American Tower (AMT) 10-K 25 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 18, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-14195
Entity Registrant Name	American Tower Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	65-0723837
Entity Address, Address Line One	116 Huntington Avenue
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	617
Local Phone Number	375-7500
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 114.3
Entity Common Stock, Shares Outstanding		444,384,437
Documents Incorporated by Reference	Portions of the definitive proxy statement (the “Definitive Proxy Statement”) to be filed with the Securities and Exchange Commission relative to the registrant’s 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Report.
Entity Central Index Key	0001053507
Document Period End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	AMT
Security Exchange Name	NYSE
1.375% Senior Notes due 2025
Document Information [Line Items]
Title of 12(b) Security	1.375% Senior Notes due 2025
Trading Symbol	AMT 25A
Security Exchange Name	NYSE
1.950% Senior Notes due 2026
Document Information [Line Items]
Title of 12(b) Security	1.950% Senior Notes due 2026
Trading Symbol	AMT 26B
Security Exchange Name	NYSE
0.500% Notes
Document Information [Line Items]
Title of 12(b) Security	0.500% Senior Notes due 2028
Trading Symbol	AMT 28A
Security Exchange Name	NYSE
1.000% Senior Notes due 2032
Document Information [Line Items]
Title of 12(b) Security	1.000% Senior Notes due 2032
Trading Symbol	AMT 32
Security Exchange Name	NYSE

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 1,746.3	$ 1,501.2
Restricted cash	115.1	76.8
Accounts receivable, net	511.6	462.2
Prepaid and other current assets	532.6	513.6
Total current assets	2,905.6	2,553.8
PROPERTY AND EQUIPMENT, net	12,808.7	12,084.4
GOODWILL	7,282.7	6,178.3
OTHER INTANGIBLE ASSETS, net	13,839.8	12,318.4
DEFERRED TAX ASSET	123.1	131.8
DEFERRED RENT ASSET	2,084.3	1,771.1
RIGHT-OF-USE ASSET	7,789.2	7,357.4
NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	400.1	406.4
TOTAL	47,233.5	42,801.6
CURRENT LIABILITIES:
Accounts payable	139.1	148.1
Accrued expenses	1,043.7	958.2
Distributions payable	544.6	455
Accrued interest	207.8	209.4
Current portion of operating lease liability	539.9	494.5
Current portion of long-term obligations	789.8	2,928.2
Unearned revenue	390.6	294.3
Total current liabilities	3,655.5	5,487.7
LONG-TERM OBLIGATIONS	28,497.7	21,127.2
OPERATING LEASE LIABILITY	6,884.4	6,510.4
ASSET RETIREMENT OBLIGATIONS	1,571.3	1,384.1
DEFERRED TAX LIABILITY	859.5	768.3
OTHER NON-CURRENT LIABILITIES	984.6	937
Total liabilities	42,453	36,214.7
COMMITMENTS AND CONTINGENCIES
REDEEMABLE NONCONTROLLING INTERESTS	212.1	1,096.5
EQUITY (shares in thousands):
Common stock: $0.01 par value; 1,000,000 shares authorized; 455,245 and 453,541 shares issued; and 444,330 and 442,890 shares outstanding, respectively	4.6	4.5
Additional paid-in capital	10,473.7	10,117.7
Distributions in excess of earnings	(1,343)	(1,016.8)
Accumulated other comprehensive loss	(3,759.4)	(2,823.6)
Treasury stock (10,915 and 10,651 shares at cost, respectively)	(1,282.4)	(1,226.4)
Total American Tower Corporation equity	4,093.5	5,055.4
Noncontrolling interests	474.9	435
Total equity	4,568.4	5,490.4
TOTAL	$ 47,233.5	$ 42,801.6

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	455,245,000	453,541,000
Common stock, shares outstanding (in shares)	444,330,000	442,890,000
Treasury stock, shares (in shares)	10,915,000	10,651,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUES:
Revenues	$ 8,041.5	$ 7,580.3	$ 7,440.1
OPERATING EXPENSES:
Property	2,189.6	2,173.7	2,128.7
Depreciation, amortization and accretion	1,882.3	1,778.4	2,110.8
Selling, general, administrative and development expense	778.7	730.4	733.2
Other operating expenses	265.8	166.3	513.3
Total operating expenses	5,154	4,891.9	5,535.1
OPERATING INCOME	2,887.5	2,688.4	1,905
OTHER INCOME (EXPENSE):
Interest expense, TV Azteca, net	0	0	(0.1)
Interest income	39.7	46.8	54.7
Interest expense	(793.5)	(814.2)	(825.5)
Loss on retirement of long-term obligations	(71.8)	(22.2)	(3.3)
Other (expense) income (including foreign currency (losses) gains of $(216.4), $6.1, and $(4.5), respectively)	(240.8)	17.6	23.8
Total other expense	(1,066.4)	(772)	(750.4)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	1,821.1	1,916.4	1,154.6
Income tax (provision) benefit	(129.6)	0.2	110.1
NET INCOME	1,691.5	1,916.6	1,264.7
Net income attributable to noncontrolling interests	(0.9)	(28.8)	(28.3)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	1,690.6	1,887.8	1,236.4
Dividends on preferred stock	0	0	(9.4)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 1,690.6	$ 1,887.8	$ 1,227
NET INCOME PER COMMON SHARE AMOUNTS:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 3.81	$ 4.27	$ 2.79
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 3.79	$ 4.24	$ 2.77
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (in thousands):
BASIC (in shares)	443,640	442,319	439,606
DILUTED (in shares)	446,104	445,520	442,960
Property
REVENUES:
Revenues	$ 7,953.6	$ 7,464.9	$ 7,314.7
Services
REVENUES:
Revenues	87.9	115.4	125.4
OPERATING EXPENSES:
Services	$ 37.6	$ 43.1	$ 49.1

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Foreign currency (losses) gains	$ (216.4)	$ 6.1	$ (4.5)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 1,691.5	$ 1,916.6	$ 1,264.7
Other comprehensive (loss) income:
Changes in fair value of cash flow hedges, each net of tax expense of $0	(0.2)	(0.1)	(0.1)
Reclassification of unrealized losses on cash flow hedges to net income, each net of tax expense of $0	0.3	0.2	0.3
Adjustment to redeemable noncontrolling interest	0	0	78.8
Purchase of noncontrolling interest	0	0	0.5
Foreign currency translation adjustments, net of tax expense (benefit) of $0.0, $0.5, and $(2.6), respectively.	(701.5)	(157.9)	(869.3)
Other comprehensive loss	(701.4)	(157.8)	(789.8)
Comprehensive income	990.1	1,758.8	474.9
Comprehensive (income) loss attributable to noncontrolling interests	(26.1)	3.8	96.9
Allocation of accumulated other comprehensive income resulting from purchases of noncontrolling interests and redeemable noncontrolling interest	(209.2)	(55.5)	0
Comprehensive income attributable to American Tower Corporation stockholders	$ 754.8	$ 1,707.1	$ 571.8

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net change in fair value of cash flow hedges, tax	$ 0	$ 0	$ 0
Reclassification of unrealized losses on cash flow hedges to net income, tax	0	0	0
Foreign currency translation adjustments, tax	$ 0	$ 0.5	$ (2.6)

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred StockSeries B Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Distributions in Excess of Earnings	Distributions in Excess of EarningsCumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of accounting standard	$ 6,828.1	$ 38.4	$ 0	$ 4.4	$ (974)	$ 10,247.5	$ (1,978.3)	$ (1,058.1)	$ 38.4	$ 586.6
BALANCE (in shares) at Dec. 31, 2017			1,375	437,729	8,909
BALANCE at Dec. 31, 2017	6,828.1	38.4	$ 0	$ 4.4	$ (974)	10,247.5	(1,978.3)	(1,058.1)	38.4	586.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation related activity (in shares)				1,782
Stock-based compensation related activity	190.4			$ 0		190.4
Issuance of common stock - stock purchase plan (in shares)				86
Issuance of common stock—stock purchase plan	10.2			$ 0		10.2
Conversion of preferred stock (in shares)			(1,375)	12,020
Conversion of preferred stock	0		$ 0	$ 0.1		(0.1)
Treasury stock activity (in shares)					(1,648)
Treasury stock activity	(232.8)				$ (232.8)
Changes in fair value of cash flow hedges, net of tax	(0.1)						(0.1)
Reclassification of unrealized gains on cash flow hedges to net income, net of tax	0.3						0.3
Foreign currency translation adjustment, net of tax	(777.2)						(744.1)			(33.1)
Adjustment to redeemable noncontrolling interest	28.1					(50.7)	78.8
Distributions to noncontrolling interest	(15)									(15)
Purchase of noncontrolling interest	(20.5)					(16.5)	0.5			(4.5)
Impact of adoption of accounting standard	5,899.6	(24.7)	$ 0	$ 4.5	$ (1,206.8)	10,380.8	(2,642.9)	(1,199.5)	(24.7)	563.5
Common stock distributions declared	(1,397.3)							(1,397.3)
Preferred stock dividends declared	(18.9)							(18.9)
Net income	1,265.9							1,236.4		29.5
BALANCE (in shares) at Dec. 31, 2018			0	451,617	10,557
BALANCE at Dec. 31, 2018	5,899.6	(24.7)	$ 0	$ 4.5	$ (1,206.8)	10,380.8	(2,642.9)	(1,199.5)	(24.7)	563.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of accounting standard	5,899.6	(24.7)	0	$ 4.5	$ (1,206.8)	10,380.8	(2,642.9)	(1,199.5)	(24.7)	563.5
Stock based compensation related activity (in shares)				1,851
Stock-based compensation related activity	143.2			$ 0		143.2
Issuance of common stock - stock purchase plan (in shares)				73
Issuance of common stock—stock purchase plan	11.3			$ 0		11.3
Treasury stock activity (in shares)					(94)
Treasury stock activity	(19.6)				$ (19.6)
Changes in fair value of cash flow hedges, net of tax	(0.1)						(0.1)
Reclassification of unrealized gains on cash flow hedges to net income, net of tax	0.2						0.2
Foreign currency translation adjustment, net of tax	(149.6)						(125.3)			(24.3)
Adjustment to redeemable noncontrolling interest	0
Distributions to noncontrolling interest	(14.6)									(14.6)
Purchase of noncontrolling interest	(68.5)					(49.5)	(3.1)			(15.9)
Impact of adoption of accounting standard	5,899.6	$ (24.7)	$ 0	$ 4.5	$ (1,226.4)	10,117.7	(2,823.6)	(1,016.8)	$ (24.7)	435
Common stock distributions declared	(1,680.4)							(1,680.4)
Reclassification to redeemable noncontrolling interest	(523)					(420.5)				(102.5)
Purchases of redeemable noncontrolling interests	0					52.4	(52.4)
Net income	1,916.6							1,887.8		28.8
BALANCE (in shares) at Dec. 31, 2019			0	453,541	10,651
BALANCE at Dec. 31, 2019	5,490.4		$ 0	$ 4.5	$ (1,226.4)	10,117.7	(2,823.6)	(1,016.8)		435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of accounting standard	5,490.4		0	$ 4.5	$ (1,226.4)	10,117.7	(2,823.6)	(1,016.8)		435
Stock based compensation related activity (in shares)				1,633
Stock-based compensation related activity	133.5			$ 0.1		133.4
Issuance of common stock - stock purchase plan (in shares)				71
Issuance of common stock—stock purchase plan	13.4			$ 0		13.4
Treasury stock activity (in shares)					(264)
Treasury stock activity	(56)				$ (56)
Changes in fair value of cash flow hedges, net of tax	(0.2)						(0.2)
Reclassification of unrealized gains on cash flow hedges to net income, net of tax	0.3						0.3
Foreign currency translation adjustment, net of tax	(686.2)						(726.7)			40.5
Adjustment to redeemable noncontrolling interest	0
Distributions to noncontrolling interest	(8.9)									(8.9)
Impact of adoption of accounting standard	5,490.4		$ 0	$ 4.6	$ (1,282.4)	10,473.7	(3,759.4)	(1,343)		474.9
Common stock distributions declared	(2,016.8)							(2,016.8)
Purchases of redeemable noncontrolling interests	0					209.2	(209.2)
Net income	1,698.9							1,690.6		8.3
BALANCE (in shares) at Dec. 31, 2020			0	455,245	10,915
BALANCE at Dec. 31, 2020	4,568.4		$ 0	$ 4.6	$ (1,282.4)	10,473.7	(3,759.4)	(1,343)		474.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of adoption of accounting standard	$ 4,568.4		$ 0	$ 4.6	$ (1,282.4)	$ 10,473.7	$ (3,759.4)	$ (1,343)		$ 474.9

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 1,691.5	$ 1,916.6	$ 1,264.7
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, amortization and accretion	1,882.3	1,778.4	2,110.8
Stock-based compensation expense	120.8	111.4	137.5
Loss on investments, unrealized foreign currency loss and other non-cash expense	299.6	46.2	47.3
Impairments, net loss on sale of long-lived assets, non-cash restructuring and merger related expenses	239.5	140	479.6
Loss on early retirement of long-term obligations	71.8	22.2	3.3
Amortization of deferred financing costs, debt discounts and premiums and other non-cash interest	32.9	25.9	22.1
Deferred income taxes	(22.5)	(55.1)	(303)
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	(175.5)	12.5	(32.1)
Prepaid and other assets	84.4	(67.6)	(101.7)
Deferred rent asset	(322)	(183.5)	(87.6)
Right-of-use asset and Operating lease liability, net	(10.9)	17.4	0
Accounts payable and accrued expenses	(69.2)	(46.8)	69.3
Accrued interest	(1.8)	32.4	8.4
Unearned revenue	60.7	2.5	85.8
Deferred rent liability	0	0	57.9
Other non-current liabilities	(0.2)	0.1	(14)
Cash provided by operating activities	3,881.4	3,752.6	3,748.3
CASH FLOWS FROM INVESTING ACTIVITIES
Payments for purchase of property and equipment and construction activities	(1,031.7)	(991.3)	(913.2)
Payments for acquisitions, net of cash acquired	(3,799.1)	(2,959.6)	(1,881.4)
Proceeds from sales of short-term investments and other non-current assets	19.6	383.5	1,252.2
Payments for short-term investments	0	(355.9)	(1,154.3)
Deposits and other	26.6	(64.2)	(52.8)
Cash used for investing activities	(4,784.6)	(3,987.5)	(2,749.5)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings under credit facilities	8,230.4	5,750	3,263.3
Proceeds from issuance of senior notes, net	7,925.1	4,876.7	584.9
Proceeds from term loans	1,940	1,300	1,500
Proceeds from issuance of securities in securitization transaction	0	0	500
Repayments of notes payable, credit facilities, term loans, senior notes, secured debt, finance leases and capital leases	(13,875.4)	(9,225.3)	(4,884.8)
Distributions to noncontrolling interest holders, net	(12.3)	(11.8)	(14.4)
Purchases of common stock	(56)	(19.6)	(232.8)
Proceeds from stock options and employee stock purchase plan	98.1	105.5	98.9
Distributions paid on common stock	(1,928.2)	(1,603)	(1,323.5)
Distributions paid on preferred stock	0	0	(18.9)
Payment for early retirement of long-term obligations	(68.2)	(21)	(3.3)
Deferred financing costs and other financing activities	(176.5)	(135.6)	(56.6)
Purchases of redeemable noncontrolling interests	(861.7)	(425.7)	0
Purchase of noncontrolling interest	0	(68.5)	(20.5)
Cash provided by (used for) financing activities	1,215.3	521.7	(607.7)
Net effect of changes in foreign currency exchange rates on cash and cash equivalents, and restricted cash	(28.7)	(13.7)	(41.1)
NET INCREASE IN CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH	283.4	273.1	350
CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH, BEGINNING OF YEAR	1,578	1,304.9	954.9
CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH, END OF YEAR	$ 1,861.4	$ 1,578	$ 1,304.9

BUSINESS AND SUMMARY OF SIGNIFI

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Business —American Tower Corporation (together with its subsidiaries, “ATC” or the “Company”) is one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. The Company refers to this business as its property operations. Additionally, the Company offers tower-related services in the United States, which the Company refers to as its services operations. These services include site application, zoning and permitting (“AZP”) and structural analysis, which primarily support the Company’s site leasing business, including the addition of new tenants and equipment on its sites. The Company’s portfolio primarily consists of towers that it owns and towers that it operates pursuant to long-term lease arrangements, as well as distributed antenna system (“DAS”) networks, which provide seamless coverage solutions in certain in-building and outdoor wireless environments. In addition to the communications sites in its portfolio, the Company manages rooftop and tower sites for property owners under various contractual arrangements. The Company also holds other telecommunications infrastructure, fiber and property interests that it leases primarily to communications service providers and third-party tower operators. American Tower Corporation is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures. The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”). Accordingly, the Company generally is not required to pay U.S. federal income taxes on income generated by its REIT operations, including the income derived from leasing space on its towers, as it receives a dividends paid deduction for distributions to stockholders that generally offsets its REIT income and gains. However, the Company remains obligated to pay U.S. federal income taxes on earnings from its domestic taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, regardless of their classification for U.S. tax purposes, continue to be subject to taxation in the jurisdictions where those assets are held or those operations are conducted. The use of TRSs enables the Company to continue to engage in certain businesses and jurisdictions while complying with REIT qualification requirements. The Company may, from time to time, change the election of previously designated TRSs to be included as part of the REIT. As of December 31, 2020, the Company’s REIT-qualified businesses included its U.S. tower leasing business and a majority of its U.S. indoor DAS networks business and services segment, as well as most of its operations in Mexico, Germany, Costa Rica, Nigeria, France, Canada and Australia. Principles of Consolidation and Basis of Presentation —The accompanying consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity method or as investments in equity securities, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated. As of December 31, 2020, the Company holds (i) a 51% controlling interest in ATC Europe B.V. (“ATC Europe”), a joint venture that primarily consists of the Company’s operations in France, Germany and Poland (PGGM holds a 49% noncontrolling interest) and (ii) a 92% controlling interest in ATC Telecom Infrastructure Private Limited (“ATC TIPL”), formerly Viom Networks Limited (“Viom”), in India (the remaining shareholders, as discussed in note 15, hold a 8% noncontrolling interest). During the year ended December 31, 2020, the Company completed the acquisition of MTN Group Limited’s (“MTN”) 49% redeemable noncontrolling interests in each of the Company’s joint ventures in Ghana and Uganda for total consideration of approximately $524.4 million, including a net adjustment of $1.4 million made during the three months ended March 31, 2020, which resulted in an increase in the Company’s controlling interests in such joint ventures from 51% to 100%. The purchase is reflected in the consolidated statements of equity as increases of $142.2 million in each of Additional Paid-in Capital and Accumulated Other Comprehensive Loss and in the consolidated balance sheets as a reduction of $524.4 million in Redeemable noncontrolling interests. Reportable Segments — During the fourth quarter of 2020, as a result of the Company’s acquisition of InSite Wireless Group, LLC (“InSite,” and the acquisition, the “InSite Acquisition”), the Company updated its reportable segments to rename U.S. property and Asia property to U.S. & Canada property and Asia-Pacific property, respectively. The Company continues to report its results in six segments – U.S. & Canada property, Asia-Pacific property, Africa property, Europe property, Latin America property and services, which are discussed further in note 21. The change in reportable segment names is solely reflective of the inclusion of Canada and Australia in the Company’s business operations, as a result of the InSite Acquisition, and had no impact on the Company’s consolidated financial statements for any prior periods. Historical financial information included in this Annual Report on Form 10-K has not been adjusted. Significant Accounting Policies and Use of Estimates —The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying consolidated financial statements. The significant estimates in the accompanying consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense and lease accounting, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure. Accounts Receivable and Deferred Rent Asset —The Company derives the largest portion of its revenues and corresponding accounts receivable and the related deferred rent asset from a relatively small number of tenants in the telecommunications industry, and 55% of its current-year revenues are derived from three tenants. The Company’s deferred rent asset is associated with non-cancellable tenant leases that contain fixed escalation clauses over the terms of the applicable lease in which revenue is recognized on a straight-line basis over the lease term. The Company mitigates its concentrations of credit risk with respect to notes and trade receivables and the related deferred rent assets by actively monitoring the creditworthiness of its borrowers and tenants. In recognizing tenant revenue, the Company assesses the collectibility of both the amounts billed and the portion recognized in advance of billing on a straight-line basis. This assessment takes tenant credit risk and business and industry conditions into consideration to ultimately determine the collectibility of the amounts billed. To the extent the amounts, based on management’s estimates, may not be collectible, revenue recognition is deferred until such point as collectibility is determined to be reasonably assured. Any amounts that were previously recognized as revenue and subsequently determined to be uncollectible are charged to bad debt expense included in Selling, general, administrative and development expense in the accompanying consolidated statements of operations. Accounts receivable is reported net of allowances for doubtful accounts related to estimated losses resulting from a tenant’s inability to make required payments and allowances for amounts invoiced whose collectibility is not reasonably assured. These allowances are generally estimated based on payment patterns, days past due and collection history, and incorporate changes in economic conditions that may not be reflected in historical trends, such as tenants in bankruptcy, liquidation or reorganization. Receivables are written-off against the allowances when they are determined to be uncollectible. Such determination includes analysis and consideration of the particular conditions of the account. Changes in the allowances were as follows: Year Ended December 31, 2020 (1) 2019 2018 Balance as of January 1, $ 163.3 $ 282.4 $ 131.0 Current year increases 105.6 104.3 157.8 Write-offs, recoveries and other (2) (21.3) (223.4) (6.4) Balance as of December 31, $ 247.6 $ 163.3 $ 282.4 _______________ (1) Year ended December 31, 2020 reflects the Company’s adoption of the current expected credit loss model for non-lease receivables. The adoption of this guidance did not have a material impact on the Company’s financial statements as the majority of the Company’s revenue is derived from its property operations and operating lease receivables are not within the scope of this guidance. (2) Amounts are primarily related to uncollectible amounts in India. In 2018, recoveries include recognition of revenue resulting from collections of previously reserved amounts. Functional Currency —The functional currency of each of the Company’s foreign operating subsidiaries is normally the respective local currency, except for Costa Rica and Argentina, 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 loss (“AOCL”) in the consolidated balance sheets and included as a component of Comprehensive income in the consolidated statements of comprehensive income. Gains and losses on foreign currency transactions are reflected in Other expense in the consolidated statements of operations. However, the effect from fluctuations in foreign currency exchange rates on intercompany debt for which repayment is not anticipated in the foreseeable future is reflected in AOCL in the consolidated balance sheets and included as a component of Comprehensive income. The Company recorded the following net foreign currency losses: Year Ended December 31, 2020 2019 2018 Foreign currency losses recorded in AOCL $ 391.0 $ 45.8 $ 385.8 Foreign currency losses (gains) recorded in Other expense 216.4 (6.1) 4.5 Total foreign currency losses $ 607.4 $ 39.7 $ 390.3 Cash and Cash Equivalents —Cash and cash equivalents include cash on hand, demand deposits and short-term investments with original maturities of three months or less. The Company maintains its deposits at high-quality financial institutions and monitors the credit ratings of those institutions. Restricted Cash— Restricted cash includes cash pledged as collateral to secure obligations and all cash whose use is otherwise limited by contractual provisions. The reconciliation of cash and cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amounts shown in the statements of cash flows is as follows: Year Ended December 31, 2020 2019 2018 Cash and cash equivalents $ 1,746.3 $ 1,501.2 $ 1,208.7 Restricted cash 115.1 76.8 96.2 Total cash, cash equivalents and restricted cash $ 1,861.4 $ 1,578.0 $ 1,304.9 Property and Equipment —Property and equipment is recorded at cost or, in the case of acquired properties, at estimated fair value on the date acquired. Cost for self-constructed towers includes direct materials and labor and certain indirect costs associated with construction of the tower, such as transportation costs, employee benefits and payroll taxes. The Company begins the capitalization of costs during the pre-construction period, which is the period during which costs are incurred to evaluate the site, and continues to capitalize costs until the tower is substantially completed and ready for occupancy by a tenant. Labor and related costs capitalized for the years ended December 31, 2020, 2019 and 2018 were $51.1 million, $48.3 million and $55.0 million, respectively. Expenditures for repairs and maintenance are expensed as incurred. Augmentation and improvements that extend an asset’s useful life or enhance capacity are capitalized. Depreciation expense is recorded using the straight-line method over the assets’ estimated useful lives. Towers and related assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease, taking into consideration lease renewal options and residual value. Towers or assets acquired through finance leases are recorded net at the present value of future minimum lease payments or the fair value of the leased asset at the inception of the lease. Property and equipment and assets held under finance leases are amortized over the shorter of the applicable lease term or the estimated useful life of the respective assets for periods generally not exceeding twenty years. The Company reviews its tower portfolio for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company reviews other long-lived assets for impairment whenever events, changes in circumstances or other evidence indicate that the carrying amount of the Company’s assets may not be recoverable. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment. Goodwill and Other Intangible Assets —The Company reviews goodwill for impairment at least annually (as of December 31) or whenever events or circumstances indicate the carrying value of an asset may not be recoverable. Goodwill is recorded in the applicable segment and assessed for impairment at the reporting unit level. The Company employs a discounted cash flow analysis when testing goodwill for impairment. The key assumptions utilized in the discounted cash flow analysis include current operating performance, terminal sales growth rate, management’s expectations of future operating results and cash requirements, the current weighted average cost of capital and an expected tax rate. The Company compares the fair value of the reporting unit, as calculated under an income approach using future discounted cash flows, to the carrying amount of the applicable reporting unit. If the carrying amount exceeds the fair value, an impairment loss would be recognized for the amount of the excess. The loss recognized is limited to the total amount of goodwill allocated to that reporting unit. During the years ended December 31, 2020, 2019 and 2018, no potential impairment was identified, as the fair value of each of the reporting units was in excess of its carrying amount. Intangible assets that are separable from goodwill and are deemed to have a definite life are amortized over their useful lives, generally ranging from three The Company reviews its network location intangible assets for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company monitors its tenant-related intangible assets on a tenant by tenant basis for indicators of impairment, such as high levels of turnover or attrition, non-renewal of a significant number of contracts or the cancellation or termination of a relationship. The Company assesses recoverability by determining whether the carrying amount of the related assets will be recovered primarily through projected undiscounted future cash flows. If the Company determines that the carrying amount of an asset may not be recoverable, the Company measures any impairment loss based on the projected future discounted cash flows to be provided from the asset or available market information relative to the asset’s fair value, as compared to the asset’s carrying amount. The Company records impairment charges, which are discussed in note 17, in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment. Derivative Financial Instruments —Derivatives are recorded on the consolidated balance sheet at fair value. If a derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are recorded in AOCL, as well as a component of comprehensive income, and are recognized in the results of operations when the hedged item affects earnings. Changes in fair value of the ineffective portions of cash flow hedges are recognized in the results of operations. For derivative instruments that are designated and qualify as fair value hedges, changes in value of the derivatives are recorded in Other expense in the consolidated statements of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments not designated as hedging instruments, changes in fair value are recognized in the results of operations in the period that the change occurs. The primary risks managed through the use of derivative instruments is interest rate risk, exposure to changes in the fair value of debt attributable to interest rate risk and currency risk. From time to time, the Company enters into interest rate swap agreements or foreign currency contracts to manage exposure to these risks. Under these agreements, the Company is exposed to counterparty credit risk to the extent that a counterparty fails to meet the terms of a contract. The Company’s exposure is limited to the current value of the contract at the time the counterparty fails to perform. The Company assesses, both at the inception of the hedge and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows or fair values of hedged items. The Company does not hold derivatives for trading purposes. Fair Value Measurements —The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Asset Retirement Obligations —When required, the Company recognizes the fair value of obligations to remove its tower assets and remediate the leased land upon which certain of its tower assets are located. Generally, the associated retirement costs are capitalized as part of the carrying amount of the related tower assets and depreciated over their estimated useful lives and the liability is accreted through the obligation’s estimated settlement date. Fair value estimates of asset retirement obligations generally involve discounting of estimated future cash flows associated with takedown costs. Periodic accretion of such liabilities due to the passage of time is included in Depreciation, amortization and accretion expense in the consolidated statements of operations. Adjustments are also made to the asset retirement obligation liability to reflect changes in the estimates of timing and amount of expected cash flows, with an offsetting adjustment made to the related long-lived tangible asset. The significant assumptions used in estimating the Company’s aggregate asset retirement obligation are: timing of tower removals; cost of tower removals; timing and number of land lease renewals; expected inflation rates; and credit-adjusted, risk-free interest rates that approximate the Company’s incremental borrowing rate. Income Taxes —As a REIT, the Company generally is not subject to U.S. federal income taxes on income generated by its REIT operations as it receives a dividends paid deduction for distributions to stockholders that generally offsets its REIT income and gains. However, the Company remains obligated to pay U.S. federal income taxes on certain earnings and continues to be subject to taxation in its foreign jurisdictions. Accordingly, the consolidated financial statements reflect provisions for federal, state, local and foreign income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, as well as operating loss and tax credit carryforwards. The Company measures deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities as a result of a change in tax rates is recognized in income in the period that includes the enactment date. The Company periodically reviews its deferred tax assets, and provides valuation allowances if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Valuation allowances would be reversed as a reduction to the provision for income taxes if related deferred tax assets are deemed realizable based on changes in facts and circumstances relevant to the assets’ recoverability. The Company classifies uncertain tax positions as income tax liabilities in Other non-current liabilities in the consolidated balance sheet, unless expected to be paid within one year. The Company reports penalties and tax-related interest expense as a component of the income tax provision and interest income from tax refunds as a component of Interest income in the consolidated statements of operations. Other Comprehensive Income (Loss) —Other comprehensive income (loss) refers to items excluded from net income that are recorded as an adjustment to equity, net of tax. The Company’s other comprehensive income (loss) primarily consisted of changes in fair value of effective derivative cash flow hedges, foreign currency translation adjustments and reclassification of unrealized losses on effective derivative cash flow hedges. The AOCL balance included accumulated foreign currency translation losses of $3.8 billion, $2.8 billion and $2.6 billion as of December 31, 2020, 2019 and 2018, respectively. Distributions —As a REIT, the Company must annually distribute to its stockholders an amount equal to at least 90% of its REIT taxable income (determined before the deduction for distributed earnings and excluding any net capital gain). Generally, the Company has distributed, and expects to continue to distribute, all or substantially all of its REIT taxable income after taking into consideration its utilization of net operating losses (“NOLs”). The amount, timing and frequency of future distributions will be at the sole discretion of the Board of Directors and will depend upon various factors, a number of which may be beyond the Company’s control, including the Company’s financial condition and operating cash flows, the amount required to maintain its qualification for taxation as a REIT and reduce any income and excise taxes that the Company otherwise would be required to pay, limitations on distributions in the Company’s existing and future debt and preferred equity instruments, the Company’s ability to utilize NOLs to offset the Company’s distribution requirements, limitations on its ability to fund distributions using cash generated through its TRSs and other factors that the Board of Directors may deem relevant. Acquisitions —For acquisitions that meet the definition of a business combination, the Company applies the acquisition method of accounting where assets acquired and liabilities assumed are recorded at fair value at the date of each acquisition, and the results of operations are included with those of the Company from the dates of the respective acquisitions. Any excess of the purchase price paid by the Company over the amounts recognized for assets acquired and liabilities assumed is recorded as goodwill. The Company continues to evaluate acquisitions for a period not to exceed one year after the applicable acquisition date of each transaction to determine whether any additional adjustments are needed to the allocation of the purchase price paid for the assets acquired and liabilities assumed. All other acquisitions are accounted for as asset acquisitions and the purchase price is allocated to the net assets acquired with no recognition of goodwill. The purchase price is not subsequently adjusted. The fair value of the assets acquired and liabilities assumed is typically determined by using either estimates of replacement costs or discounted cash flow valuation methods. When determining the fair value of tangible assets acquired, the Company must estimate the cost to replace the asset with a new asset taking into consideration such factors as age, condition and the economic useful life of the asset. When determining the fair value of intangible assets acquired and liabilities assumed, the Company must estimate the applicable discount rate and the timing and amount of future cash flows, including rate and terms of renewal and attrition. Revenue —The Company’s revenue is derived from leasing the right to use its communications sites and the land on which the sites are located (the “lease component”) and from the reimbursement of costs incurred by the Company in operating the communications sites and supporting the tenants’ equipment as well as other services and contractual rights (the “non-lease component”). Most of the Company’s revenue is derived from leasing arrangements and is accounted for as lease revenue unless the timing and pattern of revenue recognition of the non-lease component differs from the lease component. If the timing and pattern of the non-lease component revenue recognition differs from that of the lease component, the Company separately determines the stand-alone selling prices and pattern of revenue recognition for each performance obligation. Revenue related to DAS networks and fiber and other related assets results from agreements with tenants that are not leases. The Company’s revenue from leasing arrangements, including fixed escalation clauses present in non-cancellable lease arrangements, is reported on a straight-line basis over the term of the respective leases when collectibility is probable. Escalation clauses tied to a consumer price index (“CPI”), or other inflation-based indices, and other incentives present in lease agreements with the Company’s tenants are excluded from the straight-line calculation. Total property straight-line revenues for the years ended December 31, 2020, 2019 and 2018 were $322.0 million, $183.5 million and $87.6 million, respectively. Non-lease revenue— Non-lease revenue consists primarily of revenue generated from DAS networks, fiber and other property related revenue. DAS networks and fiber arrangements require that the Company provide the tenant the right to use the applicable communications infrastructure. Performance obligations are satisfied over time for the duration of the arrangements. Other property related revenue streams, which include site inspections, are not material on either an individual or consolidated basis. Services revenue— The Company offers tower-related services in the United States. These services include AZP and structural analysis. There is a single performance obligation related to AZP and revenue is recognized over time based on milestones achieved, which are determined based on costs expected to be incurred. Structural analysis services may have more than one performance obligation, contingent upon the number of contracted services. Revenue is recognized at the point in time the services are completed. Some of the Company’s contracts with tenants contain multiple performance obligations. For these arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price, which is typically based on the price charged to tenants. Since most of the Company’s contracts are leases, costs to enter into lease arrangements are capitalized under the applicable lease accounting guidance. Costs incurred to obtain non-lease contracts that are capitalized primarily relate to DAS networks and are not material to the consolidated financial statements. The Company has excluded sales tax, value added tax and similar taxes from non-lease revenue. Revenue is disaggregated by geography in a manner consistent with the Company’s business segments, which are discussed further in note 21. A summary of revenue disaggregated by source and geography is as follows: Year Ended December 31, 2020 U.S. & Canada Asia-Pacific Africa Europe Latin Total Non-lease property revenue $ 258.4 $ 9.3 $ 13.8 $ 7.9 $ 118.4 $ 407.8 Services revenue 87.9 — — — — 87.9 Total non-lease revenue $ 346.3 $ 9.3 $ 13.8 $ 7.9 $ 118.4 $ 495.7 Property lease revenue 4,258.6 1,130.1 876.4 141.7 1,139.0 7,545.8 Total revenue $ 4,604.9 $ 1,139.4 $ 890.2 $ 149.6 $ 1,257.4 $ 8,041.5 Year Ended December 31, 2019 U.S. & Canada Asia-Pacific Africa Europe Latin Total Non-lease property revenue $ 255.7 $ 8.8 $ 4.0 $ 5.1 $ 138.2 $ 411.8 Services revenue 115.4 — — — — 115.4 Total non-lease revenue $ 371.1 $ 8.8 $ 4.0 $ 5.1 $ 138.2 $ 527.2 Property lease revenue 3,933.0 1,208.2 579.9 129.5 1,202.5 7,053.1 Total revenue $ 4,304.1 $ 1,217.0 $ 583.9 $ 134.6 $ 1,340.7 $ 7,580.3 Information about non-lease receivables, contract assets and contract liabilities from contracts with tenants is as follows: December 31, 2020 December 31, 2019 Accounts receivable $ 77.2 $ 80.5 Prepaids and other current assets 21.8 8.3 Notes receivable and other non-current assets 23.7 21.3 Unearned revenue (1) 120.3 91.7 Other non-current liabilities (1) 432.4 379.2 _______________ (1) Includes capital contributions related to DAS networks. The Company records unearned revenue when payments are received from tenants in advance of the completion of the Company’s performance obligations. Long-term unearned revenue is included in Other non-current liabilities. During the year ended December 31, 2020, the Company recognized $142.3 million of revenue that was previously included in the contract liabilities balances, primarily arising from balances as of December 31, 2019. The Company records unbilled receivables, which are included in Prepaids and other current assets, when it has completed a performance obligation prior to its ability to bill under the customer arrangement. Other contract assets are included in Notes receivable and other non-current assets. The Company did not record any change in unbilled receivables attributable to non-lease property revenue recognized during each of the years ended December 31, 2020 and 2019. The change in contract assets attributable to revenue recognized during the years ended December 31, 2020 and 2019 was $6.8 million and $3.1 million, respectively. The Company does not disclose the value of unsatisfied performance obligations for agreements (i) with an origi

PREPAID AND OTHER CURRENT ASSET

PREPAID AND OTHER CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
PREPAID AND OTHER CURRENT ASSETS	PREPAID AND OTHER CURRENT ASSETS Prepaid and other current assets consisted of the following: As of December 31, 2020 December 31, 2019 Prepaid assets $ 66.1 $ 56.8 Prepaid income tax 143.7 185.8 Unbilled receivables 176.9 142.3 Value added tax and other consumption tax receivables 66.3 71.3 Other miscellaneous current assets 79.6 57.4 Prepaid and other current assets $ 532.6 $ 513.6

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property and Equipment	PROPERTY AND EQUIPMENT Property and equipment (including assets held under finance leases) consisted of the following: Estimated As of December 31, 2020 December 31, 2019 Towers Up to 20 $ 14,433.9 $ 13,930.7 Equipment (2) 3 - 20 2,327.1 1,897.3 Buildings and improvements Up to 32 634.0 638.9 Land and improvements (3) Up to 20 2,845.9 2,486.1 Construction-in-progress 431.5 372.6 Total 20,672.4 19,325.6 Less accumulated depreciation (7,863.7) (7,241.2) Property and equipment, net $ 12,808.7 $ 12,084.4 _______________ (1) Assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease taking into consideration lease renewal options and residual value. (2) Includes fiber and DAS assets. (3) Estimated useful lives apply to improvements only. Total depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $924.3 million, $905.5 million and $883.1 million, respectively. Depreciation expense includes amounts related to finance lease assets for the years ended December 31, 2020 and 2019 of $153.0 million and $168.1 million, respectively. Information about finance lease-related balances is as follows: As of December 31, Finance leases: Classification 2020 2019 Property and equipment Towers $ 2,706.3 $ 2,695.9 Accumulated depreciation (1,209.7) (1,062.0) Property and equipment, net $ 1,496.6 $ 1,633.9 Property and equipment Buildings and improvements $ 167.6 $ 167.0 Accumulated depreciation (76.3) (65.3) Property and equipment, net $ 91.3 $ 101.7 Property and equipment Land $ 129.9 $ 150.9 Property and equipment Equipment $ 48.8 $ 45.9 Accumulated depreciation (15.3) (13.1) Property and equipment, net $ 33.5 $ 32.8

