (1)	2,000	[1]
Additions	0
Effect of foreign currency translation	0
Balance as of March 31, 2014	$2,000
[1]	Balances have been revised to reflect purchase accounting measurement period adjustments.

Goodwill_and_Other_Intangible_4

Goodwill and Other Intangible Assets (Changes in the Carrying Value of Goodwill) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]	'		'
Gross Carrying Value	$8,621,111		$8,602,708
Accumulated Amortization	-2,082,494		-1,978,124
Net Book Value	6,538,617		6,624,584
Deferred financing costs, net	78,907	[1]	76,875	[1]
Other intangible assets, net	6,617,524		6,701,459
Acquired Network Location [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Gross Carrying Value	2,368,782	[2]	2,365,474	[2]
Accumulated Amortization	-827,571	[2]	-791,359	[2]
Net Book Value	1,541,211	[2]	1,574,115	[2]
Acquired Network Location [Member] | Maximum [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Estimated useful lives	'20 years		'
Acquired Customer Relationships [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Gross Carrying Value	6,216,899		6,201,868
Accumulated Amortization	-1,238,111		-1,170,239
Net Book Value	4,978,788		5,031,629
Acquired Customer Relationships [Member] | Minimum [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Estimated useful lives	'15 years		'
Acquired Customer Relationships [Member] | Maximum [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Estimated useful lives	'20 years		'
Acquired Licenses And Other Intangibles [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Gross Carrying Value	6,688		6,583
Accumulated Amortization	-2,470		-2,297
Net Book Value	4,218		4,286
Acquired Licenses And Other Intangibles [Member] | Minimum [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Estimated useful lives	'3 years		'
Acquired Licenses And Other Intangibles [Member] | Maximum [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Estimated useful lives	'20 years		'
Economic Rights, TV Azteca [Member]	'		'
Finite-Lived Intangible Assets [Line Items]	'		'
Gross Carrying Value	28,742		28,783
Accumulated Amortization	-14,342		-14,229
Net Book Value	$14,400		$14,554
Estimated useful lives	'70 years		'
[1]	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 Depreciation, amortization and accretion expense.
[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.

Goodwill_and_Other_Intangible_5

Goodwill and Other Intangible Assets (Expected Future Amortization Expenses) (Details) (USD $)	Mar. 31, 2014
In Millions, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'
2014 (remaining year)	$308.10
2015	408.2
2016	405.5
2017	403.2
2018	401.1
2019	$399

Accrued_Expenses_Details

Accrued Expenses (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Liabilities, Current [Abstract]	'	'
Accrued construction costs	$65,363	$52,446
Accrued property and real estate taxes	57,944	54,529
Payroll and related withholdings	33,164	50,843
Accrued rent	31,846	28,456
Other accrued expenses	212,132	229,050
Balance	$400,449	$415,324

Longterm_Obligations_Narrative

Long-term Obligations (Narrative) (Details)

3 Months Ended

3 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

3 Months Ended

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Oct. 02, 2013

Dec. 31, 2013

Jan. 10, 2014

Mar. 31, 2014

Mar. 31, 2014

Jan. 10, 2014

Jan. 10, 2014

Mar. 31, 2014

Jan. 10, 2014

Jan. 10, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Jan. 21, 2014

Mar. 31, 2014

Apr. 02, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Nov. 05, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

USD ($)

USD ($)

GTP Notes [Member]

Colombian Bridge Loan [Member]

Colombian Bridge Loan [Member]

Colombian Bridge Loan [Member]

Indian Facility [Member]

Secured Debt [Member]

Secured Debt [Member]

Secured Debt [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Senior Notes [Member]

Three Point Four Zero and Five Point Zero Percent Senior Notes [Member] [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

USD ($)

Short-term Debt [Member]

Short-term Debt [Member]

Short-term Debt [Member]

Revolving Credit Facility [Member]

GTP Notes [Member]

GTP Notes [Member]

Costa Rica Loan [Member]

Reopened Three Point Four Zero Percent Senior Notes [Member]

GTP Notes [Member]

Three Point Four Zero Percent Senior Notes [Member]

