American Tower (AMT) 10-Q 29 Apr 20 2020 Q1 Quarterly report Financial data

COVER

COVER - shares	3 Months Ended
	Mar. 31, 2020	Apr. 22, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 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 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
Entity Common Stock, Shares Outstanding		443,306,437
Entity Central Index Key	0001053507
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock, $0.01 par value
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

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 1,326	$ 1,501.2
Restricted cash	74.3	76.8
Accounts receivable, net	623.9	462.2
Prepaid and other current assets	480.7	513.6
Total current assets	2,504.9	2,553.8
PROPERTY AND EQUIPMENT, net	11,451.3	12,084.4
GOODWILL	5,948.8	6,178.3
OTHER INTANGIBLE ASSETS, net	11,600.6	12,318.4
DEFERRED TAX ASSET	126.4	131.8
DEFERRED RENT ASSET	1,781.8	1,771.1
RIGHT-OF-USE ASSET	6,968.3	7,357.4
NOTES RECEIVABLE AND OTHER NON-CURRENT ASSETS	407	406.4
TOTAL	40,789.1	42,801.6
CURRENT LIABILITIES:
Accounts payable	120.6	148.1
Accrued expenses	876.4	958.2
Distributions payable	483.9	455
Accrued interest	148.2	209.4
Current portion of operating lease liability	476.8	494.5
Current portion of long-term obligations	2,640	2,928.2
Unearned revenue	408.5	294.3
Total current liabilities	5,154.4	5,487.7
LONG-TERM OBLIGATIONS	21,937.4	21,127.2
OPERATING LEASE LIABILITY	6,137.8	6,510.4
ASSET RETIREMENT OBLIGATIONS	1,321.5	1,384.1
DEFERRED TAX LIABILITY	731	768.3
OTHER NON-CURRENT LIABILITIES	901	937
Total liabilities	36,183.1	36,214.7
COMMITMENTS AND CONTINGENCIES
REDEEMABLE NONCONTROLLING INTERESTS	541.4	1,096.5
EQUITY (shares in thousands):
Common stock: $.01 par value; 1,000,000 shares authorized; 454,196 and 453,541 shares issued; and 443,332 and 442,890 shares outstanding, respectively	4.5	4.5
Additional paid-in capital	10,255.6	10,117.7
Distributions in excess of earnings	(1,082.5)	(1,016.8)
Accumulated other comprehensive loss	(4,271.7)	(2,823.6)
Treasury stock (10,864 and 10,651 shares at cost, respectively)	(1,271.5)	(1,226.4)
Total American Tower Corporation equity	3,634.4	5,055.4
Noncontrolling interests	430.2	435
Total equity	4,064.6	5,490.4
TOTAL	$ 40,789.1	$ 42,801.6

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares issued (in shares)	454,196	453,541
Common stock, shares outstanding (in shares)	443,332	442,890
Treasury stock, shares (in shares)	10,864	10,651

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
REVENUES:
Total operating revenues	$ 1,993.1	$ 1,813.4
Costs of operations (exclusive of items shown separately below):
Property	544.1	533
Services	7.9	10.4
Depreciation, amortization and accretion	472.3	436.9
Selling, general, administrative and development expense	217.8	198.1
Other operating expenses	14.2	20.1
Total operating expenses	1,256.3	1,198.5
OPERATING INCOME	736.8	614.9
OTHER INCOME (EXPENSE):
Interest income	10.1	12.4
Interest expense	(208.8)	(207.5)
Loss on retirement of long-term obligations	(34.6)	(0.1)
Other (expense) income (including foreign currency (losses) gains of $(65.5) and $20.1, respectively)	(63.8)	21.9
Total other expense	(297.1)	(173.3)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	439.7	441.6
Income tax provision	(21.1)	(34)
NET INCOME	418.6	407.6
Net income attributable to noncontrolling interests	(3.6)	(10.2)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	415	397.4
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 415	$ 397.4
NET INCOME PER COMMON SHARE AMOUNTS:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.94	$ 0.90
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.93	$ 0.89
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (in thousands):
BASIC (in shares)	443,055	441,351
DILUTED (in shares)	445,832	444,621
Property
REVENUES:
Total operating revenues	$ 1,973.2	$ 1,786
Services revenue
REVENUES:
Total operating revenues	$ 19.9	$ 27.4

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Foreign currency (losses) gains	$ (65.5)	$ 20.1

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 418.6	$ 407.6
Other comprehensive (loss) income:
Changes in fair value of cash flow hedges, each net of tax expense of $0	0	(0.1)
Reclassification of unrealized losses on cash flow hedges to net income, each net of tax expense of $0	0	0.1
Foreign currency translation adjustments, net of tax (benefit) expense of ($0.0) and $1.0, respectively	(1,343.5)	12.9
Other comprehensive (loss) income	(1,343.5)	12.9
Comprehensive (loss) income	(924.9)	420.5
Allocation of accumulated other comprehensive income resulting from purchase of noncontrolling interest and redeemable noncontrolling interest	(142.2)	(52.4)
Comprehensive loss attributable to noncontrolling interests	34	0
Comprehensive (loss) income attributable to American Tower Corporation stockholders	$ (1,033.1)	$ 368.1

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Changes in fair value of cash flow hedges, tax	$ 0	$ 0
Reclassification of unrealized gains on cash flow hedges to net income, tax	0	0
Foreign currency translation adjustments, tax expense (benefit)	$ 0	$ 1

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Millions, ₨ in Billions	3 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 418.6	$ 407.6
Adjustments to reconcile net income to cash provided by operating activities
Depreciation, amortization and accretion	472.3	436.9
Stock-based compensation expense	47.7	42.5
Loss on early retirement of long-term obligations	34.6	0.1
Other Noncash Income (Expense)	81.6	28.9
Increase in net deferred rent balances	(56.2)	(5.3)
Right-of-use asset and Operating lease liability, net	1	20.2
Increase in assets	(210.8)	(33)
Increase (decrease) in liabilities	11.2	(112.8)
Cash provided by operating activities	800	785.1
CASH FLOWS FROM INVESTING ACTIVITIES
Payments for purchase of property and equipment and construction activities	(214.4)	(220.8)
Payments for acquisitions, net of cash acquired	(49.3)	(91.1)
Proceeds from sale of short-term investments and other non-current assets	5.8	254.9
Payments for short-term investments	0	(261.5)
Deposits and other	4.5	(4.8)
Cash used for investing activities	(253.4)	(323.3)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings under credit facilities	2,642.3	1,700
Proceeds from issuance of senior notes, net	1,496	1,241.6
Proceeds from term loan	750	1,300
Repayments of notes payable, credit facilities, senior notes, secured debt, term loan and finance leases	(4,351.2)	(4,025.9)
Distributions to noncontrolling interest holders, net	(13.5)	(13.8)
Purchases of common stock	(39.7)	0
Proceeds from stock options	11.1	27.2
Distributions paid on common stock	(454.9)	(377.1)
Payment for early retirement of long-term obligations	(33.5)	0
Deferred financing costs and other financing activities	(88.2)	(76.7)
Payments for Repurchase of Redeemable Noncontrolling Interest	(524.4)	(425.7)
Cash used for financing activities	(606)	(650.4)
Net effect of changes in foreign currency exchange rates on cash and cash equivalents, and restricted cash	(118.3)	(16.6)
NET DECREASE IN CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH	(177.7)	(205.2)
CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH, BEGINNING OF PERIOD	1,578	1,304.9
CASH AND CASH EQUIVALENTS, AND RESTRICTED CASH, END OF PERIOD	1,400.3	1,099.7
CASH PAID FOR INCOME TAXES (NET OF REFUNDS OF $0.1 AND $0.3, RESPECTIVELY)	35.1	36.9
CASH PAID FOR INTEREST	262	249
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment under finance leases and perpetual easements	13.1	16
Decrease in accounts payable and accrued expenses for purchases of property and equipment and construction activities	(15)	(17.7)
Settlement of third-party debt	$ (5)	$ 0

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Income tax refunds	$ 0.1	$ 0.3

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Distributions in Excess of Earnings	Noncontrolling Interests
BEGINNING BALANCE (shares) at Dec. 31, 2018		451,617,000	(10,557,000)
BEGINNING BALANCE at Dec. 31, 2018	$ 5,899.6	$ 4.5	$ (1,206.8)	$ 10,380.8	$ (2,642.9)	$ (1,199.5)	$ 563.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity (shares)		908,000
Stock-based compensation related activity	14.7	$ 0		14.7
Changes in fair value of cash flow hedges, net of tax	(0.1)				(0.1)
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	0.1				0.1
Foreign currency translation adjustment, net of tax	3				23.1		(20.1)
Distributions to noncontrolling interest	(0.3)						(0.3)
Purchase of redeemable noncontrolling interest	0			52.4	(52.4)
Common stock distributions declared	(399.6)					(399.6)
Net income	407.6					397.4	10.2
ENDING BALANCE (shares) at Mar. 31, 2019		452,525,000	(10,557,000)
ENDING BALANCE at Mar. 31, 2019	5,900.3	$ 4.5	$ (1,206.8)	10,447.9	(2,672.2)	(1,226.4)	553.3
BEGINNING BALANCE (shares) at Dec. 31, 2019		453,541,000	(10,651,000)
BEGINNING BALANCE at Dec. 31, 2019	5,490.4	$ 4.5	$ (1,226.4)	10,117.7	(2,823.6)	(1,016.8)	435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity (shares)		655,000
Stock-based compensation related activity	$ (4.3)	$ 0		(4.3)
Treasury stock activity (shares)	(213,352)		(213,000)
Treasury stock activity	$ (45.1)		$ (45.1)
Changes in fair value of cash flow hedges, net of tax	0				0
Reclassification of unrealized losses on cash flow hedges to net income, net of tax	0
Foreign currency translation adjustment, net of tax	(1,311.4)				(1,305.9)		(5.5)
Distributions to noncontrolling interest	(1.5)						(1.5)
Purchase of redeemable noncontrolling interest	0			142.2	(142.2)
Common stock distributions declared	(480.7)					(480.7)
Net income	417.2					415	2.2
ENDING BALANCE (shares) at Mar. 31, 2020		454,196,000	(10,864,000)
ENDING BALANCE at Mar. 31, 2020	$ 4,064.6	$ 4.5	$ (1,271.5)	$ 10,255.6	$ (4,271.7)	$ (1,082.5)	$ 430.2