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES The Company determines if an arrangement is a lease at the inception of the agreement. The Company considers an arrangement to be a lease if it conveys the right to control the use of the communications site or ground space underneath a communications site for a period of time in exchange for consideration. The Company is both a lessor and a lessee. Lessor —The Company is a lessor in most of its revenue arrangements, as property revenue is derived from tenant leases of specifically-identified, physically distinct space on the Company’s communications real estate assets. The Company’s lease arrangements with its tenants vary depending upon the region and the industry of the tenant and generally have initial non-cancellable terms of five The Company’s leasing arrangements outside of the U.S. may require that the Company provide power to the communications site through an electrical grid connection, diesel fuel generators or other sources and permit the Company to pass through the costs of, or otherwise charge for, these services. Many arrangements require that the communications site has power for a specified percentage of time. In most cases, if delivery of power falls below the specified service level, a corresponding reduction in revenue is recorded. The Company has determined that this performance obligation is satisfied over time for the duration of the lease. The Company typically has more than one tenant on a site and, by performing ordinary course repair and maintenance work, can often lease a site, either through renewing existing agreements or leasing to new tenants, for periods beyond the existing tenant lease term. Accordingly, the Company has minimal risk with respect to the residual value of its leased assets. Communications sites are depreciated over their estimated useful lives, which generally do not exceed twenty years. As of December 31, 2020, the Company does not have any material related party leases as a lessor. The Company generally does not enter into sales-type leases or direct financing leases. The Company’s leases generally do not include any incentives for the lessee, however, if incentives are present, they are evaluated to determine proper treatment. In addition, the Company’s leases do not include any lessee purchase options. Historically, the Company has been able to successfully renew its ground leases as needed to ensure continuation of its tower revenue. Accordingly, the Company assumes that it will have access to the land underneath its tower sites when calculating future minimum rental receipts. Future minimum rental receipts expected under non-cancellable operating lease agreements as of December 31, 2020, were as follows: Year Ended December 31, Amount (1) 2021 $ 6,194.6 2022 5,905.5 2023 5,779.5 2024 5,618.8 2025 5,410.6 Thereafter 29,660.9 Total $ 58,569.9 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company enters into arrangements as a lessee primarily for ground space underneath its communications sites. These arrangements are typically long-term lease agreements with initial non-cancellable terms of approximately five The Company’s lease liability is the present value of the remaining minimum rental payments to be made over the remaining lease term, including renewal options reasonably certain to be exercised. The Company also considers termination options and factors those into the determination of lease payments when appropriate. To determine the lease term, the Company considers all renewal periods that are reasonably certain to be exercised, taking into consideration all economic factors, including the communications site’s estimated economic life (generally 20 years) and the respective lease terms of the Company’s tenants under the existing lease arrangements on such site. The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1. During the years ended December 31, 2020 and 2019, the Company recorded $76.1 million and $9.9 million, respectively, of impairment expense related to these assets. As of December 31, 2020, the Company does not have any material related party leases as a lessee. The Company does not have any sale-leaseback arrangements as lessee and typically does not enter into leveraged leases. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of December 31, 2020, operating lease assets were included in Right-of-use asset and finance lease assets were included in Property and equipment, net in the consolidated balance sheet. Information about other lease-related balances is as follows: As of December 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 7,789.2 $ 7,357.4 Current portion of lease liability $ 539.9 $ 494.5 Lease liability 6,884.4 6,510.4 Total operating lease liability $ 7,424.3 $ 7,004.9 Finance leases: Current portion of lease liability $ 4.9 $ 6.7 Lease liability 23.0 24.0 Total finance lease liability $ 27.9 $ 30.7 As most of the Company’s leases do not specifically state an implicit rate, the Company uses a market-specific incremental borrowing rate consistent with the lease term as of the lease commencement date or upon a remeasurement event when calculating the present value of the remaining lease payments. The incremental borrowing rate reflects the cost to borrow on a securitized basis in each market. The remaining lease term does not reflect all renewal options available to the Company, only those renewal options that the Company has assessed as reasonably certain of being exercised taking into consideration the economic and other factors noted above. The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of December 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.7 13.1 Weighted-average incremental borrowing rate 5.6 % 6.1 % Finance leases: Weighted-average remaining lease term (years) 12.1 15.0 Weighted-average incremental borrowing rate 6.8 % 6.2 % The following table sets forth the components of lease cost: Year ended December 31, 2020 Year ended December 31, 2019 Operating lease cost $ 977.2 $ 1,013.1 Variable lease costs not included in lease liability (1) 280.0 261.7 _______________ (1) Includes property tax paid on behalf of the landlord. The interest expense on finance lease liabilities was $1.3 million and $1.7 million for the years ended December 31, 2020 and 2019, respectively. Assets held under finance leases are recorded in property and equipment and are depreciated over the lesser of the remaining lease term or the remaining useful life. Supplemental cash flow information is as follows: Year ended December 31, 2020 Year ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (988.3) $ (1,012.2) Operating cash flows from finance leases $ (1.3) $ (1.7) Financing cash flows from finance leases $ (9.2) $ (18.0) Non-cash items: New operating leases (1) $ 346.0 $ 409.5 Operating lease modifications and reassessments $ 843.1 $ 334.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. As of December 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating and finance lease liabilities as of December 31, 2020 were as follows: Fiscal Year Operating Lease (1) Finance Lease (1) 2021 $ 901.1 $ 6.2 2022 869.0 5.3 2023 836.4 3.6 2024 798.0 2.9 2025 751.8 2.1 Thereafter 6,423.4 26.9 Total lease payments 10,579.7 47.0 Less amounts representing interest (3,155.4) (19.1) Total lease liability 7,424.3 27.9 Less current portion of lease liability 539.9 4.9 Non-current lease liability $ 6,884.4 $ 23.0 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods.
LEASES	LEASES The Company determines if an arrangement is a lease at the inception of the agreement. The Company considers an arrangement to be a lease if it conveys the right to control the use of the communications site or ground space underneath a communications site for a period of time in exchange for consideration. The Company is both a lessor and a lessee. Lessor —The Company is a lessor in most of its revenue arrangements, as property revenue is derived from tenant leases of specifically-identified, physically distinct space on the Company’s communications real estate assets. The Company’s lease arrangements with its tenants vary depending upon the region and the industry of the tenant and generally have initial non-cancellable terms of five The Company’s leasing arrangements outside of the U.S. may require that the Company provide power to the communications site through an electrical grid connection, diesel fuel generators or other sources and permit the Company to pass through the costs of, or otherwise charge for, these services. Many arrangements require that the communications site has power for a specified percentage of time. In most cases, if delivery of power falls below the specified service level, a corresponding reduction in revenue is recorded. The Company has determined that this performance obligation is satisfied over time for the duration of the lease. The Company typically has more than one tenant on a site and, by performing ordinary course repair and maintenance work, can often lease a site, either through renewing existing agreements or leasing to new tenants, for periods beyond the existing tenant lease term. Accordingly, the Company has minimal risk with respect to the residual value of its leased assets. Communications sites are depreciated over their estimated useful lives, which generally do not exceed twenty years. As of December 31, 2020, the Company does not have any material related party leases as a lessor. The Company generally does not enter into sales-type leases or direct financing leases. The Company’s leases generally do not include any incentives for the lessee, however, if incentives are present, they are evaluated to determine proper treatment. In addition, the Company’s leases do not include any lessee purchase options. Historically, the Company has been able to successfully renew its ground leases as needed to ensure continuation of its tower revenue. Accordingly, the Company assumes that it will have access to the land underneath its tower sites when calculating future minimum rental receipts. Future minimum rental receipts expected under non-cancellable operating lease agreements as of December 31, 2020, were as follows: Year Ended December 31, Amount (1) 2021 $ 6,194.6 2022 5,905.5 2023 5,779.5 2024 5,618.8 2025 5,410.6 Thereafter 29,660.9 Total $ 58,569.9 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company enters into arrangements as a lessee primarily for ground space underneath its communications sites. These arrangements are typically long-term lease agreements with initial non-cancellable terms of approximately five The Company’s lease liability is the present value of the remaining minimum rental payments to be made over the remaining lease term, including renewal options reasonably certain to be exercised. The Company also considers termination options and factors those into the determination of lease payments when appropriate. To determine the lease term, the Company considers all renewal periods that are reasonably certain to be exercised, taking into consideration all economic factors, including the communications site’s estimated economic life (generally 20 years) and the respective lease terms of the Company’s tenants under the existing lease arrangements on such site. The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1. During the years ended December 31, 2020 and 2019, the Company recorded $76.1 million and $9.9 million, respectively, of impairment expense related to these assets. As of December 31, 2020, the Company does not have any material related party leases as a lessee. The Company does not have any sale-leaseback arrangements as lessee and typically does not enter into leveraged leases. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of December 31, 2020, operating lease assets were included in Right-of-use asset and finance lease assets were included in Property and equipment, net in the consolidated balance sheet. Information about other lease-related balances is as follows: As of December 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 7,789.2 $ 7,357.4 Current portion of lease liability $ 539.9 $ 494.5 Lease liability 6,884.4 6,510.4 Total operating lease liability $ 7,424.3 $ 7,004.9 Finance leases: Current portion of lease liability $ 4.9 $ 6.7 Lease liability 23.0 24.0 Total finance lease liability $ 27.9 $ 30.7 As most of the Company’s leases do not specifically state an implicit rate, the Company uses a market-specific incremental borrowing rate consistent with the lease term as of the lease commencement date or upon a remeasurement event when calculating the present value of the remaining lease payments. The incremental borrowing rate reflects the cost to borrow on a securitized basis in each market. The remaining lease term does not reflect all renewal options available to the Company, only those renewal options that the Company has assessed as reasonably certain of being exercised taking into consideration the economic and other factors noted above. The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of December 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.7 13.1 Weighted-average incremental borrowing rate 5.6 % 6.1 % Finance leases: Weighted-average remaining lease term (years) 12.1 15.0 Weighted-average incremental borrowing rate 6.8 % 6.2 % The following table sets forth the components of lease cost: Year ended December 31, 2020 Year ended December 31, 2019 Operating lease cost $ 977.2 $ 1,013.1 Variable lease costs not included in lease liability (1) 280.0 261.7 _______________ (1) Includes property tax paid on behalf of the landlord. The interest expense on finance lease liabilities was $1.3 million and $1.7 million for the years ended December 31, 2020 and 2019, respectively. Assets held under finance leases are recorded in property and equipment and are depreciated over the lesser of the remaining lease term or the remaining useful life. Supplemental cash flow information is as follows: Year ended December 31, 2020 Year ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (988.3) $ (1,012.2) Operating cash flows from finance leases $ (1.3) $ (1.7) Financing cash flows from finance leases $ (9.2) $ (18.0) Non-cash items: New operating leases (1) $ 346.0 $ 409.5 Operating lease modifications and reassessments $ 843.1 $ 334.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. As of December 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating and finance lease liabilities as of December 31, 2020 were as follows: Fiscal Year Operating Lease (1) Finance Lease (1) 2021 $ 901.1 $ 6.2 2022 869.0 5.3 2023 836.4 3.6 2024 798.0 2.9 2025 751.8 2.1 Thereafter 6,423.4 26.9 Total lease payments 10,579.7 47.0 Less amounts representing interest (3,155.4) (19.1) Total lease liability 7,424.3 27.9 Less current portion of lease liability 539.9 4.9 Non-current lease liability $ 6,884.4 $ 23.0 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods.
LEASES	LEASES The Company determines if an arrangement is a lease at the inception of the agreement. The Company considers an arrangement to be a lease if it conveys the right to control the use of the communications site or ground space underneath a communications site for a period of time in exchange for consideration. The Company is both a lessor and a lessee. Lessor —The Company is a lessor in most of its revenue arrangements, as property revenue is derived from tenant leases of specifically-identified, physically distinct space on the Company’s communications real estate assets. The Company’s lease arrangements with its tenants vary depending upon the region and the industry of the tenant and generally have initial non-cancellable terms of five The Company’s leasing arrangements outside of the U.S. may require that the Company provide power to the communications site through an electrical grid connection, diesel fuel generators or other sources and permit the Company to pass through the costs of, or otherwise charge for, these services. Many arrangements require that the communications site has power for a specified percentage of time. In most cases, if delivery of power falls below the specified service level, a corresponding reduction in revenue is recorded. The Company has determined that this performance obligation is satisfied over time for the duration of the lease. The Company typically has more than one tenant on a site and, by performing ordinary course repair and maintenance work, can often lease a site, either through renewing existing agreements or leasing to new tenants, for periods beyond the existing tenant lease term. Accordingly, the Company has minimal risk with respect to the residual value of its leased assets. Communications sites are depreciated over their estimated useful lives, which generally do not exceed twenty years. As of December 31, 2020, the Company does not have any material related party leases as a lessor. The Company generally does not enter into sales-type leases or direct financing leases. The Company’s leases generally do not include any incentives for the lessee, however, if incentives are present, they are evaluated to determine proper treatment. In addition, the Company’s leases do not include any lessee purchase options. Historically, the Company has been able to successfully renew its ground leases as needed to ensure continuation of its tower revenue. Accordingly, the Company assumes that it will have access to the land underneath its tower sites when calculating future minimum rental receipts. Future minimum rental receipts expected under non-cancellable operating lease agreements as of December 31, 2020, were as follows: Year Ended December 31, Amount (1) 2021 $ 6,194.6 2022 5,905.5 2023 5,779.5 2024 5,618.8 2025 5,410.6 Thereafter 29,660.9 Total $ 58,569.9 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company enters into arrangements as a lessee primarily for ground space underneath its communications sites. These arrangements are typically long-term lease agreements with initial non-cancellable terms of approximately five The Company’s lease liability is the present value of the remaining minimum rental payments to be made over the remaining lease term, including renewal options reasonably certain to be exercised. The Company also considers termination options and factors those into the determination of lease payments when appropriate. To determine the lease term, the Company considers all renewal periods that are reasonably certain to be exercised, taking into consideration all economic factors, including the communications site’s estimated economic life (generally 20 years) and the respective lease terms of the Company’s tenants under the existing lease arrangements on such site. The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1. During the years ended December 31, 2020 and 2019, the Company recorded $76.1 million and $9.9 million, respectively, of impairment expense related to these assets. As of December 31, 2020, the Company does not have any material related party leases as a lessee. The Company does not have any sale-leaseback arrangements as lessee and typically does not enter into leveraged leases. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of December 31, 2020, operating lease assets were included in Right-of-use asset and finance lease assets were included in Property and equipment, net in the consolidated balance sheet. Information about other lease-related balances is as follows: As of December 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 7,789.2 $ 7,357.4 Current portion of lease liability $ 539.9 $ 494.5 Lease liability 6,884.4 6,510.4 Total operating lease liability $ 7,424.3 $ 7,004.9 Finance leases: Current portion of lease liability $ 4.9 $ 6.7 Lease liability 23.0 24.0 Total finance lease liability $ 27.9 $ 30.7 As most of the Company’s leases do not specifically state an implicit rate, the Company uses a market-specific incremental borrowing rate consistent with the lease term as of the lease commencement date or upon a remeasurement event when calculating the present value of the remaining lease payments. The incremental borrowing rate reflects the cost to borrow on a securitized basis in each market. The remaining lease term does not reflect all renewal options available to the Company, only those renewal options that the Company has assessed as reasonably certain of being exercised taking into consideration the economic and other factors noted above. The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of December 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.7 13.1 Weighted-average incremental borrowing rate 5.6 % 6.1 % Finance leases: Weighted-average remaining lease term (years) 12.1 15.0 Weighted-average incremental borrowing rate 6.8 % 6.2 % The following table sets forth the components of lease cost: Year ended December 31, 2020 Year ended December 31, 2019 Operating lease cost $ 977.2 $ 1,013.1 Variable lease costs not included in lease liability (1) 280.0 261.7 _______________ (1) Includes property tax paid on behalf of the landlord. The interest expense on finance lease liabilities was $1.3 million and $1.7 million for the years ended December 31, 2020 and 2019, respectively. Assets held under finance leases are recorded in property and equipment and are depreciated over the lesser of the remaining lease term or the remaining useful life. Supplemental cash flow information is as follows: Year ended December 31, 2020 Year ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (988.3) $ (1,012.2) Operating cash flows from finance leases $ (1.3) $ (1.7) Financing cash flows from finance leases $ (9.2) $ (18.0) Non-cash items: New operating leases (1) $ 346.0 $ 409.5 Operating lease modifications and reassessments $ 843.1 $ 334.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. As of December 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating and finance lease liabilities as of December 31, 2020 were as follows: Fiscal Year Operating Lease (1) Finance Lease (1) 2021 $ 901.1 $ 6.2 2022 869.0 5.3 2023 836.4 3.6 2024 798.0 2.9 2025 751.8 2.1 Thereafter 6,423.4 26.9 Total lease payments 10,579.7 47.0 Less amounts representing interest (3,155.4) (19.1) Total lease liability 7,424.3 27.9 Less current portion of lease liability 539.9 4.9 Non-current lease liability $ 6,884.4 $ 23.0 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2020
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 each of the Company’s business segments were as follows: Property Services Total U.S. & Canada Asia-Pacific Africa Europe Latin America Balance as of December 31, 2018 $ 3,382.5 $ 1,045.5 $ 119.3 $ 262.0 $ 690.6 $ 2.0 $ 5,501.9 Additions and adjustments (1) 32.8 — 670.0 — — — 702.8 Effect of foreign currency translation — (23.7) 0.9 (5.8) 2.2 — (26.4) Balance as of December 31, 2019 $ 3,415.3 $ 1,021.8 $ 790.2 $ 256.2 $ 692.8 $ 2.0 $ 6,178.3 Additions and adjustments (2) 1,335.5 18.7 (153.6) — — — 1,200.6 Effect of foreign currency translation — (23.6) (11.0) 22.9 (84.5) — (96.2) Balance as of December 31, 2020 $ 4,750.8 $ 1,016.9 $ 625.6 $ 279.1 $ 608.3 $ 2.0 $ 7,282.7 _______________ (1) Additions consist of $704.3 million resulting from 2019 acquisitions, partially offset by $1.5 million from revisions to prior-year acquisitions due to measurement period adjustments. (2) U.S. & Canada and Asia-Pacific consist of an aggregate of $1,354.2 million of additions related to the InSite Acquisition. Africa consists of measurement period adjustments related to the Eaton Towers Acquisition (as defined in note 7). The Company’s other intangible assets subject to amortization consisted of the following: As of December 31, 2020 As of December 31, 2019 Estimated Useful Gross Accumulated Net Book Gross Accumulated Net Book Acquired network location intangibles (1) Up to 20 $ 5,784.0 $ (2,117.6) $ 3,666.4 $ 5,150.8 $ (1,920.4) $ 3,230.4 Acquired tenant-related intangibles Up to 20 14,322.5 (4,237.5) 10,085.0 12,674.1 (3,674.6) 8,999.5 Acquired licenses and other intangibles 3-20 97.8 (9.4) 88.4 106.7 (18.2) 88.5 Total other intangible assets $ 20,204.3 $ (6,364.5) $ 13,839.8 $ 17,931.6 $ (5,613.2) $ 12,318.4 _______________ (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, generally up to 20 years, as the Company considers these intangibles to be directly related to the tower assets. The acquired network location intangibles represent the value to the Company of the incremental revenue growth that could potentially be obtained from leasing the excess capacity on acquired communications sites. The acquired tenant-related intangibles typically represent the value to the Company of tenant contracts and relationships in place at the time of an acquisition or similar transaction, including assumptions regarding estimated renewals. The Company amortizes its acquired network location intangibles and tenant-related intangibles on a straight-line basis over their estimated useful lives. As of December 31, 2020, the remaining weighted average amortization period of the Company’s intangible assets was 15 years. Amortization of intangible assets for the years ended December 31, 2020, 2019 and 2018 was $867.2 million, $791.3 million and $1,144.1 million, respectively. Amortization expense decreased for the year ended December 31, 2019 as compared to the year ended December 31, 2018, because in 2018, the Company entered into agreements with one of its tenants in India, Tata Teleservices Limited (“Tata Teleservices”) and related entities (collectively, “Tata”), for a settlement and release of certain contractual lease obligations of Tata Teleservices. As a result, the Company recorded $327.5 million of accelerated amortization related to the Tata tenant relationship in 2018, which was subsequently retired. Based on current exchange rates, the Company expects to record amortization expense as follows over the next five years: Fiscal Year Amount 2021 $ 999.6 2022 994.0 2023 969.0 2024 959.1 2025 927.6

NOTES RECEIVABLE AND OTHER NON-

NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
Notes Receivable And Other Long Term Assets [Abstract]
NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS Notes receivable and other non-current assets consisted of the following: As of December 31, 2020 December 31, 2019 Notes receivable $ 6.5 $ 1.1 Other miscellaneous assets 393.6 405.3 Notes receivable and other non-current assets $ 400.1 $ 406.4

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONSThe Company evaluates each of its acquisitions under the accounting guidance framework to determine whether to treat an acquisition as an asset acquisition or a business combination. For those transactions treated as asset acquisitions, the purchase price is allocated to the assets or rights acquired and liabilities assumed, with no recognition of goodwill. For those transactions treated as business combinations, the estimates of the fair value of the assets or rights acquired and liabilities assumed at the date of the applicable acquisition are subject to adjustment during the measurement period (up to one year from the particular acquisition date). The primary areas of the accounting for the acquisitions that are not yet finalized relate to the fair value of certain tangible and intangible assets acquired and liabilities assumed, including tax positions, which may include contingent consideration, residual goodwill and any related tax impact. The fair value of these net assets acquired are based on management’s estimates and assumptions, as well as other information compiled by management, including valuations that utilize customary valuation procedures and techniques. While the Company believes that such preliminary estimates provide a reasonable basis for estimating the fair value of assets acquired and liabilities assumed, it evaluates any necessary information prior to finalization of the fair value. During the measurement period for those acquisitions accounted for as business combinations, the Company will adjust assets or liabilities if new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have resulted in the revised estimated values of those assets or liabilities as of that date. Impact of current year acquisitions —The Company typically acquires communications sites and other communications infrastructure assets from wireless carriers or other tower operators and subsequently integrates those sites and related assets into its existing portfolio of communications sites and related assets. The financial results of the Company’s acquisitions have been included in the Company’s consolidated statements of operations for the year ended December 31, 2020 from the date of the respective acquisition. The date of acquisition, and by extension the point at which the Company begins to recognize the results of an acquisition, may depend on, among other things, the receipt of contractual consents, the commencement and extent of leasing arrangements and the timing of the transfer of title or rights to the assets, which may be accomplished in phases. Sites acquired from communications service providers may never have been operated as a business and may instead have been utilized solely by the seller as a component of its network infrastructure. An acquisition may or may not involve the transfer of business operations or employees. For those acquisitions accounted for as business combinations, the Company recognizes acquisition and merger related expenses in the period in which they are incurred and services are received; for transactions accounted for as asset acquisitions, these costs are capitalized as part of the purchase price. Acquisition and merger related costs may include finder’s fees, advisory, legal, accounting, valuation and other professional or consulting fees and general administrative costs directly related to completing the transaction. Integration costs include incremental and non-recurring costs necessary to convert data, retain employees and otherwise enable the Company to operate acquired businesses or assets efficiently. The Company records acquisition and merger related expenses for business combinations, as well as integration costs for all acquisitions, in Other operating expenses in the consolidated statements of operations. During the years ended December 31, 2020, 2019 and 2018, the Company recorded acquisition and merger related expenses for business combinations and non-capitalized asset acquisition costs and integration costs as follows: Year Ended December 31, 2020 2019 2018 Acquisition and merger related expenses $ 15.5 $ 26.9 $ 14.1 Integration costs $ 23.1 $ 9.8 $ 16.1 During the years ended December 31, 2020 and 2019, the Company recorded net benefits of $4.4 million and $13.1 million related to pre-acquisition contingencies and settlements, respectively. 2020 Transactions The estimated aggregate impact of the acquisitions completed in 2020 on the Company’s revenues and gross margin for the year ended December 31, 2020 was approximately $14.9 million and $10.5 million, respectively. The revenues and gross margin amounts also reflect incremental revenues from the addition of new tenants to such sites subsequent to the transaction date. Acquisitions completed in 2020 were included in all of the Company’s property segments. InSite Acquisition —On December 23, 2020, the Company acquired 100% of the outstanding units of IWG Holdings, LLC, the parent company of InSite, which owned, operated and managed approximately 3,000 communications sites in the U.S. and Canada. The portfolio includes approximately 1,400 owned towers in the United States, over 200 owned towers in Canada and approximately 40 DAS networks in the United States. In addition, the portfolio includes more than 600 land parcels under communications sites in the United States, Canada and Australia, as well as approximately 400 rooftop sites. The acquired U.S. and Canada assets and operations are included in the U.S. & Canada property segment and the acquired Australian assets and operations are included in the Asia-Pacific property segment. The total consideration for the InSite Acquisition, including cash acquired, the repayment and assumption of certain debt held by InSite, was approximately $3.5 billion, subject to certain closing adjustments. The InSite Acquisition was accounted for as a business combination and is subject to post-closing adjustments. Entel Acquisition —On December 19, 2019, the Company entered into a definitive agreement to acquire approximately 3,200 communications sites in Chile and Peru from Entel PCS Telecomunicaciones S.A. and Entel Peru S.A. (“Entel”) for total consideration of approximately $0.8 billion (as of the date of signing). The Company completed the acquisition of approximately 2,400 communications sites in December 2019. During the year ended December 31, 2020, the Company completed the acquisition of an additional 530 communications sites pursuant to this agreement for an aggregate total purchase price of $137.7 million (as of the dates of acquisition), including value added tax. This acquisition is being accounted for as an acquisition of assets and is included in the table below in “Other.” The remaining communications sites are expected to continue to close in tranches, subject to certain closing conditions. Poland Acquisition —On June 16, 2020, the Company, through its Polish subsidiary, entered into a definitive agreement with Electronic Control Systems Spółka Akcyjna to acquire up to 50 communications sites in Poland for total consideration of 18.3 million Polish Zloty (“PLN”) ($4.6 million at the date of signing). During the year ended December 31, 2020, the Company completed the acquisition of 27 of these communications sites for total consideration of 12.1 million PLN ($3.1 million as of the dates of acquisition), including value added tax. This acquisition is being accounted for as an acquisition of assets and is included in the table below in “Other.” The remaining communications sites are expected to continue to close in tranches, subject to customary closing conditions. Other Acquisitions— During the year ended December 31, 2020, the Company acquired a total of 1,299 communications sites, as well as other communications infrastructure assets, in the United States, France, Mexico, Peru and South Africa, including 564 sites in connection with the Company’s agreements with Orange S.A. (“Orange”) as further described below, for an aggregate purchase price of $978.0 million. Of the aggregate purchase price, $58.9 million is reflected as a payable in the consolidated balance sheet as of December 31, 2020. The majority of these acquisitions were accounted for as asset acquisitions and are included in the table below in “Other.” The following table summarizes the allocations of the purchase prices for the fiscal year 2020 acquisitions based upon their estimated fair value at the date of acquisition: InSite Acquisition Other (1) Current assets $ 57.2 $ 40.6 Property and equipment 516.4 336.7 Intangible assets (2): Tenant-related intangible assets 1,160.1 596.5 Network location intangible assets 622.7 166.6 Other intangible assets — 1.3 Other non-current assets 300.7 112.3 Current liabilities (75.9) (10.9) Deferred tax liability (116.3) (9.8) Other non-current liabilities (267.6) (114.5) Net assets acquired 2,197.3 1,118.8 Goodwill (3) 1,354.2 — Fair value of net assets acquired 3,551.5 1,118.8 Debt assumed (4) (800.0) — Purchase price $ 2,751.5 $ 1,118.8 ______________ (1) Includes 25 sites in Peru held pursuant to long-term finance leases. (2) Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis generally over a 20 year period. (3) The Company expects goodwill to be partially deductible for tax purposes. (4) InSite Acquisition debt assumed includes $763.5 million of InSite’s indebtedness and a fair value adjustment of $36.5 million. The fair value adjustment was based primarily on reported market values using Level 2 inputs. In addition to the acquisitions discussed above, the Company purchased 103 towers related to the AT&T transaction described in note 19 for an aggregate purchase price of $55.7 million. Other Signed Acquisitions Orange— On November 28, 2019, ATC France, a majority-owned subsidiary of the Company, entered into definitive agreements with Orange for the acquisition of up to approximately 2,000 communications sites in France over a period of up to five years for total consideration in the range of approximately 500.0 million Euros (“EUR”) to 600.0 million EUR (approximately $550.5 million to $660.5 million at the date of signing) to be paid over the five 2019 Transactions Eaton Towers Acquisition —On December 31, 2019, the Company acquired 100% of the outstanding shares of Eaton Towers Holdings Limited (“Eaton Towers”), which owned and operated approximately 5,800 communications sites across five African markets (the “Eaton Towers Acquisition”). During the year ended December 31, 2020, the purchase price was reduced by approximately $4.2 million. The total consideration for the Eaton Towers Acquisition, including the Company’s assumption of Eaton Towers’ existing debt, was approximately $2.0 billion. The purchase price reflects a $14.0 million receivable from the seller for reimbursement of taxes. The Eaton Towers Acquisition was accounted for as a business combination and the allocation of the purchase price was finalized during the year ended December 31, 2020. The following table summarizes the preliminary and final allocation of the purchase price paid and the amounts of assets acquired and liabilities assumed for the Eaton Towers Acquisition based upon its estimated fair value at the date of acquisition. Balances are reflected in the accompanying consolidated balance sheet as of December 31, 2020. Preliminary Allocation Final Allocation Current assets $ 150.4 $ 151.7 Property and equipment 304.7 306.6 Intangible assets (1): Tenant-related intangible assets 1,007.6 1,107.7 Network location intangible assets 272.2 326.2 Other non-current assets 99.5 114.8 Current liabilities (82.0) (94.3) Deferred tax liability (319.3) (347.2) Other non-current liabilities (138.3) (121.3) Net assets acquired 1,294.8 1,444.2 Goodwill (2) 670.0 516.4 Fair value of net assets acquired 1,964.8 1,960.6 Debt assumed (329.8) (329.8) Purchase price $ 1,635.0 $ 1,630.8 _______________ (1) Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years. (2) The Company expects goodwill to be partially deductible for tax purposes. Pro Forma Consolidated Results (Unaudited) The following table presents the unaudited pro forma financial results as if the 2020 acquisitions had occurred on January 1, 2019 and the 2019 acquisitions had occurred on January 1, 2018. The pro forma results do not include any anticipated cost synergies, costs or other integration impacts. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the transactions been completed on the dates indicated, nor are they indicative of the future operating results of the Company. Year Ended December 31, 2020 2019 Pro forma revenues $ 8,230.9 $ 8,083.8 Pro forma net income attributable to American Tower Corporation common stockholders $ 1,515.7 $ 1,651.0 Pro forma net income per common share amounts: Basic net income attributable to American Tower Corporation common stockholders $ 3.42 $ 3.73 Diluted net income attributable to American Tower Corporation common stockholders $ 3.40 $ 3.71

ACCRUED EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2020
Accrued Liabilities, Current [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consisted of the following: As of December 31, 2020 December 31, 2019 Accrued construction costs $ 46.5 $ 27.8 Accrued income tax payable 20.6 55.2 Accrued pass-through costs 67.1 74.2 Amounts payable for acquisitions 58.9 — Amounts payable to tenants 66.4 77.9 Accrued property and real estate taxes 219.1 198.1 Accrued rent 82.6 75.6 Payroll and related withholdings 104.4 102.4 Other accrued expenses 378.1 347.0 Accrued expenses $ 1,043.7 $ 958.2