Three Point Four Zero Percent Senior Notes [Member]

Reopened Five Point Zero Percent [Member]

Five Point Zero Percent Senior Notes [Member]

Five Point Zero Percent Senior Notes [Member]

Three Point Four Zero and Five Point Zero Percent Senior Notes [Member] [Member]

Three Point Four Zero and Five Point Zero Percent Senior Notes [Member] [Member]

Credit Facility 2012 [Member]

Credit Facility 2012 [Member]

Credit Facility 2013 [Member]

Credit Facility 2013 [Member]

Credit Facility 2013 [Member]

Credit Facility 2013 [Member]

Short Term Credit Facility [Member]

Short Term Credit Facility [Member]

Mexican loan [Member]

Mexican loan [Member]

Mexican loan [Member]

Term Loan 2013 [Member]

Term Loan 2013 [Member]

Colombian Loan [Member]

USD ($)

COP

USD ($)

integer

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

LIBOR Based Borrowings [Member]

USD ($)

USD ($)

Subsequent Event [Member]

LIBOR Based Borrowings [Member]

USD ($)

LIBOR Based Borrowings [Member]

MXN

USD ($)

MXN

USD ($)

LIBOR Based Borrowings [Member]

USD ($)

Loan

Loan

Series

renewal_periods

USD ($)

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt

'

'

'

'

'

'

'

'

$1,490,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,500,000,000

'

'

Number of series of secured debt

'

'

'

'

'

'

'

6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of classes of secured debt

'

'

'

'

'

'

'

11

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayment of indebtedness

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

80,300,000

1,100,000,000

'

'

'

Remaining availability under debt instrument

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

300,000,000

'

'

'

Loss on retirement of long-term obligations

-238,000

-35,298,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments of debt extinguishment costs

0

29,234,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from the issuance of debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

763,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

Debt instrument, term

'

'

'

'

'

'

'0 years 6 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'

'

'5 years

'

'

'

'

'

'

'

'

'

'10 years

Stated percentage interest rate

'

'

'

7.89%

7.89%

7.94%

'

'

'

'

'

'

'

3.40%

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Redemption price equal to percentage of principal amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of Lines of Credit

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

88,000,000

'

710,000,000

'

'

'

'

'

'

'

'

'

'

'

Long-term debt, gross

'

'

'

'

'

'

'

'

'

32,600,000

250,000,000

250,000,000

1,000,000,000

'

500,000,000

1,000,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

38,700,000

Debt Instrument, Unamortized Premium

'

'

4,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, maximum borrowing capacity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000,000

'

'

2,000,000,000

'

'

1,000,000,000

'

'

'

5,200,000,000

'

'

'

Repurchase price as percentage of principal

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

101.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum adjusted EBITDA (in times)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit facility, outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,100,000,000

'

'

'

'

'

'

'

'

'

'

Letters of credit outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,500,000

'

'

3,200,000

'

'

'

'

'

'

'

'

'

'

Borrowings under credit facilities

0

249,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

165,000,000

'

'

'

4,900,000,000

376,900,000

'

'

'

'

Basis spread on variable rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.63%

'

'

'

1.25%

'

1.25%

'

'

'

'

1.25%

'

Commitment fee percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.23%

'

'

0.15%

'

'

0.15%

'

'

'

'

'

'

'

Line of credit facility, capacity available for specific purposes

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

750,000,000

'

'

'

'

'

'

'

500,000,000

'

'

Number of annual renewal periods

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

Number of bridge loans

'

'

'

6

6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Short term debt outstanding

'

'

'

$55,000,000

108,000,000,000

'

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Narrative) (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified		South African Facility [Member]	Colombian Long Term Credit Facility [Member]	Costa Rica Loan [Member]
		interest_rate_swap		interest_rate_swap
Derivative [Line Items]	'	'	'	'
Number of interest rate swap agreements	'	15	'	3
Derivative, lower fixed interest rate range	'	6.09%	'	'
Derivative, higher fixed interest rate range	'	7.83%	'	'
Derivative, fixed interest rate	'	'	5.78%	'
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$0.30	'	'	'