BASIS OF PRESENTATION AND SIGNI

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES The accompanying consolidated and condensed consolidated financial statements have been prepared by American Tower Corporation (together with its subsidiaries, “ATC” or the “Company”) pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The financial information included herein is unaudited. However, the Company believes that all adjustments, which are of a normal and recurring nature, considered necessary for a fair presentation of its financial position and results of operations for such periods have been included herein. The consolidated and condensed consolidated financial statements and related notes should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the “2019 Form 10-K”). The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the entire year. Principles of Consolidation and Basis of Presentation —The accompanying consolidated and condensed consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity 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 March 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 Germany and France (PGGM holds a 49% noncontrolling interest) and (ii) a 79% controlling interest in ATC Telecom Infrastructure Private Limited (“ATC TIPL”), formerly Viom Networks Limited (“Viom”), in India. During the three months ended March 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, which included an adjustment of $1.4 million in the current period, 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. Change in Reportable Segments — During the fourth quarter of 2019, the Company’s Europe, Middle East and Africa (“EMEA”) property segment was divided into the Africa property segment and the Europe property segment. As a result, the Company has six reportable segments: U.S. property, Asia property, Africa property, Europe property, Latin America property and services, which are discussed further in note 15. The change in reportable segments had no impact on the Company’s consolidated financial statements for any periods. Historical financial information included in this Quarterly Report on Form 10-Q (this “Quarterly Report”) has been adjusted to reflect the change in reportable segments. Significant Accounting Policies —The Company’s significant accounting policies are described in note 1 to the Company’s consolidated financial statements included in the 2019 Form 10-K. There have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2020. Cash and 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 statement of cash flows is as follows: Three Months Ended March 31, 2020 2019 Cash and cash equivalents $ 1,326.0 $ 1,004.8 Restricted cash 74.3 94.9 Total cash and cash equivalents and restricted cash $ 1,400.3 $ 1,099.7 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 distributed antenna system (“DAS”) networks and fiber results from agreements with tenants that are not leases. 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. There were no material changes in the receivables, contract assets and contract liabilities from contracts with tenants for the three months ended March 31, 2020. Services revenue —The Company offers tower-related services in the United States. These services include site acquisition, zoning and permitting (“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. A summary of revenue disaggregated by source and geography is as follows: Three Months Ended March 31, 2020 U.S. Asia Africa Europe Latin Total Non-lease property revenue $ 58.6 $ 2.2 $ 2.9 $ 1.5 $ 32.9 $ 98.1 Services revenue 19.9 — — — — 19.9 Total non-lease revenue $ 78.5 $ 2.2 $ 2.9 $ 1.5 $ 32.9 $ 118.0 Property lease revenue 1,031.3 284.4 222.6 33.0 303.8 1,875.1 Total revenue $ 1,109.8 $ 286.6 $ 225.5 $ 34.5 $ 336.7 $ 1,993.1 Three Months Ended March 31, 2019 U.S. Asia Africa Europe Latin Total Non-lease property revenue $ 58.8 $ 2.4 $ 0.8 $ 0.8 $ 35.0 $ 97.8 Services revenue 27.4 — — — — 27.4 Total non-lease revenue $ 86.2 $ 2.4 $ 0.8 $ 0.8 $ 35.0 $ 125.2 Property lease revenue 927.5 286.5 143.2 32.7 298.3 1,688.2 Total revenue $ 1,013.7 $ 288.9 $ 144.0 $ 33.5 $ 333.3 $ 1,813.4 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.

PREPAID AND OTHER CURRENT ASSET

PREPAID AND OTHER CURRENT ASSETS	3 Months Ended
	Mar. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
PREPAID AND OTHER CURRENT ASSETS	PREPAID AND OTHER CURRENT ASSETS Prepaid and other current assets consisted of the following: As of March 31, 2020 December 31, 2019 Prepaid assets $ 71.4 $ 56.8 Prepaid income tax 188.1 185.8 Unbilled receivables 101.8 142.3 Value added tax and other consumption tax receivables 59.3 71.3 Other miscellaneous current assets 60.1 57.4 Prepaid and other current assets $ 480.7 $ 513.6

LEASES

LEASES	3 Months Ended
	Mar. 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. During the three months ended March 31, 2020, the Company made no changes to the methods described in note 4 to its consolidated financial statements included in the 2019 Form 10-K and there were no material changes in the terms and provisions of the Company’s leases in which the Company is lessor or lessee. As of March 31, 2020, the Company does not have any material related party leases as either a lessor or a lessee. Lessor — 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 March 31, 2020 were as follows: Fiscal Year Amount (1) Remainder of 2020 $ 4,296.4 2021 5,519.8 2022 4,915.3 2023 4,734.1 2024 4,513.4 Thereafter 18,723.6 Total $ 42,702.6 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1 to the Company’s consolidated financial statements included in the 2019 Form 10-K. There were no material impairments recorded related to these assets during the three months ended March 31, 2020 and March 31, 2019. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of March 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. There were no material changes in finance lease assets during the three months ended March 31, 2020. Information about other lease-related balances is as follows: As of March 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 6,968.3 $ 7,357.4 Current portion of lease liability $ 476.8 $ 494.5 Lease liability 6,137.8 6,510.4 Total operating lease liability $ 6,614.6 $ 7,004.9 The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of March 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.4 13.1 Weighted-average incremental borrowing rate 5.9 % 6.1 % The following table sets forth the components of lease cost: Three Months Ended March 31, 2020 2019 Operating lease cost $ 250.7 $ 255.0 Variable lease costs not included in lease liability (1) 61.4 52.3 _______________ (1) Includes property tax paid on behalf of the landlord. Supplemental cash flow information is as follows: Three Months Ended March 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (252.0) $ (234.9) Non-cash items: New operating leases (1) $ 50.1 $ 62.1 Operating lease modifications and reassessments (2) $ 96.9 $ 30.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. (2) Includes a $0.7 million reduction of the operating lease liability during the three months ended March 31, 2020. As of March 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating lease liabilities as of March 31, 2020 were as follows: Fiscal Year Operating Lease (1) Remainder of 2020 $ 629.5 2021 827.7 2022 797.3 2023 765.4 2024 730.5 Thereafter 5,942.7 Total lease payments 9,693.1 Less amounts representing interest (3,078.5) Total lease liability 6,614.6 Less current portion of lease liability (476.8) Non-current lease liability $ 6,137.8 _______________ (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. During the three months ended March 31, 2020, the Company made no changes to the methods described in note 4 to its consolidated financial statements included in the 2019 Form 10-K and there were no material changes in the terms and provisions of the Company’s leases in which the Company is lessor or lessee. As of March 31, 2020, the Company does not have any material related party leases as either a lessor or a lessee. Lessor — 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 March 31, 2020 were as follows: Fiscal Year Amount (1) Remainder of 2020 $ 4,296.4 2021 5,519.8 2022 4,915.3 2023 4,734.1 2024 4,513.4 Thereafter 18,723.6 Total $ 42,702.6 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1 to the Company’s consolidated financial statements included in the 2019 Form 10-K. There were no material impairments recorded related to these assets during the three months ended March 31, 2020 and March 31, 2019. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of March 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. There were no material changes in finance lease assets during the three months ended March 31, 2020. Information about other lease-related balances is as follows: As of March 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 6,968.3 $ 7,357.4 Current portion of lease liability $ 476.8 $ 494.5 Lease liability 6,137.8 6,510.4 Total operating lease liability $ 6,614.6 $ 7,004.9 The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of March 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.4 13.1 Weighted-average incremental borrowing rate 5.9 % 6.1 % The following table sets forth the components of lease cost: Three Months Ended March 31, 2020 2019 Operating lease cost $ 250.7 $ 255.0 Variable lease costs not included in lease liability (1) 61.4 52.3 _______________ (1) Includes property tax paid on behalf of the landlord. Supplemental cash flow information is as follows: Three Months Ended March 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (252.0) $ (234.9) Non-cash items: New operating leases (1) $ 50.1 $ 62.1 Operating lease modifications and reassessments (2) $ 96.9 $ 30.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. (2) Includes a $0.7 million reduction of the operating lease liability during the three months ended March 31, 2020. As of March 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating lease liabilities as of March 31, 2020 were as follows: Fiscal Year Operating Lease (1) Remainder of 2020 $ 629.5 2021 827.7 2022 797.3 2023 765.4 2024 730.5 Thereafter 5,942.7 Total lease payments 9,693.1 Less amounts representing interest (3,078.5) Total lease liability 6,614.6 Less current portion of lease liability (476.8) Non-current lease liability $ 6,137.8 _______________ (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. During the three months ended March 31, 2020, the Company made no changes to the methods described in note 4 to its consolidated financial statements included in the 2019 Form 10-K and there were no material changes in the terms and provisions of the Company’s leases in which the Company is lessor or lessee. As of March 31, 2020, the Company does not have any material related party leases as either a lessor or a lessee. Lessor — 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 March 31, 2020 were as follows: Fiscal Year Amount (1) Remainder of 2020 $ 4,296.4 2021 5,519.8 2022 4,915.3 2023 4,734.1 2024 4,513.4 Thereafter 18,723.6 Total $ 42,702.6 _______________ (1) Balances are translated at the applicable period-end exchange rate, which may impact comparability between periods. Lessee —The Company assesses its right-of-use asset and other lease-related assets for impairment, as described in note 1 to the Company’s consolidated financial statements included in the 2019 Form 10-K. There were no material impairments recorded related to these assets during the three months ended March 31, 2020 and March 31, 2019. The Company leases certain land and office space under operating leases and land and improvements, towers and vehicles under finance leases. As of March 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. There were no material changes in finance lease assets during the three months ended March 31, 2020. Information about other lease-related balances is as follows: As of March 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 6,968.3 $ 7,357.4 Current portion of lease liability $ 476.8 $ 494.5 Lease liability 6,137.8 6,510.4 Total operating lease liability $ 6,614.6 $ 7,004.9 The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of March 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.4 13.1 Weighted-average incremental borrowing rate 5.9 % 6.1 % The following table sets forth the components of lease cost: Three Months Ended March 31, 2020 2019 Operating lease cost $ 250.7 $ 255.0 Variable lease costs not included in lease liability (1) 61.4 52.3 _______________ (1) Includes property tax paid on behalf of the landlord. Supplemental cash flow information is as follows: Three Months Ended March 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (252.0) $ (234.9) Non-cash items: New operating leases (1) $ 50.1 $ 62.1 Operating lease modifications and reassessments (2) $ 96.9 $ 30.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. (2) Includes a $0.7 million reduction of the operating lease liability during the three months ended March 31, 2020. As of March 31, 2020, the Company does not have material operating or financing leases that have not yet commenced. Maturities of operating lease liabilities as of March 31, 2020 were as follows: Fiscal Year Operating Lease (1) Remainder of 2020 $ 629.5 2021 827.7 2022 797.3 2023 765.4 2024 730.5 Thereafter 5,942.7 Total lease payments 9,693.1 Less amounts representing interest (3,078.5) Total lease liability 6,614.6 Less current portion of lease liability (476.8) Non-current lease liability $ 6,137.8 _______________ (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	3 Months Ended
	Mar. 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. Asia Africa Europe Latin America Balance as of January 1, 2020 $ 3,415.3 $ 1,021.8 $ 790.2 $ 256.2 $ 692.8 $ 2.0 $ 6,178.3 Additions and adjustments (1) — — (0.1) — — — (0.1) Effect of foreign currency translation — (57.4) (35.4) (4.1) (132.5) — (229.4) Balance as of March 31, 2020 $ 3,415.3 $ 964.4 $ 754.7 $ 252.1 $ 560.3 $ 2.0 $ 5,948.8 _______________ (1) Additions consist of $0.1 million from revisions to prior-year acquisitions due to measurement period adjustments. The Company’s other intangible assets subject to amortization consisted of the following: As of March 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 $ 4,967.0 $ (1,938.8) $ 3,028.2 $ 5,150.8 $ (1,920.4) $ 3,230.4 Acquired tenant-related intangibles Up to 20 12,193.2 (3,707.5) 8,485.7 12,674.1 (3,674.6) 8,999.5 Acquired licenses and other intangibles 3-20 93.9 (7.2) 86.7 106.7 (18.2) 88.5 Total other intangible assets $ 17,254.1 $ (5,653.5) $ 11,600.6 $ 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, or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets. The acquired network location intangibles represent the value to the Company of the incremental revenue growth that could potentially be obtained from leasing the excess capacity on acquired communications sites. The acquired tenant-related intangibles typically represent the value to the Company of tenant contracts and relationships in place at the time of an acquisition or similar transaction, including assumptions regarding estimated renewals. The Company amortizes its acquired network location intangibles and tenant-related intangibles on a straight-line basis over their estimated useful lives. As of March 31, 2020, the remaining weighted average amortization period of the Company’s intangible assets was 15 years. Amortization of intangible assets for the three months ended March 31, 2020 and 2019 was $217.5 million and $192.7 million, respectively. Based on current exchange rates, the Company expects to record amortization expense as follows over the remaining current year and the five subsequent years: Fiscal Year Amount Remainder of 2020 $ 628.4 2021 822.7 2022 818.8 2023 815.2 2024 806.3 2025 790.8