LONG-TERM OBLIGATIONS

LONG-TERM OBLIGATIONS	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
LONG-TERM OBLIGATIONS	LONG-TERM OBLIGATIONS Outstanding amounts under the Company’s long-term obligations, reflecting discounts, premiums, debt issuance costs and fair value adjustments due to interest rate swaps consisted of the following: As of December 31, 2020 December 31, 2019 Contractual Interest Rate (1) Maturity Date (1) 2019 364-Day Term Loan (1) (2) $ — $ 999.9 N/A N/A 2020 Term Loan (1) (3) 749.4 — 0.800 % February 12, 2021 2019 Multicurrency Credit Facility (1) — 700.0 — % June 28, 2023 2019 Term Loan (1) 996.1 995.2 1.275 % January 31, 2025 2019 Credit Facility (1) 2,295.0 1,600.0 1.235 % January 31, 2025 2.800% senior notes (4) — 749.4 N/A N/A 3.300% senior notes (5) — 748.5 N/A N/A 3.450% senior notes (5) — 647.7 N/A N/A 5.900% senior notes (6) — 498.9 N/A N/A 2.250% senior notes 605.1 592.1 2.250 % January 15, 2022 4.70% senior notes 699.0 698.2 4.700 % March 15, 2022 3.50% senior notes 996.1 994.3 3.500 % January 31, 2023 3.000% senior notes 721.9 704.9 3.000 % June 15, 2023 0.600% senior notes 496.8 — 0.600 % January 15, 2024 5.00% senior notes 1,001.3 1,001.7 5.000 % February 15, 2024 3.375% senior notes 645.7 644.4 3.375 % May 15, 2024 2.950% senior notes 643.1 641.3 2.950 % January 15, 2025 2.400% senior notes 745.0 — 2.400 % March 15, 2025 1.375% senior notes (7) 604.1 553.0 1.375 % April 4, 2025 4.000% senior notes 744.3 743.2 4.000 % June 1, 2025 1.300% senior notes 495.4 — 1.300 % September 15, 2025 4.400% senior notes 497.1 496.6 4.400 % February 15, 2026 1.950% senior notes (7) 605.2 554.4 1.950 % May 22, 2026 3.375% senior notes 989.5 987.9 3.375 % October 15, 2026 3.125% senior notes 397.9 397.6 3.125 % January 15, 2027 2.750% senior notes 744.3 743.5 2.750 % January 15, 2027 3.55% senior notes 744.8 744.1 3.550 % July 15, 2027 0.500% senior notes (7) 907.4 — 0.500 % January 15, 2028 3.600% senior notes 693.4 692.6 3.600 % January 15, 2028 1.500% senior notes 645.1 — 1.500 % January 31, 2028 3.950% senior notes 590.6 589.6 3.950 % March 15, 2029 3.800% senior notes 1,633.5 1,631.7 3.800 % August 15, 2029 2.900% senior notes 741.7 — 2.900 % January 15, 2030 2.100% senior notes 740.2 — 2.100 % June 15, 2030 1.875% senior notes 790.5 — 1.875 % October 15, 2030 1.000% senior notes (7) 786.1 — 1.000 % January 15, 2032 3.700% senior notes 591.9 591.8 3.700 % October 15, 2049 3.100% senior notes 1,037.7 — 3.100 % June 15, 2050 2.950% senior notes 538.2 — 2.950 % January 15, 2051 Total American Tower Corporation debt 26,113.4 20,942.5 Series 2013-2A Securities (8) 1,296.6 1,295.0 3.070 % March 15, 2023 Series 2018-1A Securities (8) 494.6 493.8 3.652 % March 15, 2028 Series 2015-1 Notes (9) — 349.6 N/A N/A Series 2015-2 Notes (10) 522.1 521.4 3.482 % June 16, 2025 InSite Debt (11) 800.0 — Various Various Other subsidiary debt (12) 32.9 422.4 Various Various Total American Tower subsidiary debt 3,146.2 3,082.2 Finance lease obligations 27.9 30.7 Total 29,287.5 24,055.4 Less current portion of long-term obligations (789.8) (2,928.2) Long-term obligations $ 28,497.7 $ 21,127.2 _______________ (1) Accrues interest at a variable rate. (2) Repaid in full on February 13, 2020 using proceeds from the 2020 Term Loan (as defined below), borrowings from the 2019 Credit Facility (as defined below) and cash on hand. (3) Repaid in full on February 5, 2021 using borrowings from the 2019 Multicurrency Credit Facility and cash on hand. (4) Repaid in full on May 11, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (5) Repaid in full on July 6, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (6) Repaid in full on January 15, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (7) Notes are denominated in EUR. (8) Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048. (9) Repaid in full on the June 2020 payment date with cash on hand. (10) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050. (11) Debt entered into by certain InSite subsidiaries acquired in connection with the InSite Acquisition (the “InSite Debt”) (12) Includes (a) the Colombian credit facility, which is denominated in Colombian Pesos (“COP”) and amortizes through April 24, 2021, (b) debt entered into by the Company’s Kenyan subsidiary in connection with an acquisition of sites in Kenya, which is denominated in U.S. Dollars (“USD”) and is payable either (i) in future installments subj ect to the satisfaction of specified conditions or (ii) three years from the note origination date, and (c) U.S. subsidiary debt related to a seller-financed acquisition. As of December 31, 2019, included (a) debt entered into by certain Eaton Towers subsidiaries acquired in connection with the Eaton Towers Acquisition (the “Eaton Towers Debt”), which was denominated i n multiple currencies, including USD, EUR, Kenyan Shilling (“KES”) and West African CFA Franc (“XOF”) and was repaid during the year ended December 31, 2020, (b) the Brazil credit facility, which was denominated in Brazilian Reais (“BRL”) and was repaid on March 6, 2020, and (c) the South African credit facility, which was denominated in South African Rand (“ZAR”) and was repaid on the December 17, 2020 maturity date. Current portion of long-term obligations — The Company’s current portion of long-term obligations primarily includes $750.0 million under its unsecured term loan entered into on February 13, 2020 (the “2020 Term Loan”). American Tower Corporation Debt Bank Facilities During the year ended December 31, 2020, the Company increased the commitments under its senior unsecured multicurrency revolving credit facility, as amended and restated in December 2019 (the “2019 Multicurrency Credit Facility”), and its senior unsecured revolving credit facility, as amended and restated in December 2019 ( the “2019 Credit Facility”), by $100.0 million each to $3.1 billion and $2.35 billion, respectively. 2019 Multicurrency Credit Facility— The Company has the ability to borrow up to $3.1 billion under the 2019 Multicurrency Credit Facility, which includes a $1.0 billion sublimit for multicurrency borrowings, a $200.0 million sublimit for letters of credit and a $50.0 million sublimit for swingline loans. During the year ended December 31, 2020, the Company borrowed an aggregate of 910.0 million EUR ($1.0 billion as of the borrowing dates) and repaid an aggregate of $1.8 billion, including 910.0 million EUR ($1.1 billion as of the repayment dates), of revolving indebtedness under the 2019 Multicurrency Credit Facility. The Company used the borrowings to repay existing indebtedness and for general corporate purposes. 2019 Credit Facility— The Company has the ability to borrow up to $2.35 billion under the 2019 Credit Facility, which includes a $200.0 million sublimit for letters of credit and a $50.0 million sublimit for swingline loans. During the year ended December 31, 2020, the Company borrowed an aggregate of $7.2 billion and repaid an aggregate of $6.5 billion of revolving indebtedness under the 2019 Credit Facility. The Company used the borrowings to fund acquisitions, including the InSite Acquisition, to repay existing indebtedness and for general corporate purposes. 2020 Term Loan— On February 13, 2020, the Company entered into the 2020 Term Loan, the net proceeds of which were used, together with borrowings under the 2019 Credit Facility and cash on hand, to repay all outstanding indebtedness under its $1.3 billion unsecured term loan entered into on February 14, 2019 (the “2019 364-Day Term Loan”). The 2020 Term Loan matures on February 12, 2021. Any outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. April 2020 Term Loan —On April 3, 2020, the Company entered into a $1.14 billion unsecured term loan due April 2, 2021, which was subsequently increased to $1.19 billion effective April 21, 2020 (the “April 2020 Term Loan”), the net proceeds of which were used to repay outstanding indebtedness under the 2019 Credit Facility. During the year ended December 31, 2020, the Company repaid all amounts outstanding under the April 2020 Term Loan with proceeds from the issuances of the 0.500% Notes, the 1.000% Notes, the 1.875% Notes and the Reopened 3.100% Notes (each as defined below). The 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the 2019 Term Loan and the 2020 Term Loan do not require amortization of principal and may be paid prior to maturity in whole or in part at the Company’s option without penalty or premium. The Company has the option of choosing either a defined base rate or LIBOR as the applicable base rate for borrowings under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the 2019 Term Loan and the 2020 Term Loan. The interest rates on the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, and the 2019 Term Loan range between 0.875% to 1.750% above LIBOR for LIBOR based borrowings or up to 0.750% above the defined base rate for base rate borrowings, in each case based upon the Company’s debt ratings. The interest rate on the 2020 Term Loan is 0.650% above LIBOR for LIBOR based borrowings or up to 0.000% above the defined base rate for base rate borrowings, in each case based upon the Company’s debt ratings. As of December 31, 2020, the key terms under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the 2019 Term Loan and the 2020 Term Loan were as follows: Outstanding Principal Balance Undrawn letters of credit Maturity Date Current margin over LIBOR Current commitment fee (1) 2019 Multicurrency Credit Facility — $ 3.8 June 28, 2023 (3) 1.125 % 0.110 % 2019 Credit Facility $ 2,295.0 $ 0.8 January 31, 2025 (3) 1.125 % 0.110 % 2019 Term Loan $ 1,000.0 (2) N/A January 31, 2025 1.125 % N/A 2020 Term Loan $ 750.0 (2) N/A February 12, 2021 0.650 % N/A _______________ (1) Fee on undrawn portion of each credit facility. (2) Borrowed at LIBOR (3) Subject to two optional renewal periods. The loan agreements for the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the 2019 Term Loan and the 2020 Term Loan contain certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Failure to comply with the financial and operating covenants of the loan agreements may constitute a default, which could result in, among other things, the amounts outstanding under the applicable agreement, including all accrued interest and unpaid fees, becoming immediately due and payable. The Company’s bank facility activity subsequent to December 31, 2020 is described further in note 23. Senior Notes Repayments of Senior Notes Repayment of 5.900% Senior Notes —On January 15, 2020, the Company redeemed all of the $500.0 million aggregate principal amount of 5.900% senior unsecured notes due 2021 at a price equal to 106.7090% of the principal amount, plus accrued and unpaid interest up to, but excluding January 15, 2020, for an aggregate redemption price of approximately $539.6 million, including $6.1 million in accrued and unpaid interest. The Company recorded a loss on retirement of long-term obligations of $34.6 million, which includes prepayment consideration of $33.5 million and the associated unamortized discount and deferred financing costs. The redemption was funded with borrowings under the 2019 Credit Facility and cash on hand. Repayment of 2.800% Senior Notes —On May 11, 2020, the Company redeemed all of the $750.0 million aggregate principal amount of 2.800% senior unsecured notes due 2020 at a price equal to the principal amount, together with accrued interest up to, but excluding May 11, 2020, for an aggregate redemption price of approximately $759.3 million, including $9.3 million in accrued interest. The redemption was funded with borrowings under the 2019 Credit Facility and cash on hand. Repayment of 3.450% Senior Notes and 3.300% Senior Notes —On July 6, 2020, the Company redeemed all of the $650.0 million aggregate principal amount of 3.450% senior unsecured notes due 2021 (the “3.450% Notes”) at a price equal to 103.5980% of the principal amount of the 3.450% Notes, plus accrued and unpaid interest up to, but excluding, July 6, 2020, for an aggregate redemption price of $680.3 million, including $6.9 million in accrued and unpaid interest. Also on July 6, 2020, the Company redeemed all of the $750.0 million aggregate principal amount of 3.300% senior unsecured notes due 2021 (the “3.300% Notes”) at a price equal to 101.5090% of the principal amount of the 3.300% Notes, plus accrued and unpaid interest up to, but excluding, July 6, 2020, for an aggregate redemption price of $771.0 million, including $9.7 million in accrued and unpaid interest. The Company recorded a loss on retirement of long-term obligations of approximately $37.2 million, which includes prepayment consideration of $34.7 million and the associated unamortized discount and deferred financing costs. The redemptions of the 3.450% Notes and the 3.300% Notes were funded with borrowings under the 2019 Credit Facility and cash on hand. Offerings of Senior Notes 2.400% Senior Notes and 2.900% Senior Notes Offering— On January 10, 2020, the Company completed a registered public offering of $750.0 million aggregate principal amount of 2.400% senior unsecured notes due 2025 (the “2.400% Notes”) and $750.0 million aggregate principal amount of 2.900% senior unsecured notes due 2030 (the “2.900% Notes”). The net proceeds from this offering were approximately $1,483.4 million, after deducting commissions and estimated expenses. The Company used the net proceeds to repay existing indebtedness under the 2019 Credit Facility. Accrued and unpaid interest is payable in U.S. Dollars semi-annually in arrears and will be computed from the offering date on the basis of a 360 day year comprised of twelve 30-day months, beginning on September 15, 2020 and July 15, 2020 for the 2.400% Notes and the 2.900% Notes, respectively. 1.300% Senior Notes, 2.100% Senior Notes and 3.100% Senior Notes Offering— On June 3, 2020, the Company completed a registered public offering of $500.0 million aggregate principal amount of 1.300% senior unsecured notes due 2025 (the “1.300% Notes”), $750.0 million aggregate principal amount of 2.100% senior unsecured notes due 2030 (the “2.100% Notes”) and $750.0 million aggregate principal amount of 3.100% senior unsecured notes due 2050 (the “Initial 3.100% Notes”) . The net proceeds from this offering were approximately $1,968.2 million, after deducting commissions and estimated expenses. The Company used the net proceeds to repay existing indebtedness under the 2019 Credit Facility and for general corporate purposes. Accrued and unpaid interest is payable in U.S. Dollars semi-annually in arrears and will be computed from the offering date on the basis of a 360 day year comprised of twelve 30-day months, beginning on March 15, 2021, December 15, 2020 and December 15, 2020 for the 1.300% Notes, the 2.100% Notes and the Initial 3.100% Notes, respectively. 0.500% Senior Notes and 1.000% Senior Notes Offering— On September 10, 2020, the Company completed a registered public offering of 750.0 million EUR ($886.1 million at the date of issuance) aggregate principal amount of 0.500% senior unsecured notes due 2028 (the “0.500% Notes”) and 650.0 million EUR ($768.0 million at the date of issuance) aggregate principal amount of 1.000% senior unsecured notes due 2032 (the “1.000% Notes”). The net proceeds from this offering were approximately 1,385.2 million EUR ($1,636.6 million at the date of issuance), after deducting commissions and estimated expenses. The Company used the net proceeds to repay existing indebtedness under the 2019 Multicurrency Credit Facility and the April 2020 Term Loan and for general corporate purposes. Accrued and unpaid interest is payable in EUR annually in arrears and will be computed on the basis of the actual number of days in the period for which interest is being calculated and the actual number of days from and including the last date on which interest was paid on the notes, beginning on January 15, 2021 for each of the 0.500% Notes and the 1.000% Notes. 1.875% Senior Notes and 3.100% Senior Notes Offering— On September 28, 2020, the Company completed a registered public offering of $300.0 million aggregate principal amount through a reopening of the Initial 3.100% Notes (the “Reopened 3.100% Notes” and, collectively with the Initial 3.100% Notes, the “3.100% Notes”) and $800.0 million aggregate principal amount of 1.875% senior unsecured notes due 2030 (the “1.875% Notes”). The net proceeds from this offering were approximately $1,092.1 million, after deducting commissions and estimated expenses. The Company used the net proceeds to repay existing indebtedness under the 2019 Credit Facility and the April 2020 Term Loan. Accrued and unpaid interest is payable in U.S. Dollars semi-annually in arrears and will be computed from the offering date (which shall be June 3, 2020 for the Reopened 3.100% Notes) on the basis of a 360 day year comprised of twelve 30-day months, beginning on April 15, 2021 and December 15, 2020 for the 1.875% Notes and the Reopened 3.100% Notes, respectively. 0.600% Senior Notes, 1.500% Senior Notes and 2.950% Senior Notes Offering— On November 20, 2020, the Company completed a registered public offering of $500.0 million aggregate principal amount of 0.600% senior unsecured notes due 2024 (the “0.600% Notes”), $650.0 million aggregate principal amount of 1.500% senior unsecured notes due 2028 (the “1.500% Notes”) and $550.0 million aggregate principal amount of 2.950% senior unsecured notes due 2051 (the “2.950% Notes” and, collectively with the 2.400% Notes, the 2.900% Notes, the 1.300% Notes, the 2.100% Notes, the 3.100% Notes, the 0.500% Notes, the 1.000% Notes, the 1.875% Notes, the 0.600% Notes and the 1.500% Notes, the “Notes”) . The net proceeds from this offering were approximately $1,678.9 million, after deducting commissions and estimated expenses. The Company used the net proceeds to repay existing indebtedness under the 2019 Credit Facility and for general corporate purposes including the funding of the InSite Acquisition. Accrued and unpaid interest is payable in U.S. Dollars semi-annually in arrears and will be computed from the offering date on the basis of a 360 day year comprised of twelve 30-day months, beginning on July 15, 2021, July 31, 2021 and July 15, 2021 for the 0.600% Notes, the 1.500% Notes and the 2.950% Notes, respectively. The following table outlines key terms related to the Company ’ s outstanding senior notes as of December 31, 2020: Adjustments to Principal Amount (1) Aggregate Principal Amount 2020 2019 Interest Issue Date Par Call Date (3) 2.250% Notes (4) $ 600.0 $ 5.1 $ (7.9) January 15 and July 15 September 30, 2016 N/A 4.70% Notes $ 700.0 (1.0) (1.8) March 15 and September 15 March 12, 2012 N/A 3.50% Notes $ 1,000.0 (3.9) (5.7) January 31 and July 31 January 8, 2013 N/A 3.000% Notes (5) $ 700.0 21.9 4.9 June 15 and December 15 December 8, 2017 N/A 0.600% Notes $ 500.0 (3.2) — January 15 and July 15 November 20, 2020 N/A 5.00% Notes (6) $ 1,000.0 1.3 1.7 February 15 and August 15 August 19, 2013 N/A 3.375% Notes $ 650.0 (4.3) (5.6) May 15 and November 15 March 15, 2019 April 15, 2024 2.950% Notes $ 650.0 (6.9) (8.7) January 15 and July 15 June 13, 2019 December 15, 2024 2.400% Notes $ 750.0 (5.0) — March 15 and September 15 January 10, 2020 February 15, 2025 1.375% Notes (7) $ 610.8 (6.7) (7.6) April 4 April 6, 2017 January 4, 2025 4.000% Notes $ 750.0 (5.7) (6.8) June 1 and December 1 May 7, 2015 March 1, 2025 1.300% Notes $ 500.0 (4.6) — March 15 and September 15 June 3, 2020 August 15, 2025 4.400% Notes $ 500.0 (2.9) (3.4) February 15 and August 15 January 12, 2016 November 15, 2025 1.950% Notes (7) $ 610.8 (5.6) (6.2) May 22 May 22, 2018 February 22, 2026 3.375% Notes $ 1,000.0 (10.5) (12.1) April 15 and October 15 May 13, 2016 July 15, 2026 3.125% Notes $ 400.0 (2.1) (2.4) January 15 and July 15 September 30, 2016 October 15, 2026 2.750% Notes $ 750.0 (5.7) (6.5) January 15 and July 15 October 3, 2019 November 15, 2026 3.55% Notes $ 750.0 (5.2) (5.9) January 15 and July 15 June 30, 2017 April 15, 2027 0.500% Notes (7) $ 916.2 (8.8) — January 15 September 10, 2020 October 15, 2027 3.600% Notes $ 700.0 (6.6) (7.4) January 15 and July 15 December 8, 2017 October 15, 2027 1.500% Notes $ 650.0 (4.9) — January 31 and July 31 November 20, 2020 November 30, 2027 3.950% Notes $ 600.0 (9.4) (10.4) March 15 and September 15 March 15, 2019 December 15, 2028 3.800% Notes $ 1,650.0 (16.5) (18.3) February 15 and August 15 June 13, 2019 May 15, 2029 2.900% Notes $ 750.0 (8.3) — January 15 and July 15 January 10, 2020 October 15, 2029 2.100% Notes $ 750.0 (9.8) — June 15 and December 15 June 3, 2020 March 15, 2030 1.875% Notes $ 800.0 (9.5) — April 15 and October 15 September 28, 2020 July 15, 2030 1.000% Notes (7) $ 794.0 (7.9) — January 15 September 10, 2020 October 15, 2031 3.700% Notes $ 600.0 (8.1) (8.2) April 15 and October 15 October 3, 2019 April 15, 2049 3.100% Notes (8) $ 1,050.0 (12.3) — June 15 and December 15 June 3, 2020 December 15, 2049 2.950% Notes $ 550.0 (11.8) — January 15 and July 15 November 20, 2020 July 15, 2050 _______________ (1) Includes unamortized discounts, premiums and debt issuance costs and fair value adjustments due to interest rate swaps. (2) Interest payments are due semi-annually for each series of senior notes, except for the 1.375% Notes, the 1.950% Notes, the 0.500% Notes and the 1.000% Notes, for which interest payments are due annually. (3) The Company may redeem the notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of the notes plus a make-whole premium, together with accrued interest to the redemption date. If the Company redeems the notes on or after the par call date, the Company will not be required to pay a make-whole premium. (4) Includes $6.3 million and ($5.9) million fair value adjustment due to interest rate swaps in 2020 and 2019, respectively. (5) Includes $25.1 million and $9.2 million fair value adjustment due to interest rate swaps in 2020 and 2019, respectively. (6) The original issue date for the 5.00% Notes was August 19, 2013. The issue date for the reopened 5.00% Notes was January 10, 2014. (7) Notes are denominated in EUR. (8) The original issue date for the Initial 3.100% Notes was June 3, 2020. The issue date for the Reopened 3.100% Notes was September 28, 2020. The Company may redeem each series of senior notes at any time, subject to the terms of the applicable supplemental indenture, in whole or in part, at a redemption price equal to 100% of the principal amount of the notes plus a make-whole premium, as applicable, together with accrued interest to the redemption date. In addition, if the Company undergoes a change of control and corresponding ratings decline, each as defined in the applicable supplemental indenture, it may be required to repurchase all of the applicable notes at a purchase price equal to 101% of the principal amount of such notes, plus accrued and unpaid interest (including additional interest, if any), up to but not including the repurchase date. The Notes rank equally with all of the Company’s other senior unsecured debt and are structurally subordinated to all existing and future indebtedness and other obligations of its subsidiaries. Each applicable supplemental indenture for the Notes contains certain covenants that restrict the Company’s ability to merge, consolidate or sell assets and its (together with its subsidiaries’) ability to incur liens. These covenants are subject to a number of exceptions, including that the Company and its subsidiaries may incur certain liens on assets, mortgages or other liens securing indebtedness if the aggregate amount of indebtedness secured by such liens does not exceed 3.5x Adjusted EBITDA, as defined in the applicable supplemental indenture. As of December 31, 2020, the Company was in compliance with each of these covenants. American Tower Subsidiary Debt Securitizations The Company has several securitizations in place. Cash flows generated by the sites that secure the securitized debt are only available for payment of such debt and are not available to pay the Company’s other obligations or the claims of its creditors. However, subject to certain restrictions, the Company holds the right to receive the excess cash flows not needed to pay the securitized debt and other obligations arising out of the securitizations. The securitized debt is the obligation of the issuers thereof or borrowers thereunder, as applicable, and their subsidiaries, and not of the Company or its other subsidiaries. American Tower Secured Revenue Notes, Series 2015-1, Class A and Series 2015-2, Class A —In May 2015, GTP Acquisition Partners I, LLC (“GTP Acquisition Partners”), one of the Company’s wholly owned subsidiaries, refinanced existing debt with cash on hand and proceeds from a private issuance (the “2015 Securitization”) of $350.0 million of American Tower Secured Revenue Notes, Series 2015-1, Class A (the “Series 2015-1 Notes”) and $525.0 million of American Tower Secured Revenue Notes, Series 2015-2, Class A (the “Series 2015-2 Notes,” and together with the Series 2015-1 Notes, the “2015 Notes”). The 2015 Notes were issued by GTP Acquisition Partners pursuant to a Third Amended and Restated Indenture and related series supplements, each dated as of May 29, 2015 (collectively, the “2015 Indenture”), between GTP Acquisition Partners and its subsidiaries (the “GTP Entities”) and The Bank of New York Mellon, as trustee. The effective weighted average life and interest rate of the 2015 Notes was 8.1 years and 3.029%, respectively, as of the date of issuance. Repayment of Series 2015-1 Notes —On the June 2020 payment date, the Company repaid the entire $350.0 million aggregate principal amount outstanding under the Series 2015-1 Notes, pursuant to the terms of the agreements governing such securities. The repayment was funded with cash on hand. The outstanding Series 2015-2 Notes are secured by (i) mortgages, deeds of trust and deeds to secure debt on substantially all of the 3,538 communications sites (the “2015 Secured Sites”) owned by the GTP Entities and their operating cash flows, (ii) a security interest in substantially all of the personal property and fixtures of the GTP Entities, including GTP Acquisition Partners’ equity interests in its subsidiaries and (iii) the rights of the GTP Entities under a management agreement. American Tower Holding Sub II, LLC, whose only material assets are its equity interests in GTP Acquisition Partners, has guaranteed repayment of the Series 2015-2 Notes and pledged its equity interests in GTP Acquisition Partners as security for such payment obligations. Secured Tower Revenue Securities, Series 2013-2A , Secured Tower Revenue Securities, Series 2018-1, Subclass A and Series 2018-1, Subclass R —On March 29, 2018, the Company completed a securitization transaction (the “2018 Securitization”), in which the American Tower Trust I (the “Trust”) issued $500.0 million aggregate principal amount of Secured Tower Revenue Securities, Series 2018-1, Subclass A (the “Series 2018-1A Securities”). To satisfy the applicable risk retention requirements of Regulation RR promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act” and, such requirements, the “Risk Retention Rules”), the Trust issued, and one of the Company’s affiliates purchased, $26.4 million aggregate principal amount of Secured Tower Revenue Securities, Series 2018-1, Subclass R (the “Series 2018-1R Securities” and, together with the Series 2018-1A Securities, the “2018 Securities”) to retain an “eligible horizontal residual interest” (as defined in the Risk Retention Rules) in an amount equal to at least 5% of the fair value of the 2018 Securities. The Secured Tower Revenue Securities, Series 2013-2A (the “Series 2013-2A Securities” and, together with the 2018 Securities the “Trust Securities”) issued in a securitization transaction in March 2013 (the “2013 Securitization” and, together with the 2018 Securitization, the “Trust Securitizations”) remain outstanding and are subject to the terms of the Second Amended and Restated Trust and Servicing Agreement entered into in connection with the 2018 Securitization. The assets of the Trust consist of a nonrecourse loan (the “Loan”) made by the Trust to American Tower Asset Sub, LLC and American Tower Asset Sub II, LLC (together, the “AMT Asset Subs”). The AMT Asset Subs are jointly and severally liable under the Loan, which is secured primarily by mortgages on the AMT Asset Subs’ interests in 5,114 broadcast and wireless communications towers and related assets (the “Trust Sites”). The component of the Loan corresponding to the Series 2013-2A Securities also remains outstanding and is subject to the terms of the Second Amended and Restated Loan and Security Agreement among the Trust and the AMT Asset Subs, dated as of March 29, 2018 (the “Loan Agreement”). The Loan Agreement includes terms and conditions, including with respect to secured assets, substantially consistent with the First Amended and Restated Loan and Security Agreement dated as of March 15, 2013. The 2018 Securities correspond to components of the Loan made to the AMT Asset Subs pursuant to the Loan Agreement and were issued in two separate subclasses of the same series. The 2018 Securities represent a pass-through interest in the components of the Loan corresponding to the 2018 Securities. The Series 2018-1A Securities have an interest rate of 3.652% and the Series 2018-1R Securities have an interest rate of 4.459%. The 2018 Securities have an expected life of approximately ten years with a final repayment date in March 2048. Subject to certain limited exceptions described below, no payments of principal will be required to be made on the components of the Loan corresponding to the 2018 Securities prior to the monthly payment date in March 2028, which is the anticipated repayment date for such components. The Loan is secured by (1) mortgages, deeds of trust and deeds to secure debt on substantially all of the Trust Sites and their operating cash flows, (2) a security interest in substantially all of the AMT Asset Subs’ personal property and fixtures and (3) the AMT Asset Subs’ rights under that certain management agreement among the AMT Asset Subs and SpectraSite Communications, LLC entered into in March 2013. American Tower Holding Sub, LLC (the “Guarantor”), whose only material assets are its equity interests in each of the AMT Asset Subs, and American Tower Guarantor Sub, LLC whose only material asset is its equity interests in the Guarantor, have each guaranteed repayment of the Loan and pledged their equity interests in their respective subsidiary or subsidiaries as security for such payment obligations. Under the terms of the Loan Agreement and the 2015 Indenture, amounts due will be paid from the cash flows generated by the Trust Sites or the 2015 Secured Sites, respectively, which must be deposited into certain reserve accounts, and thereafter distributed solely pursuant to the terms of the Loan Agreement or 2015 Indenture, as applicable. On a monthly basis, after payment of all required amounts under the Loan Agreement or 2015 Indenture, as applicable, including interest payments, subject to the conditions described below, the excess cash flows generated from the operation of such assets are released to the AMT Asset Subs or GTP Acquisition Partners, as applicable, which can then be distributed to, and used by, the Company. In order to distribute any excess cash flow to the Company, the AMT Asset Subs and GTP Acquisition Partners must each maintain a specified debt service coverage ratio (the “DSCR”), which is generally calculated as the ratio of the net cash flow (as defined in the applicable agreement) to the amount of interest, servicing fees and trustee fees required to be paid over the succeeding 12 months on the principal amount of the Loan or the 2015 Notes, as applicable, that will be outstanding on the payment date following such date of determination. If the DSCR were equal to or below 1.30x (the “Cash Trap DSCR”) for any quarter, then all cash flow in excess of amounts required to make debt service payments, fund required reserves, pay management fees and budgeted operating expenses and make other p

OTHER NON-CURRENT LIABILITIES

OTHER NON-CURRENT LIABILITIES	12 Months Ended
	Dec. 31, 2020
Other Liabilities, Noncurrent [Abstract]
OTHER NON-CURRENT LIABILITIES	OTHER NON-CURRENT LIABILITIES Other non-current liabilities consisted of the following: As of December 31, 2020 December 31, 2019 Unearned revenue $ 576.1 $ 525.9 Other miscellaneous liabilities 408.5 411.1 Other non-current liabilities $ 984.6 $ 937.0

ASSET RETIREMENT OBLIGATIONS

ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2020
Asset Retirement Obligation [Abstract]
ASSET RETIREMENT OBLIGATIONS	ASSET RETIREMENT OBLIGATIONS The changes in the carrying amount of the Company’s asset retirement obligations were as follows: 2020 2019 Beginning balance as of January 1, $ 1,384.1 $ 1,210.0 Additions 94.2 61.8 Accretion expense 90.8 81.6 Revisions in estimates (1) 8.3 56.8 Settlements (6.1) (26.1) Balance as of December 31, $ 1,571.3 $ 1,384.1 _______________ (1) Revisions in estimates include decreases to the liability of $42.1 million and $6.7 million related to foreign currency translation for the years ended December 31, 2020 and 2019, respectively. As of December 31, 2020, the estimated undiscounted future cash outlay for asset retirement obligations was $3.7 billion.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2020
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 values of the Company’s financial assets and liabilities that are required to be measured on a recurring basis at fair value were as follows: December 31, 2020 December 31, 2019 Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Interest rate swap agreements — $ 29.2 — — $ 9.0 — Embedded derivative in lease agreement — — — — — $ 10.7 Liabilities: Interest rate swap agreements — $ 0.1 — — $ 7.5 — Fair value of debt related to interest rate swap agreements (1) $ 31.4 — — $ 3.3 — — _______________ (1) Included in the carrying values of the corresponding debt obligations. Interest Rate Swap Agreements The fair value of the Company’s interest rate swap agreements is determined using pricing models with inputs that are observable in the market or can be derived principally from, or corroborated by, observable market data. For derivative instruments that are designated and qualify as fair value hedges, changes in the value of the derivatives are recognized in the consolidated statements of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments that are designated and qualify as cash flow hedges, the Company records the change in fair value for the effective portion of the cash flow hedges in AOCL in the consolidated balance sheets and reclassifies a portion of the value from AOCL into Interest expense on a quarterly basis as the cash flows from the hedged item affects earnings. The Company records the settlement of interest rate swap agreements in (Loss) gain on retirement of long-term obligations in the consolidated statements of operations in the period in which the settlement occurs. The Company entered into three interest rate swap agreements with an aggregate notional value of $500.0 million related to the 3.000% senior unsecured notes due 2023 (the “3.000% Notes”). These interest rate swaps, which were designated as fair value hedges at inception, were entered into to hedge against changes in fair value of the 3.000% Notes resulting from changes in interest rates. The interest rate swap agreements require the Company to pay interest at a variable interest rate of one-month LIBOR plus applicable spreads and to receive fixed interest at a rate of 3.000% through June 15, 2023. The Company entered into three interest rate swap agreements with an aggregate notional value of $600.0 million related to the 2.250% senior unsecured notes due 2022 (the “2.250% Notes”). These interest rate swaps, which were designated as fair value hedges at inception, were entered into to hedge against changes in fair value of the 2.250% Notes resulting from changes in interest rates. The interest rate swap agreements require the Company to pay interest at a variable interest rate of one-month LIBOR plus applicable spreads and to receive fixed interest at a rate of 2.250% through January 15, 2022. The fair value of the U.S. interest rate swap asset of $29.2 million was included in Other non-current assets on the consolidated balance sheets at December 31, 2020. The fair values of the U.S. interest rate swap asset of $9.0 million and U.S. interest rate swap liability of $7.4 million were included in Other non-current assets and Other non-current liabilities, respectively, on the consolidated balance sheets at December 31, 2019. During the year ended December 31, 2020, the Company recorded net fair value adjustments of $0.4 million related to interest rate swaps and the change in fair value of debt due to interest rate swaps in Other expense in the consolidated statements of operations. One of the Company’s Colombian subsidiaries is party to an interest rate swap agreement with certain lenders under the Colombian Credit Facility (the “Colombia Interest Rate Swap”). The Colombia Interest Rate Swap, which was designated as a cash flow hedge at inception, was entered into to manage exposure to variability in interest rates on debt. The Colombia Interest Rate Swap requires the payment of a fixed interest rate of 5.37% and pays variable interest at the three-month Inter-bank Rate through the earlier of termination of the underlying debt or April 24, 2021. As of December 31, 2020, the aggregate notional amount of the Colombia Interest Rate Swap was 30.0 billion COP ($8.7 million). The fair value of the Colombia Interest Rate Swap as of December 31, 2020 and 2019 was less than $0.1 million and $0.1 million, respectively, and was included in Other non-current liabilities on the consolidated balance sheets. Embedded Derivative in Lease Agreement In connection with the acquisition of communications sites in Nigeria, the Company entered into a site lease agreement where a portion of the monthly rent to be received is escalated based on an index outside the lessor’s economic environment. The fair value of the portion of the lease tied to the U.S. CPI was $14.6 million at the date of acquisition and was recorded in Notes receivable and other non-current assets on the consolidated balance sheets. During the year ended December 31, 2020, the Company recorded an adjustment to the embedded derivative of $10.2 million, which is included in Other income (expense) in the consolidated statements of operations. As of December 31, 2020, the Company had no embedded derivatives outstanding. Redeemable Noncontrolling Interests The Company records the carrying amount of the redeemable noncontrolling interests as described in note 15. Items Measured at Fair Value on a Nonrecurring Basis Assets Held and Used —The Company’s long-lived assets are recorded at amortized cost and, if impaired, are adjusted to fair value using Level 3 inputs. During the year ended December 31, 2020, certain long-lived assets held and used with a carrying value of $24.1 billion were written down to their net realizable value as a result of an asset impairment charge of $222.8 million. During the year ended December 31, 2019, certain long-lived assets held and used with a carrying value of $22.4 billion were written down to their net realizable value as a result of an asset impairment charge of $94.2 million. The asset impairment charges are recorded in Other operating expenses in the accompanying consolidated statements of operations. These adjustments were determined by comparing the estimated fair value utilizing projected future discounted cash flows to be provided from the long-lived assets to the asset’s carrying value. There were no other items measured at fair value on a nonrecurring basis during the year ended December 31, 2020. Fair Value of Financial Instruments —The Company’s financial instruments for which the carrying value reasonably approximates fair value at December 31, 2020 and 2019 include cash and cash equivalents, restricted cash, accounts receivable

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Beginning in the taxable year ended December 31, 2012, the Company has filed, and intends to continue to file, U.S. federal income tax returns as a REIT, and its domestic TRSs filed, and intend to continue to file, separate tax returns as required. The Company also files tax returns in various states and countries. The Company’s state tax returns reflect different combinations of the Company’s subsidiaries and are dependent on the connection each subsidiary has with a particular state and form of organization. The following information pertains to the Company’s income taxes on a consolidated basis. The income tax provision from continuing operations consisted of the following: Year Ended December 31, 2020 2019 2018 Current: Federal $ 8.7 $ (1.7) $ (1.4) State (10.7) (5.0) (1.8) Foreign (150.1) (48.2) (189.7) Deferred: Federal (1.0) 1.4 4.0 State (1.0) 0.5 0.7 Foreign 24.5 53.2 298.3 Income tax (provision) benefit $ (129.6) $ 0.2 $ 110.1 The effective tax rate (“ETR”) on income from continuing operations for the years ended December 31, 2020, 2019 and 2018 differs from the federal statutory rate primarily due to the Company’s qualification for taxation as a REIT, as well as adjustments for state and foreign items. As a REIT, the Company may deduct earnings distributed to stockholders against the income generated by its REIT operations. In addition, the Company is able to offset certain income by utilizing its remaining NOLs, subject to specified limitations. In 2019, there was an income tax law change in India that allows companies to elect into an optional concessional tax regime. The new regime allows for a lower effective tax rate from approximately 35% to approximately 25% and no minimum alternative tax, while disallowing the benefit of the minimum alternative tax credits. As a result, the Company recorded a $113.0 million one-time tax benefit during the year ended December 31, 2019 arising from revaluing its net deferred tax liability. In 2018, the income tax benefit was attributable to impairment charges and accelerated amortization on intangible assets taken in India as well as a benefit of $85.7 million related to the restructuring of international operations in certain jurisdictions. These benefits were partially offset by the receipt of the payment related to the Tata settlement. Reconciliation between the U.S. statutory rate and the effective rate from continuing operations is as follows: Year Ended December 31, 2020 2019 2018 Statutory tax rate 21 % 21 % 21 % Adjustment to reflect REIT status (1) (21) (21) (21) Foreign taxes 4 3 (8) Foreign withholding taxes 3 3 4 Uncertain tax positions 1 1 — Changes in tax laws — (6) — Impact from restructuring — (1) (6) Changes in valuation allowance (1) — — Effective tax rate 7 % (0)% (10) % _______________ (1) As a result of the ability to utilize the dividends paid deduction to offset the Company’s REIT income and gains. The domestic and foreign components of income from continuing operations before income taxes are as follows: Year Ended December 31, 2020 2019 2018 United States $ 1,683.0 $ 1,527.0 $ 1,212.7 Foreign 138.1 389.4 (58.1) Total $ 1,821.1 $ 1,916.4 $ 1,154.6 The components of the net deferred tax asset and liability and related valuation allowance were as follows: December 31, 2020 December 31, 2019 Assets: Operating lease liability $ 837.1 $ 878.5 Net operating loss carryforwards 327.1 356.6 Accrued asset retirement obligations 187.8 174.9 Stock-based compensation 9.2 5.6 Unearned revenue 34.6 31.7 Unrealized loss on foreign currency 4.9 3.8 Other accruals and allowances 83.4 65.6 Nondeductible interest 60.9 15.9 Items not currently deductible and other 65.8 10.2 Liabilities: Depreciation and amortization (1,140.3) (1,040.3) Right-of-use asset (824.0) (865.1) Deferred rent (92.9) (79.7) Investment in affiliate (1) (60.4) — Other (1.1) — Subtotal (507.9) (442.3) Valuation allowance (228.5) (194.2) Net deferred tax liabilities $ (736.4) $ (636.5) _______________ (1) Includes basis difference associated with investment in subsidiary related to the InSite Acquisition. 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 evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Valuation allowances may be reversed if, based on changes in facts and circumstances, the net deferred tax assets have been determined to be realizable. At December 31, 2020 and 2019, the Company has provided a valuation allowance of $228.5 million and $194.2 million, respectively, which primarily relates to foreign items. The increase in the valuation allowance for the year ending December 31, 2020 is due to uncertainty as to the timing of, and the Company’s ability to recover, net deferred tax assets in certain foreign operations in the foreseeable future, offset by reversals and fluctuations in foreign currency exchange rates. The amount of deferred tax assets considered realizable, however, could be adjusted if objective evidence in the form of cumulative losses is no longer present and additional weight may be given to subjective evidence such as the Company’s projections for growth. A summary of the activity in the valuation allowance is as follows: 2020 2019 2018 Balance as of January 1, $ 194.2 $ 151.9 $ 142.0 Additions (1) 64.7 42.5 15.7 Usage, expiration and reversals (22.0) — — Foreign currency translation (8.4) (0.2) (5.8) Balance as of December 31, $ 228.5 $ 194.2 $ 151.9 _______________ (1) Includes net charges to expense and allowances established due to acquisition. The recoverability of the Company’s deferred tax assets has been assessed utilizing projections based on its current operations. Accordingly, the recoverability of the deferred tax assets is not dependent on material asset sales or other non-routine transactions. Based on its current outlook of future taxable income during the carryforward period, the Company believes that deferred tax assets, other than those for which a valuation allowance has been recorded, will be realized. At December 31, 2020, the Company had net federal, state and foreign operating loss carryforwards available to reduce future taxable income. If not utilized, the Company’s NOLs expire as follows: Years ended December 31, Federal State Foreign 2021 to 2025 $ 141.6 $ 180.2 $ 12.4 2026 to 2030 0.0 193.7 85.6 2031 to 2035 9.5 48.7 3.5 2036 to 2040 61.7 183.0 — Indefinite carryforward 142.1 47.7 679.5 Total $ 354.9 $ 653.3 $ 781.0 As of December 31, 2020 and 2019, the total amount of unrecognized tax benefits that would impact the ETR, if recognized, is $105.9 million and $158.1 million, respectively. The amount of unrecognized tax benefits for the year ended December 31, 2020 includes additions to the Company’s existing tax positions of $26.2 million. The Company expects the unrecognized tax benefits to change over the next 12 months if certain tax matters ultimately settle with the applicable taxing jurisdiction during this timeframe, or if the applicable statute of limitations lapses. The impact of the amount of such changes to previously recorded uncertain tax positions could range from zero to $32.7 million. A reconciliation of the beginning and ending amount of unrecognized tax benefits are as follows: Year Ended December 31, 2020 2019 2018 Balance at January 1 $ 175.6 $ 107.7 $ 116.7 Additions based on tax positions related to the current year 4.7 33.3 8.1 Additions and reductions for tax positions of prior years (1) (5.0) 37.5 0.3 Foreign currency (9.6) (1.6) (8.1) Reduction as a result of the lapse of statute of limitations (26.0) (1.3) (2.6) Reduction as a result of effective settlements (3.5) — (6.7) Balance at December 31 $ 136.2 $ 175.6 $ 107.7 _______________ (1) Year ended December 31, 2020 includes adjustments of $(21.0) million for positions related to the Eaton Towers Acquisition that were revised in connection with settlements or effective settlements. During the year ended December 31, 2020, the statute of limitations on certain unrecognized tax benefits lapsed and certain positions were effectively settled, including effective settlements and revisions of prior year positions related to the Eaton Towers Acquisition, which resulted in a decrease in the liability for unrecognized tax benefits of $50.5 million. During the years ended December 31, 2019 and 2018, the statute of limitations on certain unrecognized tax benefits lapsed and certain positions were effectively settled, which resulted in decreases of $2.5 million and $9.3 million, respectively, in the liability for unrecognized tax benefits. The Company recorded penalties and tax-related interest expense to the tax provision of $16.4 million, $10.3 million and $8.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. In addition, due to the expiration of the statute of limitations in certain jurisdictions and certain positions that were effectively settled, the Company reduced its liability for penalties and income tax-related interest expense related to uncertain tax positions during the years ended December 31, 2020, 2019 and 2018 by $4.8 million, $2.7 million and $16.2 million, respectively. As of December 31, 2020 and 2019, the total amount of accrued income tax-related interest and penalties included in the consolidated balance sheets were $34.4 million and $26.6 million, respectively. The Company has filed for prior taxable years, and for its taxable year ended December 31, 2020 will file, numerous consolidated and separate income tax returns, including U.S. federal and state tax returns and foreign tax returns. The Company is subject to examination in the U.S. and various state and foreign jurisdictions for certain tax years. As a result of the Company’s ability to carryforward federal, state and foreign NOLs, the applicable tax years generally remain open to examination several years after the applicable loss carryforwards have been used or have expired. The Company regularly assesses the likelihood of additional assessments in each of the tax jurisdictions resulting from these examinations. The Company believes that adequate provisions have been made for income taxes for all periods through December 31, 2020.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION Summary of Stock-Based Compensation Plans —The Company maintains equity incentive plans that provide for the grant of stock-based awards to its directors, officers and employees. The 2007 Equity Incentive Plan, as amended (the “2007 Plan”), provides for the grant of non-qualified and incentive stock options, as well as restricted stock units, restricted stock and other stock-based awards. Exercise prices for non-qualified and incentive stock options are not less than the fair value of the underlying common stock on the date of grant. Equity awards typically vest ratably, generally over four years for RSUs and stock options and three years for PSUs. Stock options generally expire 10 years from the date of grant. As of December 31, 2020, the Company had the ability to grant stock-based awards with respect to an aggregate of 6.5 million shares of common stock under the 2007 Plan. In addition, the Company maintains an employee stock purchase plan (the “ESPP”) pursuant to which eligible employees may purchase shares of the Company’s common stock on the last day of each bi-annual offering period at a 15% discount from the lower of the closing market value on the first or last day of such offering period. The offering periods run from June 1 through November 30 and from December 1 through May 31 of each year. During the years ended December 31, 2020, 2019 and 2018, the Company recorded and capitalized the following stock-based compensation expenses: 2020 2019 2018 Stock-based compensation expense - Property $ 1.9 $ 1.8 $ 2.4 Stock-based compensation expense - Services 1.1 1.0 0.9 Stock-based compensation expense - SG&A 117.8 108.6 134.2 Total stock-based compensation expense $ 120.8 $ 111.4 $ 137.5 Stock-based compensation expense capitalized as property and equipment $ 1.7 $ 1.6 $ 2.0 Stock Options —There were no options granted during the years ended December 31, 2020, 2019 and 2018. The fair values of previously granted stock options were estimated on the date of grant using the Black-Scholes option pricing model based on the assumptions at the date of grant. The intrinsic value of stock options exercised during the years ended December 31, 2020, 2019 and 2018 was $176.3 million, $145.5 million and $98.8 million, respectively. As of December 31, 2020, total unrecognized compensation expense related to unvested stock options was less than $0.1 million and is expected to be recognized over a weighted average period of less than one year. The amount of cash received from the exercise of stock options was $84.7 million during the year ended December 31, 2020. The Company’s option activity for the year ended December 31, 2020 was as follows (share and per share data disclosed in full amounts): Options Weighted Weighted Aggregate Outstanding as of January 1, 2020 3,060,242 $85.90 Granted — — Exercised (1,043,981) 81.16 Forfeited — — Expired — — Outstanding as of December 31, 2020 2,016,261 $88.36 3.15 $274.4 Exercisable as of December 31, 2020 2,014,628 $88.33 3.15 $274.2 Vested or expected to vest as of December 31, 2020 2,016,261 $88.36 3.15 $274.4 The following table sets forth information regarding options outstanding at December 31, 2020 (share and per share data disclosed in full amounts): Options Outstanding Options Exercisable Range of Exercise Outstanding Weighted Weighted Average Options Weighted $50.78 - $71.07 102,447 $ 61.55 1.14 102,447 $ 61.55 $76.90 - $77.75 221,435 76.92 1.82 221,435 76.92 $81.18 - $94.23 432,352 81.58 2.66 432,352 81.58 $94.57 - $94.71 1,240,897 94.61 3.69 1,240,897 94.61 $99.67 - $121.15 19,130 111.97 5.45 17,497 111.39 $50.78 - $121.15 2,016,261 $ 88.36 3.15 2,014,628 $ 88.33 Restricted Stock Units and Performance-Based Restricted Stock Units —The Company’s RSU and PSU activity for the year ended December 31, 2020 was as follows (share and per share data disclosed in full amounts): RSUs Weighted Average Grant Date Fair Value PSUs Weighted Average Grant Date Fair Value Outstanding as of January 1, 2020 (1) 1,454,350 $ 147.67 528,908 $ 136.94 Granted (2) 456,369 243.25 151,341 216.36 Vested and Released (3) (618,013) 134.53 (282,774) 113.58 Forfeited (4) (47,631) 173.74 (76,965) 211.21 Outstanding as of December 31, 2020 1,245,075 $ 188.23 320,510 $ 177.22 Expected to vest as of December 31, 2020 1,245,075 $ 188.23 320,510 $ 177.22 Vested and deferred as of December 31, 2020 (5) 58,204 $ 181.26 — $ — _______________ (1) PSUs consist of the target number of shares issuable at the end of the three three three (2) PSUs consist of the target number of shares issuable at the end of the three three three (3) This includes 19,810 of previously vested and deferred RSUs. PSUs consist of shares vested pursuant to the 2017 PSUs. There are no additional shares to be earned related to the 2017 PSUs. (4) PSUs consist of shares forfeited in connection with the retirement of the Company’s former CEO, which includes the target number of shares issuable at the end of the three three (5) Vested and deferred RSUs are related to deferred compensation for certain former employees. The total fair value of RSUs and PSUs that vested during the year ended December 31, 2020 was $214.1 million. Restricted Stock Units— As of December 31, 2020, total unrecognized compensation expense related to unvested RSUs granted under the 2007 Plan was $125.7 million and is expected to be recognized over a weighted average period of approximately two years. Vesting of RSUs is subject generally to the employee’s continued employment or death, disability or qualified retirement (each as defined in the applicable RSU award agreement). Performance-Based Restricted Stock Units— During the years ended December 31, 2020, 2019 and 2018, the Company’s Compensation Committee granted an aggregate of 110,925 PSUs (the “2020 PSUs”), 114,823 PSUs (the “2019 PSUs”) and 131,311 PSUs (the “2018 PSUs”), respectively, to its executive officers and established the performance metrics for these awards. Threshold, target and maximum parameters were established for the metrics for a three three

REDEEMABLE NONCONTROLLING INTER

REDEEMABLE NONCONTROLLING INTERESTS	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
REDEEMABLE NONCONTROLLING INTERESTS	REDEEMABLE NONCONTROLLING INTERESTS India Redeemable Noncontrolling Interests —On April 21, 2016, the Company, through its wholly owned subsidiary, ATC Asia Pacific Pte. Ltd., acquired a 51% controlling ownership interest in ATC TIPL (formerly Viom), a telecommunications infrastructure company that owns and operates wireless communications towers and indoor DAS networks in India (the “Viom Acquisition”), which was subsequently merged with the Company’s existing India property operations. In connection with the Viom Acquisition, the Company, through one of its subsidiaries, entered into a shareholders agreement (the “Shareholders Agreement”) with Viom and the following remaining Viom shareholders: Tata Sons Limited (“Tata Sons”), Tata Teleservices, IDFC Private Equity Fund III (“IDFC”), Macquarie SBI Infrastructure Investments Pte Limited and SBI Macquarie Infrastructure Trust (together, “Macquarie,” and, collectively with Tata Sons, Tata Teleservices and IDFC, the “Remaining Shareholders”). The Shareholders Agreement also provides the Remaining Shareholders with put options, which allow them to sell outstanding shares of ATC TIPL to the Company, and the Company with call options, which allow it to buy the noncontrolling shares of ATC TIPL. The put options, which are not under the Company’s control, cannot be separated from the noncontrolling interests. As a result, the combination of the noncontrolling interests and the redemption feature requires classification as redeemable noncontrolling interests in the consolidated balance sheet, separate from equity. The noncontrolling interests become redeemable after the passage of time, and therefore, the Company records the carrying amount of the noncontrolling interests outside of permanent equity at the greater of (i) the initial carrying amount, increased or decreased for the noncontrolling interests’ share of net income or loss and foreign currency translation adjustments, or (ii) the estimated redemption value. If required, the Company will adjust the redeemable noncontrolling interests to the estimated redemption value on each balance sheet date with changes in the estimated redemption value recognized as an adjustment to Net income attributable to noncontrolling interests. The Company adjusts the estimated redemption value of the noncontrolling interests based on the operating results of ATC TIPL and previously recorded adjustments to the estimated redemption value. The put options may be exercised, requiring the Company to purchase the Remaining Shareholders’ equity interests, on specified dates through March 31, 2021. During the year ended December 31, 2019, the Company redeemed 50% of Tata Teleservices and Tata Sons’ combined holdings of ATC TIPL and 100% of IDFC’s holdings of ATC TIPL, for total consideration of INR 29.4 billion ($425.7 million at the date of redemption). As a result of the redemption, the Company’s controlling interest in ATC TIPL increased from 63% to 79% and the noncontrolling interest decreased from 37% to 21%. During the year ended December 31, 2020, the Company redeemed 100% of Tata Teleservices and Tata Sons’ remaining combined holdings of ATC TIPL, for total consideration of INR 24.8 billion ($337.3 million at the date of redemption). As a result of the redemption, the Company’s controlling interest in ATC TIPL increased from 79% to 92% and the noncontrolling interest decreased from 21% to 8%. In February 2021, the Company entered into an agreement with Macquarie to redeem 100% of their combined holdings in ATC TIPL at price of INR 175 per share, subject to certain adjustments. Accordingly, the Company expects to pay an amount equivalent to INR 12.9 billion (approximately $176.6 million) to redeem the shares in 2021, subject to regulatory approval. After the completion of the redemption, the Company will hold a 100% ownership interest in ATC TIPL. Other Redeemable Noncontrolling Interests —During the year ended December 31, 2020, the Company completed the acquisition of MTN’s noncontrolling interests in each of the Company’s joint ventures in Ghana and Uganda for total consideration of approximately $524.4 million, including a net adjustment of $1.4 million made during the three months ended March 31, 2020, which resulted in an increase in the Company’s controlling interests in such joint ventures from 51% to 100%. During the year ended December 31, 2019, the Company, through a subsidiary of ATC Europe, entered into an agreement with its local partners in France to form Eure-et-Loir Réseaux Mobiles SAS (“Eure-et-Loir”), a telecommunications infrastructure company that owns and operates wireless communications towers in France. The Company’s controlling interest in Eure-et-Loir is 51% with local partners holding a 49% noncontrolling interest. The value of the Eure-et-Loir interests as of December 31, 2020 was $2.6 million. The changes in Redeemable noncontrolling interests for the years ended December 31, 2020, 2019 and 2018 were as follows: Year Ended December 31, 2020 2019 2018 Balance as of January 1, $ 1,096.5 $ 1,004.8 $ 1,126.2 Additions to redeemable noncontrolling interests — 525.7 — Net income (loss) attributable to noncontrolling interests 6.6 35.8 (87.9) Adjustment to noncontrolling interest redemption value (14.0) (35.8) 86.7 Adjustment to noncontrolling interest due to merger — — (28.1) Purchase of redeemable noncontrolling interest (861.7) (425.7) — Foreign currency translation adjustment attributable to noncontrolling interests (15.3) (8.3) (92.1) Balance as of December 31, $ 212.1 $ 1,096.5 $ 1,004.8