Derivative_Financial_Instrumen3

Derivative Financial Instruments (Schedule of Interest Rate Swap Agreements) (Details)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
In Thousands, unless otherwise specified	USD ($)	USD ($)	South African Facility [Member]	South African Facility [Member]	South African Facility [Member]	South African Facility [Member]	Colombian Long Term Credit Facility [Member]	Colombian Long Term Credit Facility [Member]	Colombian Long Term Credit Facility [Member]	Colombian Long Term Credit Facility [Member]	Costa Rica Loan [Member]
			USD ($)	ZAR	USD ($)	ZAR	USD ($)	COP	USD ($)	COP	USD ($)
Derivative [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Notional	'	'	$43,994	463,337	$44,732	469,354	$51,390	100,996,875	$52,547	101,250,000	$42,000
Fair Value- Liability	'	-2,185	'	'	'	'	-1,840	-3,616,412	-1,557	-3,000,236	-628
Fair Value- Asset	$719	$90	'	7,577	$90	939	'	'	'	'	'

Derivative_Financial_Instrumen4

Derivative Financial Instruments (Schedule of Interest Rate Swap Agreements Impact on Other Comprehensive Income) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Summary of Derivative Instruments [Abstract]	'	'
Gain(Loss) Recognized in Other Comprehensive Income - Effective Portion	($587)	($933)
Gain(Loss) Reclassified from AOCI into Income - Effective Portion	($969)	($608)

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	48,800,000	'
Carrying value of long-term obligations, including current portion	14,300,000,000	14,500,000,000
Fair value of long-term obligations, including current portion	14,700,000,000	14,700,000,000
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	9,000,000,000	8,600,000,000
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	$5,700,000,000	$6,100,000,000

Fair_Value_Measurement_Assets_

Fair Value Measurement (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'	'
Short-term investments	$34,430	[1]	$18,612	'	'
Interest rate swap agreements	719		90	'	'
Acquisition-related contingent consideration	31,342		31,890	25,201	23,711
Interest rate swap agreements	'		2,185	'	'
Fair Value, Inputs, Level 2 [Member]	'		'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'	'
Short-term investments	34,430	[1]	18,612	'	'
Interest rate swap agreements	719		90	'	'
Interest rate swap agreements	1,840		2,185	'	'
Fair Value, Inputs, Level 3 [Member]	'		'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'	'	'
Acquisition-related contingent consideration	$31,342		$31,890	'	'
[1]	Consists of highly liquid investments with original maturities in excess of three months.

Fair_Value_Measurement_Conting

Fair Value Measurement (Contingent Consideration Change) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Balance	$31,890	$23,711
Additions	0	165
Payments	-615	-3,189
Change in fair value	582	5,255
Foreign currency translation adjustment	-515	-741
Balance	$31,342	$25,201

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Income tax expense	$17,649		$19,222
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-311,220		-211,116
Other comprehensive loss before reclassifications, net of tax	37,931		26,383
Amounts reclassified from accumulated other comprehensive loss, net of tax	879		549
Net current-period other comprehensive (loss) income	38,810		26,932
Balance at end of period	-272,410		-184,184
Unrealized Losses on Cash Flow Hedges [Member]	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Income tax expense	100		100
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-1,869	[1]	-4,780	[1]
Other comprehensive loss before reclassifications, net of tax	-780	[1]	-1,044	[1]
Amounts reclassified from accumulated other comprehensive loss, net of tax	679	[1]	350	[1]
Net current-period other comprehensive (loss) income	-101	[1]	-694	[1]
Balance at end of period	-1,970	[1]	-5,474	[1]
Treasury Lock [Member]	'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-3,029		-3,827
Other comprehensive loss before reclassifications, net of tax	0		0
Amounts reclassified from accumulated other comprehensive loss, net of tax	200		199
Net current-period other comprehensive (loss) income	200		199
Balance at end of period	-2,829		-3,628
Foreign Currency Items [Member]	'		'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'
Balance at beginning of period	-306,322		-202,509
Other comprehensive loss before reclassifications, net of tax	38,711		27,427
Amounts reclassified from accumulated other comprehensive loss, net of tax	0		0
Net current-period other comprehensive (loss) income	38,711		27,427
Balance at end of period	($267,611)		($175,082)
[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 March 31, 2014.