ACCRUED EXPENSES

ACCRUED EXPENSES	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consisted of the following: As of March 31, 2020 December 31, 2019 Accrued construction costs $ 19.4 $ 27.8 Accrued income tax payable 72.7 55.2 Accrued pass-through costs 64.5 74.2 Amounts payable to tenants 67.5 77.9 Accrued property and real estate taxes 196.0 198.1 Accrued rent 72.6 75.6 Accrued treasury stock repurchases 5.4 — Payroll and related withholdings 64.1 102.4 Other accrued expenses 314.2 347.0 Total accrued expenses $ 876.4 $ 958.2

LONG-TERM OBLIGATIONS

LONG-TERM OBLIGATIONS	3 Months Ended
	Mar. 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 March 31, 2020 December 31, 2019 Maturity Date 2019 364-Day Term Loan (1) (2) $ — $ 999.9 N/A 2020 Term Loan (1) 749.9 — February 12, 2021 2019 Multicurrency Credit Facility (1) (3) 965.4 700.0 June 28, 2023 2019 Term Loan (1) 995.4 995.2 January 31, 2025 2019 Credit Facility (1) 1,415.0 1,600.0 January 31, 2025 2.800% senior notes 749.7 749.4 June 1, 2020 3.300% senior notes 748.8 748.5 February 15, 2021 3.450% senior notes 648.0 647.7 September 15, 2021 5.900% senior notes (4) — 498.9 N/A 2.250% senior notes 605.7 592.1 January 15, 2022 4.70% senior notes 698.4 698.2 March 15, 2022 3.50% senior notes 994.7 994.3 January 31, 2023 3.000% senior notes 723.9 704.9 June 15, 2023 5.00% senior notes 1,001.6 1,001.7 February 15, 2024 3.375% senior notes 644.7 644.4 May 15, 2024 2.950% senior notes 641.7 641.3 January 15, 2025 2.400% senior notes 744.2 — March 15, 2025 1.375% senior notes 544.5 553.0 April 4, 2025 4.000% senior notes 743.5 743.2 June 1, 2025 4.400% senior notes 496.7 496.6 February 15, 2026 1.950% senior notes 545.8 554.4 May 22, 2026 3.375% senior notes 988.3 987.9 October 15, 2026 3.125% senior notes 397.7 397.6 January 15, 2027 2.750% senior notes 743.7 743.5 January 15, 2027 3.55% senior notes 744.3 744.1 July 15, 2027 3.600% senior notes 692.8 692.6 January 15, 2028 3.950% senior notes 589.8 589.6 March 15, 2029 3.800% senior notes 1,632.1 1,631.7 August 15, 2029 2.900% senior notes 741.1 — January 15, 2030 3.700% senior notes 591.8 591.8 October 15, 2049 Total American Tower Corporation debt 21,779.2 20,942.5 Series 2013-2A securities (5) 1,295.4 1,295.0 March 15, 2023 Series 2018-1A securities (5) 494.0 493.8 March 15, 2028 Series 2015-1 notes (6) 349.9 349.6 June 15, 2020 Series 2015-2 notes (7) 521.6 521.4 June 16, 2025 Other subsidiary debt (8) 111.7 422.4 Various Total American Tower subsidiary debt 2,772.6 3,082.2 Finance lease obligations 25.6 30.7 Total 24,577.4 24,055.4 Less current portion of long-term obligations (2,640.0) (2,928.2) Long-term obligations $ 21,937.4 $ 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) As of March 31, 2020 reflects borrowings denominated in Euro (“EUR”). (4) Repaid in full on January 15, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (5) Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048. (6) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2045. (7) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050. (8) Includes the South African credit facility, which is denominated in South African Rand and amortizes through December 17, 2020, the Colombian credit facility, which is denominated in Colombian Pesos and amortizes through April 24, 2021, 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 subject to the satisfaction of specified conditions or (ii) three years from the note origination date, U.S. subsidiary debt related to a seller-financed acquisition and debt entered into by certain Eaton Towers subsidiaries acquired in connection with the Eaton Towers Acquisition (as defined in note 14) (the “Eaton Towers Debt”), which is denominated in multiple currencies, including USD, EUR, Kenyan Shilling (“KES”) and West African CFA Franc. During the three months ended March 31, 2020, the Company repaid all of the outstanding Eaton Towers Debt denominated in USD and KES. Subsequent to March 31, 2020, the Company repaid an additional 24.5 million EUR (approximately $26.8 million at the date of payment) of the outstanding Eaton Towers Debt. As of December 31, 2019, included the Brazil credit facility, which was denominated in Brazilian Reais and was repaid on March 6, 2020. Current portion of long-term obligations— The Company’s current portion of long-term obligations primarily includes (i) $750.0 million under its unsecured term loan entered into on February 13, 2020 (the “2020 Term Loan”), (ii) $750.0 million aggregate principal amount of 2.800% senior unsecured notes due 2020, (iii) $350.0 million aggregate principal amount of the American Tower Secured Revenue Notes, Series 2015-1, Class A, issued by GTP Acquisition Partners I, LLC in a private securitization transaction in May 2015, with an anticipated repayment date in 2020 and (iv) $750.0 million aggregate principal amount of 3.300% senior unsecured notes due 2021. Securitized Debt— Cash flows generated by the sites that secure the securitized debt of the Company 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 service 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. 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 (the “5.900% Notes”) 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 Company’s $2.25 billion senior unsecured revolving credit facility, as amended and restated in December 2019 (the “2019 Credit Facility”), and cash on hand. Upon completion of the repayment, none of the 5.900% Notes remained outstanding. 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. The 2.400% Notes will mature on March 15, 2025 and bear interest at a rate of 2.400% per annum. The 2.900% Notes will mature on January 15, 2030 and bear interest at a rate of 2.900% per annum. Accrued and unpaid interest on the 2.400% Notes will be payable in U.S. Dollars semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2020. Accrued and unpaid interest on the 2.900% Notes will be payable in U.S. Dollars semi-annually in arrears on January 15 and July 15 of each year, beginning on July 15, 2020. Interest on the 2.400% Notes and the 2.900% Notes will accrue from January 10, 2020 and will be computed on the basis of a 360-day year comprised of twelve 30-day months. The supplemental indenture contains certain covenants that restrict the Company’s ability to merge, consolidate or sell assets and its (together with its subsidiaries’) ability to incur liens. These covenants are subject to a number of exceptions, including that the Company and its subsidiaries may incur certain liens on assets, mortgages or other liens securing indebtedness if the aggregate amount of indebtedness secured by such liens does not exceed 3.5x Adjusted EBITDA, as defined in the supplemental indenture. Bank Facilities 2019 Multicurrency Credit Facility— During the three months ended March 31, 2020, the Company borrowed an aggregate of 875.0 million EUR ($971.8 million as of the borrowing dates) and repaid an aggregate of $700.0 million of revolving indebtedness under its $3.0 billion senior unsecured multicurrency revolving credit facility, as amended and restated in December 2019 (the “2019 Multicurrency Credit Facility”). The Company used the borrowings to repay existing indebtedness and for general corporate purposes. 2019 Credit Facility— During the three months ended March 31, 2020, the Company borrowed an aggregate of $1.7 billion and repaid an aggregate of $1.9 billion of revolving indebtedness under the 2019 Credit Facility. The Company used the borrowings to repay existing indebtedness, to purchase redeemable noncontrolling interests 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 the $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. The Company has the option of choosing either a defined base rate or LIBOR as the applicable base rate for borrowings under the 2020 Term Loan. The interest rate on the 2020 Term Loan is 0.65% above LIBOR for LIBOR based borrowings or 0.00% above the defined base rate for base rate borrowings. Any outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. The 2020 Term Loan does not require amortization of principal and may be paid prior to maturity in whole or in part at the Company’s option without penalty or premium. The agreement for the 2020 Term Loan contains certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Any failure to comply with the financial and operating covenants of the loan agreement 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. As of March 31, 2020, the key terms under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the Company’s $1.0 billion unsecured term loan, as amended and restated in December 2019 (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 (1) Current commitment fee (2) 2019 Multicurrency Credit Facility $ 965.4 (3) $ 3.8 June 28, 2023 (4) 1.125 % 0.110 % 2019 Credit Facility $ 1,415.0 $ 6.1 January 31, 2025 (4) 1.125 % 0.110 % 2019 Term Loan $ 1,000.0 N/A January 31, 2025 1.125 % N/A 2020 Term Loan $ 750.0 N/A February 12, 2021 0.650 % N/A _______________ (1) LIBOR means the London Interbank Offered Rate. (2) Fee on undrawn portion of each credit facility. (3) Reflects borrowings denominated in EUR.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 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: March 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 — $ 34.8 — — $ 9.0 — Embedded derivative in lease agreement — — $ 10.5 — — $ 10.7 Liabilities: Interest rate swap agreements — $ 0.1 — — $ 7.5 — Fair value of debt related to interest rate swap agreements (1) $ 35.4 — — $ 3.3 — — Redeemable noncontrolling interests — — $ 541.4 — — $ 1,096.5 _______________ (1) Included in the carrying values of the corresponding debt obligations. During the three months ended March 31, 2020, the Company made no changes to the methods described in note 12 to its consolidated financial statements included in the 2019 Form 10-K that it used to measure the fair value of its interest rate swap agreements, the embedded derivative in one of its lease agreements and redeemable noncontrolling interests. The changes in fair value for the embedded derivative in one of its lease agreements during the three months ended March 31, 2020 and 2019 were not material to the consolidated financial statements. The changes in the carrying amount of the redeemable noncontrolling interests are described in note 10. 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 three months ended March 31, 2020 and 2019, the Company recorded $3.7 million and $18.1 million of impairments, respectively. There were no other items measured at fair value on a nonrecurring basis during the three months ended March 31, 2020 or 2019. Fair Value of Financial Instruments —The Company’s financial instruments for which the carrying value reasonably approximates fair value at March 31, 2020 and December 31, 2019 include cash and cash equivalents, restricted cash, accounts receivable and accounts payable. The Company’s estimates of fair value of its long-term obligations, including the current portion, are based primarily upon reported market values. For long-term debt not actively traded, fair value is estimated using either indicative price quotes or a discounted cash flow analysis using rates for debt with similar terms and maturities. As of March 31, 2020 and December 31, 2019, the carrying value of long-term obligations, including the current portion, was $24.6 billion and $24.1 billion, respectively. As of March 31, 2020, the fair value of long-term obligations, including the current portion, was $25.0 billion, of which $17.9 billion was measured using Level 1 inputs and $7.1 billion was measured using Level 2 inputs. As of December 31, 2019, the fair value of long-term obligations, including the current portion, was $25.0 billion, of which $17.5 billion was measured using Level 1 inputs and $7.5 billion was measured using Level 2 inputs.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company provides for income taxes at the end of each interim period based on the estimated effective tax rate (“ETR”) for the full fiscal year. Cumulative adjustments to the Company’s estimate are recorded in the interim period in which a change in the estimated annual ETR is determined. Under the provisions of the Internal Revenue Code of 1986, as amended, the Company may deduct amounts distributed to stockholders against the income generated by its real estate investment trust (“REIT”) operations. The Company continues to be subject to income taxes on the income of its domestic taxable REIT subsidiaries and income taxes in foreign jurisdictions where it conducts operations. In addition, the Company is able to offset certain income by utilizing its net operating losses, subject to specified limitations. 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. The decrease in the income tax provision during the three months ended March 31, 2020 was primarily attributable to realized foreign exchange losses in the current period and the nonrecurrence of a one-time true up adjustment during the three months ended March 31, 2019. As of March 31, 2020 and December 31, 2019, the total unrecognized tax benefits that would impact the ETR, if recognized, were approximately $144.3 million and $158.1 million, respectively. The amount of unrecognized tax benefits during the three months ended March 31, 2020 includes additions to the Company’s existing tax positions of $1.2 million, which were reduced by foreign currency exchange rate fluctuations of $12.4 million and remeasurement of acquired liabilities of $2.9 million related to the acquisition of Eaton Towers Holdings Limited. Unrecognized tax benefits are expected to change over the next 12 months if certain tax matters ultimately settle with the applicable taxing jurisdiction during this time frame, as described in note 13 to the Company’s consolidated financial statements included in the 2019 Form 10-K. The impact of the amount of these changes to previously recorded uncertain tax positions could range from zero to $47.8 million. The Company recorded the following penalties and income tax-related interest expense during the three months ended March 31, 2020 and 2019: Three Months Ended March 31, 2020 2019 Penalties and income tax-related interest expense $ 1.7 $ 1.1