EQUITY

EQUITY	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
EQUITY	EQUITY Dividends —The Company may pay dividends in cash or, subject to certain limitations, in shares of common stock or any combination of cash and shares of common stock. Sales of Equity Securities —The Company receives proceeds from sales of its equity securities pursuant to the ESPP and upon exercise of stock options granted under the 2007 Plan. During the year ended December 31, 2020, the Company received an aggregate of $98.1 million in proceeds upon exercises of stock options and sales pursuant to the ESPP. 2020 “At the Market” Stock Offering Program —In August 2020, the Company established an “at the market” stock offering program through which it may issue and sell shares of its common stock having an aggregate gross sales price of up to $1.0 billion (the “2020 ATM Program”). Sales under the 2020 ATM Program may be made by means of ordinary brokers’ transactions on the New York Stock Exchange or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or, subject to specific instructions of the Company, at negotiated prices. The Company intends to use the net proceeds from any issuances under the 2020 ATM Program for general corporate purposes, which may include, among other things, the funding of acquisitions, additions to working capital and repayment or refinancing of existing indebtedness. As of December 31, 2020, the Company has not sold any shares of common stock under the 2020 ATM Program. Stock Repurchase Programs —In March 2011, the Company’s Board of Directors approved a stock repurchase program, pursuant to which the Company is authorized to repurchase up to $1.5 billion of its common stock (the “2011 Buyback”). In December 2017, the Board of Directors approved an additional stock repurchase program, pursuant to which the Company is authorized to repurchase up to $2.0 billion of its common stock (the “2017 Buyback,” and, together with the 2011 Buyback, the “Buyback Programs”). During the year ended December 31, 2020, the Company repurchased 264,086 shares of its common stock under the 2011 Buyback for an aggregate of $56.0 million, including commissions and fees. As of December 31, 2020, the Company had repurchased a total of 14,361,283 shares of its common stock under the 2011 Buyback for an aggregate of $1.5 billion, including commissions and fees. There were no repurchases under the 2017 Buyback. Under the Buyback Programs, the Company is authorized to purchase shares from time to time through open market purchases or in privately negotiated transactions not to exceed market prices and subject to market conditions and other factors. With respect to open market purchases, the Company may use plans adopted in accordance with Rule 10b5-1 under the Exchange Act in accordance with securities laws and other legal requirements, which allows the Company to repurchase shares during periods when it may otherwise be prevented from doing so under insider trading laws or because of self-imposed trading blackout periods. 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. Repurchases under the Buyback Programs are subject to, among other things, the Company having available cash to fund the repurchases. Distributions —During the years ended December 31, 2020, 2019 and 2018, the Company declared the following cash distributions (per share data reflects actual amounts): For the year ended December 31, 2020 2019 2018 Distribution Aggregate Distribution Aggregate Distribution Aggregate Common Stock $ 4.53 $ 2,010.7 $ 3.78 $ 1,672.8 $ 3.15 $ 1,389.8 Series B Preferred Stock (1) $ — $ — $ — $ — $ 13.75 $ 18.9 _______________ (1) 5.50% Mandatory Convertible Preferred Stock, Series B, par value $0.01 per share (the “Series B Preferred Stock”), which converted into shares of the Company’s common stock pursuant to the provisions of the Certificate of Designations governing the Series B Preferred Stock in 2018. The following table characterizes the tax treatment of distributions declared per share of common stock and Mandatory Convertible Preferred Stock. For the year ended December 31, 2020 2019 2018 Per Share % Per Share % Per Share % Common Stock Ordinary dividend $ 3.3200 (1) 100.00 % $ 3.7800 100.00 % $ 3.1500 100.00 % Capital gains distribution — — — — — — Total $ 3.3200 100.00 % $ 3.7800 100.00 % $ 3.1500 100.00 % Series B Preferred Stock (2) Ordinary dividend $ — — % $ — — % $ 2.1314 (3) 100.00 % Capital gains distribution — — — — — — Total $ — — % $ — — % $ 2.1314 100.00 % _______________ (1) Excludes dividend declared on December 3, 2020 of $1.21 per share, which was paid on February 2, 2021 to common stockholders of record at the close of business on December 28, 2020 and which will apply to the 2021 tax year. (2) Represents the tax treatment on dividends per depositary share, each of which represents a 1/10th interest in a share of Series B Preferred Stock. (3) Includes a deemed distribution as a result of a conversion rate adjustment triggered on January 18, 2018. The Company accrues distributions on unvested restricted stock units, which are payable upon vesting. The amount accrued for distributions payable related to unvested restricted stock units was $12.6 million and $14.3 million as of December 31, 2020 and 2019, respectively. During the year ended December 31, 2020, the Company paid $7.8 million of distributions upon the vesting of restricted stock units. To maintain its qualification for taxation as a REIT, the Company expects to continue paying distributions, the amount, timing and frequency of which will be determined, and subject to adjustment, by the Company’s Board of Directors.

OTHER OPERATING EXPENSES

OTHER OPERATING EXPENSES	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
OTHER OPERATING EXPENSE	OTHER OPERATING EXPENSE Other operating expense consists primarily of impairment charges, net losses on sales or disposals of assets and other operating expense items. The Company records impairment charges to write down certain assets to their net realizable value after an indicator of impairment is identified and subsequent analysis determines that the asset is either partially recoverable or not recoverable. These assets consisted primarily of towers and related assets, which are typically assessed on an individual basis, network location intangibles, which relate directly to towers, tenant-related intangibles, which are assessed on a tenant basis, and right-of-use assets. Net losses on sales or disposals of assets primarily relate to certain non-core towers, other assets and miscellaneous items. Other operating expenses includes acquisition-related costs and integration costs. Other operating expenses included the following for the years ended December 31,: 2020 (1) 2019 (2) 2018 Impairment charges $ 222.8 $ 94.2 $ 394.0 Net losses on sales or disposals of assets 17.3 45.1 85.6 Other operating expenses 25.7 27.0 33.7 Total Other operating expenses $ 265.8 $ 166.3 $ 513.3 _______________ (1) For the year ended December 31, 2020, Other operating expenses includes an $11.9 million benefit in Brazil. (2) For the year ended December 31, 2019, Other operating expenses includes $13.1 million of refunds related to pre-acquisition contingencies and settlements. Impairment charges included the following for the years ended December 31,: 2020 2019 2018 (1) Tower and network location intangible assets $ 142.4 $ 77.4 $ 284.9 Tenant relationships — — 107.3 Right-of-use assets 76.1 9.9 — Other 4.3 6.9 1.8 Total impairment charges $ 222.8 $ 94.2 $ 394.0 _______________ (1) For the year ended December 31, 2018, impairment charges on tower and network location intangible assets included $258.3 million in India primarily related to carrier consolidation-driven churn events. In addition, the Company fully impaired the tenant relationship for Aircel Ltd., which resulted in an impairment charge of $107.3 million.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE The following table sets forth basic and diluted net income per common share computational data for the years ended December 31, (shares in thousands, except per share data): 2020 2019 2018 Net income attributable to American Tower Corporation stockholders $ 1,690.6 $ 1,887.8 $ 1,236.4 Dividends on preferred stock — — (9.4) Net income attributable to American Tower Corporation common stockholders $ 1,690.6 $ 1,887.8 $ 1,227.0 Basic weighted average common shares outstanding 443,640 442,319 439,606 Dilutive securities 2,464 3,201 3,354 Diluted weighted average common shares outstanding 446,104 445,520 442,960 Basic net income attributable to American Tower Corporation common stockholders per common share $ 3.81 $ 4.27 $ 2.79 Diluted net income attributable to American Tower Corporation common stockholders per common share $ 3.79 $ 4.24 $ 2.77 Shares Excluded From Dilutive Effect The following shares were not included in the computation of diluted earnings per share because the effect would be anti-dilutive for the years ended December 31, (in thousands, on a weighted average basis): 2020 2019 2018 Restricted stock awards 1 2 — Preferred stock (1) — — 1,456 _______________

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Litigation —The Company periodically becomes involved in various claims, lawsuits and proceedings that are incidental to its business. In the opinion of Company management, after consultation with counsel, there are no matters currently pending that would, in the event of an adverse outcome, materially impact the Company’s consolidated financial position, results of operations or liquidity. Verizon Transaction —In March 2015, the Company entered into an agreement with various operating entities of Verizon Communications Inc. (“Verizon”) that currently provides for the lease, sublease or management of approximately 11,250 wireless communications sites commencing March 27, 2015. The average term of the lease or sublease for all sites at the inception of the agreement was approximately 28 years, assuming renewals or extensions of the underlying ground leases for the sites. The Company has the option to purchase the leased sites in tranches, subject to the applicable lease, sublease or management rights upon its scheduled expiration. Each tower is assigned to an annual tranche, ranging from 2034 to 2047, which represents the outside expiration date for the sublease rights to the towers in that tranche. The purchase price for each tranche is a fixed amount stated in the lease for such tranche plus the fair market value of certain alterations made to the related towers. The aggregate purchase option price for the towers leased and subleased is approximately $5.0 billion. Verizon will occupy the sites as a tenant for an initial term of ten years with eight optional successive five AT&T Transaction —The Company has an agreement with SBC Communications Inc., a predecessor entity to AT&T Inc. (“AT&T”), that currently provides for the lease or sublease of approximately 2,100 towers commencing between December 2000 and August 2004. Substantially all of the towers are part of the Trust Securitizations. The average term of the lease or sublease for all sites at the inception of the agreement was approximately 27 years, assuming renewals or extensions of the underlying ground leases for the sites. The Company has the option to purchase the sites subject to the applicable lease or sublease upon its expiration. Each tower is assigned to an annual tranche, ranging from 2013 to 2032, which represents the outside expiration date for the sublease rights to that tower. The purchase price for each site is a fixed amount stated in the lease for that site plus the fair market value of certain alterations made to the related tower by AT&T. As of December 31, 2020, the Company has purchased an aggregate of 331 of the subleased towers which are subject to the applicable agreement, including 103 towers purchased during the year ended December 31, 2020 for an aggregate purchase price of $55.7 million. The aggregate purchase option price for the remaining towers leased and subleased is $973.4 million and includes per annum accretion through the applicable expiration of the lease or sublease of a site. For all such sites, AT&T has the right to continue to lease the reserved space through June 30, 2025 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 five successive five Other Contingencies —The Company is subject to income tax and other taxes in the geographic areas where it holds assets or operates, and periodically receives notifications of audits, assessments or other actions by taxing authorities. Taxing authorities may issue notices or assessments while audits are being conducted. In certain jurisdictions, taxing authorities may issue assessments with minimal examination. These notices and assessments do not represent amounts that the Company is obligated to pay and are often not reflective of the actual tax liability for which the Company will ultimately be liable. In the process of responding to assessments of taxes that the Company believes are not enforceable, the Company avails itself of both administrative and judicial remedies. The Company evaluates the circumstances of each notification or assessment based on the information available and, in those instances in which the Company does not anticipate a successful defense of positions taken in its tax filings, a liability is recorded in the appropriate amount based on the underlying assessment. On December 5, 2016, the Company received an income tax assessment of Essar Telecom Infrastructure Private Limited (“ETIPL”) from the India Income Tax Department (the “Tax Department”) for the fiscal year ending 2008 in the amount of INR 4.75 billion ($69.8 million on the date of assessment) related to capital contributions. The Company challenged the assessment before the Office of Commissioner of Income Tax - Appeals, which ruled in the Company’s favor in January 2018. However, the Tax Department has appealed this ruling at a higher appellate authority. The Company estimates that there is a more likely than not probability that the Company’s position will be sustained upon appeal. Accordingly, no liability has been recorded. Additionally, the assessment was made with respect to transactions that took place in the tax year commencing in 2007, prior to the Company’s acquisition of ETIPL. Under the Company’s definitive acquisition agreement with 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. Guaranties and Indemnifications —The Company enters into agreements from time to time in the ordinary course of business pursuant to which it agrees to guarantee or indemnify third parties for certain claims. The Company has also entered into purchase and sale agreements relating to the sale or acquisition of assets containing customary indemnification provisions. The Company’s indemnification obligations under these agreements generally are limited solely to damages resulting from breaches of representations and warranties or covenants under the applicable agreements. In addition, payments under such indemnification clauses are generally conditioned on the other party making a claim that is subject to whatever defenses the Company may have and are governed by dispute resolution procedures specified in the particular agreement. Further, the Company’s obligations under these agreements may be limited in duration and amount, and in some instances, the Company may have recourse against third parties for payments made by the Company. The Company has not historically made any material payments under these agreements and, as of December 31, 2020, is not aware of any agreements that could result in a material payment. If the Company is unable to close the Pending Telxius Acquisition, as defined in note 23, the Company would be liable under the terms of the agreements to make certain payments to Telxius, which could be material.

SUPPLEMENTAL CASH FLOW INFORMAT

SUPPLEMENTAL CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
SUPPLEMENTAL CASH FLOW INFORMATION	SUPPLEMENTAL CASH FLOW INFORMATION Supplemental cash flow information and non-cash investing and financing activities are as follows for the years ended December 31,: 2020 2019 2018 Supplemental cash flow information: Cash paid for interest $ 762.3 $ 750.2 $ 789.7 Cash paid for income taxes (net of refunds of $27.0, $11.2 and $25.0, respectively) 146.3 147.5 163.9 Non-cash investing and financing activities: Increase (decrease) in accounts payable and accrued expenses for purchases of property and equipment and construction activities 45.8 (21.0) 8.3 Purchases of property and equipment under finance leases, perpetual easements and capital leases 75.0 81.3 57.8 Fair value of debt assumed through acquisitions (1) 800.0 329.8 — Acquisition of Commercialization Rights (2) — — 24.8 Debt financed acquisition of communication sites — — 54.2 Settlement of third-party debt (5.0) — — _______________ (1) For the year ended December 31, 2020, consists of the InSite Debt. (2) Related to the note extinguishment with TV Azteca, S.A. de C.V. in 2018.

BUSINESS SEGMENTS

BUSINESS SEGMENTS	12 Months Ended
	Dec. 31, 2020
Segment Reporting, Measurement Disclosures [Abstract]
Business Segments	BUSINESS SEGMENTS The Company’s primary business is leasing space on multitenant communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. This business is referred to as the Company’s property operations. During the fourth quarter of 2020, as a result of the InSite Acquisition, the Company updated the names of its reportable segments to rename U.S. property and Asia property to U.S. & Canada property and Asia-Pacific property, respectively. The Company continues to report its results in six segments – U.S. & Canada property, Asia-Pacific property, Africa property, Europe property, Latin America property and services. This change was made to better align the names of the Company’s reportable segments with the geographical areas of the Company’s business operations following the InSite Acquisition. The change in the names the Company’s reportable segments is solely reflective of the inclusion of Canada and Australia in its business operations, as a result of the InSite Acquisition. The change in reportable segments had no impact on the Company’s consolidated financial statements for any prior periods. Historical financial information included in this Annual Report on Form 10-K has not been adjusted. As of December 31, 2020, the Company’s property operations consisted of the following: • U.S. & Canada: property operations in Canada and the United States; • Asia-Pacific: property operations in Australia and India; • Africa: property operations in Burkina Faso, Ghana, Kenya, Niger, Nigeria, South Africa and Uganda; • Europe: property operations in France, Germany and Poland; and • Latin America: property operations in Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, Paraguay and Peru. The Company’s services segment offers tower-related services in the United States, including AZP and structural analysis, which primarily support its site leasing business, including the addition of new tenants and equipment on its sites. The services segment is a strategic business unit that offers different services from, and requires different resources, skill sets and marketing strategies than, the property operating segments. The accounting policies applied in compiling segment information below are similar to those described in note 1. Among other factors, in evaluating financial performance in each business segment, management uses segment gross margin and segment operating profit. The Company defines segment gross margin as segment revenue less segment operating expenses excluding stock-based compensation expense recorded in costs of operations; Depreciation, amortization and accretion; Selling, general, administrative and development expense; and Other operating expenses. The Company defines segment operating profit as segment gross margin less Selling, general, administrative and development expense attributable to the segment, excluding stock-based compensation expense and corporate expenses. For reporting purposes, for periods through September 30, 2018, the Latin America property segment gross margin and segment operating profit also included Interest income (expense), TV Azteca, net. These measures of segment gross margin and segment operating profit are also before Interest income, Interest expense, Gain (loss) on retirement of long-term obligations, Other income (expense), Net income (loss) attributable to noncontrolling interests and Income tax benefit (provision). The categories of expenses indicated above, such as depreciation, have been excluded from segment operating performance as they are not considered in the review of information or the evaluation of results by management. There are no significant revenues resulting from transactions between the Company’s operating segments. All intercompany transactions are eliminated to reconcile segment results and assets to the consolidated statements of operations and consolidated balance sheets. Summarized financial information concerning the Company’s reportable segments for the years ended December 31, 2020, 2019 and 2018 is shown in the following tables. The “Other” column (i) represents amounts excluded from specific segments, such as business development operations, stock-based compensation expense and corporate expenses included in Selling, general, administrative and development expense; Other operating expenses; Interest income; Interest expense; Gain (loss) on retirement of long-term obligations; and Other income (expense), and (ii) reconciles segment operating profit to Income from continuing operations before income taxes. Property Total Other Total Year ended December 31, 2020 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues $ 4,517.0 $ 1,139.4 $ 890.2 $ 149.6 $ 1,257.4 $ 7,953.6 $ 87.9 $ 8,041.5 Segment operating expenses (1) 808.0 661.4 297.7 28.1 392.5 2,187.7 36.5 2,224.2 Segment gross margin 3,709.0 478.0 592.5 121.5 864.9 5,765.9 51.4 5,817.3 Segment selling, general, administrative and development expense (1) 162.2 97.4 94.4 23.0 93.1 470.1 14.8 484.9 Segment operating profit $ 3,546.8 $ 380.6 $ 498.1 $ 98.5 $ 771.8 $ 5,295.8 $ 36.6 $ 5,332.4 Stock-based compensation expense $ 120.8 120.8 Other selling, general, administrative and development expense 176.0 176.0 Depreciation, amortization and accretion 1,882.3 1,882.3 Other expense (2) 1,332.2 1,332.2 Income from continuing operations before income taxes $ 1,821.1 Capital expenditures (3) (4) $ 360.6 $ 112.9 $ 334.9 $ 31.6 $ 221.1 $ 1,061.1 $ — $ 10.1 $ 1,071.2 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $3.0 million and $117.8 million, respectively. (2) Primarily includes interest expense, losses from foreign currency exchange rate fluctuations and $222.8 million in impairment charges. (3) Includes $9.2 million of finance lease payments included in Repayments of notes payable, credit facilities, term loans, senior notes, secured debt and finance leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows. (4) Includes $36.9 million of perpetual land easement payments reported in Deferred financing costs and other financing activities in the cash flows from financing activities in the Company’s consolidated statements of cash flows. Property Total Other Total Year ended December 31, 2019 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues $ 4,188.7 $ 1,217.0 $ 583.9 $ 134.6 $ 1,340.7 $ 7,464.9 $ 115.4 $ 7,580.3 Segment operating expenses (1) 807.9 715.9 209.0 27.8 411.3 2,171.9 42.1 2,214.0 Segment gross margin 3,380.8 501.1 374.9 106.8 929.4 5,293.0 73.3 5,366.3 Segment selling, general, administrative and development expense (1) 175.5 99.9 53.7 23.2 101.0 453.3 12.0 465.3 Segment operating profit $ 3,205.3 $ 401.2 $ 321.2 $ 83.6 $ 828.4 $ 4,839.7 $ 61.3 $ 4,901.0 Stock-based compensation expense $ 111.4 111.4 Other selling, general, administrative and development expense 156.5 156.5 Depreciation, amortization and accretion 1,778.4 1,778.4 Other expense (2) 938.3 938.3 Income from continuing operations before income taxes $ 1,916.4 Capital expenditures (3) (4) $ 359.5 $ 134.5 $ 258.5 $ 13.2 $ 260.4 $ 1,026.1 $ — $ 12.8 $ 1,038.9 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.8 million and $108.6 million, respectively. (2) Primarily includes interest expense. (3) Includes $18.0 million of finance lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes, secured debt and finance leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows. (4) Includes $29.6 million of perpetual land easement payments reported in Deferred financing costs and other financing activities in the cash flows from financing activities in the Company’s consolidated statements of cash flows. Property Total Other Total Year ended December 31, 2018 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues (1) $ 3,822.1 $ 1,540.5 $ 545.5 $ 141.8 $ 1,264.8 $ 7,314.7 $ 125.4 $ 7,440.1 Segment operating expenses (2) 771.0 710.9 208.0 30.1 406.3 2,126.3 48.2 2,174.5 Interest income, TV Azteca, net — — — — (0.1) (0.1) — (0.1) Segment gross margin 3,051.1 829.6 337.5 111.7 858.4 5,188.3 77.2 5,265.5 Segment selling, general, administrative and development expense (2) 165.2 110.7 48.0 21.1 83.5 428.5 14.4 442.9 Segment operating profit $ 2,885.9 $ 718.9 $ 289.5 $ 90.6 $ 774.9 $ 4,759.8 $ 62.8 $ 4,822.6 Stock-based compensation expense $ 137.5 137.5 Other selling, general, administrative and development expense 156.1 156.1 Depreciation, amortization and accretion 2,110.8 2,110.8 Other expense (3) 1,263.6 1,263.6 Income from continuing operations before income taxes $ 1,154.6 Capital expenditures (4) $ 376.9 $ 101.0 $ 212.5 $ 20.2 $ 220.7 $ 931.3 $ — $ 13.9 $ 945.2 _______________ (1) Asia-Pacific segment revenues include a net impact of $333.7 million as a result of the settlement payment received from Tata in the fourth quarter of 2018. (2) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $3.3 million and $134.2 million, respectively. (3) Primarily includes interest expense and $394.0 million in impairment charges. (4) Includes $32.0 million of capital lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes, secured debt and capital leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows. Additional information relating to the total assets of the Company’s operating segments is as follows for the years ended December 31,: 2020 2019 2018 Total Assets (1): U.S. & Canada property $ 27,352.9 $ 22,624.6 $ 18,782.0 Asia-Pacific property 5,191.8 5,307.8 4,938.8 Africa property 4,894.8 4,711.1 1,929.7 Europe property 1,868.6 1,535.3 1,438.1 Latin America property 7,434.2 8,125.5 5,594.7 Services 38.7 26.8 46.3 Other (2) 452.5 470.5 280.8 Total assets $ 47,233.5 $ 42,801.6 $ 33,010.4 _______________ (1) Balances are translated at the applicable period end exchange rate, which may impact comparability between periods. (2) Balances include corporate assets such as cash and cash equivalents, certain tangible and intangible assets and income tax accounts that have not been allocated to specific segments. Summarized geographic information related to the Company’s operating revenues for the years ended December 31, 2020, 2019 and 2018 and long-lived assets as of December 31, 2020 and 2019 is as follows: 2020 2019 2018 Operating Revenues: U.S. & Canada: Canada (1) (2) $ 0.3 $ — $ — United States 4,604.6 4,304.1 3,947.5 Asia-Pacific (2): Australia (1) 0.0 — — India 1,139.4 1,217.0 1,540.5 Africa (2): Burkina Faso 43.9 — — Ghana 174.3 124.3 125.4 Kenya 97.7 27.3 7.0 Niger 40.0 — — Nigeria 249.5 229.9 220.7 South Africa 128.7 129.1 125.3 Uganda 156.1 73.3 67.1 Europe (2): France 79.4 68.0 72.7 Germany 70.0 66.6 69.1 Poland (1) 0.2 — — Latin America (2): Argentina 22.1 17.3 16.0 Brazil 506.4 605.5 595.5 Chile 67.3 43.3 44.2 Colombia 96.1 102.1 103.8 Costa Rica 23.4 21.1 18.4 Mexico 483.0 515.3 456.5 Paraguay 12.5 12.6 10.4 Peru 46.6 23.5 20.0 Total operating revenues $ 8,041.5 $ 7,580.3 $ 7,440.1 _______________ (1) The Company launched operations in Canada and Australia through the InSite Acquisition, which closed on December 23, 2020. The Company launched operations in Poland through the Poland Acquisition, which closed on June 16, 2020. (2) Balances are translated at the applicable exchange rate, which may impact comparability between periods. 2020 2019 Long-Lived Assets (1): U.S. & Canada: Canada (2) $ 373.7 $ — United States 19,977.8 16,578.7 Asia-Pacific (2): Australia 20.0 — India 3,482.3 3,708.8 Africa (2): Burkina Faso 315.7 275.3 Ghana 676.8 671.0 Kenya 730.0 761.7 Niger 215.7 199.8 Nigeria 663.7 648.6 South Africa 424.4 409.4 Uganda 867.3 847.3 Europe (2): France 1,176.5 917.1 Germany 370.9 357.3 Poland 2.9 — Latin America (2): Argentina 111.9 100.0 Brazil 1,629.9 2,138.4 Chile 538.7 437.6 Colombia 350.7 375.2 Costa Rica 123.1 124.1 Mexico 1,395.2 1,524.9 Paraguay 103.6 111.3 Peru 380.4 394.6 Total long-lived assets $ 33,931.2 $ 30,581.1 _______________ (1) Includes Property and equipment, net, Goodwill and Other intangible assets, net. (2) Balances are translated at the applicable period end exchange rate, which may impact comparability between periods. The following tenants within the property and services segments individually accounted for 10% or more of the Company’s consolidated operating revenues for the years ended December 31,: 2020 2019 2018 AT&T 22 % 22 % 19 % T-Mobile 19 % 10 % 9 % Verizon Wireless 14 % 15 % 15 %

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2020
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONSDuring the years ended December 31, 2020, 2019 and 2018, the Company had no significant related party transactions.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS Pending Telxius Acquisition— On January 13, 2021, the Company entered into two agreements with Telxius Telecom, S.A. (“Telxius”), a subsidiary of Telefónica, S.A., pursuant to which the Company expects to acquire Telxius’ European and Latin American tower divisions, comprising approximately 31,000 communications sites in Argentina, Brazil, Chile, Germany, Peru and Spain, for approximately 7.7 billion EUR (approximately $9.4 billion at the date of signing) (the “Pending Telxius Acquisition”), subject to limited adjustments. The Pending Telxius Acquisition is expected to close in tranches beginning in the second quarter of 2021, subject to customary closing conditions, including government and regulatory approval. Repayment of the 2020 Term Loan —On February 5, 2021, the Company repaid all amounts outstanding under the 2020 Term Loan with borrowings from the 2019 Multicurrency Credit Facility and cash on hand. Amendments to Bank Facilities —On February 10, 2021, the Company amended and restated the 2019 Multicurrency Credit Facility and the 2019 Credit Facility and entered into an amendment agreement with respect to the 2019 Term Loan. These amendments, among other things, i. extend the maturity dates by one year to June 28, 2024 and January 31, 2026 for the 2019 Multicurrency Credit Facility and the 2019 Credit Facility, respectively, ii. increase the commitments under the 2019 Multicurrency Credit Facility and the 2019 Credit Facility to $4.1 billion and $2.9 billion, respectively, of which 1.3 billion EUR borrowed under the 2019 Multicurrency Credit Facility is to be reserved to finance the Pending Telxius Acquisition, iii. increase the maximum Revolving Loan Commitments, after giving effect to any Incremental Commitments (each as defined in the loan agreements for each of the 2019 Multicurrency Credit Facility and the 2019 Credit Facility) to $6.1 billion and $4.4 billion under the 2019 Multicurrency Credit Facility and the 2019 Credit Facility, respectively, iv. expand the sublimit for multicurrency borrowings under the 2019 Multicurrency Credit Facility from $1.0 billion to $3.0 billion and add a EUR borrowing option for the 2019 Credit Facility with a $1.5 billion sublimit, v. amend the limitation of the Company’s permitted ratio of Total Debt to Adjusted EBITDA (each as defined in each of the loan agreements for each of the facilities) to be no greater than 7.50 to 1.00 for the four fiscal quarters following the consummation of the Pending Telxius Acquisition, stepping down to 6.00 to 1.00 thereafter (with a further step up to 7.00 to 1.00 if the Company consummates a Qualified Acquisition (as defined in each of the loan agreements for the facilities)), vi. amend the limitation on indebtedness of, and guaranteed by, the Company’s subsidiaries to the greater of (a) $3.0 billion and (b) 50% of Adjusted EBITDA (as defined in each of the loan agreements for the facilities) of the Company and its subsidiaries on a consolidated basis and vii. increase the threshold for certain defaults with respect to judgments, attachments or acceleration of indebtedness from $400.0 million to $500.0 million. 2021 Delayed Draw Term Loans —On February 10, 2021, the Company entered into (i) a 1.1 billion EUR (approximately $1.3 billion at the date of signing) unsecured term loan, the proceeds of which are to be used to fund the Pending Telxius Acquisition, with a maturity date that is 364 days from the date of the first draw thereunder and bears interest at a rate based on the senior unsecured debt rating of the Company, which, based on the Company’s current debt ratings, is 1.000% above the Euro Interbank Offered Rate (“EURIBOR”) (the “2021 364-Day Delayed Draw Term Loan”) and (ii) an 825.0 million EUR (approximately $1.0 billion at the date of signing) unsecured term loan, the proceeds of which are to be used to fund the Pending Telxius Acquisition, with a maturity date that is three years from the date of the first draw thereunder and bears interest at a rate based on the senior unsecured debt rating of the Company, which, based on the Company’s current debt ratings, is 1.125% above EURIBOR (the “2021 Three The loan agreements for the 2021 Delayed Draw Term Loans contain certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Failure to comply with the financial and operating covenants of the loan agreements could not only prevent the Company from being able to borrow additional funds under the revolving credit facilities, but may constitute a default, which could result in, among other things, the amounts outstanding, including all accrued interest and unpaid fees, becoming immediately due and payable. Bridge Facility —In connection with entering into the Pending Telxius Acquisition, the Company entered into a commitment letter (the “Commitment Letter”), dated January 13, 2021, with Bank of America, N.A. and BofA Securities, Inc. (together, “BoA”) pursuant to which BoA has committed to provide up to 7.5 billion EUR (approximately $9.1 billion at date of signing) in bridge loans (the “Bridge Loan Commitment”) to ensure financing for the Pending Telxius Acquisition. Effective February 10, 2021, the Bridge Loan Commitment was reduced to 4.275 billion EUR (approximately $5.2 billion at the date of signing) as a result of an aggregate of 3.225 billion EUR (approximately $3.9 billion at the date of signing) of additional committed amounts under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility and the 2021 Delayed Draw Term Loans, as described above. The Commitment Letter contains, and the credit agreement in respect of the Bridge Loan Commitment, if any, will contain, certain customary conditions to funding, including, without limitation, (i) the execution and delivery of definitive financing agreements for the Bridge Loan Commitment and (ii) other customary closing conditions set forth in the Commitment Letter. The Company will pay certain customary commitment fees and, in the event it makes any borrowings in connection with the Bridge Loan Commitment, funding and other fees.

Schedule III - SCHEDULE OF REAL

Schedule III - SCHEDULE OF REAL ESTATE AND ACCUMULATED DEPRECIATION	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Schedule of Real Estate and Accumulated Depreciation	SCHEDULE III—SCHEDULE OF REAL ESTATE AND ACCUMULATED DEPRECIATION (dollars in millions) Description Encumbrances Initial cost Cost Gross amount Accumulated Date of Date Life on which 183,860 Sites (1) $ 3,136.7 (2) (3) (3) $ 18,492.9 (4) $ (6,921.0) Various Various Up to 20 years _______________ (1) No single site exceeds 5% of the total amounts indicated in the table above. (2) Certain assets secure debt of $3.1 billion. (3) The Company has omitted this information, as it would be impracticable to compile such information on a site-by-site basis. (4) Does not include those sites under construction. 2020 2019 2018 Gross amount at beginning $ 17,429.3 $ 15,960.1 $ 15,349.0 Additions during period: Acquisitions 722.4 887.0 721.4 Discretionary capital projects (1) 308.0 258.1 173.5 Discretionary ground lease purchases (2) 214.3 189.8 180.4 Redevelopment capital expenditures (3) 176.7 213.6 177.3 Capital improvements (4) 91.4 161.2 94.0 Start-up capital expenditures (5) 119.4 71.3 113.1 Other (6) 72.8 45.2 (3.0) Total additions 1,705.0 1,826.2 1,456.7 Deductions during period: Cost of real estate sold or disposed (259.7) (304.6) (395.7) Other (7) (381.7) (52.4) (449.9) Total deductions: (641.4) (357.0) (845.6) Balance at end $ 18,492.9 $ 17,429.3 $ 15,960.1 2020 2019 2018 Gross amount of accumulated depreciation at beginning $ (6,382.2) $ (5,724.7) $ (5,181.2) Additions during period: Depreciation (771.5) (768.4) (751.4) Other — — — Total additions (771.5) (768.4) (751.4) Deductions during period: Amount of accumulated depreciation for assets sold or disposed 132.3 121.4 129.3 Other (7) 100.4 (10.5) 78.6 Total deductions 232.7 110.9 207.9 Balance at end $ (6,921.0) $ (6,382.2) $ (5,724.7) _______________ (1) Includes amounts incurred primarily for the construction of new sites. (2) Includes amounts incurred to purchase or otherwise secure the land under communications sites. (3) Includes amounts incurred to increase the capacity of existing sites, which results in new incremental tenant revenue. (4) Includes amounts incurred to enhance existing sites by adding additional functionality, capacity or general asset improvements. (5) Includes amounts incurred in connection with acquisitions or new market launches. Start-up capital expenditures includes non-recurring expenditures contemplated in acquisitions, new market launch business cases or initial deployment of new technologies or platform expansion initiatives that lead to an increase in site-level cash flow generation. (6) Primarily includes regional improvements and other additions. (7) Primarily includes foreign currency exchange rate fluctuations and other deductions.