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Income Tax Expense (Benefit), Continuing Operations [Abstract]	'	'	'
Unrecognized tax benefits that would impact effective tax rate	$33.40	'	$31.10
Impact of change in unrecognized tax benefit, lower	0	'	'
Impact of change in unrecognized tax benefits, upper	10.8	'	'
Penalties and tax-related interest expense during period	1.3	1.4	'
Unrecognized tax benefits, income tax penalties and interest accrued	$32.40	'	$30.90

StockBased_Compensation_Narrat

Stock-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock-based compensation expense	$24,604,000	$21,042,000
Capitalized stock-based compensation expense	400,000	400,000
Accelerated recognition of stock-based compensation expense related to awards granted to retirement eligible employees, additional expense recognized	8,500,000	6,700,000
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)	$14.84	'
Total unrecognized compensation expense	52,700,000	'
Total compensation cost not yet recognized, period for recognition	'3 years	'
Restricted Stock Units [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Total unrecognized compensation expense	$117,900,000	'
Total compensation cost not yet recognized, period for recognition	'3 years	'
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	14	'

StockBased_Compensation_Summar

Stock-Based Compensation (Summary of the Company's Option Activity) (Details)	3 Months Ended
	Mar. 31, 2014
Options Activity, Outstanding [Roll Forward]	'
Outstanding	6,106,171
Granted	1,855,366
Exercised	-343,863
Forfeited	-18,741
Expired	-32,888
Outstanding	7,566,045

StockBased_Compensation_Assump

Stock-Based Compensation (Assumptions Used to Determine the Grant Date Fair Value for Options Granted) (Details) (Employee Stock Option [Member])	3 Months Ended
	Mar. 31, 2014
Employee Stock Option [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Minimum range of risk-free interest rate	1.46%
Maximum range of risk-free interest rate	1.72%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.64%
Expected life of option grants	'4 years 4 months 52 days
Minimum range of expected volatility of underlying stock price	23.09%
Maximum range of expected volatility of underlying stock price	23.35%
Expected volatility of underlying stock price over the option period	23.09%
Expected annual dividend yield	1.50%

StockBased_Compensation_Summar1

Stock-Based Compensation (Summary of the Company's Restricted Stock Unit Activity) (Details) (Restricted Stock Units [Member])	3 Months Ended
	Mar. 31, 2014
Restricted Stock Units [Member]	'
Restricted Stock Unit Activity, Outstanding [Roll Forward]	'
Outstanding	1,840,137
Granted	775,197
Vested	-669,501
Forfeited	-25,062
Outstanding	1,920,771

StockBased_Compensation_ESPP_D

Stock-Based Compensation ESPP (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	$0.40	$0.40

Equity_Narrative_Details

Equity (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity, Class of Treasury Stock [Line Items]	'	'
Accrued dividend, restricted stock units	$1,800,000	'
Paid dividend, restricted stock units	600,000	'
Proceeds from stock options	13,795,000	6,140,000
Common Stock	'	'
Equity, Class of Treasury Stock [Line Items]	'	'
Authorized repurchase of common stock	1,500,000,000	'
Treasury Stock	'	'
Equity, Class of Treasury Stock [Line Items]	'	'
Remaining stock value of buyback	$1,100,000,000	'

Equity_Schedule_Of_Dividends_D

Equity (Schedule Of Dividends) (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Dividends Payable [Line Items]	'	'
Distribution per share (in dollars per share)	$0.32	$0.26
Aggregate Payment Amount	$554	$0
First Quarter [Member]	'	'
Dividends Payable [Line Items]	'	'
Declaration Date	6-Mar-14	'
Payment Date	25-Apr-14	'
Record Date	10-Apr-14	'
Distribution per share (in dollars per share)	$0.32	'
Aggregate Payment Amount	$126,600	'

Earnings_Per_Common_Share_Narr

Earnings Per Common Share (Narrative) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Shares issuable upon conversion of the stock-based awards	1.7	0.4