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	3 Months Ended
	Mar. 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 time-based restricted stock units (“RSUs”) and stock options and three years for performance-based restricted stock units (“PSUs”). Stock options generally expire ten years from the date of grant. As of March 31, 2020, the Company had the ability to grant stock-based awards with respect to an aggregate of 6.4 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 three months ended March 31, 2020 and 2019, the Company recorded and capitalized the following stock-based compensation expense: Three Months Ended March 31, 2020 2019 Stock-based compensation expense Property $ 0.6 $ 0.6 Stock-based compensation expense Services 0.3 0.3 Stock-based compensation expense SG&A 46.8 41.6 Total stock-based compensation expense $ 47.7 $ 42.5 Stock-based compensation expense capitalized as property and equipment $ 0.5 $ 0.5 Stock Options —As of March 31, 2020, total unrecognized compensation expense related to unvested stock options was less than $0.1 million, which is expected to be recognized over a weighted average period of less than one year. The Company’s option activity for the three months ended March 31, 2020 was as follows (shares disclosed in full amounts): Number of Options Outstanding as of January 1, 2020 3,060,242 Granted — Exercised (130,706) Forfeited — Expired — Outstanding as of March 31, 2020 2,929,536 Restricted Stock Units— As of March 31, 2020, total unrecognized compensation expense related to unvested RSUs granted under the 2007 Plan was $189.6 million and is expected to be recognized over a weighted average period of approximately three 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 three months ended March 31, 2020, 2019 and 2018, the Company’s Compensation Committee granted an aggregate of 93,332 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-year performance period with respect to each of the 2020 PSUs, the 2019 PSUs and the 2018 PSUs and will be used to calculate the number of shares that will be issuable when each award vests, which may range from zero to 200% of the target amounts. At the end of each three-year performance period, the number of shares that vest will depend on the degree of achievement against the pre-established performance goals. PSUs will be paid out in common stock at the end of each performance period, subject generally to the executive’s continued employment or death, disability or qualified retirement (each as defined in the applicable PSU award agreement). PSUs will accrue dividend equivalents prior to vesting, which will be paid out only in respect of shares that actually vest. Restricted Stock Units and Performance-Based Restricted Stock Units —The Company’s RSU and PSU activity for the three months ended March 31, 2020 was as follows (shares disclosed in full amounts): RSUs PSUs Outstanding as of January 1, 2020 (1) 1,454,350 528,908 Granted (2) 432,104 93,332 Vested and Released (3) (592,390) (205,434) Forfeited (11,730) — Outstanding as of March 31, 2020 1,282,334 416,806 Vested and deferred as of March 31, 2020 (4) — 77,340 _______________ (1) PSUs consist of the target number of shares issuable at the end of the three-year performance period for the 2019 PSUs and 2018 PSUs, or 114,823 and 131,311 shares, respectively, and the shares issuable at the end of the three-year performance period for the PSUs granted in 2017 (“2017 PSUs”) based on achievement against the performance metrics for the three-year performance period, or 282,774 shares. (2) PSUs consist of the target number of shares issuable at the end of the three-year performance period for the 2020 PSUs, or 93,332 shares. (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) Vested and deferred RSUs are related to deferred compensation for certain former employees. During the three months ended March 31, 2020, the Company recorded $12.9 million in stock-based compensation expense for equity awards in which the performance goals have been established and were probable of being achieved. The remaining unrecognized compensation expense related to these awards at March 31, 2020 was $11.6 million based on the Company’s current assessment of the probability of achieving the performance goals. The weighted average period over which the cost will be recognized is approximately two years.

REDEEMABLE NONCONTROLLING INTER

REDEEMABLE NONCONTROLLING INTERESTS	3 Months Ended
	Mar. 31, 2020
Noncontrolling Interest [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 Limited (“Tata Teleservices”), IDFC Private Equity Fund III (“IDFC”), Macquarie SBI Infrastructure Investments Pte Limited and SBI Macquarie Infrastructure Trust (collectively, 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. During the three months ended March 31, 2020, the Company made no changes to the methods of determining redemption value described in note 15 to its consolidated financial statements included in the 2019 Form 10-K. The put options may be exercised, requiring the Company to purchase the Remaining Shareholders’ equity interests, on specified dates through March 31, 2021. The price of the put options will be based on the fair market value of the exercising Remaining Shareholders’ interest in the Company’s India operations at the time the option is exercised. Put options held by certain of the Remaining Shareholders are subject to a floor price of INR 216 per share. 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%. In April 2019, Tata Teleservices and Tata Sons delivered notice of exercise of their put options with respect to 100% of their remaining holdings in ATC TIPL. Accordingly, the Company expects to pay an amount equivalent to INR 24.8 billion (approximately $328.0 million at the March 31, 2020 exchange rate) to redeem the put shares in 2020, subject to regulatory approval. After the completion of the redemption, the Company will hold an approximately 92% ownership interest in ATC TIPL. Other Redeemable Noncontrolling Interests— During the three months ended March 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, which included an adjustment of $1.4 million in the current period, 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 March 31, 2020 was $2.7 million. The changes in Redeemable noncontrolling interests were as follows: Three Months Ended March 31, 2020 2019 Balance as of January 1, $ 1,096.5 $ 1,004.8 Net income (loss) attributable to noncontrolling interests 7.7 (3.7) Adjustment to noncontrolling interest redemption value (6.3) 3.7 Purchase of redeemable noncontrolling interest (524.4) (425.7) Foreign currency translation adjustment attributable to noncontrolling interests (32.1) 9.9 Balance as of March 31, $ 541.4 $ 589.0

EQUITY

EQUITY	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
EQUITY	EQUITY Sales of Equity Securities —The Company receives proceeds from the sale of its equity securities pursuant to the ESPP and upon exercise of stock options granted under the 2007 Plan. During the three months ended March 31, 2020, the Company received an aggregate of $11.1 million in proceeds upon exercises of stock options. 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 three months ended March 31, 2020, the Company repurchased 213,352 shares of its common stock under the 2011 Buyback for an aggregate of $45.1 million (of which $5.4 million was accrued as of March 31, 2020). During the three months ended March 31, 2020, there were no repurchases under the 2017 Buyback. As of March 31, 2020, the Company has repurchased a total of 14,310,549 shares of its common stock under the 2011 Buyback for an aggregate of $1.5 billion, including commissions and fees. As of March 31, 2020, the Company has not made any repurchases under the 2017 Buyback. Under the Buyback Programs, the Company is authorized to purchase shares from time to time through open market purchases, in privately negotiated transactions not to exceed market prices, and (with respect to such open market purchases) pursuant to plans adopted in accordance with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended, in accordance with securities laws and other legal requirements and subject to market conditions and other factors. The Company expects to fund any further purchases of its common stock through a combination of cash on hand, cash generated by operations and borrowings under its credit facilities. Purchases under the Buyback Programs are subject to, among other things, the Company having available cash to fund the purchases. Distributions —During the three months ended March 31, 2020, the Company declared or paid the following cash distributions (per share data reflects actual amounts): Declaration Date Payment Date Record Date Distribution per share Aggregate Payment Amount (1) Common Stock March 12, 2020 April 29, 2020 April 14, 2020 $ 1.08 $ 478.8 December 11, 2019 January 14, 2020 December 27, 2019 $ 1.01 $ 447.3 _______________ (1) Does not include amounts accrued for distributions payable related to unvested restricted stock units. During the three months ended March 31, 2019, the Company declared or paid the following cash distributions (per share data reflects actual amounts): Declaration Date Payment Date Record Date Distribution per share Aggregate Payment Amount (1) Common Stock March 7, 2019 April 26, 2019 April 11, 2019 $ 0.90 $ 397.8 December 5, 2018 January 14, 2019 December 27, 2018 $ 0.84 $ 370.5 _______________ (1) Does not include amounts accrued for distributions payable related to unvested restricted stock units. The Company accrues distributions on unvested restricted stock units, which are payable upon vesting. As of March 31, 2020, the amount accrued for distributions payable related to unvested restricted stock units was $8.6 million. During the three months ended March 31, 2020 and 2019, the Company paid $7.6 million and $6.6 million of distributions upon the vesting of restricted stock units, respectively. 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.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	3 Months Ended
	Mar. 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 (shares in thousands, except per share data): Three Months Ended March 31, 2020 2019 Net income attributable to American Tower Corporation common stockholders $ 415.0 $ 397.4 Basic weighted average common shares outstanding 443,055 441,351 Dilutive securities 2,777 3,270 Diluted weighted average common shares outstanding 445,832 444,621 Basic net income attributable to American Tower Corporation common stockholders per common share $ 0.94 $ 0.90 Diluted net income attributable to American Tower Corporation common stockholders per common share $ 0.93 $ 0.89 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 (in thousands, on a weighted average basis): Three Months Ended March 31, 2020 2019 Restricted stock units 86 105

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 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-year terms; each such term shall be governed by standard master lease agreement terms established as a part of the transaction. AT&T Transaction —The Company has an agreement with SBC Communications Inc., a predecessor entity to AT&T Inc. (“AT&T”), that currently provides for the lease or sublease of approximately 2,200 towers commencing between December 2000 and August 2004. Substantially all of the towers are part of the securitization transactions completed in March 2013 and March 2018. 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 March 31, 2020, the Company has purchased an aggregate of 228 of the subleased towers which are subject to the applicable agreement. The aggregate purchase option price for the remaining towers leased and subleased is $960.4 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-year terms. Other Contingencies —The Company is subject to income tax and other taxes in the geographic areas where it operates, and periodically receives notifications of audits, assessments or other actions by taxing authorities. 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 of ETIPL, the seller is obligated to indemnify and defend the Company with respect to any tax-related liability that may arise from activities prior to March 31, 2010.