BUSINESS AND SUMMARY OF SIGNI_2

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business —American Tower Corporation (together with its subsidiaries, “ATC” or the “Company”) is one of the largest global real estate investment trusts and a leading independent owner, operator and developer of multitenant communications real estate. The Company’s primary business is the leasing of space on communications sites to wireless service providers, radio and television broadcast companies, wireless data providers, government agencies and municipalities and tenants in a number of other industries. The Company refers to this business as its property operations. Additionally, the Company offers tower-related services in the United States, which the Company refers to as its services operations. These services include site application, zoning and permitting (“AZP”) and structural analysis, which primarily support the Company’s site leasing business, including the addition of new tenants and equipment on its sites. The Company’s portfolio primarily consists of towers that it owns and towers that it operates pursuant to long-term lease arrangements, as well as distributed antenna system (“DAS”) networks, which provide seamless coverage solutions in certain in-building and outdoor wireless environments. In addition to the communications sites in its portfolio, the Company manages rooftop and tower sites for property owners under various contractual arrangements. The Company also holds other telecommunications infrastructure, fiber and property interests that it leases primarily to communications service providers and third-party tower operators. American Tower Corporation is a holding company that conducts its operations through its directly and indirectly owned subsidiaries and joint ventures. ATC’s principal domestic operating subsidiaries are American Towers LLC and SpectraSite Communications, LLC. ATC conducts its international operations primarily through its subsidiary, American Tower International, Inc., which in turn conducts operations through its various international holding and operating subsidiaries and joint ventures. The Company operates as a real estate investment trust for U.S. federal income tax purposes (“REIT”). Accordingly, the Company generally is not required to pay U.S. federal income taxes on income generated by its REIT operations, including the income derived from leasing space on its towers, as it receives a dividends paid deduction for distributions to stockholders that generally offsets its REIT income and gains. However, the Company remains obligated to pay U.S. federal income taxes on earnings from its domestic taxable REIT subsidiaries (“TRSs”). In addition, the Company’s international assets and operations, regardless of their classification for U.S. tax purposes, continue to be subject to taxation in the jurisdictions where those assets are held or those operations are conducted.
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation—The accompanying consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity method or as investments in equity securities, depending upon the Company’s ability to exercise significant influence over operating and financial policies. All intercompany accounts and transactions have been eliminated.
Reportable Segments	Reportable Segments — During the fourth quarter of 2020, as a result of the Company’s acquisition of InSite Wireless Group, LLC (“InSite,” and the acquisition, the “InSite Acquisition”), the Company updated its reportable segments to rename U.S.
Significant Accounting Policies and Use of Estimates	Significant Accounting Policies and Use of Estimates —The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results may differ from those estimates, and such differences could be material to the accompanying consolidated financial statements. The significant estimates in the accompanying consolidated financial statements include impairment of long-lived assets (including goodwill), asset retirement obligations, revenue recognition, rent expense and lease accounting, income taxes and accounting for business combinations and acquisitions of assets. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued as additional evidence for certain estimates or to identify matters that require additional disclosure.
Accounts Receivable and Deferred Rent Asset	Accounts Receivable and Deferred Rent Asset —The Company derives the largest portion of its revenues and corresponding accounts receivable and the related deferred rent asset from a relatively small number of tenants in the telecommunications industry, and 55% of its current-year revenues are derived from three tenants. The Company’s deferred rent asset is associated with non-cancellable tenant leases that contain fixed escalation clauses over the terms of the applicable lease in which revenue is recognized on a straight-line basis over the lease term. The Company mitigates its concentrations of credit risk with respect to notes and trade receivables and the related deferred rent assets by actively monitoring the creditworthiness of its borrowers and tenants. In recognizing tenant revenue, the Company assesses the collectibility of both the amounts billed and the portion recognized in advance of billing on a straight-line basis. This assessment takes tenant credit risk and business and industry conditions into consideration to ultimately determine the collectibility of the amounts billed. To the extent the amounts, based on management’s estimates, may not be collectible, revenue recognition is deferred until such point as collectibility is determined to be reasonably assured. Any amounts that were previously recognized as revenue and subsequently determined to be uncollectible are charged to bad debt expense included in Selling, general, administrative and development expense in the accompanying consolidated statements of operations.
Functional Currency	Functional Currency —The functional currency of each of the Company’s foreign operating subsidiaries is normally the respective local currency, except for Costa Rica and Argentina, 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 loss
Cash and Cash Equivalents	Cash and Cash Equivalents —Cash and cash equivalents include cash on hand, demand deposits and short-term investments with original maturities of three months or less. The Company maintains its deposits at high-quality financial institutions and monitors the credit ratings of those institutions.
Restricted Cash	Restricted Cash— Restricted cash includes cash pledged as collateral to secure obligations and all cash whose use is otherwise limited by contractual provisions.
Property and Equipment	Property and Equipment —Property and equipment is recorded at cost or, in the case of acquired properties, at estimated fair value on the date acquired. Cost for self-constructed towers includes direct materials and labor and certain indirect costs associated with construction of the tower, such as transportation costs, employee benefits and payroll taxes. The Company begins the capitalization of costs during the pre-construction period, which is the period during which costs are incurred to evaluate the site, and continues to capitalize costs until the tower is substantially completed and ready for occupancy by a tenant. Labor and related costs capitalized for the years ended December 31, 2020, 2019 and 2018 were $51.1 million, $48.3 million and $55.0 million, respectively. Expenditures for repairs and maintenance are expensed as incurred. Augmentation and improvements that extend an asset’s useful life or enhance capacity are capitalized. Depreciation expense is recorded using the straight-line method over the assets’ estimated useful lives. Towers and related assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease, taking into consideration lease renewal options and residual value. Towers or assets acquired through finance leases are recorded net at the present value of future minimum lease payments or the fair value of the leased asset at the inception of the lease. Property and equipment and assets held under finance leases are amortized over the shorter of the applicable lease term or the estimated useful life of the respective assets for periods generally not exceeding twenty years. The Company reviews its tower portfolio for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company reviews other long-lived assets for impairment whenever events, changes in circumstances or other evidence indicate that the carrying amount of the Company’s assets may not be recoverable. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets —The Company reviews goodwill for impairment at least annually (as of December 31) or whenever events or circumstances indicate the carrying value of an asset may not be recoverable. Goodwill is recorded in the applicable segment and assessed for impairment at the reporting unit level. The Company employs a discounted cash flow analysis when testing goodwill for impairment. The key assumptions utilized in the discounted cash flow analysis include current operating performance, terminal sales growth rate, management’s expectations of future operating results and cash requirements, the current weighted average cost of capital and an expected tax rate. The Company compares the fair value of the reporting unit, as calculated under an income approach using future discounted cash flows, to the carrying amount of the applicable reporting unit. If the carrying amount exceeds the fair value, an impairment loss would be recognized for the amount of the excess. The loss recognized is limited to the total amount of goodwill allocated to that reporting unit. During the years ended December 31, 2020, 2019 and 2018, no potential impairment was identified, as the fair value of each of the reporting units was in excess of its carrying amount. Intangible assets that are separable from goodwill and are deemed to have a definite life are amortized over their useful lives, generally ranging from three The Company reviews its network location intangible assets for indicators of impairment on an individual tower basis. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company monitors its tenant-related intangible assets on a tenant by tenant basis for indicators of impairment, such as high levels of turnover or attrition, non-renewal of a significant number of contracts or the cancellation or termination of a relationship. The Company assesses recoverability by determining whether the carrying amount of the related assets will be recovered primarily through projected undiscounted future cash flows. If the Company determines that the carrying amount of an asset may not be recoverable, the Company measures any impairment loss based on the projected future discounted cash flows to be provided from the asset or available market information relative to the asset’s fair value, as compared to the asset’s carrying amount. The Company records impairment charges, which are discussed in note 17, in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment.
Derivatives Financial Instruments	Derivative Financial Instruments —Derivatives are recorded on the consolidated balance sheet at fair value. If a derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are recorded in AOCL, as well as a component of comprehensive income, and are recognized in the results of operations when the hedged item affects earnings. Changes in fair value of the ineffective portions of cash flow hedges are recognized in the results of operations. For derivative instruments that are designated and qualify as fair value hedges, changes in value of the derivatives are recorded in Other expense in the consolidated statements of operations in the current period, along with the offsetting gain or loss on the hedged item attributable to the hedged risk. For derivative instruments not designated as hedging instruments, changes in fair value are recognized in the results of operations in the period that the change occurs. The primary risks managed through the use of derivative instruments is interest rate risk, exposure to changes in the fair value of debt attributable to interest rate risk and currency risk. From time to time, the Company enters into interest rate swap agreements or foreign currency contracts to manage exposure to these risks. Under these agreements, the Company is exposed to counterparty credit risk to the extent that a counterparty fails to meet the terms of a contract. The Company’s exposure is limited to the current value of the contract at the time the counterparty fails to perform. The Company assesses, both at the inception of the hedge and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows or fair values of hedged items. The Company does not hold derivatives for trading purposes.
Fair Value Measurements	Fair Value Measurements—The Company determines the fair value of its financial instruments based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.
Asset Retirement Obligations	Asset Retirement Obligations —When required, the Company recognizes the fair value of obligations to remove its tower assets and remediate the leased land upon which certain of its tower assets are located. Generally, the associated retirement costs are capitalized as part of the carrying amount of the related tower assets and depreciated over their estimated useful lives and the liability is accreted through the obligation’s estimated settlement date. Fair value estimates of asset retirement obligations generally involve discounting of estimated future cash flows associated with takedown costs. Periodic accretion of such liabilities due to the passage of time is included in Depreciation, amortization and accretion expense in the consolidated statements of operations. Adjustments are also made to the asset retirement obligation liability to reflect changes in the estimates of timing and amount of expected cash flows, with an offsetting adjustment made to the related long-lived tangible
Income Taxes	Income Taxes —As a REIT, the Company generally is not subject to U.S. federal income taxes on income generated by its REIT operations as it receives a dividends paid deduction for distributions to stockholders that generally offsets its REIT income and gains. However, the Company remains obligated to pay U.S. federal income taxes on certain earnings and continues to be subject to taxation in its foreign jurisdictions. Accordingly, the consolidated financial statements reflect provisions for federal, state, local and foreign income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, as well as operating loss and tax credit carryforwards. The Company measures deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities as a result of a change in tax rates is recognized in income in the period that includes the enactment date. The Company periodically reviews its deferred tax assets, and provides valuation allowances if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Valuation allowances would be reversed as a reduction to the provision for income taxes if related deferred tax assets are deemed realizable based on changes in facts and circumstances relevant to the assets’ recoverability. The Company classifies uncertain tax positions as income tax liabilities in Other non-current liabilities in the consolidated balance sheet, unless expected to be paid within one year. The Company reports penalties and tax-related interest expense as a component of the income tax provision and interest income from tax refunds as a component of Interest income in the consolidated statements of operations.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss)—Other comprehensive income (loss) refers to items excluded from net income that are recorded as an adjustment to equity, net of tax. The Company’s other comprehensive income (loss) primarily consisted of changes in fair value of effective derivative cash flow hedges, foreign currency translation adjustments and reclassification of unrealized losses on effective derivative cash flow hedges.
Distributions	Distributions —As a REIT, the Company must annually distribute to its stockholders an amount equal to at least 90% of its REIT taxable income (determined before the deduction for distributed earnings and excluding any net capital gain). Generally, the Company has distributed, and expects to continue to distribute, all or substantially all of its REIT taxable income after taking into consideration its utilization of net operating losses (“NOLs”). The amount, timing and frequency of future distributions will be at the sole discretion of the Board of Directors and will depend upon various factors, a number of which may be beyond the Company’s control, including the Company’s financial condition and operating cash flows, the amount required to maintain its qualification for taxation as a REIT and reduce any income and excise taxes that the Company otherwise would be required to pay, limitations on distributions in the Company’s existing and future debt and preferred equity instruments, the Company’s ability to utilize NOLs to offset the Company’s distribution requirements, limitations on its ability to fund distributions using cash generated through its TRSs and other factors that the Board of Directors may deem relevant.
Acquisitions	Acquisitions —For acquisitions that meet the definition of a business combination, the Company applies the acquisition method of accounting where assets acquired and liabilities assumed are recorded at fair value at the date of each acquisition, and the results of operations are included with those of the Company from the dates of the respective acquisitions. Any excess of the purchase price paid by the Company over the amounts recognized for assets acquired and liabilities assumed is recorded as goodwill. The Company continues to evaluate acquisitions for a period not to exceed one year after the applicable acquisition date of each transaction to determine whether any additional adjustments are needed to the allocation of the purchase price paid for the assets acquired and liabilities assumed. All other acquisitions are accounted for as asset acquisitions and the purchase price is allocated to the net assets acquired with no recognition of goodwill. The purchase price is not subsequently adjusted. The fair value of the assets acquired and liabilities assumed is typically determined by using either estimates of replacement costs or discounted cash flow valuation methods. When determining the fair value of tangible assets acquired, the Company must estimate the cost to replace the asset with a new asset taking into consideration such factors as age, condition and the economic useful life of the asset. When determining the fair value of intangible assets acquired and liabilities assumed, the
Revenue	Revenue —The Company’s revenue is derived from leasing the right to use its communications sites and the land on which the sites are located (the “lease component”) and from the reimbursement of costs incurred by the Company in operating the communications sites and supporting the tenants’ equipment as well as other services and contractual rights (the “non-lease component”). Most of the Company’s revenue is derived from leasing arrangements and is accounted for as lease revenue unless the timing and pattern of revenue recognition of the non-lease component differs from the lease component. If the timing and pattern of the non-lease component revenue recognition differs from that of the lease component, the Company separately determines the stand-alone selling prices and pattern of revenue recognition for each performance obligation. Revenue related to DAS networks and fiber and other related assets results from agreements with tenants that are not leases. The Company’s revenue from leasing arrangements, including fixed escalation clauses present in non-cancellable lease arrangements, is reported on a straight-line basis over the term of the respective leases when collectibility is probable. Escalation clauses tied to a consumer price index (“CPI”), or other inflation-based indices, and other incentives present in lease agreements with the Company’s tenants are excluded from the straight-line calculation. Total property straight-line revenues for the years ended December 31, 2020, 2019 and 2018 were $322.0 million, $183.5 million and $87.6 million, respectively. Non-lease revenue— Non-lease revenue consists primarily of revenue generated from DAS networks, fiber and other property related revenue. DAS networks and fiber arrangements require that the Company provide the tenant the right to use the applicable communications infrastructure. Performance obligations are satisfied over time for the duration of the arrangements. Other property related revenue streams, which include site inspections, are not material on either an individual or consolidated basis. Services revenue— The Company offers tower-related services in the United States. These services include AZP and structural analysis. There is a single performance obligation related to AZP and revenue is recognized over time based on milestones achieved, which are determined based on costs expected to be incurred. Structural analysis services may have more than one performance obligation, contingent upon the number of contracted services. Revenue is recognized at the point in time the services are completed. Some of the Company’s contracts with tenants contain multiple performance obligations. For these arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price, which is typically based on the price charged to tenants. Since most of the Company’s contracts are leases, costs to enter into lease arrangements are capitalized under the applicable lease accounting guidance. Costs incurred to obtain non-lease contracts that are capitalized primarily relate to DAS networks and are not material to the consolidated financial statements. The Company has excluded sales tax, value added tax and similar taxes from non-lease revenue. The Company records unearned revenue when payments are received from tenants in advance of the completion of the Company’s performance obligations. Long-term unearned revenue is included in Other non-current liabilities. During the year ended December 31, 2020, the Company recognized $142.3 million of revenue that was previously included in the contract liabilities balances, primarily arising from balances as of December 31, 2019. The Company records unbilled receivables, which are included in Prepaids and other current assets, when it has completed a performance obligation prior to its ability to bill under the customer arrangement. Other contract assets are included in Notes receivable and other non-current assets. The Company did not record any change in unbilled receivables attributable to non-lease property revenue recognized during each of the years ended December 31, 2020 and 2019. The change in contract assets attributable to revenue recognized during the years ended December 31, 2020 and 2019 was $6.8 million and $3.1 million, respectively.
Lease Accounting and Rent Expense	Lease Accounting and Rent Expense —The Company accounts for leases using a right-of-use model, which recognizes that, at the date of commencement, a lessee has a financial obligation to make lease payments to the lessor for the right to use the underlying asset during the lease term. The lessee recognizes a corresponding right-of-use asset related to this right. The Company recognizes a right-of-use lease asset and lease liability for operating and finance leases. The right-of-use asset is measured as the sum of the lease liability, prepaid or accrued lease payments, any initial direct costs incurred and any other applicable amounts. The Company reviews its right-of-use assets for impairment whenever events, changes in circumstances or other evidence indicate that the carrying amount of the Company’s assets may not be recoverable. The Company reviews its right-of-use assets for indicators of impairment at the lowest level of identifiable cash flows, as part of its tower portfolio. Impairments primarily result from a tower not having current tenant leases or from having expenses in excess of revenues. The Company records impairment charges in Other operating expenses in the consolidated statements of operations in the period in which the Company identifies such impairment. The calculation of the lease liability requires the Company to make certain assumptions for each lease, including lease term and discount rate implicit in each lease, which could significantly impact the gross lease obligation, the duration and the present value of the lease liability. When calculating the lease term, the Company considers the renewal, cancellation and termination rights available to the Company and the lessor. The Company determines the discount rate by calculating the incremental borrowing rate on a collateralized basis at the commencement of a lease or upon a change in the lease term. Many of the leases underlying the Company’s tower sites have fixed rent escalations, which provide for periodic increases in the amount of ground rent payable by the Company over time. In addition, certain of the Company’s tenant leases require the Company to exercise available renewal options pursuant to the underlying ground lease if the tenant exercises its renewal option. The Company’s calculation of the lease liability includes straight-line ground rent expense for these leases based on the term of the underlying ground lease plus all periods, if any, for which failure to renew the lease imposes an economic penalty to the Company such that renewal appears to be reasonably assured.
Selling, General, Administrative and Development Expense	Selling, General, Administrative and Development Expense —Selling, general and administrative expense consists of overhead expenses related to the Company’s property and services operations and corporate overhead costs not specifically allocable to
Stock-Based Compensation	Stock-Based Compensation —Stock-based compensation expense is measured at the accounting measurement date based on the fair value of the award and is generally recognized as an expense over the service period, which typically represents the vesting period. The Company provides for accelerated vesting and extended exercise periods of stock options and restricted stock units upon an employee’s death or permanent disability, or upon an employee’s qualified retirement, provided certain eligibility criteria are met. Accordingly, the Company recognizes compensation expense for stock options and time-based restricted stock units (“RSUs”) over the shorter of (i) the four The Company grants performance-based restricted stock units (“PSUs”) to its executive officers. Threshold, target and maximum parameters are established for a three three The fair value of stock options is determined using the Black-Scholes option-pricing model and the fair value of RSUs and PSUs is based on the fair value of the Company’s common stock on the date of grant. The Company recognizes all stock-based compensation expense in either Selling, general, administrative and development expense, costs of operations or as part of the costs associated with the construction of the tower assets.
Litigation Costs	Litigation Costs —The Company periodically becomes involved in various claims and lawsuits that are incidental to its business. The Company regularly monitors the status of pending legal actions to evaluate both the magnitude and likelihood of any potential loss. The Company accrues for these potential losses when it is probable that a liability has been incurred and the amount of loss, or possible range of loss, can be reasonably estimated. Should the ultimate losses on contingencies or litigation vary from estimates, adjustments to those liabilities may be required. The Company also incurs legal costs in connection with these matters and records estimates of these expenses, which are reflected in Selling, general, administrative and development expense in the accompanying consolidated statements of operations.
Earnings Per Common Share-Basic and Diluted	Earnings Per Common Share — Basic and Diluted
Retirement Plan	Retirement Plan—The Company has a 401(k) plan covering substantially all employees who meet certain age and employment requirements.
Accounting Standards Updates	Accounting Standards Updates In June 2016, the Financial Accounting Standards Board (the “FASB”) issued guidance that modifies how entities measure credit losses on most financial instruments. The new guidance replaces the current "incurred loss" model with an "expected credit loss" model that requires consideration of a broader range of information to estimate expected credit losses over the lifetime of the asset. Operating lease receivables are not within the scope of this guidance. Effective January 1, 2020, the Company adopted the new guidance using the modified retrospective approach. There was no cumulative-effect adjustment to Distributions in excess of earnings on the consolidated balance sheet as of the effective date. The adoption of this guidance did not have a material impact on the Company’s financial statements. Results for reporting periods beginning January 1, 2020 are presented under the new standard, while prior-period amounts are not adjusted and continue to be reported in accordance with accounting under the previously applicable guidance. In January 2017, the FASB issued guidance on accounting for goodwill impairments. The guidance eliminates Step 2 from the goodwill impairment test and requires, among other things, recognition of an impairment loss when the carrying value of a reporting unit exceeds its fair value. The loss recognized is limited to the total amount of goodwill allocated to that reporting unit. Effective January 1, 2020, the Company adopted the new guidance on a prospective basis. The adoption of this guidance did not have a material impact on the Company’s financial statements. In March 2020, the FASB issued guidance to provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The guidance applies only to contracts, hedging relationships and other transactions that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform. The expedients and exceptions provided by the guidance do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, except for hedging relationships existing as of December 31, 2022 for which an entity has elected certain optional expedients that are retained through the end of the hedging relationship. As of December 31, 2020, the Company has not modified any contracts as a result of reference rate reform and is evaluating the impact this standard may have on its financial statements.

BUSINESS AND SUMMARY OF SIGNI_3

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Changes in Allowances	Changes in the allowances were as follows: Year Ended December 31, 2020 (1) 2019 2018 Balance as of January 1, $ 163.3 $ 282.4 $ 131.0 Current year increases 105.6 104.3 157.8 Write-offs, recoveries and other (2) (21.3) (223.4) (6.4) Balance as of December 31, $ 247.6 $ 163.3 $ 282.4 _______________ (1) Year ended December 31, 2020 reflects the Company’s adoption of the current expected credit loss model for non-lease receivables. The adoption of this guidance did not have a material impact on the Company’s financial statements as the majority of the Company’s revenue is derived from its property operations and operating lease receivables are not within the scope of this guidance. (2) Amounts are primarily related to uncollectible amounts in India. In 2018, recoveries include recognition of revenue resulting from collections of previously reserved amounts.
Schedule of Net Foreign Currency Losses	The Company recorded the following net foreign currency losses: Year Ended December 31, 2020 2019 2018 Foreign currency losses recorded in AOCL $ 391.0 $ 45.8 $ 385.8 Foreign currency losses (gains) recorded in Other expense 216.4 (6.1) 4.5 Total foreign currency losses $ 607.4 $ 39.7 $ 390.3
Schedule of Cash, cash Equivalents, and Restricted Cash	The reconciliation of cash and cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amounts shown in the statements of cash flows is as follows: Year Ended December 31, 2020 2019 2018 Cash and cash equivalents $ 1,746.3 $ 1,501.2 $ 1,208.7 Restricted cash 115.1 76.8 96.2 Total cash, cash equivalents and restricted cash $ 1,861.4 $ 1,578.0 $ 1,304.9
Schedule of Revenue Disaggregated by Source and Geography	Revenue is disaggregated by geography in a manner consistent with the Company’s business segments, which are discussed further in note 21. A summary of revenue disaggregated by source and geography is as follows: Year Ended December 31, 2020 U.S. & Canada Asia-Pacific Africa Europe Latin Total Non-lease property revenue $ 258.4 $ 9.3 $ 13.8 $ 7.9 $ 118.4 $ 407.8 Services revenue 87.9 — — — — 87.9 Total non-lease revenue $ 346.3 $ 9.3 $ 13.8 $ 7.9 $ 118.4 $ 495.7 Property lease revenue 4,258.6 1,130.1 876.4 141.7 1,139.0 7,545.8 Total revenue $ 4,604.9 $ 1,139.4 $ 890.2 $ 149.6 $ 1,257.4 $ 8,041.5 Year Ended December 31, 2019 U.S. & Canada Asia-Pacific Africa Europe Latin Total Non-lease property revenue $ 255.7 $ 8.8 $ 4.0 $ 5.1 $ 138.2 $ 411.8 Services revenue 115.4 — — — — 115.4 Total non-lease revenue $ 371.1 $ 8.8 $ 4.0 $ 5.1 $ 138.2 $ 527.2 Property lease revenue 3,933.0 1,208.2 579.9 129.5 1,202.5 7,053.1 Total revenue $ 4,304.1 $ 1,217.0 $ 583.9 $ 134.6 $ 1,340.7 $ 7,580.3
Schedule of Information About Non-Lease Receivables, Contract Assets and Contract Liabilities From Contracts With Tenants	Information about non-lease receivables, contract assets and contract liabilities from contracts with tenants is as follows: December 31, 2020 December 31, 2019 Accounts receivable $ 77.2 $ 80.5 Prepaids and other current assets 21.8 8.3 Notes receivable and other non-current assets 23.7 21.3 Unearned revenue (1) 120.3 91.7 Other non-current liabilities (1) 432.4 379.2 _______________

PREPAID AND OTHER CURRENT ASS_2

PREPAID AND OTHER CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid and Other Current Assets	Prepaid and other current assets consisted of the following: As of December 31, 2020 December 31, 2019 Prepaid assets $ 66.1 $ 56.8 Prepaid income tax 143.7 185.8 Unbilled receivables 176.9 142.3 Value added tax and other consumption tax receivables 66.3 71.3 Other miscellaneous current assets 79.6 57.4 Prepaid and other current assets $ 532.6 $ 513.6

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment (including assets held under finance leases) consisted of the following: Estimated As of December 31, 2020 December 31, 2019 Towers Up to 20 $ 14,433.9 $ 13,930.7 Equipment (2) 3 - 20 2,327.1 1,897.3 Buildings and improvements Up to 32 634.0 638.9 Land and improvements (3) Up to 20 2,845.9 2,486.1 Construction-in-progress 431.5 372.6 Total 20,672.4 19,325.6 Less accumulated depreciation (7,863.7) (7,241.2) Property and equipment, net $ 12,808.7 $ 12,084.4 _______________ (1) Assets on leased land are depreciated over the shorter of the estimated useful life of the asset or the term of the corresponding ground lease taking into consideration lease renewal options and residual value. (2) Includes fiber and DAS assets. (3) Estimated useful lives apply to improvements only.
Schedule of Finance Lease Assets Included In Property Plant And Equipment	Information about finance lease-related balances is as follows: As of December 31, Finance leases: Classification 2020 2019 Property and equipment Towers $ 2,706.3 $ 2,695.9 Accumulated depreciation (1,209.7) (1,062.0) Property and equipment, net $ 1,496.6 $ 1,633.9 Property and equipment Buildings and improvements $ 167.6 $ 167.0 Accumulated depreciation (76.3) (65.3) Property and equipment, net $ 91.3 $ 101.7 Property and equipment Land $ 129.9 $ 150.9 Property and equipment Equipment $ 48.8 $ 45.9 Accumulated depreciation (15.3) (13.1) Property and equipment, net $ 33.5 $ 32.8

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of Future Minimum Rental Receipts Expected Under Operating Leases	Future minimum rental receipts expected under non-cancellable operating lease agreements as of December 31, 2020, were as follows: Year Ended December 31, Amount (1) 2021 $ 6,194.6 2022 5,905.5 2023 5,779.5 2024 5,618.8 2025 5,410.6 Thereafter 29,660.9 Total $ 58,569.9
Schedule of Information About Other Lease-Related Balances	Information about other lease-related balances is as follows: As of December 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 7,789.2 $ 7,357.4 Current portion of lease liability $ 539.9 $ 494.5 Lease liability 6,884.4 6,510.4 Total operating lease liability $ 7,424.3 $ 7,004.9 Finance leases: Current portion of lease liability $ 4.9 $ 6.7 Lease liability 23.0 24.0 Total finance lease liability $ 27.9 $ 30.7
Schedule of Lease Terms, Components of Lease Costs and Supplemental Cash Flow Information	The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of December 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.7 13.1 Weighted-average incremental borrowing rate 5.6 % 6.1 % Finance leases: Weighted-average remaining lease term (years) 12.1 15.0 Weighted-average incremental borrowing rate 6.8 % 6.2 % The following table sets forth the components of lease cost: Year ended December 31, 2020 Year ended December 31, 2019 Operating lease cost $ 977.2 $ 1,013.1 Variable lease costs not included in lease liability (1) 280.0 261.7 _______________ (1) Includes property tax paid on behalf of the landlord. Supplemental cash flow information is as follows: Year ended December 31, 2020 Year ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (988.3) $ (1,012.2) Operating cash flows from finance leases $ (1.3) $ (1.7) Financing cash flows from finance leases $ (9.2) $ (18.0) Non-cash items: New operating leases (1) $ 346.0 $ 409.5 Operating lease modifications and reassessments $ 843.1 $ 334.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions.
Schedule of Maturities of Finance Lease Liabilities	Maturities of operating and finance lease liabilities as of December 31, 2020 were as follows: Fiscal Year Operating Lease (1) Finance Lease (1) 2021 $ 901.1 $ 6.2 2022 869.0 5.3 2023 836.4 3.6 2024 798.0 2.9 2025 751.8 2.1 Thereafter 6,423.4 26.9 Total lease payments 10,579.7 47.0 Less amounts representing interest (3,155.4) (19.1) Total lease liability 7,424.3 27.9 Less current portion of lease liability 539.9 4.9 Non-current lease liability $ 6,884.4 $ 23.0 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods.
Schedule of Maturities of Operating Lease Liabilities	Maturities of operating and finance lease liabilities as of December 31, 2020 were as follows: Fiscal Year Operating Lease (1) Finance Lease (1) 2021 $ 901.1 $ 6.2 2022 869.0 5.3 2023 836.4 3.6 2024 798.0 2.9 2025 751.8 2.1 Thereafter 6,423.4 26.9 Total lease payments 10,579.7 47.0 Less amounts representing interest (3,155.4) (19.1) Total lease liability 7,424.3 27.9 Less current portion of lease liability 539.9 4.9 Non-current lease liability $ 6,884.4 $ 23.0 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods.

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in the carrying Value of Goodwill	The changes in the carrying value of goodwill for each of the Company’s business segments were as follows: Property Services Total U.S. & Canada Asia-Pacific Africa Europe Latin America Balance as of December 31, 2018 $ 3,382.5 $ 1,045.5 $ 119.3 $ 262.0 $ 690.6 $ 2.0 $ 5,501.9 Additions and adjustments (1) 32.8 — 670.0 — — — 702.8 Effect of foreign currency translation — (23.7) 0.9 (5.8) 2.2 — (26.4) Balance as of December 31, 2019 $ 3,415.3 $ 1,021.8 $ 790.2 $ 256.2 $ 692.8 $ 2.0 $ 6,178.3 Additions and adjustments (2) 1,335.5 18.7 (153.6) — — — 1,200.6 Effect of foreign currency translation — (23.6) (11.0) 22.9 (84.5) — (96.2) Balance as of December 31, 2020 $ 4,750.8 $ 1,016.9 $ 625.6 $ 279.1 $ 608.3 $ 2.0 $ 7,282.7 _______________ (1) Additions consist of $704.3 million resulting from 2019 acquisitions, partially offset by $1.5 million from revisions to prior-year acquisitions due to measurement period adjustments.
Schedule of Finite Intangible Assets	The Company’s other intangible assets subject to amortization consisted of the following: As of December 31, 2020 As of December 31, 2019 Estimated Useful Gross Accumulated Net Book Gross Accumulated Net Book Acquired network location intangibles (1) Up to 20 $ 5,784.0 $ (2,117.6) $ 3,666.4 $ 5,150.8 $ (1,920.4) $ 3,230.4 Acquired tenant-related intangibles Up to 20 14,322.5 (4,237.5) 10,085.0 12,674.1 (3,674.6) 8,999.5 Acquired licenses and other intangibles 3-20 97.8 (9.4) 88.4 106.7 (18.2) 88.5 Total other intangible assets $ 20,204.3 $ (6,364.5) $ 13,839.8 $ 17,931.6 $ (5,613.2) $ 12,318.4 _______________ (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, generally up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.
Schedule of Expected Future Amortization Expenses	Based on current exchange rates, the Company expects to record amortization expense as follows over the next five years: Fiscal Year Amount 2021 $ 999.6 2022 994.0 2023 969.0 2024 959.1 2025 927.6

NOTES RECEIVABLE AND OTHER NO_2

NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
Notes Receivable And Other Long Term Assets [Abstract]
Notes Receivable and Other Non-current Assets	Notes receivable and other non-current assets consisted of the following: As of December 31, 2020 December 31, 2019 Notes receivable $ 6.5 $ 1.1 Other miscellaneous assets 393.6 405.3 Notes receivable and other non-current assets $ 400.1 $ 406.4

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Schedule of Merger and Acquisition Related Costs	During the years ended December 31, 2020, 2019 and 2018, the Company recorded acquisition and merger related expenses for business combinations and non-capitalized asset acquisition costs and integration costs as follows: Year Ended December 31, 2020 2019 2018 Acquisition and merger related expenses $ 15.5 $ 26.9 $ 14.1 Integration costs $ 23.1 $ 9.8 $ 16.1
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the allocations of the purchase prices for the fiscal year 2020 acquisitions based upon their estimated fair value at the date of acquisition: InSite Acquisition Other (1) Current assets $ 57.2 $ 40.6 Property and equipment 516.4 336.7 Intangible assets (2): Tenant-related intangible assets 1,160.1 596.5 Network location intangible assets 622.7 166.6 Other intangible assets — 1.3 Other non-current assets 300.7 112.3 Current liabilities (75.9) (10.9) Deferred tax liability (116.3) (9.8) Other non-current liabilities (267.6) (114.5) Net assets acquired 2,197.3 1,118.8 Goodwill (3) 1,354.2 — Fair value of net assets acquired 3,551.5 1,118.8 Debt assumed (4) (800.0) — Purchase price $ 2,751.5 $ 1,118.8 ______________ (1) Includes 25 sites in Peru held pursuant to long-term finance leases. (2) Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis generally over a 20 year period. (3) The Company expects goodwill to be partially deductible for tax purposes. (4) InSite Acquisition debt assumed includes $763.5 million of InSite’s indebtedness and a fair value adjustment of $36.5 million. The fair value adjustment was based primarily on reported market values using Level 2 inputs. The following table summarizes the preliminary and final allocation of the purchase price paid and the amounts of assets acquired and liabilities assumed for the Eaton Towers Acquisition based upon its estimated fair value at the date of acquisition. Balances are reflected in the accompanying consolidated balance sheet as of December 31, 2020. Preliminary Allocation Final Allocation Current assets $ 150.4 $ 151.7 Property and equipment 304.7 306.6 Intangible assets (1): Tenant-related intangible assets 1,007.6 1,107.7 Network location intangible assets 272.2 326.2 Other non-current assets 99.5 114.8 Current liabilities (82.0) (94.3) Deferred tax liability (319.3) (347.2) Other non-current liabilities (138.3) (121.3) Net assets acquired 1,294.8 1,444.2 Goodwill (2) 670.0 516.4 Fair value of net assets acquired 1,964.8 1,960.6 Debt assumed (329.8) (329.8) Purchase price $ 1,635.0 $ 1,630.8 _______________ (1) Tenant-related intangible assets and network location intangible assets are amortized on a straight-line basis over periods of up to 20 years. (2) The Company expects goodwill to be partially deductible for tax purposes.
Schedule of Pro Forma Information	The following table presents the unaudited pro forma financial results as if the 2020 acquisitions had occurred on January 1, 2019 and the 2019 acquisitions had occurred on January 1, 2018. The pro forma results do not include any anticipated cost synergies, costs or other integration impacts. Accordingly, such pro forma amounts are not necessarily indicative of the results that actually would have occurred had the transactions been completed on the dates indicated, nor are they indicative of the future operating results of the Company. Year Ended December 31, 2020 2019 Pro forma revenues $ 8,230.9 $ 8,083.8 Pro forma net income attributable to American Tower Corporation common stockholders $ 1,515.7 $ 1,651.0 Pro forma net income per common share amounts: Basic net income attributable to American Tower Corporation common stockholders $ 3.42 $ 3.73 Diluted net income attributable to American Tower Corporation common stockholders $ 3.40 $ 3.71

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2020
Accrued Liabilities, Current [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: As of December 31, 2020 December 31, 2019 Accrued construction costs $ 46.5 $ 27.8 Accrued income tax payable 20.6 55.2 Accrued pass-through costs 67.1 74.2 Amounts payable for acquisitions 58.9 — Amounts payable to tenants 66.4 77.9 Accrued property and real estate taxes 219.1 198.1 Accrued rent 82.6 75.6 Payroll and related withholdings 104.4 102.4 Other accrued expenses 378.1 347.0 Accrued expenses $ 1,043.7 $ 958.2

LONG-TERM OBLIGATIONS (Tables)

LONG-TERM OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Outstanding amounts under the Company’s long-term obligations, reflecting discounts, premiums, debt issuance costs and fair value adjustments due to interest rate swaps consisted of the following: As of December 31, 2020 December 31, 2019 Contractual Interest Rate (1) Maturity Date (1) 2019 364-Day Term Loan (1) (2) $ — $ 999.9 N/A N/A 2020 Term Loan (1) (3) 749.4 — 0.800 % February 12, 2021 2019 Multicurrency Credit Facility (1) — 700.0 — % June 28, 2023 2019 Term Loan (1) 996.1 995.2 1.275 % January 31, 2025 2019 Credit Facility (1) 2,295.0 1,600.0 1.235 % January 31, 2025 2.800% senior notes (4) — 749.4 N/A N/A 3.300% senior notes (5) — 748.5 N/A N/A 3.450% senior notes (5) — 647.7 N/A N/A 5.900% senior notes (6) — 498.9 N/A N/A 2.250% senior notes 605.1 592.1 2.250 % January 15, 2022 4.70% senior notes 699.0 698.2 4.700 % March 15, 2022 3.50% senior notes 996.1 994.3 3.500 % January 31, 2023 3.000% senior notes 721.9 704.9 3.000 % June 15, 2023 0.600% senior notes 496.8 — 0.600 % January 15, 2024 5.00% senior notes 1,001.3 1,001.7 5.000 % February 15, 2024 3.375% senior notes 645.7 644.4 3.375 % May 15, 2024 2.950% senior notes 643.1 641.3 2.950 % January 15, 2025 2.400% senior notes 745.0 — 2.400 % March 15, 2025 1.375% senior notes (7) 604.1 553.0 1.375 % April 4, 2025 4.000% senior notes 744.3 743.2 4.000 % June 1, 2025 1.300% senior notes 495.4 — 1.300 % September 15, 2025 4.400% senior notes 497.1 496.6 4.400 % February 15, 2026 1.950% senior notes (7) 605.2 554.4 1.950 % May 22, 2026 3.375% senior notes 989.5 987.9 3.375 % October 15, 2026 3.125% senior notes 397.9 397.6 3.125 % January 15, 2027 2.750% senior notes 744.3 743.5 2.750 % January 15, 2027 3.55% senior notes 744.8 744.1 3.550 % July 15, 2027 0.500% senior notes (7) 907.4 — 0.500 % January 15, 2028 3.600% senior notes 693.4 692.6 3.600 % January 15, 2028 1.500% senior notes 645.1 — 1.500 % January 31, 2028 3.950% senior notes 590.6 589.6 3.950 % March 15, 2029 3.800% senior notes 1,633.5 1,631.7 3.800 % August 15, 2029 2.900% senior notes 741.7 — 2.900 % January 15, 2030 2.100% senior notes 740.2 — 2.100 % June 15, 2030 1.875% senior notes 790.5 — 1.875 % October 15, 2030 1.000% senior notes (7) 786.1 — 1.000 % January 15, 2032 3.700% senior notes 591.9 591.8 3.700 % October 15, 2049 3.100% senior notes 1,037.7 — 3.100 % June 15, 2050 2.950% senior notes 538.2 — 2.950 % January 15, 2051 Total American Tower Corporation debt 26,113.4 20,942.5 Series 2013-2A Securities (8) 1,296.6 1,295.0 3.070 % March 15, 2023 Series 2018-1A Securities (8) 494.6 493.8 3.652 % March 15, 2028 Series 2015-1 Notes (9) — 349.6 N/A N/A Series 2015-2 Notes (10) 522.1 521.4 3.482 % June 16, 2025 InSite Debt (11) 800.0 — Various Various Other subsidiary debt (12) 32.9 422.4 Various Various Total American Tower subsidiary debt 3,146.2 3,082.2 Finance lease obligations 27.9 30.7 Total 29,287.5 24,055.4 Less current portion of long-term obligations (789.8) (2,928.2) Long-term obligations $ 28,497.7 $ 21,127.2 _______________ (1) Accrues interest at a variable rate. (2) Repaid in full on February 13, 2020 using proceeds from the 2020 Term Loan (as defined below), borrowings from the 2019 Credit Facility (as defined below) and cash on hand. (3) Repaid in full on February 5, 2021 using borrowings from the 2019 Multicurrency Credit Facility and cash on hand. (4) Repaid in full on May 11, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (5) Repaid in full on July 6, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (6) Repaid in full on January 15, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (7) Notes are denominated in EUR. (8) Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048. (9) Repaid in full on the June 2020 payment date with cash on hand. (10) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050. (11) Debt entered into by certain InSite subsidiaries acquired in connection with the InSite Acquisition (the “InSite Debt”) (12) Includes (a) the Colombian credit facility, which is denominated in Colombian Pesos (“COP”) and amortizes through April 24, 2021, (b) debt entered into by the Company’s Kenyan subsidiary in connection with an acquisition of sites in Kenya, which is denominated in U.S. Dollars (“USD”) and is payable either (i) in future installments subj ect to the satisfaction of specified conditions or (ii) three years from the note origination date, and (c) U.S. subsidiary debt related to a seller-financed acquisition. As of December 31, 2019, included (a) debt entered into by certain Eaton Towers subsidiaries acquired in connection with the Eaton Towers Acquisition (the “Eaton Towers Debt”), which was denominated i n multiple currencies, including USD, EUR, Kenyan Shilling (“KES”) and West African CFA Franc (“XOF”) and was repaid during the year ended December 31, 2020, (b) the Brazil credit facility, which was denominated in Brazilian Reais (“BRL”) and was repaid on March 6, 2020, and (c) the South African credit facility, which was denominated in South African Rand (“ZAR”) and was repaid on the December 17, 2020 maturity date. Amounts outstanding and key terms of other subsidiary debt consisted of the following as of December 31, (in millions, except percentages): Carrying Value Carrying Value Interest Rate Maturity Date 2020 2019 2020 2019 South African Credit Facility (2) — 288.7 $ — $ 20.6 N/A N/A Colombian Credit Facility (3) 40,000.0 79,647.3 $ 11.6 $ 24.3 8.45 % April 24, 2021 Brazil Credit Facility (4) — 65.4 $ — $ 16.2 Various January 15, 2022 Kenya Debt (5) 20.1 29.6 $ 20.1 $ 29.6 8.00 % October 1, 2021 U.S. Subsidiary Debt (6) 1.2 1.9 $ 1.2 $ 1.9 — % January 1, 2022 Eaton Towers Debt (7): USD Denominated — 238.8 $ — $ 238.8 N/A N/A EUR Denominated — 26.2 $ — $ 29.5 N/A N/A XOF Denominated — 16,836.8 $ — $ 28.8 N/A N/A KES Denominated — 3,319.2 $ — $ 32.7 N/A N/A _______________ (1) Includes applicable deferred financing costs. (2) Denominated in ZAR, with an original principal amount of 830.0 million ZAR. On December 23, 2016, the borrower borrowed an additional 500.0 million ZAR. Debt accrued interest at a variable rate. On the December 17, 2020 maturity date, the Company repaid all outstanding amounts under the South African Credit Facility. (3) Denominated in COP, with an original principal amount of 200.0 billion COP. Debt accrues interest at a variable rate. The loan agreement for the Colombian Credit Facility requires that the borrower manage exposure to variability in interest rates on certain of the amounts outstanding under the Colombian Credit Facility. The borrower no longer maintains the ability to draw on the Colombian Credit Facility. (4) Denominated in BRL, with an original principal amount of 271.0 million BRL. Debt accrued interest at a variable rate. On March 6, 2020, the Company repaid all outstanding amounts under the Brazil Credit Facility. (5) Denominated in USD, with an original principal amount of $51.8 million. The loan agreement for the Kenya Debt requires that the debt be paid either (i) in future installments subject to the satisfaction of specified conditions or (ii) three years from the note origination date with an optional two (6) Related to a seller-financed acquisition. Denominated in USD with an original principal amount of $2.5 million. As of December 31, 2020, the key terms were as follows: Carrying Value Interest Rate Maturity Date 2020 2019 2016-1 Securitized Debt (1) Series 2016-1A Class A $ 218.0 $ — 2.883 % November 15, 2023 Series 2016-1A Class B 22.4 — 4.557 % November 15, 2023 Series 2016-1A Class C 75.7 — 6.414 % November 15, 2023 2018-1 Securitized Debt (2) Series 2018-1A Class A 235.4 — 4.103 % December 15, 2025 Series 2018-1A Class B 60.5 — 4.844 % December 15, 2025 Series 2018-1A Class C 22.8 — 6.115 % December 15, 2025 2020-1 Securitized Debt (3) Series 2020-1A Class A 121.5 — 1.496 % September 15, 2025 Series 2020-1A Class B 21.7 — 2.488 % September 15, 2025 Series 2020-1A Class C 22.0 — 4.213 % September 15, 2025 Total InSite Debt $ 800.0 $ — _______________ (1) Maturity dates reflect the anticipated repayment dates; final legal maturity is November 15, 2046. (2) Maturity dates reflect the anticipated repayment dates; final legal maturity is December 15, 2048. (3) Maturity dates reflect the anticipated repayment dates; final legal maturity is September 15, 2050.
Schedule of Credit Facilities	As of December 31, 2020, the key terms under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the 2019 Term Loan and the 2020 Term Loan were as follows: Outstanding Principal Balance Undrawn letters of credit Maturity Date Current margin over LIBOR Current commitment fee (1) 2019 Multicurrency Credit Facility — $ 3.8 June 28, 2023 (3) 1.125 % 0.110 % 2019 Credit Facility $ 2,295.0 $ 0.8 January 31, 2025 (3) 1.125 % 0.110 % 2019 Term Loan $ 1,000.0 (2) N/A January 31, 2025 1.125 % N/A 2020 Term Loan $ 750.0 (2) N/A February 12, 2021 0.650 % N/A _______________ (1) Fee on undrawn portion of each credit facility. (2) Borrowed at LIBOR
Schedule of Key Terms Related to Senior Notes	The following table outlines key terms related to the Company ’ s outstanding senior notes as of December 31, 2020: Adjustments to Principal Amount (1) Aggregate Principal Amount 2020 2019 Interest Issue Date Par Call Date (3) 2.250% Notes (4) $ 600.0 $ 5.1 $ (7.9) January 15 and July 15 September 30, 2016 N/A 4.70% Notes $ 700.0 (1.0) (1.8) March 15 and September 15 March 12, 2012 N/A 3.50% Notes $ 1,000.0 (3.9) (5.7) January 31 and July 31 January 8, 2013 N/A 3.000% Notes (5) $ 700.0 21.9 4.9 June 15 and December 15 December 8, 2017 N/A 0.600% Notes $ 500.0 (3.2) — January 15 and July 15 November 20, 2020 N/A 5.00% Notes (6) $ 1,000.0 1.3 1.7 February 15 and August 15 August 19, 2013 N/A 3.375% Notes $ 650.0 (4.3) (5.6) May 15 and November 15 March 15, 2019 April 15, 2024 2.950% Notes $ 650.0 (6.9) (8.7) January 15 and July 15 June 13, 2019 December 15, 2024 2.400% Notes $ 750.0 (5.0) — March 15 and September 15 January 10, 2020 February 15, 2025 1.375% Notes (7) $ 610.8 (6.7) (7.6) April 4 April 6, 2017 January 4, 2025 4.000% Notes $ 750.0 (5.7) (6.8) June 1 and December 1 May 7, 2015 March 1, 2025 1.300% Notes $ 500.0 (4.6) — March 15 and September 15 June 3, 2020 August 15, 2025 4.400% Notes $ 500.0 (2.9) (3.4) February 15 and August 15 January 12, 2016 November 15, 2025 1.950% Notes (7) $ 610.8 (5.6) (6.2) May 22 May 22, 2018 February 22, 2026 3.375% Notes $ 1,000.0 (10.5) (12.1) April 15 and October 15 May 13, 2016 July 15, 2026 3.125% Notes $ 400.0 (2.1) (2.4) January 15 and July 15 September 30, 2016 October 15, 2026 2.750% Notes $ 750.0 (5.7) (6.5) January 15 and July 15 October 3, 2019 November 15, 2026 3.55% Notes $ 750.0 (5.2) (5.9) January 15 and July 15 June 30, 2017 April 15, 2027 0.500% Notes (7) $ 916.2 (8.8) — January 15 September 10, 2020 October 15, 2027 3.600% Notes $ 700.0 (6.6) (7.4) January 15 and July 15 December 8, 2017 October 15, 2027 1.500% Notes $ 650.0 (4.9) — January 31 and July 31 November 20, 2020 November 30, 2027 3.950% Notes $ 600.0 (9.4) (10.4) March 15 and September 15 March 15, 2019 December 15, 2028 3.800% Notes $ 1,650.0 (16.5) (18.3) February 15 and August 15 June 13, 2019 May 15, 2029 2.900% Notes $ 750.0 (8.3) — January 15 and July 15 January 10, 2020 October 15, 2029 2.100% Notes $ 750.0 (9.8) — June 15 and December 15 June 3, 2020 March 15, 2030 1.875% Notes $ 800.0 (9.5) — April 15 and October 15 September 28, 2020 July 15, 2030 1.000% Notes (7) $ 794.0 (7.9) — January 15 September 10, 2020 October 15, 2031 3.700% Notes $ 600.0 (8.1) (8.2) April 15 and October 15 October 3, 2019 April 15, 2049 3.100% Notes (8) $ 1,050.0 (12.3) — June 15 and December 15 June 3, 2020 December 15, 2049 2.950% Notes $ 550.0 (11.8) — January 15 and July 15 November 20, 2020 July 15, 2050 _______________ (1) Includes unamortized discounts, premiums and debt issuance costs and fair value adjustments due to interest rate swaps. (2) Interest payments are due semi-annually for each series of senior notes, except for the 1.375% Notes, the 1.950% Notes, the 0.500% Notes and the 1.000% Notes, for which interest payments are due annually. (3) The Company may redeem the notes at any time, in whole or in part, at a redemption price equal to 100% of the principal amount of the notes plus a make-whole premium, together with accrued interest to the redemption date. If the Company redeems the notes on or after the par call date, the Company will not be required to pay a make-whole premium. (4) Includes $6.3 million and ($5.9) million fair value adjustment due to interest rate swaps in 2020 and 2019, respectively. (5) Includes $25.1 million and $9.2 million fair value adjustment due to interest rate swaps in 2020 and 2019, respectively. (6) The original issue date for the 5.00% Notes was August 19, 2013. The issue date for the reopened 5.00% Notes was January 10, 2014. (7) Notes are denominated in EUR.
Schedule of Key Terms of India Indebtedness	Amounts outstanding and key terms of the India indebtedness consisted of the following as of December 31, 2020 (in millions, except percentages): Amount Outstanding (INR) Amount Outstanding (USD) Interest Rate (Range) Maturity Date (Range) Working capital facilities (1) — $ — 7.45% -8.75% March 18, 2021 - October 23, 2021 _______________ (1) 5.6 billion Indian Rupees (“INR”) ($76.9 million) of borrowing capacity as of December 31, 2020.
Schedule of Maturities of Long-term Debt	Aggregate principal maturities of long-term debt, including finance leases, for the next five years and thereafter are expected to be: Fiscal Year Amount 2021 $ 789.8 2022 1,304.6 2023 3,318.9 2024 2,151.9 2025 7,566.0 Thereafter 14,331.5 Total cash obligations 29,462.7 Unamortized discounts, premiums and debt issuance costs and fair value adjustments, net (175.2) Balance as of December 31, 2020 $ 29,287.5