Earnings_Per_Common_Share_Sche

Earnings Per Common Share (Schedule of Earnings Per Basic And Diluted by Common Class) (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Net income from continuing operations attributable to American Tower Corporation	$202,499	$171,407
Basic weighted average common shares outstanding (in shares)	395,146	395,239
Dilutive securities (in shares)	3,974	4,420
Diluted weighted average common shares outstanding (in shares)	399,120	399,659
Basic net income attributable to American Tower Corporation per common share (in dollars per share)	$0.51	$0.43
Diluted net income attributable to American Tower Corporation per common share (in dollars per share)	$0.51	$0.43

Commitments_And_Contingencies_

Commitments And Contingencies (Narrative) (Details)	0 Months Ended	3 Months Ended
	Jan. 21, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
	INR	USD ($)	At T Transaction [Member]	ALLTEL Transaction [Member]
			USD ($)	USD ($)
			term	towers
			towers
Long-term Purchase Commitment [Line Items]	'	'	'	'
Number of towers leased or subleased	'	'	2,450	'
Lessee leasing arrangements, operating leases, term of contract	'	'	'27 years	'
Number of communications sites acquired	'	'	4	'
Aggregate purchase option price for towers	'	'	$611,200,000	$71,700,000
Purchase price accretion rate (per year)	'	'	10.00%	3.00%
Right to continue to lease space, number of terms	'	'	4	'
Lessee leasing arrangements, operating leases, renewal term	'	'	'5 years	'
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	'	'	'	111,800,000
India Tax Assessment	22,600,000,000	$369,000,000	'	'

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details) (USD $)

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

12 Months Ended

3 Months Ended

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Oct. 02, 2013

Mar. 31, 2014

Oct. 02, 2013

Oct. 02, 2013

Jan. 31, 2013

Nov. 08, 2013

Aug. 08, 2013

Nov. 08, 2013

Aug. 08, 2013

Nov. 29, 2013

Dec. 31, 2013

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Other International Acquisitions 2014 [Member]

Other US Acquisition 2014 [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

Mexico Axtel Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

Z-Sites Acquisition [Member]

Other International Acquisition 2013 [Member]

Other US Acquisition 2013 [Member]

Colombia Movil Acquisition [Member]

Ghana Acquisition [Member]

sites

sites

International [Member]

UNITED STATES

sites

Brazil [Member]

Brazil [Member]

Mexico [Member]

Mexico [Member]

sites

sites

sites

sites

sites

sites

sites

sites

sites

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition, Percentage of Voting Interests Acquired

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

Goodwill, Purchase Accounting Adjustments

'

'

'

'

'

$100,000

'

'

'

'

'

'

'

'

'

'

'

'

Business combination, acquisition and merger related expenses

9,800,000

13,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of communications sites acquired

'

'

12

3

'

'

510

4,860

883

1,940

'

1,483

'

238

714

55

'

'

Aggregate purchase price

'

'

3,100,000

3,100,000

4,900,000,000

4,858,083,000

'

'

248,500,000

349,000,000

'

436,000,000

'

122,800,000

89,800,000

65,600,000

'

'

Estimated contingent consideration fair value

'

'

'

'

'

7,500,000

'

'

'

'

'

'

'

'

4,100,000

'

23,100,000

700,000

Value added tax receivable

'

'

400,000

'

'

'

'

'

'

'

'

60,300,000

'

'

4,900,000

'

'

'

Number of property interests acquired

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

23

'

'

Business acquisition, cost of acquired entity, cash paid

'

'

3,200,000

'

3,300,000,000

3,330,462,000

[1]

'

'

'

'

'

436,900,000

'

'

'

65,200,000

'

'

Noncash or Part Noncash Acquisition, Value of Assets Acquired

'

'

100,000

'

'

'

'

'

'

'

'

900,000

'

'

'

'

'

'

Noncash or part noncash acquisition, value of liabilities assumed

1,500,000,000

'

'

'

1,500,000,000

1,527,621,000

'

'

'

'

'

'

'

'

'

400,000

'

'

Maximum number of communications sites to be acquired

'