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Impact of current year acquisitions —The Company typically acquires communications sites from wireless carriers or other tower operators and subsequently integrates those sites into its existing portfolio of communications sites. The financial results of the Company’s acquisitions have been included in the Company’s consolidated statements of operations for the three months ended March 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. The 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 acquired, with no recognition of goodwill. 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 three months ended March 31, 2020 and 2019, the Company recorded acquisition and merger related expenses for business combinations and non-capitalized asset acquisition costs and integration costs as follows: Three Months Ended March 31, 2020 2019 Acquisition and merger related expenses $ 7.6 $ 2.0 Integration costs $ 6.6 $ 4.1 During the three months ended March 31, 2019, the Company received $5.7 million related to a pre-acquisition contingency in France. 2020 Transactions The estimated aggregate impact of the acquisitions completed in 2020 on the Company’s revenues and gross margin for the three months ended March 31, 2020 was approximately $0.1 million and less than $0.1 million, respectively. The revenues and gross margin amounts also reflect incremental revenues from the addition of new tenants to such sites subsequent to the transaction date. 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. 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 (the “Entel Acquisition”). During the three months ended March 31, 2020, the Company completed the acquisition of an additional 156 communications sites pursuant to this agreement for an aggregate total purchase price of $39.7 million, which are being accounted for as an acquisition of assets and are included below. The remaining communications sites are expected to continue to close in tranches, subject to certain closing conditions. Other Acquisitions —During the three months ended March 31, 2020, the Company acquired a total of 37 communications sites in the United States, Mexico and Peru, as well as other communications infrastructure assets, for an aggregate purchase price of $11.2 million. These acquisitions were accounted for as asset acquisitions. 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: Allocation (1) Current assets $ 0.3 Property and equipment 25.9 Intangible assets (2): Tenant-related intangible assets 14.1 Network location intangible assets 4.2 Other intangible assets 1.3 Other non-current assets 10.6 Current liabilities (0.9) Deferred tax liability — Other non-current liabilities (4.6) Net assets acquired 50.9 Goodwill — Fair value of net assets acquired 50.9 Debt assumed — Purchase price $ 50.9 _______________ (1) Includes 7 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 over periods of up to 20 years. Other Signed Acquisitions Orange— On November 28, 2019, ATC France, a majority-owned subsidiary of the Company, entered into definitive agreements with Orange S.A. for the acquisition of up to approximately 2,000 communications sites in France over a period of up to five years. On April 1, 2020, the Company completed the acquisition of 113 of these communications sites. The remaining communications sites are expected to continue to close in tranches for total consideration in the range of approximately 500.0 million 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-year term. 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 owns and operates approximately 5,800 communications sites across five African markets (the “Eaton Towers Acquisition”). 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 $9.7 million receivable from the seller for reimbursement of taxes. The Eaton Towers Acquisition was accounted for as a business combination and is subject to post-closing adjustments. During the three months ended March 31, 2020, certain adjustments were made to assets of $15.1 million and liabilities of $15.0 million with a corresponding reduction in goodwill of $0.1 million and there were no other material post-closing adjustments. The full reconciliation and finalization of the assets acquired and liabilities assumed, including those subject to valuation, have not been completed and, as a result, there may be additional post-closing adjustments. 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 date indicated, nor are they indicative of the future operating results of the Company. Three Months Ended March 31, 2020 2019 Pro forma revenues $ 1,993.8 $ 1,899.3 Pro forma net income attributable to American Tower Corporation common stockholders $ 414.9 $ 380.3 Pro forma net income per common share amounts: Basic net income attributable to American Tower Corporation common stockholders $ 0.94 $ 0.86 Diluted net income attributable to American Tower Corporation common stockholders $ 0.93 $ 0.86

BUSINESS SEGMENTS

BUSINESS SEGMENTS	3 Months Ended
	Mar. 31, 2020
Segment Reporting [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 2019, as a result of recent acquisitions, including the Eaton Towers Acquisition, and changes to its organizational structure, the Company reviewed and changed its reportable segments to divide its EMEA property segment into two segments: Africa property and Europe property. Prior to this revision, the Company operated in five business segments: (i) U.S. property, (ii) Asia property, (iii) EMEA property, (iv) Latin America property and (v) services. The change is consistent with how the chief operating decision maker reviews financial performance and operating and business management strategies for each of the six segments. The change in reportable segments had no impact on the Company’s consolidated financial statements for any periods. Historical financial information included in this Quarterly Report has been adjusted to reflect the change in reportable segments. As of March 31, 2020, the Company’s property operations consisted of the following: • U.S.: property operations in the United States; • Asia: property operations in India; • Africa: property operations in Burkina Faso, Ghana, Kenya, Niger, Nigeria, South Africa and Uganda; • Europe: property operations in France and Germany; 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 to the Company’s consolidated financial statements included in the 2019 Form 10-K and as updated in note 1 above. 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. 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 three months ended March 31, 2020 and 2019 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 Three Months Ended March 31, 2020 U.S. Asia Africa Europe Latin America Segment revenues $ 1,089.9 $ 286.6 225.5 $ 34.5 $ 336.7 $ 1,973.2 $ 19.9 $ 1,993.1 Segment operating expenses (1) 190.0 164.0 77.7 6.6 105.2 543.5 7.6 551.1 Segment gross margin 899.9 122.6 147.8 27.9 231.5 1,429.7 12.3 1,442.0 Segment selling, general, administrative and development expense (1) 42.0 32.6 17.1 5.5 26.6 123.8 3.5 127.3 Segment operating profit $ 857.9 $ 90.0 $ 130.7 $ 22.4 $ 204.9 $ 1,305.9 $ 8.8 $ 1,314.7 Stock-based compensation expense $ 47.7 47.7 Other selling, general, administrative and development expense 43.7 43.7 Depreciation, amortization and accretion 472.3 472.3 Other expense (2) 311.3 311.3 Income from continuing operations before income taxes $ 439.7 Total assets $ 22,486.9 $ 4,986.0 $ 4,510.3 $ 1,554.5 $ 6,739.0 $ 40,276.7 $ 29.0 $ 483.4 $ 40,789.1 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.9 million and $46.8 million, respectively. (2) Primarily includes interest expense. Property Total Other Total Three Months Ended March 31, 2019 U.S. Asia Africa Europe Latin America Segment revenues $ 986.3 $ 288.9 $ 144.0 $ 33.5 $ 333.3 $ 1,786.0 $ 27.4 $ 1,813.4 Segment operating expenses (1) 191.3 178.0 53.5 6.2 103.4 532.4 10.1 542.5 Segment gross margin 795.0 110.9 90.5 27.3 229.9 1,253.6 17.3 1,270.9 Segment selling, general, administrative and development expense (1) 41.7 26.6 13.2 5.2 27.7 114.4 3.4 117.8 Segment operating profit $ 753.3 $ 84.3 $ 77.3 $ 22.1 $ 202.2 $ 1,139.2 $ 13.9 $ 1,153.1 Stock-based compensation expense $ 42.5 42.5 Other selling, general, administrative and development expense 38.7 38.7 Depreciation, amortization and accretion 436.9 436.9 Other expense (2) 193.4 193.4 Income from continuing operations before income taxes $ 441.6 Total assets $ 22,160.9 $ 5,427.6 $ 2,085.5 $ 1,552.0 $ 7,306.4 $ 38,532.4 $ 43.8 $ 350.6 $ 38,926.8 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.9 million and $41.6 million, respectively. (2) Primarily includes interest expense.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS 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. The April 2020 Term Loan matures on April 2, 2021. The Company has the option of choosing either a defined base rate or LIBOR as the applicable base rate for borrowings under the April 2020 Term Loan. The interest rate on the April 2020 Term Loan is 1.75% above LIBOR for LIBOR based borrowings or 0.75% above the defined base rate for base rate borrowings. Any outstanding principal and accrued but unpaid interest will be due and payable in full at maturity. The April 2020 Term Loan does not require amortization of principal and may be paid prior to maturity in whole or in part at the Company’s option without penalty or premium. The agreement for the April 2020 Term Loan contains certain reporting, information, financial and operating covenants and other restrictions (including limitations on additional debt, guaranties, sales of assets and liens) with which the Company must comply. Any failure to comply with the financial and operating covenants of the loan agreement 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. Notice of Redemption of 2.800% Senior Notes —On April 9, 2020, the Company delivered notice of its election to call for redemption all of its outstanding 2.800% senior unsecured notes due 2020 (the “2.800% Notes”). The Company intends to redeem the 2.800% Notes at a price equal to the principal amount of the 2.800% Notes, together with accrued interest, if any, up to, but excluding, the redemption date, which has been set for May 11, 2020.

BASIS OF PRESENTATION AND SIG_2

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation—The accompanying consolidated and condensed consolidated financial statements include the accounts of the Company and those entities in which it has a controlling interest. Investments in entities that the Company does not control are accounted for using the equity 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.
Change in Reportable Segments	Change in Reportable Segments — During the fourth quarter of 2019, the Company’s Europe, Middle East and Africa (“EMEA”) property segment was divided into the Africa property segment and the Europe property segment. As a result, the Company has six reportable segments: U.S. property, Asia property, Africa property, Europe property, Latin America property and services, which are discussed further in note 15. The change in reportable segments had no impact on the Company’s consolidated financial statements for any periods. Historical financial information included in this Quarterly Report on Form 10-Q (this “Quarterly Report”) has been adjusted to reflect the change in reportable segments.
Cash and Cash Equivalents and Restricted Cash	Cash and 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 statement of cash flows is as follows: Three Months Ended March 31, 2020 2019 Cash and cash equivalents $ 1,326.0 $ 1,004.8 Restricted cash 74.3 94.9 Total cash and cash equivalents and restricted cash $ 1,400.3 $ 1,099.7
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 distributed antenna system (“DAS”) networks and fiber results from agreements with tenants that are not leases. 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. There were no material changes in the receivables, contract assets and contract liabilities from contracts with tenants for the three months ended March 31, 2020.
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.