OTHER NON-CURRENT LIABILITIES (

OTHER NON-CURRENT LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2020
Other Liabilities, Noncurrent [Abstract]
Schedule of Other Non-Current Liabilities	Other non-current liabilities consisted of the following: As of December 31, 2020 December 31, 2019 Unearned revenue $ 576.1 $ 525.9 Other miscellaneous liabilities 408.5 411.1 Other non-current liabilities $ 984.6 $ 937.0

ASSET RETIREMENT OBLIGATIONS (T

ASSET RETIREMENT OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2020
Asset Retirement Obligation [Abstract]
Schedule of Carrying Value of Asset Retirement Obligations	The changes in the carrying amount of the Company’s asset retirement obligations were as follows: 2020 2019 Beginning balance as of January 1, $ 1,384.1 $ 1,210.0 Additions 94.2 61.8 Accretion expense 90.8 81.6 Revisions in estimates (1) 8.3 56.8 Settlements (6.1) (26.1) Balance as of December 31, $ 1,571.3 $ 1,384.1 _______________ (1) Revisions in estimates include decreases to the liability of $42.1 million and $6.7 million related to foreign currency translation for the years ended December 31, 2020 and 2019, respectively.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value Level of Inputs	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.
Schedule of Fair Value of Assets and Liabilities Measured on a Recurring Basis	The fair values of the Company’s financial assets and liabilities that are required to be measured on a recurring basis at fair value were as follows: December 31, 2020 December 31, 2019 Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Assets: Interest rate swap agreements — $ 29.2 — — $ 9.0 — Embedded derivative in lease agreement — — — — — $ 10.7 Liabilities: Interest rate swap agreements — $ 0.1 — — $ 7.5 — Fair value of debt related to interest rate swap agreements (1) $ 31.4 — — $ 3.3 — —

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income Tax Provision from Continuing Operations	The following information pertains to the Company’s income taxes on a consolidated basis. The income tax provision from continuing operations consisted of the following: Year Ended December 31, 2020 2019 2018 Current: Federal $ 8.7 $ (1.7) $ (1.4) State (10.7) (5.0) (1.8) Foreign (150.1) (48.2) (189.7) Deferred: Federal (1.0) 1.4 4.0 State (1.0) 0.5 0.7 Foreign 24.5 53.2 298.3 Income tax (provision) benefit $ (129.6) $ 0.2 $ 110.1
Schedule of Reconciliation Between The U.S. Statutory Rate and The Effective Rate from Continuing Operations	Reconciliation between the U.S. statutory rate and the effective rate from continuing operations is as follows: Year Ended December 31, 2020 2019 2018 Statutory tax rate 21 % 21 % 21 % Adjustment to reflect REIT status (1) (21) (21) (21) Foreign taxes 4 3 (8) Foreign withholding taxes 3 3 4 Uncertain tax positions 1 1 — Changes in tax laws — (6) — Impact from restructuring — (1) (6) Changes in valuation allowance (1) — — Effective tax rate 7 % (0)% (10) % _______________ (1) As a result of the ability to utilize the dividends paid deduction to offset the Company’s REIT income and gains.
Schedule of Components of Income from Continuing Operations Before Income Taxes and Income on Equity Method Investments	The domestic and foreign components of income from continuing operations before income taxes are as follows: Year Ended December 31, 2020 2019 2018 United States $ 1,683.0 $ 1,527.0 $ 1,212.7 Foreign 138.1 389.4 (58.1) Total $ 1,821.1 $ 1,916.4 $ 1,154.6
Schedule of Components of The Net Deferred Tax Asset and Related Valuation Allowance	The components of the net deferred tax asset and liability and related valuation allowance were as follows: December 31, 2020 December 31, 2019 Assets: Operating lease liability $ 837.1 $ 878.5 Net operating loss carryforwards 327.1 356.6 Accrued asset retirement obligations 187.8 174.9 Stock-based compensation 9.2 5.6 Unearned revenue 34.6 31.7 Unrealized loss on foreign currency 4.9 3.8 Other accruals and allowances 83.4 65.6 Nondeductible interest 60.9 15.9 Items not currently deductible and other 65.8 10.2 Liabilities: Depreciation and amortization (1,140.3) (1,040.3) Right-of-use asset (824.0) (865.1) Deferred rent (92.9) (79.7) Investment in affiliate (1) (60.4) — Other (1.1) — Subtotal (507.9) (442.3) Valuation allowance (228.5) (194.2) Net deferred tax liabilities $ (736.4) $ (636.5) _______________ (1) Includes basis difference associated with investment in subsidiary related to the InSite Acquisition.
Schedule of Valuation Allowance	A summary of the activity in the valuation allowance is as follows: 2020 2019 2018 Balance as of January 1, $ 194.2 $ 151.9 $ 142.0 Additions (1) 64.7 42.5 15.7 Usage, expiration and reversals (22.0) — — Foreign currency translation (8.4) (0.2) (5.8) Balance as of December 31, $ 228.5 $ 194.2 $ 151.9 _______________
Schedule of Net Operating Loss Carryforwards Expire	At December 31, 2020, the Company had net federal, state and foreign operating loss carryforwards available to reduce future taxable income. If not utilized, the Company’s NOLs expire as follows: Years ended December 31, Federal State Foreign 2021 to 2025 $ 141.6 $ 180.2 $ 12.4 2026 to 2030 0.0 193.7 85.6 2031 to 2035 9.5 48.7 3.5 2036 to 2040 61.7 183.0 — Indefinite carryforward 142.1 47.7 679.5 Total $ 354.9 $ 653.3 $ 781.0
Schedule of Change in Unrecognized Tax Benefit	A reconciliation of the beginning and ending amount of unrecognized tax benefits are as follows: Year Ended December 31, 2020 2019 2018 Balance at January 1 $ 175.6 $ 107.7 $ 116.7 Additions based on tax positions related to the current year 4.7 33.3 8.1 Additions and reductions for tax positions of prior years (1) (5.0) 37.5 0.3 Foreign currency (9.6) (1.6) (8.1) Reduction as a result of the lapse of statute of limitations (26.0) (1.3) (2.6) Reduction as a result of effective settlements (3.5) — (6.7) Balance at December 31 $ 136.2 $ 175.6 $ 107.7 _______________

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expenses	During the years ended December 31, 2020, 2019 and 2018, the Company recorded and capitalized the following stock-based compensation expenses: 2020 2019 2018 Stock-based compensation expense - Property $ 1.9 $ 1.8 $ 2.4 Stock-based compensation expense - Services 1.1 1.0 0.9 Stock-based compensation expense - SG&A 117.8 108.6 134.2 Total stock-based compensation expense $ 120.8 $ 111.4 $ 137.5 Stock-based compensation expense capitalized as property and equipment $ 1.7 $ 1.6 $ 2.0
Schedule of the Company's Option Activity	The Company’s option activity for the year ended December 31, 2020 was as follows (share and per share data disclosed in full amounts): Options Weighted Weighted Aggregate Outstanding as of January 1, 2020 3,060,242 $85.90 Granted — — Exercised (1,043,981) 81.16 Forfeited — — Expired — — Outstanding as of December 31, 2020 2,016,261 $88.36 3.15 $274.4 Exercisable as of December 31, 2020 2,014,628 $88.33 3.15 $274.2 Vested or expected to vest as of December 31, 2020 2,016,261 $88.36 3.15 $274.4
Schedule of Options Outstanding	The following table sets forth information regarding options outstanding at December 31, 2020 (share and per share data disclosed in full amounts): Options Outstanding Options Exercisable Range of Exercise Outstanding Weighted Weighted Average Options Weighted $50.78 - $71.07 102,447 $ 61.55 1.14 102,447 $ 61.55 $76.90 - $77.75 221,435 76.92 1.82 221,435 76.92 $81.18 - $94.23 432,352 81.58 2.66 432,352 81.58 $94.57 - $94.71 1,240,897 94.61 3.69 1,240,897 94.61 $99.67 - $121.15 19,130 111.97 5.45 17,497 111.39 $50.78 - $121.15 2,016,261 $ 88.36 3.15 2,014,628 $ 88.33
Schedule of the Company's Restricted Stock Unit Activity	The Company’s RSU and PSU activity for the year ended December 31, 2020 was as follows (share and per share data disclosed in full amounts): RSUs Weighted Average Grant Date Fair Value PSUs Weighted Average Grant Date Fair Value Outstanding as of January 1, 2020 (1) 1,454,350 $ 147.67 528,908 $ 136.94 Granted (2) 456,369 243.25 151,341 216.36 Vested and Released (3) (618,013) 134.53 (282,774) 113.58 Forfeited (4) (47,631) 173.74 (76,965) 211.21 Outstanding as of December 31, 2020 1,245,075 $ 188.23 320,510 $ 177.22 Expected to vest as of December 31, 2020 1,245,075 $ 188.23 320,510 $ 177.22 Vested and deferred as of December 31, 2020 (5) 58,204 $ 181.26 — $ — (1) PSUs consist of the target number of shares issuable at the end of the three three three (2) PSUs consist of the target number of shares issuable at the end of the three three three (3) This includes 19,810 of previously vested and deferred RSUs. PSUs consist of shares vested pursuant to the 2017 PSUs. There are no additional shares to be earned related to the 2017 PSUs. (4) PSUs consist of shares forfeited in connection with the retirement of the Company’s former CEO, which includes the target number of shares issuable at the end of the three three

REDEEMABLE NONCONTROLLING INT_2

REDEEMABLE NONCONTROLLING INTERESTS (Tables)	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Schedule of Redeemable Noncontrolling Interests	The changes in Redeemable noncontrolling interests for the years ended December 31, 2020, 2019 and 2018 were as follows: Year Ended December 31, 2020 2019 2018 Balance as of January 1, $ 1,096.5 $ 1,004.8 $ 1,126.2 Additions to redeemable noncontrolling interests — 525.7 — Net income (loss) attributable to noncontrolling interests 6.6 35.8 (87.9) Adjustment to noncontrolling interest redemption value (14.0) (35.8) 86.7 Adjustment to noncontrolling interest due to merger — — (28.1) Purchase of redeemable noncontrolling interest (861.7) (425.7) — Foreign currency translation adjustment attributable to noncontrolling interests (15.3) (8.3) (92.1) Balance as of December 31, $ 212.1 $ 1,096.5 $ 1,004.8

EQUITY (Tables)

EQUITY (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Dividends Declared	During the years ended December 31, 2020, 2019 and 2018, the Company declared the following cash distributions (per share data reflects actual amounts): For the year ended December 31, 2020 2019 2018 Distribution Aggregate Distribution Aggregate Distribution Aggregate Common Stock $ 4.53 $ 2,010.7 $ 3.78 $ 1,672.8 $ 3.15 $ 1,389.8 Series B Preferred Stock (1) $ — $ — $ — $ — $ 13.75 $ 18.9 _______________
Schedule of Stock by Class	The following table characterizes the tax treatment of distributions declared per share of common stock and Mandatory Convertible Preferred Stock. For the year ended December 31, 2020 2019 2018 Per Share % Per Share % Per Share % Common Stock Ordinary dividend $ 3.3200 (1) 100.00 % $ 3.7800 100.00 % $ 3.1500 100.00 % Capital gains distribution — — — — — — Total $ 3.3200 100.00 % $ 3.7800 100.00 % $ 3.1500 100.00 % Series B Preferred Stock (2) Ordinary dividend $ — — % $ — — % $ 2.1314 (3) 100.00 % Capital gains distribution — — — — — — Total $ — — % $ — — % $ 2.1314 100.00 % _______________ (1) Excludes dividend declared on December 3, 2020 of $1.21 per share, which was paid on February 2, 2021 to common stockholders of record at the close of business on December 28, 2020 and which will apply to the 2021 tax year. (2) Represents the tax treatment on dividends per depositary share, each of which represents a 1/10th interest in a share of Series B Preferred Stock. (3) Includes a deemed distribution as a result of a conversion rate adjustment triggered on January 18, 2018.

OTHER OPERATING EXPENSES (Table

OTHER OPERATING EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Schedule of Other Operating Expenses	Other operating expenses included the following for the years ended December 31,: 2020 (1) 2019 (2) 2018 Impairment charges $ 222.8 $ 94.2 $ 394.0 Net losses on sales or disposals of assets 17.3 45.1 85.6 Other operating expenses 25.7 27.0 33.7 Total Other operating expenses $ 265.8 $ 166.3 $ 513.3 _______________ (1) For the year ended December 31, 2020, Other operating expenses includes an $11.9 million benefit in Brazil. (2) For the year ended December 31, 2019, Other operating expenses includes $13.1 million of refunds related to pre-acquisition contingencies and settlements.
Schedule of Impairment Charges	Impairment charges included the following for the years ended December 31,: 2020 2019 2018 (1) Tower and network location intangible assets $ 142.4 $ 77.4 $ 284.9 Tenant relationships — — 107.3 Right-of-use assets 76.1 9.9 — Other 4.3 6.9 1.8 Total impairment charges $ 222.8 $ 94.2 $ 394.0 _______________ (1) For the year ended December 31, 2018, impairment charges on tower and network location intangible assets included $258.3 million in India primarily related to carrier consolidation-driven churn events. In addition, the Company fully impaired the tenant relationship for Aircel Ltd., which resulted in an impairment charge of $107.3 million.

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Basic and Diluted by Common Class	The following table sets forth basic and diluted net income per common share computational data for the years ended December 31, (shares in thousands, except per share data): 2020 2019 2018 Net income attributable to American Tower Corporation stockholders $ 1,690.6 $ 1,887.8 $ 1,236.4 Dividends on preferred stock — — (9.4) Net income attributable to American Tower Corporation common stockholders $ 1,690.6 $ 1,887.8 $ 1,227.0 Basic weighted average common shares outstanding 443,640 442,319 439,606 Dilutive securities 2,464 3,201 3,354 Diluted weighted average common shares outstanding 446,104 445,520 442,960 Basic net income attributable to American Tower Corporation common stockholders per common share $ 3.81 $ 4.27 $ 2.79 Diluted net income attributable to American Tower Corporation common stockholders per common share $ 3.79 $ 4.24 $ 2.77
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following shares were not included in the computation of diluted earnings per share because the effect would be anti-dilutive for the years ended December 31, (in thousands, on a weighted average basis): 2020 2019 2018 Restricted stock awards 1 2 — Preferred stock (1) — — 1,456 _______________

SUPPLEMENTAL CASH FLOW INFORM_2

SUPPLEMENTAL CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Schedule of Supplemental Cash Flow Information and Non-Cash Investing and Financing Activities	Supplemental cash flow information and non-cash investing and financing activities are as follows for the years ended December 31,: 2020 2019 2018 Supplemental cash flow information: Cash paid for interest $ 762.3 $ 750.2 $ 789.7 Cash paid for income taxes (net of refunds of $27.0, $11.2 and $25.0, respectively) 146.3 147.5 163.9 Non-cash investing and financing activities: Increase (decrease) in accounts payable and accrued expenses for purchases of property and equipment and construction activities 45.8 (21.0) 8.3 Purchases of property and equipment under finance leases, perpetual easements and capital leases 75.0 81.3 57.8 Fair value of debt assumed through acquisitions (1) 800.0 329.8 — Acquisition of Commercialization Rights (2) — — 24.8 Debt financed acquisition of communication sites — — 54.2 Settlement of third-party debt (5.0) — — _______________ (1) For the year ended December 31, 2020, consists of the InSite Debt. (2) Related to the note extinguishment with TV Azteca, S.A. de C.V. in 2018.

BUSINESS SEGMENTS (Tables)

BUSINESS SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting, Measurement Disclosures [Abstract]
Schedule of Summarized Financial Information Concerning the Company's Reportable Segments	Summarized financial information concerning the Company’s reportable segments for the years ended December 31, 2020, 2019 and 2018 is shown in the following tables. The “Other” column (i) represents amounts excluded from specific segments, such as business development operations, stock-based compensation expense and corporate expenses included in Selling, general, administrative and development expense; Other operating expenses; Interest income; Interest expense; Gain (loss) on retirement of long-term obligations; and Other income (expense), and (ii) reconciles segment operating profit to Income from continuing operations before income taxes. Property Total Other Total Year ended December 31, 2020 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues $ 4,517.0 $ 1,139.4 $ 890.2 $ 149.6 $ 1,257.4 $ 7,953.6 $ 87.9 $ 8,041.5 Segment operating expenses (1) 808.0 661.4 297.7 28.1 392.5 2,187.7 36.5 2,224.2 Segment gross margin 3,709.0 478.0 592.5 121.5 864.9 5,765.9 51.4 5,817.3 Segment selling, general, administrative and development expense (1) 162.2 97.4 94.4 23.0 93.1 470.1 14.8 484.9 Segment operating profit $ 3,546.8 $ 380.6 $ 498.1 $ 98.5 $ 771.8 $ 5,295.8 $ 36.6 $ 5,332.4 Stock-based compensation expense $ 120.8 120.8 Other selling, general, administrative and development expense 176.0 176.0 Depreciation, amortization and accretion 1,882.3 1,882.3 Other expense (2) 1,332.2 1,332.2 Income from continuing operations before income taxes $ 1,821.1 Capital expenditures (3) (4) $ 360.6 $ 112.9 $ 334.9 $ 31.6 $ 221.1 $ 1,061.1 $ — $ 10.1 $ 1,071.2 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $3.0 million and $117.8 million, respectively. (2) Primarily includes interest expense, losses from foreign currency exchange rate fluctuations and $222.8 million in impairment charges. (3) Includes $9.2 million of finance lease payments included in Repayments of notes payable, credit facilities, term loans, senior notes, secured debt and finance leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows. (4) Includes $36.9 million of perpetual land easement payments reported in Deferred financing costs and other financing activities in the cash flows from financing activities in the Company’s consolidated statements of cash flows. Property Total Other Total Year ended December 31, 2019 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues $ 4,188.7 $ 1,217.0 $ 583.9 $ 134.6 $ 1,340.7 $ 7,464.9 $ 115.4 $ 7,580.3 Segment operating expenses (1) 807.9 715.9 209.0 27.8 411.3 2,171.9 42.1 2,214.0 Segment gross margin 3,380.8 501.1 374.9 106.8 929.4 5,293.0 73.3 5,366.3 Segment selling, general, administrative and development expense (1) 175.5 99.9 53.7 23.2 101.0 453.3 12.0 465.3 Segment operating profit $ 3,205.3 $ 401.2 $ 321.2 $ 83.6 $ 828.4 $ 4,839.7 $ 61.3 $ 4,901.0 Stock-based compensation expense $ 111.4 111.4 Other selling, general, administrative and development expense 156.5 156.5 Depreciation, amortization and accretion 1,778.4 1,778.4 Other expense (2) 938.3 938.3 Income from continuing operations before income taxes $ 1,916.4 Capital expenditures (3) (4) $ 359.5 $ 134.5 $ 258.5 $ 13.2 $ 260.4 $ 1,026.1 $ — $ 12.8 $ 1,038.9 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $2.8 million and $108.6 million, respectively. (2) Primarily includes interest expense. (3) Includes $18.0 million of finance lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes, secured debt and finance leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows. (4) Includes $29.6 million of perpetual land easement payments reported in Deferred financing costs and other financing activities in the cash flows from financing activities in the Company’s consolidated statements of cash flows. Property Total Other Total Year ended December 31, 2018 U.S. & Canada Asia-Pacific Africa Europe Latin America Segment revenues (1) $ 3,822.1 $ 1,540.5 $ 545.5 $ 141.8 $ 1,264.8 $ 7,314.7 $ 125.4 $ 7,440.1 Segment operating expenses (2) 771.0 710.9 208.0 30.1 406.3 2,126.3 48.2 2,174.5 Interest income, TV Azteca, net — — — — (0.1) (0.1) — (0.1) Segment gross margin 3,051.1 829.6 337.5 111.7 858.4 5,188.3 77.2 5,265.5 Segment selling, general, administrative and development expense (2) 165.2 110.7 48.0 21.1 83.5 428.5 14.4 442.9 Segment operating profit $ 2,885.9 $ 718.9 $ 289.5 $ 90.6 $ 774.9 $ 4,759.8 $ 62.8 $ 4,822.6 Stock-based compensation expense $ 137.5 137.5 Other selling, general, administrative and development expense 156.1 156.1 Depreciation, amortization and accretion 2,110.8 2,110.8 Other expense (3) 1,263.6 1,263.6 Income from continuing operations before income taxes $ 1,154.6 Capital expenditures (4) $ 376.9 $ 101.0 $ 212.5 $ 20.2 $ 220.7 $ 931.3 $ — $ 13.9 $ 945.2 _______________ (1) Asia-Pacific segment revenues include a net impact of $333.7 million as a result of the settlement payment received from Tata in the fourth quarter of 2018. (2) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $3.3 million and $134.2 million, respectively. (3) Primarily includes interest expense and $394.0 million in impairment charges. (4) Includes $32.0 million of capital lease payments included in Repayments of notes payable, credit facilities, term loan, senior notes, secured debt and capital leases in the cash flows from financing activities in the Company’s consolidated statements of cash flows.
Schedule of Reconciliation of Assets from Segments to Consolidated	Additional information relating to the total assets of the Company’s operating segments is as follows for the years ended December 31,: 2020 2019 2018 Total Assets (1): U.S. & Canada property $ 27,352.9 $ 22,624.6 $ 18,782.0 Asia-Pacific property 5,191.8 5,307.8 4,938.8 Africa property 4,894.8 4,711.1 1,929.7 Europe property 1,868.6 1,535.3 1,438.1 Latin America property 7,434.2 8,125.5 5,594.7 Services 38.7 26.8 46.3 Other (2) 452.5 470.5 280.8 Total assets $ 47,233.5 $ 42,801.6 $ 33,010.4 _______________ (1) Balances are translated at the applicable period end exchange rate, which may impact comparability between periods. (2) Balances include corporate assets such as cash and cash equivalents, certain tangible and intangible assets and income tax accounts that have not been allocated to specific segments.
Schedule of Disclosure on Geographic Areas, Long-Lived Assets	Summarized geographic information related to the Company’s operating revenues for the years ended December 31, 2020, 2019 and 2018 and long-lived assets as of December 31, 2020 and 2019 is as follows: 2020 2019 2018 Operating Revenues: U.S. & Canada: Canada (1) (2) $ 0.3 $ — $ — United States 4,604.6 4,304.1 3,947.5 Asia-Pacific (2): Australia (1) 0.0 — — India 1,139.4 1,217.0 1,540.5 Africa (2): Burkina Faso 43.9 — — Ghana 174.3 124.3 125.4 Kenya 97.7 27.3 7.0 Niger 40.0 — — Nigeria 249.5 229.9 220.7 South Africa 128.7 129.1 125.3 Uganda 156.1 73.3 67.1 Europe (2): France 79.4 68.0 72.7 Germany 70.0 66.6 69.1 Poland (1) 0.2 — — Latin America (2): Argentina 22.1 17.3 16.0 Brazil 506.4 605.5 595.5 Chile 67.3 43.3 44.2 Colombia 96.1 102.1 103.8 Costa Rica 23.4 21.1 18.4 Mexico 483.0 515.3 456.5 Paraguay 12.5 12.6 10.4 Peru 46.6 23.5 20.0 Total operating revenues $ 8,041.5 $ 7,580.3 $ 7,440.1 _______________ (1) The Company launched operations in Canada and Australia through the InSite Acquisition, which closed on December 23, 2020. The Company launched operations in Poland through the Poland Acquisition, which closed on June 16, 2020. (2) Balances are translated at the applicable exchange rate, which may impact comparability between periods. 2020 2019 Long-Lived Assets (1): U.S. & Canada: Canada (2) $ 373.7 $ — United States 19,977.8 16,578.7 Asia-Pacific (2): Australia 20.0 — India 3,482.3 3,708.8 Africa (2): Burkina Faso 315.7 275.3 Ghana 676.8 671.0 Kenya 730.0 761.7 Niger 215.7 199.8 Nigeria 663.7 648.6 South Africa 424.4 409.4 Uganda 867.3 847.3 Europe (2): France 1,176.5 917.1 Germany 370.9 357.3 Poland 2.9 — Latin America (2): Argentina 111.9 100.0 Brazil 1,629.9 2,138.4 Chile 538.7 437.6 Colombia 350.7 375.2 Costa Rica 123.1 124.1 Mexico 1,395.2 1,524.9 Paraguay 103.6 111.3 Peru 380.4 394.6 Total long-lived assets $ 33,931.2 $ 30,581.1 _______________ (1) Includes Property and equipment, net, Goodwill and Other intangible assets, net.
Schedule of Revenue by Major Customers	The following tenants within the property and services segments individually accounted for 10% or more of the Company’s consolidated operating revenues for the years ended December 31,: 2020 2019 2018 AT&T 22 % 22 % 19 % T-Mobile 19 % 10 % 9 % Verizon Wireless 14 % 15 % 15 %

BUSINESS AND SUMMARY OF SIGNI_4

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Principles of Consolidation (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Consideration paid for redemption		$ 861.7	$ 425.7	$ 0
Purchases of redeemable noncontrolling interests		0	0
Additional Paid-in Capital
Schedule of Equity Method Investments [Line Items]
Purchases of redeemable noncontrolling interests		209.2	52.4
Accumulated Other Comprehensive Loss
Schedule of Equity Method Investments [Line Items]
Purchases of redeemable noncontrolling interests		$ (209.2)	$ (52.4)
ATC, TIPL
Schedule of Equity Method Investments [Line Items]
Controlling interest percentage		92.00%	79.00%	63.00%
Noncontrolling owners, ownership percentage		8.00%	21.00%	37.00%
Ghana Subsidiary | MTN Group Limited
Schedule of Equity Method Investments [Line Items]
Noncontrolling owners, ownership percentage		49.00%
Uganda Subsidiary | MTN Group Limited
Schedule of Equity Method Investments [Line Items]
Noncontrolling owners, ownership percentage		49.00%
Ghana And Uganda Subsidiaries
Schedule of Equity Method Investments [Line Items]
Controlling interest percentage		100.00%	51.00%
Consideration paid for redemption		$ 524.4
Consideration adjustment	$ 1.4
Ghana And Uganda Subsidiaries | Additional Paid-in Capital
Schedule of Equity Method Investments [Line Items]
Purchases of redeemable noncontrolling interests		142.2
Ghana And Uganda Subsidiaries | Accumulated Other Comprehensive Loss
Schedule of Equity Method Investments [Line Items]
Purchases of redeemable noncontrolling interests		$ 142.2
ATC Europe
Schedule of Equity Method Investments [Line Items]
Company's ownership percentage		51.00%
ATC Europe | PGGM
Schedule of Equity Method Investments [Line Items]
Company's ownership percentage		49.00%

BUSINESS AND SUMMARY OF SIGNI_5

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Segments (Details) - segment	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	6	6

BUSINESS AND SUMMARY OF SIGNI_6

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES- Accounts Receivable and Deferred Rent Asset (Details)	12 Months Ended
	Dec. 31, 2020tenant
Concentration Risk [Line Items]
Number of tenants	1
Customer Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration risk, percentage	55.00%
Number of tenants	3

BUSINESS AND SUMMARY OF SIGNI_7

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Changes in Allowances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of January 1,	$ 163.3	$ 282.4	$ 131
Current year increases	105.6	104.3	157.8
Write-offs, recoveries and other	(21.3)	(223.4)	(6.4)
Balance as of December 31,	$ 247.6	$ 163.3	$ 282.4

BUSINESS AND SUMMARY OF SIGNI_8

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Net Foreign Currency Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Foreign currency losses recorded in AOCL	$ 391	$ 45.8	$ 385.8
Foreign currency losses (gains) recorded in Other expense	216.4	(6.1)	4.5
Total foreign currency losses	$ 607.4	$ 39.7	$ 390.3

BUSINESS AND SUMMARY OF SIGNI_9

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash, Cash Equivalents, And Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 1,746.3	$ 1,501.2	$ 1,208.7
Restricted cash	115.1	76.8	96.2
Total cash, cash equivalents and restricted cash	$ 1,861.4	$ 1,578	$ 1,304.9	$ 954.9

BUSINESS AND SUMMARY OF SIGN_10

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Labor costs capitalized	$ 51.1	$ 48.3	$ 55
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of respective assets	20 years

BUSINESS AND SUMMARY OF SIGN_11

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Other Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2020
Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years

BUSINESS AND SUMMARY OF SIGN_12

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Foreign currency translation losses	$ 3,759.4	$ 2,823.6
Accumulated Foreign Currency Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Foreign currency translation losses	$ 3,800	$ 2,800	$ 2,600

BUSINESS AND SUMMARY OF SIGN_13

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Revenue Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property straight-line revenues	$ 322	$ 183.5	$ 87.6
Revenue recognized	142.3
Other Noncurrent Assets
Property, Plant and Equipment [Line Items]
Change in contract asset, revenue recognized	$ 6.8	$ 3.1

BUSINESS AND SUMMARY OF SIGN_14

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 495.7	$ 527.2
Property lease revenue	7,545.8	7,053.1
Revenues	8,041.5	7,580.3	$ 7,440.1
U.S. & Canada
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	346.3	371.1
Property lease revenue	4,258.6	3,933
Revenues	4,604.9	4,304.1
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9.3	8.8
Property lease revenue	1,130.1	1,208.2
Revenues	1,139.4	1,217
Africa
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13.8	4
Property lease revenue	876.4	579.9
Revenues	890.2	583.9
Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7.9	5.1
Property lease revenue	141.7	129.5
Revenues	149.6	134.6
Latin America
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	118.4	138.2
Property lease revenue	1,139	1,202.5
Revenues	1,257.4	1,340.7
Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	407.8	411.8
Non-lease property revenue | U.S. & Canada
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	258.4	255.7
Non-lease property revenue | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9.3	8.8
Non-lease property revenue | Africa
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13.8	4
Non-lease property revenue | Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7.9	5.1
Non-lease property revenue | Latin America
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	118.4	138.2
Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87.9	115.4
Revenues	87.9	115.4	$ 125.4
Services revenue | U.S. & Canada
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87.9	115.4
Services revenue | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Services revenue | Africa
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Services revenue | Europe
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Services revenue | Latin America
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0

BUSINESS AND SUMMARY OF SIGN_15

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Schedule of Non-lease Recievables Contract Assets and Liabilities From Contracts with Tenants (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Contract Assets And Liabilities From Contracts With Customers [Line Items]
Prepaids and other current assets	$ 532.6	$ 513.6
Notes receivable and other non-current assets	400.1	406.4
Other non-current liabilities	984.6	937
Total non-lease revenue
Schedule of Contract Assets And Liabilities From Contracts With Customers [Line Items]
Accounts receivable	77.2	80.5
Prepaids and other current assets	21.8	8.3
Notes receivable and other non-current assets	23.7	21.3
Unearned revenue	120.3	91.7
Other non-current liabilities	$ 432.4	$ 379.2

BUSINESS AND SUMMARY OF SIGN_16

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Rent Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Straight-line ground rent expense	$ 51.6	$ 44.4	$ 57.9

BUSINESS AND SUMMARY OF SIGN_17

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Shares paid for tax withholding for share based compensation (in shares)	2,400,000
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares paid for tax withholding for share based compensation (in shares)	300,000
Restricted stock awards | 2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	0.00%
PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	200.00%
PSUs | 2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years

BUSINESS AND SUMMARY OF SIGN_18

BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Retirement Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Employers matching percentage	100.00%	100.00%	100.00%
Employee maximum annual contribution eligible for match	5.00%	5.00%	5.00%
Company's contribution	$ 13.2	$ 11.8	$ 11.2

PREPAID AND OTHER CURRENT ASS_3

PREPAID AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid assets	$ 66.1	$ 56.8
Prepaid income tax	143.7	185.8
Unbilled receivables	176.9	142.3
Value added tax and other consumption tax receivables	66.3	71.3
Other miscellaneous current assets	79.6	57.4
Prepaid and other current assets	$ 532.6	$ 513.6

PROPERTY AND EQUIPMENT-Summary

PROPERTY AND EQUIPMENT-Summary of Property and Equipment Including Finance Lease Right-of-Use Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total	$ 20,672.4	$ 19,325.6
Less accumulated depreciation	(7,863.7)	(7,241.2)
Property and equipment, net	$ 12,808.7	12,084.4
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Towers
Property, Plant and Equipment [Line Items]
Total	$ 14,433.9	13,930.7
Towers | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Equipment
Property, Plant and Equipment [Line Items]
Total	$ 2,327.1	1,897.3
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total	$ 634	638.9
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	32 years
Land andimprovements
Property, Plant and Equipment [Line Items]
Total	$ 2,845.9	2,486.1
Land andimprovements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Construction-in-progress
Property, Plant and Equipment [Line Items]
Total	$ 431.5	$ 372.6

PROPERTY AND EQUIPMENT -Narrati

PROPERTY AND EQUIPMENT -Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 924.3	$ 905.5	$ 883.1
Amortization of right-of-use asset	$ 153	$ 168.1

PROPERTY AND EQUIPMENT -Schedul

PROPERTY AND EQUIPMENT -Schedule of Finance Lease Assets Included in Property Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Towers
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,706.3	$ 2,695.9
Accumulated depreciation	(1,209.7)	(1,062)
Property and equipment, net	1,496.6	1,633.9
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property and equipment	167.6	167
Accumulated depreciation	(76.3)	(65.3)
Property and equipment, net	91.3	101.7
Land
Property, Plant and Equipment [Line Items]
Property and equipment	129.9	150.9
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment	48.8	45.9
Accumulated depreciation	(15.3)	(13.1)
Property and equipment, net	$ 33.5	$ 32.8

LEASES -Narrative (Details)

LEASES -Narrative (Details)	12 Months Ended
	Dec. 31, 2020USD ($)renewalOptiontenant	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Lessor, Lease, Description [Line Items]
Number of tenants | tenant	1
Operating lease, number of renewal options | renewalOption	1
Impairment charges	$ 222,800,000	$ 94,200,000	$ 394,000,000
Interest expense on finance lease liabilities	1,300,000	1,700,000
Lease Agreements
Lessor, Lease, Description [Line Items]
Impairment charges	$ 76,100,000	$ 9,900,000
Minimum
Lessor, Lease, Description [Line Items]
Lessor, term of lease	5 years
Operating lease, term of contract	5 years
Maximum
Lessor, Lease, Description [Line Items]
Lessor, term of lease	10 years
Estimated useful lives	20 years
Operating lease, term of contract	10 years
Maximum | Towers
Lessor, Lease, Description [Line Items]
Estimated useful lives	20 years
Maximum | Communication Sites
Lessor, Lease, Description [Line Items]
Estimated useful lives	20 years

LEASES - Future Minimum Rental

LEASES - Future Minimum Rental Receipts Expected Under Operating Leases (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 6,194.6
2022	5,905.5
2023	5,779.5
2024	5,618.8
2025	5,410.6
Thereafter	29,660.9
Total	$ 58,569.9

LEASES -Information About Other

LEASES -Information About Other Lease-related Balances (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating leases:
Right-of-use asset	$ 7,789.2	$ 7,357.4
Current portion of lease liability	539.9	494.5
Lease liability	6,884.4	6,510.4
Total lease liability	7,424.3	7,004.9
Finance leases:
Current portion of lease liability	4.9	6.7
Lease liability	23	24
Total lease liability	$ 27.9	$ 30.7

LEASES -Schedule Of Weighted Av

LEASES -Schedule Of Weighted Average Lease Terms And Discount Rates (Details)	Dec. 31, 2020	Dec. 31, 2019
Operating leases:
Weighted-average remaining lease term (years)	13 years 8 months 12 days	13 years 1 month 6 days
Weighted-average incremental borrowing rate	5.60%	6.10%
Finance leases:
Weighted-average remaining lease term (years)	12 years 1 month 6 days	15 years
Weighted-average incremental borrowing rate	6.80%	6.20%

LEASES -Lease Costs (Details)

LEASES -Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 977.2	$ 1,013.1
Variable lease costs not included in lease liability	$ 280	$ 261.7

LEASES -Supplemental Cash Flow

LEASES -Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ (988.3)	$ (1,012.2)
Operating cash flows from finance leases	(1.3)	(1.7)
Financing cash flows from finance leases	(9.2)	(18)
Non-Cash Items [Abstract]
New operating leases	346	409.5
Operating lease modifications and reassessments	$ 843.1	$ 334.1

LEASES -Maturities Of Operating

LEASES -Maturities Of Operating And Finance Leases (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Lease
2021	$ 901.1
2022	869
2023	836.4
2024	798
2025	751.8
Thereafter	6,423.4
Total lease payments	10,579.7
Less amounts representing interest	(3,155.4)
Total lease liability	7,424.3	$ 7,004.9
Less current portion of lease liability	539.9	494.5
Non-current lease liability	6,884.4	6,510.4
Finance Lease
2021	6.2
2022	5.3
2023	3.6
2024	2.9
2025	2.1
Thereafter	26.9
Total lease payments	47
Less amounts representing interest	(19.1)
Total lease liability	27.9	30.7
Less current portion of lease liability	4.9	6.7
Non-current lease liability	$ 23	$ 24

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS -Changes In The Carrying Value Of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 6,178.3	$ 5,501.9
Additions and adjustments	1,200.6	702.8
Effect of foreign currency translation	(96.2)	(26.4)
Goodwill, ending balance	7,282.7	6,178.3
2019 Acquisitions
Goodwill [Roll Forward]
Additions and adjustments		704.3
2018 Acquisitions
Goodwill [Roll Forward]
Goodwill, measurement period adjustments		1.5
Insite Acquisition
Goodwill [Roll Forward]
Additions and adjustments	1,354.2
Eaton Towers Acquisition
Goodwill [Roll Forward]
Goodwill, beginning balance	670
Goodwill, ending balance	516.4	670
Services
Goodwill [Roll Forward]
Goodwill, beginning balance	2	2
Additions and adjustments	0	0
Effect of foreign currency translation	0	0
Goodwill, ending balance	2	2
U.S. & Canada | Property
Goodwill [Roll Forward]
Goodwill, beginning balance	3,415.3	3,382.5
Additions and adjustments	1,335.5	32.8
Effect of foreign currency translation	0	0
Goodwill, ending balance	4,750.8	3,415.3
Asia-Pacific | Property
Goodwill [Roll Forward]
Goodwill, beginning balance	1,021.8	1,045.5
Additions and adjustments	18.7	0
Effect of foreign currency translation	(23.6)	(23.7)
Goodwill, ending balance	1,016.9	1,021.8
Africa | Property
Goodwill [Roll Forward]
Goodwill, beginning balance	790.2	119.3
Additions and adjustments	(153.6)	670
Effect of foreign currency translation	(11)	0.9
Goodwill, ending balance	625.6	790.2
Europe | Property
Goodwill [Roll Forward]
Goodwill, beginning balance	256.2	262
Additions and adjustments	0	0
Effect of foreign currency translation	22.9	(5.8)
Goodwill, ending balance	279.1	256.2
Latin America | Property
Goodwill [Roll Forward]
Goodwill, beginning balance	692.8	690.6
Additions and adjustments	0	0
Effect of foreign currency translation	(84.5)	2.2
Goodwill, ending balance	$ 608.3	$ 692.8

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS -Other Intangible Assets Subject To Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 20,204.3	$ 17,931.6
Accumulated Amortization	(6,364.5)	(5,613.2)
Net Book Value	$ 13,839.8	12,318.4
Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years
Acquired network location intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 5,784	5,150.8
Accumulated Amortization	(2,117.6)	(1,920.4)
Net Book Value	$ 3,666.4	3,230.4
Acquired network location intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years
Acquired tenant-related intangibles
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years
Gross Carrying Value	$ 14,322.5	12,674.1
Accumulated Amortization	(4,237.5)	(3,674.6)
Net Book Value	$ 10,085	8,999.5
Acquired tenant-related intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years
Acquired licenses and other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 97.8	106.7
Accumulated Amortization	(9.4)	(18.2)
Net Book Value	$ 88.4	$ 88.5
Acquired licenses and other intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	3 years
Acquired licenses and other intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	20 years

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS -Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 867.2	$ 791.3	$ 1,144.1
Acquired tenant-related intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			$ 327.5
Weighted Average
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, remaining amortization period	15 years

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLE ASSETS -Expected Future Amortization Expenses (Details) $ in Millions	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 999.6
2022	994
2023	969
2024	959.1
2025	$ 927.6

NOTES RECEIVABLE AND OTHER NO_3

NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Notes Receivable And Other Long Term Assets [Abstract]
Notes receivable	$ 6.5	$ 1.1
Other miscellaneous assets	393.6	405.3
Notes receivable and other non-current assets	$ 400.1	$ 406.4

ACQUISITIONS -Merger and Integr

ACQUISITIONS -Merger and Integration Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Combinations [Abstract]
Acquisition and merger related expenses	$ 15.5	$ 26.9	$ 14.1
Integration costs	$ 23.1	$ 9.8	$ 16.1

ACQUISITIONS -Narrative (Detail

ACQUISITIONS -Narrative (Details) € in Millions, zł in Millions, $ in Millions

Dec. 23, 2020USD ($)towernetworkcommunicationSitelandParcel

Dec. 19, 2020USD ($)

Jun. 16, 2020USD ($)communicationSite

Jun. 16, 2020PLN (zł)communicationSite

Nov. 28, 2019USD ($)communicationSite

Nov. 28, 2019EUR (€)communicationSite

Dec. 31, 2020USD ($)communicationSite

Dec. 31, 2020PLN (zł)

Dec. 31, 2020USD ($)communicationSite

Dec. 31, 2019USD ($)communicationSitemarket

Dec. 31, 2018USD ($)

Dec. 19, 2019communicationSite

Business Acquisition [Line Items]

Proceeds from previous acquisition

$ 4.4

$ 13.1

Acquisitions, pro forma information, revenue of acquiree since acquisition date, actual

14.9

Acquisitions, pro forma information, gross margin of acquiree since acquisition date actual

10.5

Accounts payable

$ 139.1

139.1

148.1

Aggregate purchase price

$ 1,031.7

$ 991.3

$ 913.2

AT&T Transaction

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

103

103

Aggregate purchase price

$ 55.7

Entel Acquisition

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

2,400

3,200

Asset acquisition, consideration transferred

$ 800

Entel Acquisition | Communication Sites

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

530

530

Asset acquisition, consideration transferred

$ 137.7

Poland Acquisition

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

50

50

Asset acquisition, consideration transferred

$ 4.6

zł 18.3

$ 3.1

zł 12.1

Poland Acquisition | Communication Sites

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

27

27

Other Acquisitions 2020

Business Acquisition [Line Items]

Asset acquisition, consideration transferred

$ 1,118.8

Other Acquisitions 2020 | Communication Sites

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

1,299

1,299

Orange S.A.