'

'

'

'

'

'

'

'

'

2,790

'

1,666

'

'

'

'

'

Business combination, contingent consideration arrangements, range of outcomes, value, low

0

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

0

0

Business combination, contingent consideration arrangements, range of outcomes, value, high

48,800,000

'

'

'

'

12,100,000

'

'

'

'

'

'

'

'

'

'

36,000,000

700,000

Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability, purchases

0

165,000

'

'

9,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Business combination, contingent consideration arrangements, change in amount of contingent consideration, liability

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

500,000

'

Business acquisition, contingent consideration, actual cash payment

'

'

'

'

'

600,000

'

'

'

'

'

'

'

'

'

'

'

'

Borrowings under credit facilities

0

249,000,000

'

'

2,800,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Business Combination, Integration Related Costs

$2,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

Cash consideration includes $14.5 million of an additional purchase price adjustment which was paid to the sellers during the three months ended March 31, 2014 and is reflected in Accrued expenses on the consolidated balance sheet included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.

Acquisitions_Schedule_of_Aggre

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

3 Months Ended

0 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Oct. 02, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Other International Acquisitions 2014 [Member]

Other International Acquisitions 2014 [Member]

Other US Acquisition 2014 [Member]

Other US Acquisition 2014 [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

MIPT Acquisition [Member]

Mexico Axtel Acquisition [Member]

Mexico Axtel Acquisition [Member]

Z-Sites Acquisition [Member]

Z-Sites Acquisition [Member]

Other International Acquisition 2013 [Member]

Other International Acquisition 2013 [Member]

Other US Acquisition 2013 [Member]

Other US Acquisition 2013 [Member]

Other US Acquisition 2013 [Member]

Maximum [Member]

Maximum [Member]

MEXICO

MEXICO

MEXICO

BRAZIL

BRAZIL

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Purchase Price Allocation [Member]

Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

MIPT Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

NII Holdings Acquisition [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Preliminary Purchase Price Allocation [Member]

Acquired Network Location [Member]

Acquired Network Location [Member]

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Value Added Tax Receivable, Current

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$60,300,000

'

'

'

'

Current assets

'

'

505,000

'

13,000

'

'

'

'

'

0

[1]

'

0

'

4,863,000

'

'

1,220,000

'

'

'

'

61,183,000

[2]

'

0

'

Cash and cash equivalents

'

'

'

'

'

'

'

'

35,967,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted cash

'

'

'

'

'

'

'

'

30,883,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accounts receivable, net

'

'

'

'

'

'

'

'

10,021,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Prepaid and other current assets

'

'

'

'

'

'

'

'

22,984,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Non-current assets

'

'

'

'

'

'

'

'

'

'

2,626,000

[1]

'

6,157,000

'

1,991,000

'

'

44,000

'

'

'

'

11,969,000

[2]

'

4,484,000

'

Property and equipment

'

'

1,964,000

'

1,916,000

'

'

'

996,901,000

'

86,100,000

[1]

'

24,832,000

'

44,844,000

'

'

23,803,000

'

'

'

'

147,364,000

[2]

'

105,784,000

'

Intangible assets:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Customer-related intangible assets

'

'

395,000

[3]

'

1,087,000

[3]

'

'

'

2,629,188,000

[4]

'

119,392,000

[1],[3]

'

64,213,000

[3]

'

20,590,000

[3]

'

'

29,325,000

[3]

'

'

'

'

135,175,000

[2],[3]

'

149,333,000

[3]

'

Network location intangible assets

'

'

'

369,000

[3]

'

301,000

[3]

'

'

'

467,300,000

[4]

'

43,031,000

[1],[3]

'

17,123,000

[3]

'

20,727,000

[3]

'

'

7,607,000

[3]

'

'

'

'

63,791,000

[2],[3]

'

93,867,000

[3]

Notes receivable and other non-current assets

'

'

'

'

'

'

'

'

4,220,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Current liabilities

'

'

0

'

-172,000

'

'

'

'

'

0

[1]

'

0

'

0

'

'

-454,000

'

'

'

'

0

[2]

'

0

'