BASIS OF PRESENTATION AND SIG_3

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reconciliation of Cash and 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 statement of cash flows is as follows: Three Months Ended March 31, 2020 2019 Cash and cash equivalents $ 1,326.0 $ 1,004.8 Restricted cash 74.3 94.9 Total cash and cash equivalents and restricted cash $ 1,400.3 $ 1,099.7
Summary of Revenue Disaggregated by Source and Geography	A summary of revenue disaggregated by source and geography is as follows: Three Months Ended March 31, 2020 U.S. Asia Africa Europe Latin Total Non-lease property revenue $ 58.6 $ 2.2 $ 2.9 $ 1.5 $ 32.9 $ 98.1 Services revenue 19.9 — — — — 19.9 Total non-lease revenue $ 78.5 $ 2.2 $ 2.9 $ 1.5 $ 32.9 $ 118.0 Property lease revenue 1,031.3 284.4 222.6 33.0 303.8 1,875.1 Total revenue $ 1,109.8 $ 286.6 $ 225.5 $ 34.5 $ 336.7 $ 1,993.1 Three Months Ended March 31, 2019 U.S. Asia Africa Europe Latin Total Non-lease property revenue $ 58.8 $ 2.4 $ 0.8 $ 0.8 $ 35.0 $ 97.8 Services revenue 27.4 — — — — 27.4 Total non-lease revenue $ 86.2 $ 2.4 $ 0.8 $ 0.8 $ 35.0 $ 125.2 Property lease revenue 927.5 286.5 143.2 32.7 298.3 1,688.2 Total revenue $ 1,013.7 $ 288.9 $ 144.0 $ 33.5 $ 333.3 $ 1,813.4

PREPAID AND OTHER CURRENT ASS_2

PREPAID AND OTHER CURRENT ASSETS (Tables)	3 Months Ended
	Mar. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid and other current assets	Prepaid and other current assets consisted of the following: As of March 31, 2020 December 31, 2019 Prepaid assets $ 71.4 $ 56.8 Prepaid income tax 188.1 185.8 Unbilled receivables 101.8 142.3 Value added tax and other consumption tax receivables 59.3 71.3 Other miscellaneous current assets 60.1 57.4 Prepaid and other current assets $ 480.7 $ 513.6

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Schedule of Future Minimum Rental Receipts Expected Under Non-Cancellable Operating Lease Agreements	Future minimum rental receipts expected under non-cancellable operating lease agreements as of March 31, 2020 were as follows: Fiscal Year Amount (1) Remainder of 2020 $ 4,296.4 2021 5,519.8 2022 4,915.3 2023 4,734.1 2024 4,513.4 Thereafter 18,723.6 Total $ 42,702.6 _______________
Schedule of Information About Other Lease-related Balances	Information about other lease-related balances is as follows: As of March 31, 2020 December 31, 2019 Operating leases: Right-of-use asset $ 6,968.3 $ 7,357.4 Current portion of lease liability $ 476.8 $ 494.5 Lease liability 6,137.8 6,510.4 Total operating lease liability $ 6,614.6 $ 7,004.9
Components of Operating Lease Cost	The weighted-average remaining lease terms and incremental borrowing rates are as follows: As of March 31, 2020 December 31, 2019 Operating leases: Weighted-average remaining lease term (years) 13.4 13.1 Weighted-average incremental borrowing rate 5.9 % 6.1 % The following table sets forth the components of lease cost: Three Months Ended March 31, 2020 2019 Operating lease cost $ 250.7 $ 255.0 Variable lease costs not included in lease liability (1) 61.4 52.3 _______________ (1) Includes property tax paid on behalf of the landlord. Supplemental cash flow information is as follows: Three Months Ended March 31, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ (252.0) $ (234.9) Non-cash items: New operating leases (1) $ 50.1 $ 62.1 Operating lease modifications and reassessments (2) $ 96.9 $ 30.1 _______________ (1) Amount includes new operating leases and leases acquired in connection with acquisitions. (2) Includes a $0.7 million reduction of the operating lease liability during the three months ended March 31, 2020.
Maturity of Operating Lease Liabilities	Maturities of operating lease liabilities as of March 31, 2020 were as follows: Fiscal Year Operating Lease (1) Remainder of 2020 $ 629.5 2021 827.7 2022 797.3 2023 765.4 2024 730.5 Thereafter 5,942.7 Total lease payments 9,693.1 Less amounts representing interest (3,078.5) Total lease liability 6,614.6 Less current portion of lease liability (476.8) Non-current lease liability $ 6,137.8 _______________ (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)	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
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. Asia Africa Europe Latin America Balance as of January 1, 2020 $ 3,415.3 $ 1,021.8 $ 790.2 $ 256.2 $ 692.8 $ 2.0 $ 6,178.3 Additions and adjustments (1) — — (0.1) — — — (0.1) Effect of foreign currency translation — (57.4) (35.4) (4.1) (132.5) — (229.4) Balance as of March 31, 2020 $ 3,415.3 $ 964.4 $ 754.7 $ 252.1 $ 560.3 $ 2.0 $ 5,948.8 _______________
Intangible assets subject to amortization	The Company’s other intangible assets subject to amortization consisted of the following: As of March 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 $ 4,967.0 $ (1,938.8) $ 3,028.2 $ 5,150.8 $ (1,920.4) $ 3,230.4 Acquired tenant-related intangibles Up to 20 12,193.2 (3,707.5) 8,485.7 12,674.1 (3,674.6) 8,999.5 Acquired licenses and other intangibles 3-20 93.9 (7.2) 86.7 106.7 (18.2) 88.5 Total other intangible assets $ 17,254.1 $ (5,653.5) $ 11,600.6 $ 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, or up to 20 years, as the Company considers these intangibles to be directly related to the tower assets.
Expected future amortization expenses	Based on current exchange rates, the Company expects to record amortization expense as follows over the remaining current year and the five subsequent years: Fiscal Year Amount Remainder of 2020 $ 628.4 2021 822.7 2022 818.8 2023 815.2 2024 806.3 2025 790.8

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses consisted of the following: As of March 31, 2020 December 31, 2019 Accrued construction costs $ 19.4 $ 27.8 Accrued income tax payable 72.7 55.2 Accrued pass-through costs 64.5 74.2 Amounts payable to tenants 67.5 77.9 Accrued property and real estate taxes 196.0 198.1 Accrued rent 72.6 75.6 Accrued treasury stock repurchases 5.4 — Payroll and related withholdings 64.1 102.4 Other accrued expenses 314.2 347.0 Total accrued expenses $ 876.4 $ 958.2

LONG-TERM OBLIGATIONS (Tables)

LONG-TERM OBLIGATIONS (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule of 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 March 31, 2020 December 31, 2019 Maturity Date 2019 364-Day Term Loan (1) (2) $ — $ 999.9 N/A 2020 Term Loan (1) 749.9 — February 12, 2021 2019 Multicurrency Credit Facility (1) (3) 965.4 700.0 June 28, 2023 2019 Term Loan (1) 995.4 995.2 January 31, 2025 2019 Credit Facility (1) 1,415.0 1,600.0 January 31, 2025 2.800% senior notes 749.7 749.4 June 1, 2020 3.300% senior notes 748.8 748.5 February 15, 2021 3.450% senior notes 648.0 647.7 September 15, 2021 5.900% senior notes (4) — 498.9 N/A 2.250% senior notes 605.7 592.1 January 15, 2022 4.70% senior notes 698.4 698.2 March 15, 2022 3.50% senior notes 994.7 994.3 January 31, 2023 3.000% senior notes 723.9 704.9 June 15, 2023 5.00% senior notes 1,001.6 1,001.7 February 15, 2024 3.375% senior notes 644.7 644.4 May 15, 2024 2.950% senior notes 641.7 641.3 January 15, 2025 2.400% senior notes 744.2 — March 15, 2025 1.375% senior notes 544.5 553.0 April 4, 2025 4.000% senior notes 743.5 743.2 June 1, 2025 4.400% senior notes 496.7 496.6 February 15, 2026 1.950% senior notes 545.8 554.4 May 22, 2026 3.375% senior notes 988.3 987.9 October 15, 2026 3.125% senior notes 397.7 397.6 January 15, 2027 2.750% senior notes 743.7 743.5 January 15, 2027 3.55% senior notes 744.3 744.1 July 15, 2027 3.600% senior notes 692.8 692.6 January 15, 2028 3.950% senior notes 589.8 589.6 March 15, 2029 3.800% senior notes 1,632.1 1,631.7 August 15, 2029 2.900% senior notes 741.1 — January 15, 2030 3.700% senior notes 591.8 591.8 October 15, 2049 Total American Tower Corporation debt 21,779.2 20,942.5 Series 2013-2A securities (5) 1,295.4 1,295.0 March 15, 2023 Series 2018-1A securities (5) 494.0 493.8 March 15, 2028 Series 2015-1 notes (6) 349.9 349.6 June 15, 2020 Series 2015-2 notes (7) 521.6 521.4 June 16, 2025 Other subsidiary debt (8) 111.7 422.4 Various Total American Tower subsidiary debt 2,772.6 3,082.2 Finance lease obligations 25.6 30.7 Total 24,577.4 24,055.4 Less current portion of long-term obligations (2,640.0) (2,928.2) Long-term obligations $ 21,937.4 $ 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) As of March 31, 2020 reflects borrowings denominated in Euro (“EUR”). (4) Repaid in full on January 15, 2020 with borrowings from the 2019 Credit Facility and cash on hand. (5) Maturity date reflects the anticipated repayment date; final legal maturity is March 15, 2048. (6) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2045. (7) Maturity date reflects the anticipated repayment date; final legal maturity is June 15, 2050.
Schedule of line of credit facilities	As of March 31, 2020, the key terms under the 2019 Multicurrency Credit Facility, the 2019 Credit Facility, the Company’s $1.0 billion unsecured term loan, as amended and restated in December 2019 (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 (1) Current commitment fee (2) 2019 Multicurrency Credit Facility $ 965.4 (3) $ 3.8 June 28, 2023 (4) 1.125 % 0.110 % 2019 Credit Facility $ 1,415.0 $ 6.1 January 31, 2025 (4) 1.125 % 0.110 % 2019 Term Loan $ 1,000.0 N/A January 31, 2025 1.125 % N/A 2020 Term Loan $ 750.0 N/A February 12, 2021 0.650 % N/A _______________ (1) LIBOR means the London Interbank Offered Rate. (2) Fee on undrawn portion of each credit facility. (3) Reflects borrowings denominated in EUR.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of fair value of assets and liabilities	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: March 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 — $ 34.8 — — $ 9.0 — Embedded derivative in lease agreement — — $ 10.5 — — $ 10.7 Liabilities: Interest rate swap agreements — $ 0.1 — — $ 7.5 — Fair value of debt related to interest rate swap agreements (1) $ 35.4 — — $ 3.3 — — Redeemable noncontrolling interests — — $ 541.4 — — $ 1,096.5 _______________

INCOME TAXES (Tables)

INCOME TAXES (Tables)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of penalties and income tax-related interest expense	The Company recorded the following penalties and income tax-related interest expense during the three months ended March 31, 2020 and 2019: Three Months Ended March 31, 2020 2019 Penalties and income tax-related interest expense $ 1.7 $ 1.1

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of stock-based compensation expenses	During the three months ended March 31, 2020 and 2019, the Company recorded and capitalized the following stock-based compensation expense: Three Months Ended March 31, 2020 2019 Stock-based compensation expense Property $ 0.6 $ 0.6 Stock-based compensation expense Services 0.3 0.3 Stock-based compensation expense SG&A 46.8 41.6 Total stock-based compensation expense $ 47.7 $ 42.5 Stock-based compensation expense capitalized as property and equipment $ 0.5 $ 0.5
Summary of the company's option activity	The Company’s option activity for the three months ended March 31, 2020 was as follows (shares disclosed in full amounts): Number of Options Outstanding as of January 1, 2020 3,060,242 Granted — Exercised (130,706) Forfeited — Expired — Outstanding as of March 31, 2020 2,929,536
Summary of the company's restricted stock unit activity	The Company’s RSU and PSU activity for the three months ended March 31, 2020 was as follows (shares disclosed in full amounts): RSUs PSUs Outstanding as of January 1, 2020 (1) 1,454,350 528,908 Granted (2) 432,104 93,332 Vested and Released (3) (592,390) (205,434) Forfeited (11,730) — Outstanding as of March 31, 2020 1,282,334 416,806 Vested and deferred as of March 31, 2020 (4) — 77,340 _______________ (1) PSUs consist of the target number of shares issuable at the end of the three-year performance period for the 2019 PSUs and 2018 PSUs, or 114,823 and 131,311 shares, respectively, and the shares issuable at the end of the three-year performance period for the PSUs granted in 2017 (“2017 PSUs”) based on achievement against the performance metrics for the three-year performance period, or 282,774 shares. (2) PSUs consist of the target number of shares issuable at the end of the three-year performance period for the 2020 PSUs, or 93,332 shares. (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) Vested and deferred RSUs are related to deferred compensation for certain former employees.