Business Acquisition [Line Items]

Asset acquisition, consideration transferred

$ 978

Accounts payable

$ 58.9

$ 58.9

Orange S.A. | Communication Sites

Business Acquisition [Line Items]

Number of communications sites acquired | communicationSite

2,000

2,000

564

564

Purchase period

5 years

5 years

Orange S.A. | Communication Sites | Minimum

Business Acquisition [Line Items]

Asset acquisition, consideration transferred

$ 550.5

€ 500

Orange S.A. | Communication Sites | Maximum

Business Acquisition [Line Items]

Asset acquisition, consideration transferred

$ 660.5

€ 600

Insite Acquisition

Business Acquisition [Line Items]

Percentage of voting interest acquired

100.00%

Number of communications sites acquired | communicationSite

3,000

Number of land parcels under communication sites | landParcel

600

Purchase price

$ 2,751.5

$ 3,500

Insite Acquisition | United States

Business Acquisition [Line Items]

Number towers | tower

1,400

Number of DAS Networks | network

40

Number of rooftop sites | communicationSite

400

Insite Acquisition | Canada

Business Acquisition [Line Items]

Number towers | tower

200

Eaton Towers Acquisition

Business Acquisition [Line Items]

Percentage of voting interest acquired

100.00%

Number of communications sites acquired | communicationSite

5,800

Purchase price

$ 1,630.8

$ 1,635

Number of markets in which the entity operates | market

5

Purchase price adjustment

$ 4.2

Debt assumed

2,000

Consideration transferred, receivable from seller

$ 14

ACQUISITIONS - Schedule of Allo

ACQUISITIONS - Schedule of Allocation of Purchase and the Amount of Assets Acquired (Details) $ in Millions	Dec. 23, 2020USD ($)communicationSite	Dec. 31, 2020USD ($)site	Dec. 31, 2019USD ($)communicationSite	Dec. 31, 2018USD ($)
Business Combination
Goodwill		$ 7,282.7	$ 6,178.3	$ 5,501.9
Other Acquisitions 2020
Asset Acquisition [Abstract]
Current assets		40.6
Property and equipment		336.7
Other non-current assets		112.3
Current liabilities		(10.9)
Deferred tax liability		(9.8)
Other non-current liabilities		(114.5)
Net assets acquired		1,118.8
Fair value of net assets acquired		1,118.8
Debt assumed		0
Purchase price		$ 1,118.8
Maximum
Asset Acquisition [Abstract]
Intangible assets, useful life		20 years
Peru | Other Acquisitions 2020
Asset Acquisition [Abstract]
Number of communications sites acquired | site		25
Tenant-related intangible assets
Asset Acquisition [Abstract]
Intangible assets, useful life		20 years
Tenant-related intangible assets | Other Acquisitions 2020
Asset Acquisition [Abstract]
Intangible assets		$ 596.5
Tenant-related intangible assets | Maximum
Asset Acquisition [Abstract]
Intangible assets, useful life		20 years
Network location intangible assets | Other Acquisitions 2020
Asset Acquisition [Abstract]
Intangible assets		$ 166.6
Network location intangible assets | Maximum
Asset Acquisition [Abstract]
Intangible assets, useful life		20 years
Other intangible assets | Other Acquisitions 2020
Asset Acquisition [Abstract]
Intangible assets		$ 1.3
Insite Acquisition
Business Combination
Current assets	$ 57.2
Property and equipment	516.4
Other non-current assets	300.7
Current liabilities	(75.9)
Deferred tax liability	(116.3)
Other non-current liabilities	(267.6)
Net assets acquired	2,197.3
Goodwill	1,354.2
Fair value of net assets acquired	3,551.5
Debt assumed	(800)
Purchase price	$ 2,751.5	3,500
Asset Acquisition [Abstract]
Number of communications sites acquired | communicationSite	3,000
Debt assumed, fair value adjustment	$ 36.5
Insite Acquisition | Debt
Business Combination
Debt assumed	(763.5)
Insite Acquisition | Tenant-related intangible assets
Business Combination
Intangible assets	1,160.1
Insite Acquisition | Network location intangible assets
Business Combination
Intangible assets	622.7
Insite Acquisition | Other intangible assets
Business Combination
Intangible assets	$ 0
Eaton Towers Acquisition
Business Combination
Current assets		151.7	150.4
Property and equipment		306.6	304.7
Other non-current assets		114.8	99.5
Current liabilities		(94.3)	(82)
Deferred tax liability		(347.2)	(319.3)
Other non-current liabilities		(121.3)	(138.3)
Net assets acquired		1,444.2	1,294.8
Goodwill		516.4	670
Fair value of net assets acquired		1,960.6	1,964.8
Debt assumed		(329.8)	(329.8)
Purchase price		1,630.8	$ 1,635
Asset Acquisition [Abstract]
Number of communications sites acquired | communicationSite			5,800
Eaton Towers Acquisition | Tenant-related intangible assets
Business Combination
Intangible assets		1,107.7	$ 1,007.6
Eaton Towers Acquisition | Network location intangible assets
Business Combination
Intangible assets		$ 326.2	$ 272.2

ACQUISITIONS -Pro Forma Informa

ACQUISITIONS -Pro Forma Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
Pro forma revenues	$ 8,230.9	$ 8,083.8
Pro forma net income attributable to American Tower Corporation common stockholders	$ 1,515.7	$ 1,651
Pro forma net income per common share amounts:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 3.42	$ 3.73
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 3.40	$ 3.71

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities, Current [Abstract]
Accrued construction costs	$ 46.5	$ 27.8
Accrued income tax payable	20.6	55.2
Accrued pass-through costs	67.1	74.2
Amounts payable for acquisitions	58.9	0
Amounts payable to tenants	66.4	77.9
Accrued property and real estate taxes	219.1	198.1
Accrued rent	82.6	75.6
Payroll and related withholdings	104.4	102.4
Other accrued expenses	378.1	347
Accrued expenses	$ 1,043.7	$ 958.2

LONG-TERM OBLIGATIONS - Schedul

LONG-TERM OBLIGATIONS - Schedule of Outstanding Amounts (Details) - USD ($)

Mar. 29, 2018

Dec. 31, 2020

Nov. 20, 2020

Sep. 28, 2020

Sep. 10, 2020

Jul. 06, 2020

Jun. 03, 2020

May 11, 2020

Jan. 15, 2020

Jan. 10, 2020

Dec. 31, 2019

May 29, 2015

Jan. 10, 2014

Aug. 19, 2013

Debt Instrument [Line Items]

Long-term debt

$ 1,900,000

Finance lease obligations

$ 27,900,000

30,700,000

Total

29,287,500,000

24,055,400,000

Less current portion of long-term obligations

(789,800,000)

(2,928,200,000)

Long-term obligations

28,497,700,000

21,127,200,000

Payment terms, repayment period

12 months

Parent

Debt Instrument [Line Items]

Long-term debt

26,113,400,000

20,942,500,000

Subsidiaries

Debt Instrument [Line Items]

Long-term debt

$ 3,146,200,000

3,082,200,000

Minimum

Debt Instrument [Line Items]

Long-term debt, stated interest rate

7.45%

Maximum

Debt Instrument [Line Items]

Long-term debt, stated interest rate

8.75%

1.375% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.375%

1.950% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.95%

0.500% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

0.50%

1.000% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.00%

Insite Debt | Subsidiaries

Debt Instrument [Line Items]

Long-term debt

$ 800,000,000

0

Revolving Credit Facility | 2019 Multicurrency Credit Facility | Parent

Debt Instrument [Line Items]

Long-term debt

700,000,000

Debt interest rate, effective percentage

0.00%

Revolving Credit Facility | 2019 Credit Facility

Debt Instrument [Line Items]

Long-term debt

1,600,000,000

Debt interest rate, effective percentage

1.235%

Unsecured Debt | 2019 364-Day Term Loan | Parent

Debt Instrument [Line Items]

Long-term debt

$ 0

999,900,000

Unsecured Debt | 2020 Term Loan | Parent

Debt Instrument [Line Items]

Long-term debt

$ 749,400,000

0

Debt interest rate, effective percentage

0.80%

Unsecured Debt | 3.50% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt

$ 996,100,000

995,200,000

Debt interest rate, effective percentage

1.275%

Unsecured Debt | Other subsidiary debt | Subsidiaries

Debt Instrument [Line Items]

Long-term debt

$ 32,900,000

422,400,000

Payment terms, repayment period

3 years

Senior Notes | 2.800% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.80%

Senior Notes | 2.800% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.80%

Long-term debt

$ 0

749,400,000

Senior Notes | 3.300% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.30%

3.30%

Long-term debt

$ 0

748,500,000

Senior Notes | 3.450% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.45%

3.45%

Long-term debt

$ 0

647,700,000

Senior Notes | 5.900% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

5.90%

5.90%

Long-term debt

$ 0

498,900,000

Senior Notes | 2.250% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.25%

Senior Notes | 2.250% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.25%

Long-term debt

$ 605,100,000

592,100,000

Senior Notes | 4.70% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

4.70%

Long-term debt

$ 699,000,000

698,200,000

Senior Notes | 3.50% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.50%

Long-term debt

$ 996,100,000

994,300,000

Senior Notes | 3.000% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.00%

Senior Notes | 3.000% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.00%

Long-term debt

$ 721,900,000

704,900,000

Senior Notes | 0.600% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

0.60%

0.60%

Long-term debt

$ 496,800,000

0

Senior Notes | 5.00% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

5.00%

5.00%

Senior Notes | 5.00% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

5.00%

Long-term debt

$ 1,001,300,000

1,001,700,000

Senior Notes | 3.375% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.375%

Senior Notes | 3.375% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.375%

Long-term debt

$ 645,700,000

644,400,000

Senior Notes | 2.950% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.95%

Senior Notes | 2.950% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.95%

Long-term debt

$ 643,100,000

641,300,000

Senior Notes | 2.400% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.40%

Senior Notes | 2.400% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.40%

2.40%

Long-term debt

$ 745,000,000

0

Senior Notes | 1.375% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.375%

Senior Notes | 1.375% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.375%

Long-term debt

$ 604,100,000

553,000,000

Senior Notes | 4.000% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

4.00%

Senior Notes | 4.000% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

4.00%

Long-term debt

$ 744,300,000

743,200,000

Senior Notes | 1.300% Notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.30%

Senior Notes | 1.300% Notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.30%

1.30%

Long-term debt

$ 495,400,000

0

Senior Notes | 4.400% Notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

4.40%

Senior Notes | 4.400% Notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

4.40%

Long-term debt

$ 497,100,000

496,600,000

Senior Notes | 1.950% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.95%

Senior Notes | 1.950% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.95%

Long-term debt

$ 605,200,000

554,400,000

Senior Notes | 3.375% Notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.375%

Senior Notes | 3.375% Notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.375%

Long-term debt

$ 989,500,000

987,900,000

Senior Notes | 3.125% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.125%

Senior Notes | 3.125% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.125%

Long-term debt

$ 397,900,000

397,600,000

Senior Notes | 2.750% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.75%

Senior Notes | 2.750% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.75%

Long-term debt

$ 744,300,000

743,500,000

Senior Notes | 3.55% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.55%

Senior Notes | 3.55% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.55%

Long-term debt

$ 744,800,000

744,100,000

Senior Notes | 0.500% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

0.50%

0.50%

Senior Notes | 0.500% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

0.50%

0.50%

Long-term debt

$ 907,400,000

0

Senior Notes | 3.600% Notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.60%

Senior Notes | 3.600% Notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.60%

Long-term debt

$ 693,400,000

692,600,000

Senior Notes | 1.500% Notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.50%

Senior Notes | 1.500% Notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.50%

1.50%

1.50%

Long-term debt

$ 645,100,000

0

Senior Notes | 3.950% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.95%

Senior Notes | 3.950% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.95%

Long-term debt

$ 590,600,000

589,600,000

Senior Notes | 3.800% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.80%

Senior Notes | 3.800% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.80%

Long-term debt

$ 1,633,500,000

1,631,700,000

Senior Notes | 2.900% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.90%

Senior Notes | 2.900% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.90%

2.90%

Long-term debt

$ 741,700,000

0

Senior Notes | 2.100% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.10%

Senior Notes | 2.100% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.10%

2.10%

Long-term debt

$ 740,200,000

0

Senior Notes | 1.875% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.875%

Senior Notes | 1.875% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.875%

1.875%

Long-term debt

$ 790,500,000

0

Senior Notes | 1.000% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.00%

Senior Notes | 1.000% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

1.00%

Long-term debt

$ 786,100,000

0

Senior Notes | 3.700% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.70%

Senior Notes | 3.700% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.70%

Long-term debt

$ 591,900,000

591,800,000

Senior Notes | 3.100% senior notes

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.10%

3.10%

3.10%

Senior Notes | 3.100% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.10%

3.10%

3.10%

Long-term debt

$ 1,037,700,000

0

Senior Notes | 2.950% senior notes | Parent

Debt Instrument [Line Items]

Long-term debt, stated interest rate

2.95%

Long-term debt

$ 538,200,000

0

Secured Debt | Series 2013-2A Securities | Subsidiaries

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.07%

Long-term debt

$ 1,296,600,000

1,295,000,000

Secured Debt | Series 2018-1A Securities | Subsidiaries

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.652%

Long-term debt

$ 494,600,000

493,800,000

Secured Debt | Series 2015-1 Class

Debt Instrument [Line Items]

Long-term debt

$ 350,000,000

Secured Debt | Series 2015-1 Class | Subsidiaries

Debt Instrument [Line Items]

Long-term debt

$ 0

349,600,000

Secured Debt | Series 2015-2 Class

Debt Instrument [Line Items]

Long-term debt

$ 525,000,000

Secured Debt | Series 2015-2 Class | Subsidiaries

Debt Instrument [Line Items]

Long-term debt, stated interest rate

3.482%

Long-term debt

$ 522,100,000

521,400,000

Secured Debt | Insite Debt

Debt Instrument [Line Items]

Long-term debt

$ 800,000,000

$ 0

LONG-TERM OBLIGATIONS - Current

LONG-TERM OBLIGATIONS - Current Portion of Debt and Bank Facilities Narrative (Details) € in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 10, 2020USD ($)	Sep. 10, 2020EUR (€)	Apr. 21, 2020USD ($)	Apr. 03, 2020USD ($)	Feb. 14, 2019USD ($)
Debt Instrument [Line Items]
Current portion of long-term obligations		$ 789,800,000		$ 2,928,200,000
Borrowings under credit facilities		$ 8,230,400,000		$ 5,750,000,000	$ 3,263,300,000
Minimum
Debt Instrument [Line Items]
Long-term debt, stated interest rate		7.45%
Maximum
Debt Instrument [Line Items]
Long-term debt, stated interest rate		8.75%
2020 Term Loan | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.00%	0.00%
2020 Term Loan | Maximum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.65%	0.65%
2019 Multicurrency Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 3,100,000,000
Borrowings under credit facilities		1,000,000,000	€ 910
Repayments of lines of credit	$ 1,100,000,000	$ 1,800,000,000	€ 910
2019 Multicurrency Credit Facility | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.75%	0.75%
2019 Multicurrency Credit Facility | Revolving Credit Facility | Minimum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.875%	0.875%
2019 Multicurrency Credit Facility | Revolving Credit Facility | Maximum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%	1.75%
2019 Multicurrency Credit Facility | Multicurrency Borrowings | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 1,000,000,000
2019 Multicurrency Credit Facility | Letter of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		200,000,000
2019 Multicurrency Credit Facility | Swingline Loan | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		50,000,000
2019 Multicurrency Credit Facility | Parent | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, borrowing capacity, increase		$ 100,000,000
2019 Multicurrency Credit Facility | Parent | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.125%	1.125%
2019 Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 2,350,000,000
Borrowings under credit facilities		7,200,000,000
Repayments of lines of credit		$ 6,500,000,000
2019 Credit Facility | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.75%	0.75%
2019 Credit Facility | Revolving Credit Facility | Minimum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.875%	0.875%
2019 Credit Facility | Revolving Credit Facility | Maximum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%	1.75%
2019 Credit Facility | Swingline Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 50,000,000
2019 Credit Facility | Letter of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		200,000,000
2019 Credit Facility | Parent | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, borrowing capacity, increase		$ 100,000,000
2019 Credit Facility | Parent | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.125%	1.125%
2019 Term Loan | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.75%	0.75%
2019 Term Loan | Revolving Credit Facility | Minimum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.875%	0.875%
2019 Term Loan | Revolving Credit Facility | Maximum | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.75%	1.75%
0.500% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate		0.50%
Senior Notes | 1.000% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate		1.00%				1.00%	1.00%
Senior Notes | 1.000% senior notes | Parent
Debt Instrument [Line Items]
Debt instrument, face amount						$ 768,000,000	€ 650
Senior Notes | 1.875% senior notes | Parent
Debt Instrument [Line Items]
Long-term debt, stated interest rate		1.875%
Senior Notes | 3.100% senior notes | Parent
Debt Instrument [Line Items]
Long-term debt, stated interest rate		3.10%
Senior Notes | 0.500% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate		0.50%				0.50%	0.50%
Senior Notes | 0.500% senior notes | Parent
Debt Instrument [Line Items]
Debt instrument, face amount						$ 886,100,000	€ 750
Long-term debt, stated interest rate		0.50%				0.50%	0.50%
Unsecured Debt | 2020 Term Loan | Parent
Debt Instrument [Line Items]
Current portion of long-term obligations		$ 750,000,000
Unsecured Debt | 2020 Term Loan | Parent | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		0.65%	0.65%
Unsecured Debt | 2019 364-Day Term Loan | Parent
Debt Instrument [Line Items]
Debt instrument, face amount										$ 1,300,000,000
Debt term										364 days
Unsecured Debt | 2019 Term Loan | Parent | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.125%	1.125%
Unsecured Debt | April 2020 Term Loan | Parent
Debt Instrument [Line Items]
Debt instrument, face amount								$ 1,190,000,000	$ 1,140,000,000

LONG-TERM OBLIGATIONS -Schedule

LONG-TERM OBLIGATIONS -Schedule of Credit Facilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)renewalPeriod
Line of Credit Facility [Line Items]
Annual renewal periods, number | renewalPeriod	2
2019 Multicurrency Credit Facility | Revolving Credit Facility | Parent
Line of Credit Facility [Line Items]
Outstanding Principal Balance	$ 0
Undrawn letters of credit	$ 3.8
Current Commitment fee, percentage	0.11%
2019 Credit Facility | Revolving Credit Facility | Parent
Line of Credit Facility [Line Items]
Outstanding Principal Balance	$ 2,295
Undrawn letters of credit	$ 0.8
Current Commitment fee, percentage	0.11%
2019 Term Loan | Unsecured Debt | Parent
Line of Credit Facility [Line Items]
Outstanding Principal Balance	$ 1,000
2020 Term Loan | Unsecured Debt | Parent
Line of Credit Facility [Line Items]
Outstanding Principal Balance	$ 750
LIBOR | 2019 Multicurrency Credit Facility | Revolving Credit Facility | Parent
Line of Credit Facility [Line Items]
Current margin over LIBOR	1.125%
LIBOR | 2019 Credit Facility | Revolving Credit Facility | Parent
Line of Credit Facility [Line Items]
Current margin over LIBOR	1.125%
LIBOR | 2019 Term Loan | Unsecured Debt | Parent
Line of Credit Facility [Line Items]
Current margin over LIBOR	1.125%
LIBOR | 2020 Term Loan | Unsecured Debt | Parent
Line of Credit Facility [Line Items]
Current margin over LIBOR	0.65%

LONG-TERM Debt OBLIGATIONS -Sen

LONG-TERM Debt OBLIGATIONS -Senior Notes (Details) € in Millions, $ in Millions	Nov. 20, 2020USD ($)	Sep. 28, 2020USD ($)	Sep. 10, 2020USD ($)	Sep. 10, 2020EUR (€)	Jul. 06, 2020USD ($)	Jun. 03, 2020USD ($)	Jan. 15, 2020USD ($)	Jan. 10, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 10, 2020EUR (€)	May 11, 2020USD ($)
Debt Instrument [Line Items]
Loss on retirement of long-term obligations					$ 37.2				$ 71.8	$ 22.2	$ 3.3
Unamortized discount and deferred financing costs					$ 34.7
Proceeds from issuance of debt	$ 1,678.9	$ 1,092.1							$ 1,940	$ 1,300	$ 1,500
Senior Notes
Debt Instrument [Line Items]
Redemption price percentage									100.00%	100.00%
Repurchase price as percentage of principal									101.00%
Maximum adjusted EBITDA									3.5
Senior Notes | Parent
Debt Instrument [Line Items]
Proceeds from issuance of debt			$ 1,636.6	€ 1,385.2		$ 1,968.2		$ 1,483.4
5.900% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate							5.90%		5.90%
Face amount of repurchased debt							$ 500
Redemption price percentage							106.709%
Debt instrument, repurchase amount including interest							$ 539.6
Interest payable							6.1
Loss on retirement of long-term obligations							(34.6)
Debt instrument, fees							$ 33.5
2.800% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.80%
2.800% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate													2.80%
Face amount of repurchased debt													$ 750
Debt instrument, repurchase amount including interest													759.3
Interest payable													$ 9.3
3.450% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate					3.45%				3.45%
Face amount of repurchased debt					$ 650
Redemption price percentage					103.598%
Debt instrument, repurchase amount including interest					$ 680.3
Interest payable					$ 6.9
3.300% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate					3.30%				3.30%
Face amount of repurchased debt					$ 750
Redemption price percentage					101.509%
Debt instrument, repurchase amount including interest					$ 771
Interest payable					$ 9.7
2.400% Notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.40%
2.400% Notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate								2.40%	2.40%
Debt instrument, face amount								$ 750
2.900% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.90%
2.900% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate								2.90%	2.90%
Debt instrument, face amount								$ 750
1.300% Notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									1.30%
1.300% Notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate						1.30%			1.30%
Debt instrument, face amount						$ 500
2.100% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.10%
2.100% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate						2.10%			2.10%
Debt instrument, face amount						$ 750
3.100% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate		3.10%				3.10%			3.10%
3.100% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate		3.10%				3.10%			3.10%
Debt instrument, face amount		$ 300				$ 750
0.500% senior notes
Debt Instrument [Line Items]
Debt, stated interest rate									0.50%
0.500% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate			0.50%						0.50%			0.50%
0.500% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate			0.50%						0.50%			0.50%
Debt instrument, face amount			$ 886.1									€ 750
1.000% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate			1.00%						1.00%			1.00%
1.000% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt instrument, face amount			$ 768									€ 650
1.875% senior notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									1.875%
1.875% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate		1.875%							1.875%
Debt instrument, face amount		$ 800
0.600% senior notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate	0.60%								0.60%
Debt instrument, face amount	$ 500
1.500% Notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									1.50%
1.500% Notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate	1.50%	1.50%							1.50%
Debt instrument, face amount	$ 650
2.950% Notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.95%
2.950% Notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate									2.95%
Debt instrument, face amount	$ 550
2.950% Notes | Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate									2.95%
2.950% Notes | Senior Notes | Parent
Debt Instrument [Line Items]
Debt, stated interest rate	2.95%

LONG-TERM OBLIGATIONS - Outline

LONG-TERM OBLIGATIONS - Outline of Key Terms Related to Outstanding Senior Notes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 28, 2020	Sep. 10, 2020	Jun. 03, 2020	Jan. 10, 2014	Aug. 19, 2013
2.250% Notes | Interest Rate Swap
Debt Instrument [Line Items]
Adjustments to Interest rate swap agreements	$ 6,300,000	$ (5,900,000)
1.35% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.375%
1.950% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.95%
0.500% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	0.50%
1.000% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.00%
Senior Notes
Debt Instrument [Line Items]
Redemption price percentage	100.00%	100.00%
Senior Notes | 2.250% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.25%
Aggregate Principal Amount	$ 600,000,000
Adjustments to Principal Amount	5,100,000	$ 7,900,000
Senior Notes | 4.70% Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	700,000,000
Adjustments to Principal Amount	(1,000,000)	1,800,000
Senior Notes | 3.50% Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	1,000,000,000
Adjustments to Principal Amount	$ 3,900,000	5,700,000
Senior Notes | 3.000% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.00%
Aggregate Principal Amount	$ 700,000,000
Adjustments to Principal Amount	21,900,000	(4,900,000)
Senior Notes | 3.000% Notes | Interest Rate Swap
Debt Instrument [Line Items]
Adjustments to Interest rate swap agreements	25,100,000	9,200,000
Senior Notes | 0.600% Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	500,000,000
Adjustments to Principal Amount	3,200,000	0
Senior Notes | 5.00% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate						5.00%	5.00%
Aggregate Principal Amount	1,000,000,000
Adjustments to Principal Amount	$ 1,300,000	(1,700,000)
Senior Notes | 3.375% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.375%
Aggregate Principal Amount	$ 650,000,000
Adjustments to Principal Amount	$ 4,300,000	5,600,000
Senior Notes | 2.950% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.95%
Aggregate Principal Amount	$ 650,000,000
Adjustments to Principal Amount	$ 6,900,000	8,700,000
Senior Notes | 2.400% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.40%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 5,000,000	0
Senior Notes | 1.35% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.375%
Aggregate Principal Amount	$ 610,800,000
Adjustments to Principal Amount	$ 6,700,000	(7,600,000)
Senior Notes | 4.000% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	4.00%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 5,700,000	(6,800,000)
Senior Notes | 1.300% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.30%
Aggregate Principal Amount	$ 500,000,000
Adjustments to Principal Amount	$ 4,600,000	0
Senior Notes | 4.400% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	4.40%
Aggregate Principal Amount	$ 500,000,000
Adjustments to Principal Amount	$ 2,900,000	3,400,000
Senior Notes | 1.950% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.95%
Aggregate Principal Amount	$ 610,800,000
Adjustments to Principal Amount	$ 5,600,000	6,200,000
Senior Notes | 3.375% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.375%
Aggregate Principal Amount	$ 1,000,000,000
Adjustments to Principal Amount	$ 10,500,000	12,100,000
Senior Notes | 3.125% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.125%
Aggregate Principal Amount	$ 400,000,000
Adjustments to Principal Amount	$ 2,100,000	2,400,000
Senior Notes | 2.750% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.75%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 5,700,000	6,500,000
Senior Notes | 3.55% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.55%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 5,200,000	(5,900,000)
Senior Notes | 0.500% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	0.50%			0.50%
Aggregate Principal Amount	$ 916,200,000
Adjustments to Principal Amount	$ 8,800,000	0
Senior Notes | 3.600% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.60%
Aggregate Principal Amount	$ 700,000,000
Adjustments to Principal Amount	$ 6,600,000	7,400,000
Senior Notes | 1.500% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.50%
Aggregate Principal Amount	$ 650,000,000
Adjustments to Principal Amount	$ 4,900,000	0
Senior Notes | 3.950% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.95%
Aggregate Principal Amount	$ 600,000,000
Adjustments to Principal Amount	$ 9,400,000	(10,400,000)
Senior Notes | 3.800% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.80%
Aggregate Principal Amount	$ 1,650,000,000
Adjustments to Principal Amount	$ 16,500,000	18,300,000
Senior Notes | 2.900% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.90%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 8,300,000	0
Senior Notes | 2.100% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.10%
Aggregate Principal Amount	$ 750,000,000
Adjustments to Principal Amount	$ 9,800,000	0
Senior Notes | 1.875% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.875%
Aggregate Principal Amount	$ 800,000,000
Adjustments to Principal Amount	$ (9,500,000)	0
Senior Notes | 1.000% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	1.00%
Aggregate Principal Amount	$ 794,000,000
Adjustments to Principal Amount	$ (7,900,000)	0
Senior Notes | 3.700% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.70%
Aggregate Principal Amount	$ 600,000,000
Adjustments to Principal Amount	$ (8,100,000)	(8,200,000)
Senior Notes | 3.100% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	3.10%		3.10%		3.10%
Aggregate Principal Amount	$ 1,050,000,000
Adjustments to Principal Amount	$ (12,300,000)	0
Senior Notes | 2.950% Notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate	2.95%
Aggregate Principal Amount	$ 550,000,000
Adjustments to Principal Amount	$ (11,800,000)	$ 0

LONG-TERM DEBT OBLIGATIONS - Su

LONG-TERM DEBT OBLIGATIONS - Subsidiary Debt Narrative (Details)	Jun. 20, 2020USD ($)	Mar. 29, 2018USD ($)numberOfQuartersite	May 29, 2015USD ($)communicationSite	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Long-term debt					$ 1,900,000
Number of trust sites assets | site		5,114
Payment terms, repayment period		12 months
Series 2015-1 Class | Secured Debt
Debt Instrument [Line Items]
Long-term debt			$ 350,000,000
Repayments of long-term debt	$ 350,000,000
Series 2015-2 Class | Secured Debt
Debt Instrument [Line Items]
Long-term debt			$ 525,000,000
Commercial Mortgage Pass Through Certificates Series 2015 | Secured Debt
Debt Instrument [Line Items]
Weighted average life			8 years 1 month 6 days
Weighted average interest rate			3.029%
Number towers | communicationSite			3,538
Restricted cash and cash equivalents				$ 11,200,000
Series 2018-1A Securities | Secured Debt
Debt Instrument [Line Items]
Period during which no prepayment consideration is due		36 months
Series 2018-1A Securities | Secured Debt | Series 2018-1A Securities
Debt Instrument [Line Items]
Outstanding Principal Balance		$ 500,000,000
Debt, stated interest rate		3.652%
Series 2018-1A Securities | Secured Debt | Secured Tower Revenue Securities, Series 2018-1R
Debt Instrument [Line Items]
Debt, stated interest rate		4.459%
Series 2018-1A Securities | Secured Debt | Secured Tower Revenue Securities, Series 2018-1R | Affiliated Entity
Debt Instrument [Line Items]
Outstanding Principal Balance		$ 26,400,000
Series 2013-1A and Series 2013-2A Securities | Secured Debt
Debt Instrument [Line Items]
Cash trap debt service credit ratio		1.30
Debt covenant, number of consecutive quarters required for release of funds | numberOfQuarter		2
Minimum debt service credit ratio		1.15
Debt covenant, threshold for majority of holders in event of default		50.00%
Restricted cash and cash equivalents				$ 69,800,000
Series 2013-1A Securities | Secured Debt
Debt Instrument [Line Items]
Period during which no prepayment consideration is due		18 months

LONG-TERM OBLIGATIONS -Schedu_2

LONG-TERM OBLIGATIONS -Schedule of India Indebtedness (Details) ₨ in Millions, $ in Millions	Dec. 31, 2020USD ($)	Dec. 31, 2020INR (₨)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Long-term debt			$ 1.9
Minimum
Debt Instrument [Line Items]
Long-term debt, stated interest rate	7.45%	7.45%
Maximum
Debt Instrument [Line Items]
Long-term debt, stated interest rate	8.75%	8.75%
Viom Working Capital Facilities | Line of Credit
Debt Instrument [Line Items]
Long-term debt	$ 0	₨ 0
Line of credit facility, remaining borrowing capacity	$ 76.9	₨ 5,600

LONG-TERM OBLIGATIONS - Sched_2

LONG-TERM OBLIGATIONS - Schedule of Other Subsidiary Debt (Details) € in Millions, R$ in Millions, R in Millions, Ksh in Millions, $ in Millions, $ in Millions, in Millions

Dec. 23, 2016ZAR (R)

Dec. 31, 2020USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2020EUR (€)

Dec. 31, 2020ZAR (R)

Dec. 31, 2020COP ($)

Dec. 31, 2020BRL (R$)

Dec. 31, 2020XOF ( )

Dec. 31, 2020KES (Ksh)

Dec. 31, 2019EUR (€)

Dec. 31, 2019ZAR (R)

Dec. 31, 2019COP ($)

Dec. 31, 2019BRL (R$)

Dec. 31, 2019XOF ( )

Dec. 31, 2019KES (Ksh)

Debt Instrument [Line Items]

Long-term debt

$ 1.9

Borrowings under credit facilities

$ 8,230.4

5,750

$ 3,263.3

Installment payment period

3 years

Installment payment, optional extension period

2 years

Kenya Debt

Debt Instrument [Line Items]

Long-term debt

$ 20.1

29.6

Long-term debt, stated interest rate

8.00%

8.00%

8.00%

8.00%

8.00%

8.00%

8.00%

Original principal amount

$ 51.8

US Subsidiary Debt

Debt Instrument [Line Items]

Long-term debt

1.2

1.9

Principal amount

2.5

Eaton Towers, USD Denominated Debt

Debt Instrument [Line Items]

Long-term debt

0

238.8

Eaton Towers, EUR Denominated Debt

Debt Instrument [Line Items]

Long-term debt

0

29.5

€ 0

€ 26.2

Easton Towers, XOF Denominated Debt

Debt Instrument [Line Items]

Long-term debt

0

28.8

0

16,836.8

Easton Towers, KES Denominated Debt

Debt Instrument [Line Items]

Long-term debt

0

32.7

Ksh 0

Ksh 3,319.2

Revolving Credit Facility | South African Facility

Debt Instrument [Line Items]

Borrowings under credit facilities | R

R 500

Revolving Credit Facility | Colombian Credit Facility

Debt Instrument [Line Items]

Original principal amount

$ 200,000

Unsecured Debt | Brazil Credit Facility

Debt Instrument [Line Items]

Original principal amount | R$

R$ 271.0

Revolving Credit Facility | South African Facility

Debt Instrument [Line Items]

Long-term line of credit

0

20.6

R 0

R 288.7

Original principal amount | R

R 830

Revolving Credit Facility | Colombian Credit Facility

Debt Instrument [Line Items]

Long-term line of credit

$ 11.6

24.3

$ 40,000

$ 79,647.3

Long-term debt, stated interest rate

8.45%

8.45%

8.45%

8.45%

8.45%

8.45%

8.45%

Revolving Credit Facility | Brazil Credit Facility

Debt Instrument [Line Items]

Long-term line of credit

$ 0

$ 16.2

R$ 0.0

R$ 65.4

LONG-TERM OBLIGATIONS - InSite

LONG-TERM OBLIGATIONS - InSite Debt Narrative (Details) - USD ($) $ in Millions	Jan. 15, 2021	Jul. 06, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Loss on retirement of long-term obligations		$ 37.2	$ 71.8	$ 22.2	$ 3.3
Insite Debt | Insite Acquisition | Subsequent Event
Debt Instrument [Line Items]
Redemption price	$ 826.4
Accrued and unpaid interest	2.3
Loss on retirement of long-term obligations	$ (24.5)

LONG-TERM OBLIGATIONS - Sched_3

LONG-TERM OBLIGATIONS - Schedule of InSite Debt Key Terms (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt		$ 1.9
Insite Debt | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 800	0
Subsidiaries
Debt Instrument [Line Items]
Long-term debt	3,146.2	3,082.2
Subsidiaries | Securitized Debt, Series 2016-1A Class A | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 218	0
Long-term debt, stated interest rate	2.883%
Subsidiaries | Securitized Debt, Series 2016-1A Class B | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 22.4	0
Long-term debt, stated interest rate	4.557%
Subsidiaries | Securitized Debt, Series 2016-1A Class C | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 75.7	0
Long-term debt, stated interest rate	6.414%
Subsidiaries | Securitized Debt, Series 2018-1A Class A | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 235.4	0
Long-term debt, stated interest rate	4.103%
Subsidiaries | Securitized Debt, Series 2018-1A Class B | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 60.5	0
Long-term debt, stated interest rate	4.844%
Subsidiaries | Securitized Debt, Series 2018-1A Class C | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 22.8	0
Long-term debt, stated interest rate	6.115%
Subsidiaries | Securitized Debt, Series 2020-1A Class A | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 121.5	0
Long-term debt, stated interest rate	1.496%
Subsidiaries | Securitized Debt, Series 2020-1A Class B | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 21.7	0
Long-term debt, stated interest rate	2.488%
Subsidiaries | Securitized Debt, Series 2020-1A Class C | Secured Debt
Debt Instrument [Line Items]
Long-term debt	$ 22	0
Long-term debt, stated interest rate	4.213%
Subsidiaries | Insite Debt
Debt Instrument [Line Items]
Long-term debt	$ 800	$ 0

LONG-TERM OBLIGATIONS - Finance

LONG-TERM OBLIGATIONS - Finance Lease Obligations Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Finance lease obligations	$ 27.9	$ 30.7

LONG-TERM OBLIGATIONS -Maturiti

LONG-TERM OBLIGATIONS -Maturities of Long Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2021	$ 789.8
2022	1,304.6
2023	3,318.9
2024	2,151.9
2025	7,566
Thereafter	14,331.5
Total cash obligations	29,462.7
Unamortized discounts, premiums and debt issuance costs and fair value adjustments, net	(175.2)
Total	$ 29,287.5	$ 24,055.4

OTHER NON-CURRENT LIABILITIES_2

OTHER NON-CURRENT LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities, Noncurrent [Abstract]
Unearned revenue	$ 576.1	$ 525.9
Other miscellaneous liabilities	408.5	411.1
Other non-current liabilities	$ 984.6	$ 937