Accounts payable

'

'

'

'

'

'

'

'

-9,249,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accrued expenses

'

'

'

'

'

'

'

'

-37,004,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accrued interest

'

'

'

'

'

'

'

'

-3,253,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Current portion of long-term obligations

'

'

'

'

'

'

'

'

-2,820,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unearned revenue

'

'

'

'

'

'

'

'

-35,753,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term obligations (2)

'

'

'

'

'

'

'

'

-1,573,366,000

[5]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Asset retirement obligations

'

'

'

'

'

'

'

'

-43,089,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other non-current liabilities

'

'

-28,000

'

-37,000

'

'

'

-37,326,000

'

-9,377,000

[1]

'

-1,502,000

'

-8,168,000

'

'

-786,000

'

'

'

'

-10,478,000

[2]

'

-13,188,000

'

Fair value of net assets acquired

'

'

3,205,000

'

3,108,000

'

'

'

2,455,604,000

'

241,772,000

[1]

'

110,823,000

'

84,847,000

'

'

60,759,000

'

'

'

'

409,004,000

[2]

'

340,280,000

'

Goodwill

3,737,681,000

3,729,792,000

[6]

40,000

[7]

'

0

[7]

'

'

'

874,858,000

[8]

'

6,751,000

[1],[9]

'

11,953,000

[9]

'

4,970,000

'

'

4,403,000

'

'

'

'

27,928,000

[2],[9]

'

8,704,000

[9]

'

Acquired finite-live intangible assets, weighted average useful life

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'20 years

'20 years

'

'

'

'

'

Noncash or part noncash acquisition, value of liabilities assumed

1,500,000,000

'

'

'

'

'

1,500,000,000

1,527,621,000

'

'

'

'

'

'

'

'

400,000

'

'

'

'

'

'

'

'

'

Liabilities, Fair Value Adjustment

'

'

'

'

'

'

'

$53,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

The allocation of the purchase price was finalized during the year ended December 31, 2013.

[2]

Current assets includes approximately $60.3 million of value added tax.

[3]

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

[4]

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

[5]

Long-term obligations included $1.5 billion of MIPT’s existing indebtedness and a fair value adjustment of $53.0 million. The fair value adjustment was based primarily on reported market values using Level 2 inputs.

[6]

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

[7]

Goodwill was allocated to the Company’s international rental and management segment and the Company expects goodwill recorded will be deductible for tax purposes.

[8]

Goodwill was allocated to the Company’s domestic and international rental and management segments, as applicable, and the Company expects goodwill recorded will not be deductible for tax purposes.

[9]

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.

Acquisitions_Pro_Forma_Informa

Acquisitions (Pro Forma Information) (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014
Business Acquisition [Line Items]	'
Operating revenues	$924,821
Net income attributable to American Tower Corporation	$136,355
Basic earnings per share (in dollars per share)	$0.34
Diluted earnings per share (in dollars per share)	$0.34

Acquisitions_Schedule_of_Consi

Acquisitions (Schedule of Consideration Transferred) (Details) (USD $)	0 Months Ended	3 Months Ended
	Oct. 02, 2013	Mar. 31, 2014
Fair Value Of Consideration Transferred [Line Items]	'	'
Noncash or part noncash acquisition, value of liabilities assumed	'	$1,500,000,000
MIPT Acquisition [Member]	'	'
Fair Value Of Consideration Transferred [Line Items]	'	'
Partial payment of aggregate purchase price	'	14,500,000
Aggregate purchase price	4,900,000,000	4,858,083,000
Noncash or part noncash acquisition, value of liabilities assumed	1,500,000,000	1,527,621,000
Business acquisition, cost of acquired entity, cash paid	$3,300,000,000	$3,330,462,000	[1]
[1]	Cash consideration includes $14.5 million of an additional purchase price adjustment which was paid to the sellers during the three months ended March 31, 2014 and is reflected in Accrued expenses on the consolidated balance sheet included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.