REDEEMABLE NONCONTROLLING INT_2

REDEEMABLE NONCONTROLLING INTERESTS (Tables)	3 Months Ended
	Mar. 31, 2020
Noncontrolling Interest [Abstract]
Changes in Redeemable noncontrolling interest	The changes in Redeemable noncontrolling interests were as follows: Three Months Ended March 31, 2020 2019 Balance as of January 1, $ 1,096.5 $ 1,004.8 Net income (loss) attributable to noncontrolling interests 7.7 (3.7) Adjustment to noncontrolling interest redemption value (6.3) 3.7 Purchase of redeemable noncontrolling interest (524.4) (425.7) Foreign currency translation adjustment attributable to noncontrolling interests (32.1) 9.9 Balance as of March 31, $ 541.4 $ 589.0

EQUITY (Tables)

EQUITY (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Schedule of declared or paid cash distributions	During the three months ended March 31, 2020, the Company declared or paid the following cash distributions (per share data reflects actual amounts): Declaration Date Payment Date Record Date Distribution per share Aggregate Payment Amount (1) Common Stock March 12, 2020 April 29, 2020 April 14, 2020 $ 1.08 $ 478.8 December 11, 2019 January 14, 2020 December 27, 2019 $ 1.01 $ 447.3 _______________ (1) Does not include amounts accrued for distributions payable related to unvested restricted stock units. During the three months ended March 31, 2019, the Company declared or paid the following cash distributions (per share data reflects actual amounts): Declaration Date Payment Date Record Date Distribution per share Aggregate Payment Amount (1) Common Stock March 7, 2019 April 26, 2019 April 11, 2019 $ 0.90 $ 397.8 December 5, 2018 January 14, 2019 December 27, 2018 $ 0.84 $ 370.5 _______________

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 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 (shares in thousands, except per share data): Three Months Ended March 31, 2020 2019 Net income attributable to American Tower Corporation common stockholders $ 415.0 $ 397.4 Basic weighted average common shares outstanding 443,055 441,351 Dilutive securities 2,777 3,270 Diluted weighted average common shares outstanding 445,832 444,621 Basic net income attributable to American Tower Corporation common stockholders per common share $ 0.94 $ 0.90 Diluted net income attributable to American Tower Corporation common stockholders per common share $ 0.93 $ 0.89
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 (in thousands, on a weighted average basis): Three Months Ended March 31, 2020 2019 Restricted stock units 86 105

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
Schedule of acquisition and merger related costs	During the three months ended March 31, 2020 and 2019, the Company recorded acquisition and merger related expenses for business combinations and non-capitalized asset acquisition costs and integration costs as follows: Three Months Ended March 31, 2020 2019 Acquisition and merger related expenses $ 7.6 $ 2.0 Integration costs $ 6.6 $ 4.1
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: Allocation (1) Current assets $ 0.3 Property and equipment 25.9 Intangible assets (2): Tenant-related intangible assets 14.1 Network location intangible assets 4.2 Other intangible assets 1.3 Other non-current assets 10.6 Current liabilities (0.9) Deferred tax liability — Other non-current liabilities (4.6) Net assets acquired 50.9 Goodwill — Fair value of net assets acquired 50.9 Debt assumed — Purchase price $ 50.9 _______________ (1) Includes 7 sites in Peru held pursuant to long-term finance leases.
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 date indicated, nor are they indicative of the future operating results of the Company. Three Months Ended March 31, 2020 2019 Pro forma revenues $ 1,993.8 $ 1,899.3 Pro forma net income attributable to American Tower Corporation common stockholders $ 414.9 $ 380.3 Pro forma net income per common share amounts: Basic net income attributable to American Tower Corporation common stockholders $ 0.94 $ 0.86 Diluted net income attributable to American Tower Corporation common stockholders $ 0.93 $ 0.86

BUSINESS SEGMENTS (Tables)

BUSINESS SEGMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Summarized financial information concerning the company's reportable segments	Summarized financial information concerning the Company’s reportable segments for the three months ended March 31, 2020 and 2019 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 Three Months Ended March 31, 2020 U.S. Asia Africa Europe Latin America Segment revenues $ 1,089.9 $ 286.6 225.5 $ 34.5 $ 336.7 $ 1,973.2 $ 19.9 $ 1,993.1 Segment operating expenses (1) 190.0 164.0 77.7 6.6 105.2 543.5 7.6 551.1 Segment gross margin 899.9 122.6 147.8 27.9 231.5 1,429.7 12.3 1,442.0 Segment selling, general, administrative and development expense (1) 42.0 32.6 17.1 5.5 26.6 123.8 3.5 127.3 Segment operating profit $ 857.9 $ 90.0 $ 130.7 $ 22.4 $ 204.9 $ 1,305.9 $ 8.8 $ 1,314.7 Stock-based compensation expense $ 47.7 47.7 Other selling, general, administrative and development expense 43.7 43.7 Depreciation, amortization and accretion 472.3 472.3 Other expense (2) 311.3 311.3 Income from continuing operations before income taxes $ 439.7 Total assets $ 22,486.9 $ 4,986.0 $ 4,510.3 $ 1,554.5 $ 6,739.0 $ 40,276.7 $ 29.0 $ 483.4 $ 40,789.1 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.9 million and $46.8 million, respectively. (2) Primarily includes interest expense. Property Total Other Total Three Months Ended March 31, 2019 U.S. Asia Africa Europe Latin America Segment revenues $ 986.3 $ 288.9 $ 144.0 $ 33.5 $ 333.3 $ 1,786.0 $ 27.4 $ 1,813.4 Segment operating expenses (1) 191.3 178.0 53.5 6.2 103.4 532.4 10.1 542.5 Segment gross margin 795.0 110.9 90.5 27.3 229.9 1,253.6 17.3 1,270.9 Segment selling, general, administrative and development expense (1) 41.7 26.6 13.2 5.2 27.7 114.4 3.4 117.8 Segment operating profit $ 753.3 $ 84.3 $ 77.3 $ 22.1 $ 202.2 $ 1,139.2 $ 13.9 $ 1,153.1 Stock-based compensation expense $ 42.5 42.5 Other selling, general, administrative and development expense 38.7 38.7 Depreciation, amortization and accretion 436.9 436.9 Other expense (2) 193.4 193.4 Income from continuing operations before income taxes $ 441.6 Total assets $ 22,160.9 $ 5,427.6 $ 2,085.5 $ 1,552.0 $ 7,306.4 $ 38,532.4 $ 43.8 $ 350.6 $ 38,926.8 _______________ (1) Segment operating expenses and segment selling, general, administrative and development expenses exclude stock-based compensation expense of $0.9 million and $41.6 million, respectively. (2) Primarily includes interest expense.

BASIS OF PRESENTATION AND SIG_4

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions, ₨ in Billions	3 Months Ended				12 Months Ended
	Mar. 31, 2020USD ($)segment	Dec. 31, 2019segment	Sep. 30, 2019segment	Mar. 31, 2019USD ($)	Dec. 31, 2019INR (₨)	Dec. 31, 2019USD ($)	Dec. 31, 2018
Concentration Risk [Line Items]
Purchase of redeemable noncontrolling interest	$ 524.4			$ 425.7	₨ 29.4	$ 425.7
Purchase of redeemable noncontrolling interest	$ 0			0
Number of reportable segments | segment	6	6	5
Additional Paid-in Capital
Concentration Risk [Line Items]
Purchase of redeemable noncontrolling interest	$ (142.2)			(52.4)
Accumulated Other Comprehensive Loss
Concentration Risk [Line Items]
Purchase of redeemable noncontrolling interest	$ 142.2			$ 52.4
ATC Europe
Concentration Risk [Line Items]
Ownership interest percentage	51.00%
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)	49.00%
ATC, TIPL
Concentration Risk [Line Items]
Ownership interest percentage	79.00%	63.00%			63.00%	63.00%
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)	21.00%						37.00%
Ghana and Uganda Subsidiaries
Concentration Risk [Line Items]
Ownership interest percentage	100.00%	51.00%			51.00%	51.00%
Purchase of redeemable noncontrolling interest	$ 524.4
Payments for repurchase of redeemable noncontrolling interest, interest portion	$ 1.4
Uganda Subsidiary
Concentration Risk [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)	49.00%
Ghana Subsidiary
Concentration Risk [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)	49.00%

BASIS OF PRESENTATION AND SIG_5

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - CASH AND CASH EQUIVALENTS AND RESTRICTED CASH (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 1,326	$ 1,501.2	$ 1,004.8
Restricted cash	74.3	76.8	94.9
Total cash and cash equivalents and restricted cash	$ 1,400.3	$ 1,578	$ 1,099.7	$ 1,304.9

BASIS OF PRESENTATION AND SIG_6

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - SUMMARY OF REVENUE DISAGGREGATED BY SOURCE AND GEOGRAPHY (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 118	$ 125.2
Property lease revenue	1,875.1	1,688.2
Total operating revenues	1,993.1	1,813.4
Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	98.1	97.8
Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	19.9	27.4
Total operating revenues	19.9	27.4
U.S.
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	78.5	86.2
Property lease revenue	1,031.3	927.5
Total operating revenues	1,109.8	1,013.7
U.S. | Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	58.6	58.8
U.S. | Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	19.9	27.4
Asia
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.2	2.4
Property lease revenue	284.4	286.5
Total operating revenues	286.6	288.9
Asia | Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.2	2.4
Asia | Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Africa
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.9	0.8
Property lease revenue	222.6	143.2
Total operating revenues	225.5	144
Africa | Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.9	0.8
Africa | Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.5	0.8
Property lease revenue	33	32.7
Total operating revenues	34.5	33.5
Europe | Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.5	0.8
Europe | Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Latin America
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	32.9	35
Property lease revenue	303.8	298.3
Total operating revenues	336.7	333.3
Latin America | Non-lease property revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	32.9	35
Latin America | Services revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 0	$ 0

PREPAID AND OTHER CURRENT ASS_3

PREPAID AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid assets	$ 71.4	$ 56.8
Prepaid income tax	188.1	185.8
Unbilled receivables	101.8	142.3
Value added tax and other consumption tax receivables	59.3	71.3
Other miscellaneous current assets	60.1	57.4
Prepaid and other current assets	$ 480.7	$ 513.6

LEASES - MATURITIES OF MINIMUM

LEASES - MATURITIES OF MINIMUM RENTAL RECEIPTS EXPECTED UNDER NON-CANCELLABLE OPERATING LEASES (Details) $ in Millions	Mar. 31, 2020USD ($)
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
Remainder of 2020	$ 4,296.4
2021	5,519.8
2022	4,915.3
2023	4,734.1
2024	4,513.4
Thereafter	18,723.6
Total	$ 42,702.6

LEASES - SCHEDULE OF INFORMATIO

LEASES - SCHEDULE OF INFORMATION ABOUT OTHER LEASE RELATED BALANCES (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Operating leases:
Right-of-use asset	$ 6,968.3	$ 7,357.4
Current portion of lease liability	476.8	494.5
Lease liability	6,137.8	6,510.4
Total lease liability	$ 6,614.6	$ 7,004.9