ASSET RETIREMENT OBLIGATIONS -C

ASSET RETIREMENT OBLIGATIONS -Changes In Carrying Value Of Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance as of January 1,	$ 1,384.1	$ 1,210
Additions	94.2	61.8
Accretion expense	90.8	81.6
Revisions in estimates	8.3	56.8
Settlements	(6.1)	(26.1)
Balance as of December 31,	1,571.3	1,384.1
Asset retirement obligation, foreign currency translation loss	$ 42.1	$ 6.7

ASSET RETIREMENT OBLIGATIONS -N

ASSET RETIREMENT OBLIGATIONS -Narrative (Details) $ in Billions	Dec. 31, 2020USD ($)
Asset Retirement Obligation [Abstract]
Estimated undiscounted future cash outlay for asset retirement obligations	$ 3.7

FAIR VALUE MEASUREMENTS -Assets

FAIR VALUE MEASUREMENTS -Assets And Liabilities Measured At Fair Value On a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jul. 01, 2015
Assets:
Embedded derivative in lease agreement			$ 14.6
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Assets:
Embedded derivative in lease agreement	$ 0	$ 0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Interest Rate Swap
Assets:
Interest rate swap agreements	0	0
Liabilities:
Interest rate swap agreements	0	0
Fair value of debt related to interest rate swap agreements	31.4	3.3
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets:
Embedded derivative in lease agreement	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Interest Rate Swap
Assets:
Interest rate swap agreements	29.2	9
Liabilities:
Interest rate swap agreements	0.1	7.5
Fair value of debt related to interest rate swap agreements	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Assets:
Embedded derivative in lease agreement	0	10.7
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest Rate Swap
Assets:
Interest rate swap agreements	0	0
Liabilities:
Interest rate swap agreements	0	0
Fair value of debt related to interest rate swap agreements	$ 0	$ 0

FAIR VALUE MEASUREMENTS -Narrat

FAIR VALUE MEASUREMENTS -Narrative (Details) $ in Millions, $ in Billions	12 Months Ended
	Dec. 31, 2020USD ($)interestRateSwap	Dec. 31, 2019USD ($)	Dec. 31, 2020COP ($)interestRateSwap	Jul. 01, 2015USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative in lease agreement				$ 14.6
Long-lived assets held	$ 33,931.2	$ 30,581.1
Impairment of long-lived assets held for use	222.8	94.2
Total debt and capital lease obligations	29,287.5	24,055.4
Long-term debt, fair value	31,400
Assets held and used, original carrying value	24,100	22,400
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value adjustments recognized in other expense	10.2
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative in lease agreement	0	10.7
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative in lease agreement	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative in lease agreement	0	0
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value		25,000
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	24,000	17,500
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	7,400	7,500
Interest Rate Swap | Other Noncurrent Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap asset	29.2	9
Interest Rate Swap | Other Noncurrent Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liability		7.4
Interest Rate Swap | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap asset	0	0
Interest rate swap liability	0	0
Interest Rate Swap | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap asset	0	0
Interest rate swap liability	0	0
Interest Rate Swap | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap asset	29.2	9
Interest rate swap liability	0.1	7.5
Interest Rate Swap | Colombia
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fair value	0.1	0.1
Senior Notes | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative fair value adjustment, net	0.4
3.000% senior notes | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 500
3.000% senior notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, stated interest rate	3.00%		3.00%
3.000% senior notes | Senior Notes | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps entered into | interestRateSwap	3		3
Interest rate swap liability	$ 25.1	9.2
2.250% senior notes | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	600
Interest rate swap liability	$ 6.3	$ (5.9)
2.250% senior notes | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, stated interest rate	2.25%		2.25%
2.250% senior notes | Senior Notes | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps entered into | interestRateSwap	3		3
Colombian Credit Facility | Revolving Credit Facility | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fixed interest rate	5.37%		5.37%
Derivative asset, notional amount	$ 8.7		$ 30

INCOME TAXES -Income Tax Provis

INCOME TAXES -Income Tax Provision From Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 8.7	$ (1.7)	$ (1.4)
State	(10.7)	(5)	(1.8)
Foreign	(150.1)	(48.2)	(189.7)
Deferred:
Federal	(1)	1.4	4
State	(1)	0.5	0.7
Foreign	24.5	53.2	298.3
Income tax (provision) benefit	$ (129.6)	$ 0.2	$ 110.1

INCOME TAXES -Narrative (Detail

INCOME TAXES -Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Effective income tax rate, percent	7.00%	0.00%	(10.00%)
Tax benefit		$ 113,000,000	$ 85,700,000
Valuation allowance	$ 228,500,000	194,200,000	151,900,000	$ 142,000,000
Unrecognized tax benefits that would impact the ETR	105,900,000	158,100,000
Increase (decrease) in unrecognized tax benefit	26,200,000
Decrease in unrecognized tax benefits, from lapse of statue of limitations and effective settlements	50,500,000	2,500,000	9,300,000
Unrecognized tax benefits, income tax penalties and interest	16,400,000	10,300,000	8,000,000
Decrease in income tax penalties and interest expense	4,800,000	2,700,000	$ 16,200,000
Unrecognized tax benefits, income tax penalties and interest accrued	34,400,000	$ 26,600,000
Maximum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	32,700,000
Minimum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	$ 0
Foreign | Maximum
Income Tax Contingency [Line Items]
Effective income tax rate, percent		35.00%
Foreign | Minimum
Income Tax Contingency [Line Items]
Effective income tax rate, percent		25.00%

INCOME TAXES - Reconciliation B

INCOME TAXES - Reconciliation Between The U.S. Statutory Rate And The Effective Rate From Continuing Operations (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory tax rate	21.00%	21.00%	21.00%
Tax adjustment related to REIT	(21.00%)	(21.00%)	(21.00%)
Foreign taxes	4.00%	3.00%	(8.00%)
Foreign withholding taxes	3.00%	3.00%	4.00%
Uncertain tax positions	1.00%	1.00%	0.00%
Changes in tax laws	0.00%	(6.00%)	0.00%
Impact from restructuring	0.00%	(1.00%)	(6.00%)
Changes in valuation allowance	(1.00%)	0.00%	0.00%
Effective tax rate	7.00%	0.00%	(10.00%)

INCOME TAXES (Components Of Inc

INCOME TAXES (Components Of Income From Continuing Operations Before Income Taxes And Income On Equity Method Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States	$ 1,683	$ 1,527	$ 1,212.7
Foreign	138.1	389.4	(58.1)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	$ 1,821.1	$ 1,916.4	$ 1,154.6

INCOME TAXES- Components Of The

INCOME TAXES- Components Of The Net Deferred Tax Asset And Related Valuation Allowance (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets:
Operating lease liability	$ 837.1	$ 878.5
Net operating loss carryforwards	327.1	356.6
Accrued asset retirement obligations	187.8	174.9
Stock-based compensation	9.2	5.6
Unearned revenue	34.6	31.7
Unrealized loss on foreign currency	4.9	3.8
Other accruals and allowances	83.4	65.6
Nondeductible interest	60.9	15.9
Items not currently deductible and other	65.8	10.2
Liabilities:
Depreciation and amortization	(1,140.3)	(1,040.3)
Right-of-use asset	(824)	(865.1)
Deferred rent	(92.9)	(79.7)
Investment in noncontrolled affiliates	60.4	0
Other	(1.1)	0
Subtotal	(507.9)	(442.3)
Valuation allowance	(228.5)	(194.2)	$ (151.9)	$ (142)
Net deferred tax liabilities	$ (736.4)	$ (636.5)

INCOME TAXES - Valuation Allowa

INCOME TAXES - Valuation Allowance Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of January 1,	$ 194.2	$ 151.9	$ 142
Additions	64.7	42.5	15.7
Usage, expiration and reversals	(22)	0	0
Foreign currency translation	(8.4)	(0.2)	(5.8)
Balance as of December 31,	$ 228.5	$ 194.2	$ 151.9

INCOME TAXES - Net Operating Lo

INCOME TAXES - Net Operating Loss Carryforwards Expire (Details) $ in Millions	Dec. 31, 2020USD ($)
Federal
Operating Loss Carryforwards [Line Items]
2021 to 2025	$ 141.6
2026 to 2030	0
2031 to 2035	9.5
2036 to 2040	61.7
Indefinite carryforward	142.1
Total	354.9
State
Operating Loss Carryforwards [Line Items]
2021 to 2025	180.2
2026 to 2030	193.7
2031 to 2035	48.7
2036 to 2040	183
Indefinite carryforward	47.7
Total	653.3
Foreign
Operating Loss Carryforwards [Line Items]
2021 to 2025	12.4
2026 to 2030	85.6
2031 to 2035	3.5
2036 to 2040	0
Indefinite carryforward	679.5
Total	$ 781

INCOME TAXES - Reconciliation O

INCOME TAXES - Reconciliation Of The Beginning And Ending Amount Of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 175.6	$ 107.7	$ 116.7
Additions based on tax positions related to the current year	4.7	33.3	8.1
Additions and reductions for tax positions of prior years (1)	(5)
Additions and reductions for tax positions of prior years (1)		37.5	0.3
Foreign currency	(9.6)	(1.6)	(8.1)
Reduction as a result of the lapse of statute of limitations	(26)	(1.3)	(2.6)
Reduction as a result of effective settlements	(3.5)	0	(6.7)
Balance at December 31	$ 136.2	$ 175.6	$ 107.7

STOCK-BASED COMPENSATION -Narra

STOCK-BASED COMPENSATION -Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Discount from market price			15.00%
Stock-based compensation expense			$ 120.8	$ 111.4	$ 137.5
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected recognition of stock award compensation expense weighted average period in years			2 years
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense			$ 4.3
Expected recognition of stock award compensation expense weighted average period in years			2 years
Three year performance grant, shares granted (in shares)	17,593	40,186	110,925	114,823	131,311
Stock-based compensation expense			$ 20.9
PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares			0.00%
PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares			200.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock options exercised			$ 176.3	$ 145.5	$ 98.8
Total unrecognized compensation expense			$ 0.1
Expected recognition of stock award compensation expense weighted average period in years			1 year
Cash received from exercise of stock options			$ 84.7
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock units vested during period			$ 214.1
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issuable under stock incentive plan (in shares)			6,500,000
2007 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Total unrecognized compensation expense			$ 125.7
2007 Plan | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
2007 Plan | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			10 years

STOCK-BASED COMPENSATION -Summa

STOCK-BASED COMPENSATION -Summary Of Stock-based Compensation Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 120.8	$ 111.4	$ 137.5
Stock-based compensation expense capitalized as property and equipment	1.7	1.6	2
Property
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1.9	1.8	2.4
Service
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1.1	1	0.9
Selling, General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 117.8	$ 108.6	$ 134.2

STOCK-BASED COMPENSATION (Summa

STOCK-BASED COMPENSATION (Summary Of The Company's Option Activity) (Details) - Employee Stock Option $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Options
Outstanding (in shares) | shares	3,060,242
Granted (in shares) | shares	0
Exercised (in shares) | shares	(1,043,981)
Forfeited (in shares) | shares	0
Expired (in shares) | shares	0
Outstanding (in shares) | shares	2,016,261
Exercisable (in shares) | shares	2,014,628
Vested or expected to vest (in shares) | shares	2,016,261
Weighted Average Exercise Price Per Share
Outstanding (in dollars per share) | $ / shares	$ 85.90
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	81.16
Forfeited (in dollars per share) | $ / shares	0
Expired (in dollars per share) | $ / shares	0
Outstanding (in dollars per share) | $ / shares	88.36
Exercisable (in dollars per share) | $ / shares	88.33
Vested or expected to vest (in dollars per share) | $ / shares	$ 88.36
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining life, outstanding	3 years 1 month 24 days
Weighted average remaining life, exercisable	3 years 1 month 24 days
Weighted average remaining life, vested or expected to vest	3 years 1 month 24 days
Aggregate intrinsic value, outstanding | $	$ 274.4
Aggregate intrinsic value, exercisable | $	274.2
Aggregate intrinsic value, vested or expected to vest | $	$ 274.4

STOCK-BASED COMPENSATION -Sched

STOCK-BASED COMPENSATION -Schedule Of Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
$50.78 - $71.07
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	$ 50.78
Exercise price per share, maximum	$ 71.07
Outstanding number of options (in shares) | shares	102,447
Weighted average exercise price per share (in dollars per share)	$ 61.55
Weighted average remaining life	1 year 1 month 20 days
Options exercisable (in shares) | shares	102,447
Weighted average exercise price per share (in dollars per share)	$ 61.55
$76.90 - $77.75
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	76.90
Exercise price per share, maximum	$ 77.75
Outstanding number of options (in shares) | shares	221,435
Weighted average exercise price per share (in dollars per share)	$ 76.92
Weighted average remaining life	1 year 9 months 25 days
Options exercisable (in shares) | shares	221,435
Weighted average exercise price per share (in dollars per share)	$ 76.92
$81.18 - $94.23
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	81.18
Exercise price per share, maximum	$ 94.23
Outstanding number of options (in shares) | shares	432,352
Weighted average exercise price per share (in dollars per share)	$ 81.58
Weighted average remaining life	2 years 7 months 28 days
Options exercisable (in shares) | shares	432,352
Weighted average exercise price per share (in dollars per share)	$ 81.58
$94.57 - $94.71
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	94.57
Exercise price per share, maximum	$ 94.71
Outstanding number of options (in shares) | shares	1,240,897
Weighted average exercise price per share (in dollars per share)	$ 94.61
Weighted average remaining life	3 years 8 months 8 days
Options exercisable (in shares) | shares	1,240,897
Weighted average exercise price per share (in dollars per share)	$ 94.61
$99.67 - $121.15
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	99.67
Exercise price per share, maximum	$ 121.15
Outstanding number of options (in shares) | shares	19,130
Weighted average exercise price per share (in dollars per share)	$ 111.97
Weighted average remaining life	5 years 5 months 12 days
Options exercisable (in shares) | shares	17,497
Weighted average exercise price per share (in dollars per share)	$ 111.39
$50.78 - $121.15
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price per share, minimum	50.78
Exercise price per share, maximum	$ 121.15
Outstanding number of options (in shares) | shares	2,016,261
Weighted average exercise price per share (in dollars per share)	$ 88.36
Weighted average remaining life	3 years 1 month 24 days
Options exercisable (in shares) | shares	2,014,628
Weighted average exercise price per share (in dollars per share)	$ 88.33

STOCK-BASED COMPENSATION -Sum_2

STOCK-BASED COMPENSATION -Summary Of Restricted Stock Activity (Details) - $ / shares	3 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vesting period			3 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding (in shares)		1,454,350	1,454,350
Granted (in shares)			456,369
Vested (in shares)			(618,013)
Forfeited (in shares)			(47,631)
Outstanding (in shares)		1,454,350	1,454,350	1,454,350		1,245,075
Expected to vest, net of estimated forfeitures (in shares)						1,245,075
Vested And deferred at end of period (in shares)			58,204
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding (in dollars per share)		$ 147.67	$ 147.67
Granted (in dollars per share)			243.25
Vested (in dollars per share)			134.53
Forfeitures (in dollars per share)			173.74
Outstanding (in dollars per share)			$ 188.23	$ 147.67
Expected to vest, (in dollars per share)						$ 188.23
Vested and deferred (in dollars per share)						$ 181.26
Vested and deferred (in shares)			58,204			58,204	19,810
PSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding (in shares)		528,908	528,908
Granted (in shares)			151,341
Vested (in shares)			(282,774)
Forfeited (in shares)			(76,965)
Outstanding (in shares)		528,908	528,908	528,908		320,510
Expected to vest, net of estimated forfeitures (in shares)						320,510
Vested And deferred at end of period (in shares)			0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding (in dollars per share)		$ 136.94	$ 136.94
Granted (in dollars per share)			216.36
Vested (in dollars per share)			113.58
Forfeitures (in dollars per share)			211.21
Outstanding (in dollars per share)			$ 177.22	$ 136.94
Expected to vest, (in dollars per share)						$ 177.22
Vested and deferred (in dollars per share)						$ 0
Three year performance grant, shares granted (in shares)	17,593	40,186	110,925	114,823	131,311
Three year performance grant, shares issuable based on first, second and third years (in shares)				282,774
Vested and deferred (in shares)			0			0
Three year performance grant, shares issuable based on exceeding performance metric (in shares)			40,416

REDEEMABLE NONCONTROLLING INT_3

REDEEMABLE NONCONTROLLING INTERESTS -Narrative (Details) $ / shares in Units, $ in Millions, ₨ in Billions	1 Months Ended		3 Months Ended	12 Months Ended
	Feb. 28, 2021USD ($)$ / shares	Feb. 28, 2021INR (₨)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2020INR (₨)	Dec. 31, 2019USD ($)	Dec. 31, 2019INR (₨)	Dec. 31, 2018USD ($)	Apr. 21, 2016
Redeemable Noncontrolling Interest [Line Items]
Consideration paid for redemption				$ 861.7		$ 425.7		$ 0
Long-term debt, fair value				31,400
Tata Teleservices
Redeemable Noncontrolling Interest [Line Items]
Consideration paid for redemption				$ 337.3	₨ 24.8	$ 425.7	₨ 29.4
ATC, TIPL
Redeemable Noncontrolling Interest [Line Items]
Controlling interest percentage				92.00%		79.00%	79.00%	63.00%
Noncontrolling owners, ownership percentage				8.00%		21.00%	21.00%	37.00%
ATC, TIPL | Subsequent Event | Scenario, Forecast
Redeemable Noncontrolling Interest [Line Items]
Controlling interest percentage	100.00%
ATC, TIPL | Tata Teleservices
Redeemable Noncontrolling Interest [Line Items]
Percentage of ownership				100.00%	100.00%	50.00%	50.00%
ATC, TIPL | IDFC
Redeemable Noncontrolling Interest [Line Items]
Percentage of ownership						100.00%	100.00%
ATC, TIPL | Macquarie | Subsequent Event | Scenario, Forecast
Redeemable Noncontrolling Interest [Line Items]
Percentage of ownership	100.00%	100.00%
Consideration paid for redemption	$ 176.6	₨ 12.9
Temporary equity redemption price per share (in INR per share) | $ / shares	$ 175
Ghana And Uganda Subsidiaries
Redeemable Noncontrolling Interest [Line Items]
Consideration paid for redemption				$ 524.4
Controlling interest percentage				100.00%		51.00%	51.00%
Consideration adjustment			$ 1.4
Eure-et-Loir
Redeemable Noncontrolling Interest [Line Items]
Controlling interest percentage				51.00%
Noncontrolling owners, ownership percentage				49.00%
Carrying value				$ 2.6
India Transaction
Redeemable Noncontrolling Interest [Line Items]
Percentage of voting interest acquired									51.00%

REDEEMABLE NONCONTROLLING INT_4

REDEEMABLE NONCONTROLLING INTERESTS -Changes In Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in redeemable noncontrolling interest [Roll Forward]
Balance as of January 1,	$ 1,096.5	$ 1,004.8	$ 1,126.2
Additions to redeemable noncontrolling interests	0	525.7	0
Net income (loss) attributable to noncontrolling interests	6.6	35.8	(87.9)
Adjustment to noncontrolling interest redemption value	(14)	(35.8)	86.7
Noncontrolling interest, decrease due to merger	0	0	(28.1)
Purchases of redeemable noncontrolling interests	(861.7)	(425.7)	0
Foreign currency translation adjustment attributable to noncontrolling interests	(15.3)	(8.3)	(92.1)
Balance as of December 31,	$ 212.1	$ 1,096.5	$ 1,004.8

EQUITY-Narrative (Details)

EQUITY-Narrative (Details) € in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2020USD ($)	Dec. 31, 2020USD ($)shares	Dec. 31, 2020EUR (€)shares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2011USD ($)
Class of Stock [Line Items]
Proceeds from stock options and employee stock purchase plan		$ 98,100,000		$ 105,500,000	$ 98,900,000
Aggregate gross sales price	$ 1,000,000,000
Treasury stock activity		$ 56,000,000		$ 19,600,000	$ 232,800,000
Treasury stock, shares (in shares) | shares		10,915,000		10,651,000
Treasury stock		$ 1,282,400,000		$ 1,226,400,000
Accrued dividend RSU		12,600,000		$ 14,300,000
ATC Europe
Class of Stock [Line Items]
Dividends declared		16,200,000	€ 13.2
Dividends Declared and Paid
Class of Stock [Line Items]
Paid dividend RSU		$ 7,800,000
2011 Buyback
Class of Stock [Line Items]
Authorized repurchase of common stock							$ 1,500,000,000
Treasury stock activity (in shares) | shares		264,086	264,086
Treasury stock, shares (in shares) | shares		14,361,283
Treasury stock		$ 1,500,000,000
2017 Buyback
Class of Stock [Line Items]
Authorized repurchase of common stock						$ 2,000,000,000
Treasury stock activity		$ 0

EQUITY -Distributions Declared

EQUITY -Distributions Declared (Detail) - USD ($) $ / shares in Units, $ in Millions	Dec. 11, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Dividends Payable [Line Items]
Payments of ordinary dividends, common stock		$ 1,928.2	$ 1,603	$ 1,323.5
Preferred stock dividends declared				$ 18.9
Dividends per depository share, percentage		0.10
Common Stock
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)	$ 1.21	$ 3.3200	$ 3.7800	$ 3.1500
Dividends declared, common stock, percent of total		100.00%	100.00%	100.00%
Common Stock | Ordinary Income
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)		$ 3.3200	$ 3.7800	$ 3.1500
Dividends declared, common stock, percent of total		100.00%	100.00%	100.00%
Common Stock | Dividends Declared and Paid
Dividends Payable [Line Items]
Common stock, dividends declared per share (in dollars per share)		$ 4.53	$ 3.78	$ 3.15
Payments of ordinary dividends, common stock		$ 2,010.7	$ 1,672.8	$ 1,389.8
Series B Preferred Stock | Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)		$ 0	$ 0	$ 2.1314
Dividends declared, preferred stock, declared		0.00%	0.00%	100.00%
Series B Preferred Stock | Convertible Preferred Stock Subject to Mandatory Redemption | Ordinary Income
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)		$ 0	$ 0	$ 2.1314
Dividends declared, preferred stock, declared		0.00%	0.00%	100.00%
Series B Preferred Stock | Dividends Declared and Paid | Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividends per share, declared (in dollars per share)		$ 0	$ 0	$ 13.75
Preferred stock dividends declared		$ 0	$ 0	$ 18.9
Preferred stock (1) | Series B Preferred Stock | Convertible Preferred Stock Subject to Mandatory Redemption
Dividends Payable [Line Items]
Preferred stock, dividend rate, percentage			5.50%
Preferred stock, par value (in dollars per share)			$ 0.01

OTHER OPERATING EXPENSES (Detai

OTHER OPERATING EXPENSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Expenses [Line Items]
Impairment charges	$ 222.8	$ 94.2	$ 394
Net losses on sales or disposals of assets	17.3	45.1	85.6
Other operating expenses	25.7	27	33.7
Total other operating expenses	265.8	166.3	$ 513.3
Proceeds from previous acquisition	4.4	$ 13.1
Brazil
Other Expenses [Line Items]
Other operating expenses	$ 11.9

OTHER OPERATING EXPENSES-Impair

OTHER OPERATING EXPENSES-Impairment Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of intangible asset impairment [Line Items]
Impairment charges	$ 222.8	$ 94.2	$ 394
Tower and network location intangible assets
Schedule of intangible asset impairment [Line Items]
Impairment charges	142.4	77.4	284.9
Tenant relationships
Schedule of intangible asset impairment [Line Items]
Impairment charges	0	0	107.3
Right-of-use assets
Schedule of intangible asset impairment [Line Items]
Impairment charges	76.1	9.9	0
Other
Schedule of intangible asset impairment [Line Items]
Impairment charges	$ 4.3	$ 6.9	1.8
Aircel, Asia | Tenant relationships
Schedule of intangible asset impairment [Line Items]
Impairment charges			107.3
Asia Pacific | Tower and network location intangible assets
Schedule of intangible asset impairment [Line Items]
Impairment charges			$ 258.3

EARNINGS PER COMMON SHARE -Sche

EARNINGS PER COMMON SHARE -Schedule Of Earnings Per Basic And Diluted By Common Class (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income attributable to American Tower Corporation stockholders	$ 1,690.6	$ 1,887.8	$ 1,236.4
Dividends on preferred stock	0	0	(9.4)
Net income attributable to American Tower Corporation common stockholders	$ 1,690.6	$ 1,887.8	$ 1,227
Basic weighted average common shares outstanding (in shares)	443,640	442,319	439,606
Dilutive securities (shares)	2,464	3,201	3,354
Diluted weighted average common shares outstanding (in shares)	446,104	445,520	442,960
Basic net income attributable to american tower corporation common stockholders (in dollars per share)	$ 3.81	$ 4.27	$ 2.79
Diluted net income attributable to american tower corporation common stockholders (in dollars per share)	$ 3.79	$ 4.24	$ 2.77

EARNINGS PER COMMON SHARE -Sc_2

EARNINGS PER COMMON SHARE -Schedule Of Shares Excluded From Computation Of Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earnings per share (in shares)	1	2	0
Preferred stock (1)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earnings per share (in shares)	0	0	1,456

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Narrative) (Details) ₨ in Millions, $ in Millions	Dec. 05, 2016USD ($)	Dec. 05, 2016INR (₨)	Mar. 27, 2015USD ($)communications_siterenewalPeriod	Dec. 31, 2020USD ($)communications_sitecommunicationSiterenewalOption	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Loss Contingencies [Line Items]
Aggregate purchase price				$ 1,031.7	$ 991.3	$ 913.2
Loss contingency, foreign income tax assessment	$ 69.8	₨ 4,750
Verizon Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units | communications_site			11,250
Right to lease, weighted average term			28 years
Aggregate purchase option price for towers			$ 5,000
Customer lease, initial term			10 years
Successive terms to renew lease | renewalPeriod			8
AT&T Transaction
Loss Contingencies [Line Items]
Number of units leased | communications_site				2,100
Aggregate purchase option price for towers				$ 973.4
Successive terms to renew lease | renewalOption				5
Renewal term			5 years	5 years
Operating lease, term of contract				27 years
Number of sites acquired life to date | communicationSite				331
Number of communications sites acquired | communicationSite				103
Aggregate purchase price				$ 55.7

SUPPLEMENTAL CASH FLOW INFORM_3

SUPPLEMENTAL CASH FLOW INFORMATION - (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental cash flow information:
Cash paid for interest	$ 762.3	$ 750.2	$ 789.7
Tax refunds	27	11.2	25
Cash paid for income taxes (net of refunds of $27.0, $11.2 and $25.0, respectively)	146.3	147.5	163.9
Non-cash investing and financing activities:
Increase (decrease) in accounts payable and accrued expenses for purchases of property and equipment and construction activities	45.8	(21)	8.3
Purchases of property and equipment under finance leases, perpetual easements and capital leases	75	81.3	57.8
Fair value of debt assumed through acquisitions (1)	800	329.8	0
Acquisition of commercialization rights	0	0	24.8
Debt financed acquisition of communication sites	0	0	54.2
Settlement of third-party debt	$ (5)	$ 0	$ 0

BUSINESS SEGMENTS -Narrative (D

BUSINESS SEGMENTS -Narrative (Details) - segment	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020
Segment Reporting [Abstract]
Number of reportable segments	6	6

BUSINESS SEGMENTS -Summarized S

BUSINESS SEGMENTS -Summarized Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Segment revenues		$ 8,041.5	$ 7,580.3	$ 7,440.1
Interest expense, TV Azteca, net		0	0	(0.1)
Stock-based compensation expense		120.8	111.4	137.5
Other selling, general, administrative and development expense		176	156.5	156.1
Depreciation, amortization and accretion		1,882.3	1,778.4	2,110.8
Other expense		1,332.2	938.3	1,263.6
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES		1,821.1	1,916.4	1,154.6
Capital expenditures		1,071.2	1,038.9	945.2
Impairment charges		222.8	94.2	394
Finance lease payments		9.2	18
Payments for perpetual land easements		36.9	29.6
Capital lease payments				32
Operating Expense
Segment Reporting Information [Line Items]
Stock-based compensation expense		3	2.8	3.3
Selling General Administrative And Development Expense
Segment Reporting Information [Line Items]
Stock-based compensation expense		117.8	108.6	134.2
Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		8,041.5	7,580.3	7,440.1
Segment operating expenses		2,224.2	2,214	2,174.5
Segment gross margin		5,817.3	5,366.3	5,265.5
Selling, general, administrative and development expense		484.9	465.3	442.9
OPERATING INCOME		5,332.4	4,901	4,822.6
Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				(0.1)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Stock-based compensation expense		120.8	111.4	137.5
Other selling, general, administrative and development expense		176	156.5	156.1
Depreciation, amortization and accretion		1,882.3	1,778.4	2,110.8
Other expense		1,332.2	938.3	1,263.6
Capital expenditures		10.1	12.8	13.9
Impairment charges		222.8		394
Property | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		7,953.6	7,464.9	7,314.7
Segment operating expenses		2,187.7	2,171.9	2,126.3
Segment gross margin		5,765.9	5,293	5,188.3
Selling, general, administrative and development expense		470.1	453.3	428.5
OPERATING INCOME		5,295.8	4,839.7	4,759.8
Capital expenditures		1,061.1	1,026.1	931.3
Property | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				(0.1)
U.S. & Canada
Segment Reporting Information [Line Items]
Segment revenues		4,604.9	4,304.1
U.S. & Canada | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		4,517	4,188.7	3,822.1
Segment operating expenses		808	807.9	771
Segment gross margin		3,709	3,380.8	3,051.1
Selling, general, administrative and development expense		162.2	175.5	165.2
OPERATING INCOME		3,546.8	3,205.3	2,885.9
Capital expenditures		360.6	359.5	376.9
U.S. & Canada | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				0
Asia-Pacific
Segment Reporting Information [Line Items]
Segment revenues		1,139.4	1,217
Asia-Pacific | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		1,139.4	1,217	1,540.5
Segment operating expenses		661.4	715.9	710.9
Segment gross margin		478	501.1	829.6
Selling, general, administrative and development expense		97.4	99.9	110.7
OPERATING INCOME		380.6	401.2	718.9
Capital expenditures		112.9	134.5	101
Revenue net of settlement payment received	$ 333.7
Asia-Pacific | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				0
Africa
Segment Reporting Information [Line Items]
Segment revenues		890.2	583.9
Africa | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		890.2	583.9	545.5
Segment operating expenses		297.7	209	208
Segment gross margin		592.5	374.9	337.5
Selling, general, administrative and development expense		94.4	53.7	48
OPERATING INCOME		498.1	321.2	289.5
Capital expenditures		334.9	258.5	212.5
Africa | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				0
Europe
Segment Reporting Information [Line Items]
Segment revenues		149.6	134.6
Europe | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		149.6	134.6	141.8
Segment operating expenses		28.1	27.8	30.1
Segment gross margin		121.5	106.8	111.7
Selling, general, administrative and development expense		23	23.2	21.1
OPERATING INCOME		98.5	83.6	90.6
Capital expenditures		31.6	13.2	20.2
Europe | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				0
Latin America
Segment Reporting Information [Line Items]
Segment revenues		1,257.4	1,340.7
Latin America | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		1,257.4	1,340.7	1,264.8
Segment operating expenses		392.5	411.3	406.3
Segment gross margin		864.9	929.4	858.4
Selling, general, administrative and development expense		93.1	101	83.5
OPERATING INCOME		771.8	828.4	774.9
Capital expenditures		221.1	260.4	220.7
Latin America | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				(0.1)
Services | Operating Segments
Segment Reporting Information [Line Items]
Segment revenues		87.9	115.4	125.4
Segment operating expenses		36.5	42.1	48.2
Segment gross margin		51.4	73.3	77.2
Selling, general, administrative and development expense		14.8	12	14.4
OPERATING INCOME		36.6	61.3	62.8
Capital expenditures		$ 0	$ 0	0
Services | Operating Segments | TV Azteca
Segment Reporting Information [Line Items]
Interest expense, TV Azteca, net				$ 0

BUSINESS SEGMENTS -Additional I

BUSINESS SEGMENTS -Additional Information Relating to the Company's Operating Segments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 47,233.5	$ 42,801.6	$ 33,010.4
Operating Segments | Services
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	38.7	26.8	46.3
Operating Segments | U.S. & Canada
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	27,352.9	22,624.6	18,782
Operating Segments | Asia-Pacific
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,191.8	5,307.8	4,938.8
Operating Segments | Africa
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,894.8	4,711.1	1,929.7
Operating Segments | Europe
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	1,868.6	1,535.3	1,438.1
Operating Segments | Latin America
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	7,434.2	8,125.5	5,594.7
Segment Reconciling Items
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 452.5	$ 470.5	$ 280.8

BUSINESS SEGMENTS -Summary of G

BUSINESS SEGMENTS -Summary of Geographic Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 8,041.5	$ 7,580.3	$ 7,440.1
Long-lived assets held	33,931.2	30,581.1
U.S. & Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	4,604.9	4,304.1
U.S. & Canada | Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	0.3	0	0
Long-lived assets held	373.7	0
U.S. & Canada | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	4,604.6	4,304.1	3,947.5
Long-lived assets held	19,977.8	16,578.7
Asia-Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	1,139.4	1,217
Asia-Pacific | Australia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	0	0	0
Long-lived assets held	20	0
Asia-Pacific | India
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	1,139.4	1,217	1,540.5
Long-lived assets held	3,482.3	3,708.8
Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	890.2	583.9
Africa | Burkina Faso
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	43.9	0	0
Long-lived assets held	315.7	275.3
Africa | Ghana
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	174.3	124.3	125.4
Long-lived assets held	676.8	671
Africa | Kenya
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	97.7	27.3	7
Long-lived assets held	730	761.7
Africa | Niger
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	40	0	0
Long-lived assets held	215.7	199.8
Africa | Nigeria
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	249.5	229.9	220.7
Long-lived assets held	663.7	648.6
Africa | South Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	128.7	129.1	125.3
Long-lived assets held	424.4	409.4
Africa | Uganda
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	156.1	73.3	67.1
Long-lived assets held	867.3	847.3
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	149.6	134.6
Europe | France
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	79.4	68	72.7
Long-lived assets held	1,176.5	917.1
Europe | Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	70	66.6	69.1
Long-lived assets held	370.9	357.3
Europe | Poland
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	0.2	0	0
Long-lived assets held	2.9	0
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	1,257.4	1,340.7
Latin America | Argentina
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	22.1	17.3	16
Long-lived assets held	111.9	100
Latin America | Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	506.4	605.5	595.5
Long-lived assets held	1,629.9	2,138.4
Latin America | Chile
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	67.3	43.3	44.2
Long-lived assets held	538.7	437.6
Latin America | Colombia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	96.1	102.1	103.8
Long-lived assets held	350.7	375.2
Latin America | Costa Rica
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	23.4	21.1	18.4
Long-lived assets held	123.1	124.1
Latin America | Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	483	515.3	456.5
Long-lived assets held	1,395.2	1,524.9
Latin America | Paraguay
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	12.5	12.6	10.4
Long-lived assets held	103.6	111.3
Latin America | Peru
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	46.6	23.5	$ 20
Long-lived assets held	$ 380.4	$ 394.6

BUSINESS SEGMENTS -Major Custom

BUSINESS SEGMENTS -Major Customers (Details) - Customer Concentration Risk - Sales Revenue, Net	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Major Customer [Line Items]
Concentration risk, percentage	55.00%
AT&T
Revenue, Major Customer [Line Items]
Concentration risk, percentage	22.00%	22.00%	19.00%
T-Mobile
Revenue, Major Customer [Line Items]
Concentration risk, percentage	19.00%	10.00%	9.00%
Verizon Wireless
Revenue, Major Customer [Line Items]
Concentration risk, percentage	14.00%	15.00%	15.00%

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details)	Feb. 10, 2021EUR (€)	Jun. 30, 2021USD ($)communicationSite	Jun. 30, 2021EUR (€)communicationSite	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 10, 2021USD ($)	Feb. 10, 2021EUR (€)	Jan. 13, 2021USD ($)	Jan. 13, 2021EUR (€)
Subsequent Event [Line Items]
Borrowings under credit facilities				$ 8,230,400,000		$ 5,750,000,000	$ 3,263,300,000
2019 Multicurrency Credit Facility | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity				3,100,000,000
Borrowings under credit facilities				1,000,000,000	€ 910,000,000
Debt covenant, default threshold				400,000,000
2019 Multicurrency Credit Facility | Letter of Credit
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity				1,000,000,000
2019 Credit Facility | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity				2,350,000,000
Borrowings under credit facilities				$ 7,200,000,000
Subsequent Event | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								$ 3,900,000,000	€ 3,225,000,000
Subsequent Event | Revolving Credit Facility | Bridge Loan
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								5,200,000,000	€ 4,275,000,000	$ 9,100,000,000	€ 7,500,000,000
Subsequent Event | 2019 Multicurrency Credit Facility | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								$ 6,100,000,000
Debt covenant, Total Debt to Adjusted EBITDA ratio (no greater than)								7.50	7.50
Debt covenant, Total Debt to Adjusted EBITDA ratio, step down								6	6
Debt covenant, Total Debt to Adjusted EBITDA ratio, after a Qualified Acquisition								7	7
Debt covenant, limitation on indebtedness guaranteed by subsidiaries								$ 3,000,000,000
Debt covenant, limitation of indebtedness guaranteed by subsidiaries, Adjusted EBITDA, percentage								50.00%	50.00%
Debt covenant, default threshold								$ 500,000,000
Subsequent Event | 2019 Multicurrency Credit Facility | Letter of Credit
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								3,000,000,000
Subsequent Event | 2019 Multicurrency Credit Facility | Line of Credit | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								4,100,000,000
Borrowings under credit facilities | €	€ 1,300,000,000
Subsequent Event | 2019 Credit Facility | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								$ 4,400,000,000
Debt covenant, Total Debt to Adjusted EBITDA ratio (no greater than)								7.50	7.50
Debt covenant, Total Debt to Adjusted EBITDA ratio, step down								6	6
Debt covenant, Total Debt to Adjusted EBITDA ratio, after a Qualified Acquisition								7	7
Debt covenant, limitation on indebtedness guaranteed by subsidiaries								$ 3,000,000,000
Debt covenant, limitation of indebtedness guaranteed by subsidiaries, Adjusted EBITDA, percentage								50.00%	50.00%
Subsequent Event | 2019 Credit Facility | Letter of Credit
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity | €									€ 1,500,000,000
Subsequent Event | 2019 Credit Facility | Line of Credit | Revolving Credit Facility
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity								$ 2,900,000,000
Subsequent Event | 2021 364-Day Delayed Draw Term Loan | Unsecured Debt
Subsequent Event [Line Items]
Debt instrument, face amount								1,300,000,000	1,100,000,000
Debt instrument, term	364 days
Subsequent Event | 2021 364-Day Delayed Draw Term Loan | Unsecured Debt | EURIBOR
Subsequent Event [Line Items]
Basis spread on variable rate	1.00%
Subsequent Event | 2021 Three Year Delayed Draw Term Loan | Unsecured Debt
Subsequent Event [Line Items]
Debt instrument, face amount								$ 1,000,000,000	€ 825,000,000
Debt instrument, term	3 years
Subsequent Event | 2021 Three Year Delayed Draw Term Loan | Unsecured Debt | EURIBOR
Subsequent Event [Line Items]
Basis spread on variable rate	1.125%
Subsequent Event | Scenario, Forecast | Telxius Telecom S.A.
Subsequent Event [Line Items]
Number of communications sites acquired | communicationSite		31,000	31,000
Purchase price		$ 9,400,000,000	€ 7,700,000,000

Schedule III - SCHEDULE OF RE_2

Schedule III - SCHEDULE OF REAL ESTATE AND ACCUMULATED DEPRECIATION -Schedule of Real Estate and Accumulated Depreciation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)communicationSite	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Number of units | communicationSite	183,860
Encumbrances	$ 3,136.7	$ 3,100
Gross amount carried at close of current period	18,492.9	17,429.3	$ 15,960.1	$ 15,349
Accumulated depreciation at close of current period	$ (6,921)	$ (6,382.2)	$ (5,724.7)	$ (5,181.2)
Percentage exceeds total amounts		5.00%
Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statements is computed	20 years

Schedule III - SCHEDULE OF RE_3

Schedule III - SCHEDULE OF REAL ESTATE AND ACCUMULATED DEPRECIATION -Activity of real Estate and Accumulated Depreciation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Additions during period:
Gross amount at beginning	$ 17,429.3	$ 15,960.1	$ 15,349
Acquisitions	722.4	887	721.4
Discretionary capital projects	308	258.1	173.5
Discretionary ground lease purchases	214.3	189.8	180.4
Redevelopment capital expenditures	176.7	213.6	177.3
Capital improvements	91.4	161.2	94
Start-up capital expenditures	119.4	71.3	113.1
Other	72.8	45.2	(3)
Total additions	1,705	1,826.2	1,456.7
Deductions during period:
Cost of real estate sold or disposed	(259.7)	(304.6)	(395.7)
Other	(381.7)	(52.4)	(449.9)
Total deductions	(641.4)	(357)	(845.6)
Balance at end	18,492.9	17,429.3	15,960.1
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Gross amount of accumulated depreciation at beginning	(6,382.2)	(5,724.7)	(5,181.2)
Additions during period:
Depreciation	(771.5)	(768.4)	(751.4)
Other additions	0	0	0
Total additions	(771.5)	(768.4)	(751.4)
Deductions during period:
Amount of accumulated depreciation for assets sold or disposed	132.3	121.4	129.3
Other deductions	100.4	(10.5)	78.6
Total deductions	232.7	110.9	207.9
Balance at end	$ (6,921)	$ (6,382.2)	$ (5,724.7)