Business_Segments_Narrative_De

Business Segments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2014
	segment
Segment Reporting, Measurement Disclosures [Abstract]	'
Number of reportable segments	3

Business_Segments_Summarized_F

Business Segments (Summarized Financial Information Concerning the Company's Reportable Segments) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]	'		'		'
Segment revenues	$984,089		$802,728		'
Segment operating expenses	260,265	[1]	201,328	[2]	'
Interest income, TV Azteca, net	2,595		3,543		'
Segment gross margin	726,419		604,943		'
Segment selling, general, administrative and development expense	59,155	[1]	55,334	[2]	'
Segment operating profit	667,264		549,609		'
Stock-based compensation expense	24,604		21,042		'
Other selling, general, administrative and development expense	26,774		25,215		'
Depreciation, amortization and accretion	245,763		185,804		'
Other expense (principally interest expense and other (expense) income)	159,161		137,378		'
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	210,962		180,170		'
Total assets	20,417,407		14,463,740		20,272,571
Operating Expense [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Stock-based compensation expense	500		400		'
Selling General Administrative And Development Expense [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Stock-based compensation expense	24,100		20,600		'
Operating Segments [Member] | Rental And Management [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Segment revenues	960,120		777,433		'
Segment operating expenses	250,463	[1]	191,049	[2]	'
Interest income, TV Azteca, net	2,595		3,543		'
Segment gross margin	712,252		589,927		'
Segment selling, general, administrative and development expense	56,625	[1]	52,433	[2]	'
Segment operating profit	655,627		537,494		'
Total assets	20,150,407		14,042,115		'
Operating Segments [Member] | Rental And Management [Member] | Domestic [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Segment revenues	635,779		515,676		'
Segment operating expenses	121,509	[1]	91,833	[2]	'
Interest income, TV Azteca, net	0		0		'
Segment gross margin	514,270		423,843		'
Segment selling, general, administrative and development expense	27,409	[1]	22,898	[2]	'
Segment operating profit	486,861		400,945		'
Total assets	13,527,578		8,477,955		'
Operating Segments [Member] | Rental And Management [Member] | International [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Segment revenues	324,341		261,757		'
Segment operating expenses	128,954	[1]	99,216	[2]	'
Interest income, TV Azteca, net	2,595		3,543		'
Segment gross margin	197,982		166,084		'
Segment selling, general, administrative and development expense	29,216	[1]	29,535	[2]	'
Segment operating profit	168,766		136,549		'
Total assets	6,622,829		5,564,160		'
Operating Segments [Member] | Network Development Services [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Segment revenues	23,969		25,295		'
Segment operating expenses	9,802	[1]	10,279	[2]	'
Interest income, TV Azteca, net	0		0		'
Segment gross margin	14,167		15,016		'
Segment selling, general, administrative and development expense	2,530	[1]	2,901	[2]	'
Segment operating profit	11,637		12,115		'
Total assets	65,417		66,857		'
Operating Segments [Member] | All Other Segments [Member]	'		'		'
Segment Reporting Information [Line Items]	'		'		'
Stock-based compensation expense	24,604		21,042		'
Other selling, general, administrative and development expense	26,774		25,215		'
Depreciation, amortization and accretion	245,763		185,804		'
Other expense (principally interest expense and other (expense) income)	159,161		137,378		'
Total assets	$201,583		$354,768		'
[1]	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.5 million and $24.1 million, respectively.
[2]	Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.4 million and $20.6 million, respectively.

Subsequent_Events_Narrative_De

Subsequent Events (Narrative) (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2014	Apr. 03, 2014
		Richland Acquisition [Member]
		Subsequent Event [Member]
		sites
Subsequent Event [Line Items]	'	'
Number of communications sites acquired	'	60
Number of property interests acquired	'	4
Aggregate purchase price	'	$381,100,000
Noncash or Part Noncash Acquisition, Value of Assets Acquired	'	4,800,000
Business acquisition, cost of acquired entity, cash paid	'	385,900,000
Business Combination, Partial Cash Consideration Transferred	'	182,900,000
Business Acquisition Cost Of Acquired Entity, Purchase Price Reflected In Accounts Payable	'	6,500,000
Noncash or part noncash acquisition, value of liabilities assumed	$1,500,000,000	$196,500,000