LEASES - SCHEDULE OF WEIGHTED A

LEASES - SCHEDULE OF WEIGHTED AVERAGE LEASE TERMS AND DISCOUNT RATES BY SEGMENT (Details)	Mar. 31, 2020	Dec. 31, 2019
Operating leases:
Weighted-average remaining lease term (years)	13 years 4 months 24 days	13 years 1 month 6 days
Weighted-average incremental borrowing rate	5.90%	6.10%

LEASES - LEASE COSTS (Details)

LEASES - LEASE COSTS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Abstract]
Operating lease cost	$ 250.7	$ 255
Variable lease payments not included in lease liability	$ 61.4	$ 52.3

LEASES - SUPPLEMENTAL CASH FLOW

LEASES - SUPPLEMENTAL CASH FLOW INFOMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ (252)	$ (234.9)
Non-cash items:
New operating leases	50.1	62.1
Operating lease modifications and reassessments	96.9	$ 30.1
Decrease in operating lease liability	$ 0.7

LEASES - MATURITIES OF OPERATIN

LEASES - MATURITIES OF OPERATING AND FINANCE LEASE LIABILITIES (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Operating Lease
Remainder of 2020	$ 629.5
2021	827.7
2022	797.3
2023	765.4
2024	730.5
Thereafter	5,942.7
Total lease payments	9,693.1
Less amounts representing interest	(3,078.5)
Total lease liability	6,614.6	$ 7,004.9
Less current portion of lease liability	(476.8)	(494.5)
Non-current lease liability	$ 6,137.8	$ 6,510.4

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS - CHANGES IN THE CARRYING VALUE OF GOODWILL (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 6,178.3
Additions and adjustments	(0.1)
Effect of foreign currency translation	(229.4)
Goodwill, ending balance	5,948.8
Property, US
Goodwill [Roll Forward]
Goodwill, beginning balance	3,415.3
Additions and adjustments	0
Effect of foreign currency translation	0
Goodwill, ending balance	3,415.3
Property, Asia
Goodwill [Roll Forward]
Goodwill, beginning balance	1,021.8
Additions and adjustments	0
Effect of foreign currency translation	(57.4)
Goodwill, ending balance	964.4
Property, Africa
Goodwill [Roll Forward]
Goodwill, beginning balance	790.2
Additions and adjustments	(0.1)
Effect of foreign currency translation	(35.4)
Goodwill, ending balance	754.7
Property, Europe
Goodwill [Roll Forward]
Goodwill, beginning balance	256.2
Additions and adjustments	0
Effect of foreign currency translation	(4.1)
Goodwill, ending balance	252.1
Property, Latin America
Goodwill [Roll Forward]
Goodwill, beginning balance	692.8
Additions and adjustments	0
Effect of foreign currency translation	(132.5)
Goodwill, ending balance	560.3
Services
Goodwill [Roll Forward]
Goodwill, beginning balance	2
Additions and adjustments	0
Effect of foreign currency translation	0
Goodwill, ending balance	$ 2

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS - INTANGIBLE ASSETS SUBJECT TO AMORTIZATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 17,254.1	$ 17,931.6
Accumulated Amortization	(5,653.5)	(5,613.2)
Net Book Value	11,600.6	12,318.4
Acquired network location intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	4,967	5,150.8
Accumulated Amortization	(1,938.8)	(1,920.4)
Net Book Value	$ 3,028.2	3,230.4
Acquired network location intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Lives (years)	20 years
Acquired tenant-related intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 12,193.2	12,674.1
Accumulated Amortization	(3,707.5)	(3,674.6)
Net Book Value	$ 8,485.7	8,999.5
Acquired tenant-related intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Lives (years)	20 years
Acquired licenses and other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 93.9	106.7
Accumulated Amortization	(7.2)	(18.2)
Net Book Value	$ 86.7	$ 88.5
Acquired licenses and other intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Lives (years)	3 years
Acquired licenses and other intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Lives (years)	20 years

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS - NARRATIVE (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 217.5	$ 192.7
Weighted Average
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	15 years

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLE ASSETS - EXPECTED FUTURE AMORTIZATION EXPENSE (Details) $ in Millions	Mar. 31, 2020USD ($)
Fiscal Year
Remainder of 2020	$ 628.4
2021	822.7
2022	818.8
2023	815.2
2024	806.3
2025	$ 790.8

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued construction costs	$ 19.4	$ 27.8
Accrued income tax payable	72.7	55.2
Accrued pass-through costs	64.5	74.2
Amounts payable to tenants	67.5	77.9
Accrued property and real estate taxes	196	198.1
Accrued rent	72.6	75.6
Accrued treasury stock repurchases	5.4	0
Payroll and related withholdings	64.1	102.4
Other accrued expenses	314.2	347
Total accrued expenses	$ 876.4	$ 958.2

LONG-TERM OBLIGATIONS - SCHEDUL

LONG-TERM OBLIGATIONS - SCHEDULE OF LONG-TERM OBLIGATIONS (Details) € in Millions, $ in Millions	3 Months Ended	4 Months Ended
	Mar. 31, 2020USD ($)	Apr. 29, 2020EUR (€)	Apr. 29, 2020USD ($)	Jan. 15, 2020	Jan. 10, 2020	Dec. 31, 2019USD ($)	Feb. 14, 2019
Debt Instrument [Line Items]
Finance lease obligations	$ 25.6					$ 30.7
Total	24,577.4					24,055.4
Less current portion of long-term obligations	(2,640)					(2,928.2)
Long-term obligations	21,937.4					21,127.2
American Tower Corporation
Debt Instrument [Line Items]
Long-term debt	21,779.2					20,942.5
American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	$ 2,772.6					3,082.2
2019 364-Day Term Loan | Unsecured debt | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt term	364 days						364 days
Long-term debt	$ 0					999.9
2020 Term Loan | Unsecured debt | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt	749.9					0
2019 Multicurrency Credit Facility | Credit Facility | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt	965.4					700
2019 Term Loan | Unsecured debt | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt	995.4					995.2
2019 Credit Facility | Credit Facility | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt	$ 1,415					1,600
2.800% senior notes | Senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.80%
2.800% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.80%
Long-term debt	$ 749.7					749.4
3.300% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.30%
Long-term debt	$ 748.8					748.5
3.450% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.45%
Long-term debt	$ 648					647.7
5.900% Senior Notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	5.90%			5.90%
Long-term debt	$ 0					498.9
2.250% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.25%
Long-term debt	$ 605.7					592.1
4.70% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	4.70%
Long-term debt	$ 698.4					698.2
3.50% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.50%
Long-term debt	$ 994.7					994.3
3.000% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.00%
Long-term debt	$ 723.9					704.9
5.00% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	5.00%
Long-term debt	$ 1,001.6					1,001.7
3.375% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.375%
Long-term debt	$ 644.7					644.4
2.950% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.95%
Long-term debt	$ 641.7					641.3
2.400% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.40%				2.40%
Long-term debt	$ 744.2					0
1.375% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	1.375%
Long-term debt	$ 544.5					553
4.000% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	4.00%
Long-term debt	$ 743.5					743.2
4.400% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	4.40%
Long-term debt	$ 496.7					496.6
1.950% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	1.95%
Long-term debt	$ 545.8					554.4
3.375% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.375%
Long-term debt	$ 988.3					987.9
3.125% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.125%
Long-term debt	$ 397.7					397.6
2.750% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.75%
Long-term debt	$ 743.7					743.5
3.55% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.55%
Long-term debt	$ 744.3					744.1
3.600% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.60%
Long-term debt	$ 692.8					692.6
3.950% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.95%
Long-term debt	$ 589.8					589.6
3.800% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.80%
Long-term debt	$ 1,632.1					1,631.7
2.900% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	2.90%				2.90%
Long-term debt	$ 741.1					0
3.700% senior notes | Senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)	3.70%
Long-term debt	$ 591.8					591.8
Series 2013-2A securities | Secured debt | American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	1,295.4					1,295
Series 2018-1A securities | Secured debt | American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	494					493.8
Series 2015-1 notes | Secured debt | American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	349.9					349.6
Series 2015-2 notes | Secured debt | American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	521.6					521.4
Other subsidiary debt | Unsecured debt | American Tower subsidiary
Debt Instrument [Line Items]
Long-term debt	$ 111.7					$ 422.4
Debt repayment period	3 years
Other subsidiary debt | Unsecured debt | American Tower subsidiary | Subsequent Event
Debt Instrument [Line Items]
Repayment of loans		€ 24.5	$ 26.8

LONG-TERM OBLIGATIONS - NARRATI

LONG-TERM OBLIGATIONS - NARRATIVE (Details) € in Millions	Feb. 13, 2020USD ($)	Jan. 15, 2020USD ($)	Jan. 10, 2020USD ($)	Mar. 31, 2020EUR (€)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Feb. 14, 2019USD ($)
Debt Instrument [Line Items]
Current portion of long-term obligations					$ 2,640,000,000		$ 2,928,200,000
Loss on retirement of long-term obligations					34,600,000	$ 100,000
Proceeds from issuance of debt					750,000,000	1,300,000,000
Borrowings under credit facilities					2,642,300,000	$ 1,700,000,000
2019 Multicurrency Credit Facility | Credit Facility | American Tower Corporation
Debt Instrument [Line Items]
Borrowings under credit facilities				€ 875	971,800,000
Repayment of indebtedness under credit facility					700,000,000
Line of credit maximum borrowing capacity					3,000,000,000
2019 Credit Facility | Credit Facility | American Tower Corporation
Debt Instrument [Line Items]
Borrowings under credit facilities					1,700,000,000
Repayment of indebtedness under credit facility					$ 1,900,000,000
Line of credit maximum borrowing capacity							$ 2,250,000,000
2019 Credit Facility | Credit Facility | Current margin over LIBOR | American Tower Corporation
Debt Instrument [Line Items]
Current margin over LIBOR (as a percent)				1.125%	1.125%
Unsecured debt | 2020 Term Loan | American Tower Corporation
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 750,000,000
Unsecured debt | 2020 Term Loan | Current margin over LIBOR | American Tower Corporation
Debt Instrument [Line Items]
Current margin over LIBOR (as a percent)	0.65%			0.65%	0.65%
Unsecured debt | 2020 Term Loan | Base Rate | American Tower Corporation
Debt Instrument [Line Items]
Current margin over LIBOR (as a percent)	0.00%
Unsecured debt | 2019 364-Day Term Loan | American Tower Corporation
Debt Instrument [Line Items]
Senior note public offering, amount								$ 1,300,000,000
Long-term debt term					364 days			364 days
Senior notes
Debt Instrument [Line Items]
Maximum adjusted EBITDA					3.5
Senior notes | 2.800% senior notes
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)					2.80%
Senior notes | 2.800% senior notes | American Tower Corporation
Debt Instrument [Line Items]
Current portion of long-term obligations					$ 750,000,000
Long-term debt, stated interest rate (as a percent)					2.80%
Senior notes | 3.300% senior notes | American Tower Corporation
Debt Instrument [Line Items]
Current portion of long-term obligations					$ 750,000,000
Long-term debt, stated interest rate (as a percent)					3.30%
Senior notes | 5.900% Senior Notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)		5.90%			5.90%
Debt redeemed aggregate principal amount		$ 500,000,000
Debt redemption price rate (as a percent)		106.709%
Debt redeemed aggregate redemption price		$ 539,600,000
Accrued and unpaid interest		6,100,000
Loss on retirement of long-term obligations		34,600,000
Prepayment consideration		$ 33,500,000
Senior notes | 2.400% senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)			2.40%		2.40%
Senior note public offering, amount			$ 750,000,000
Senior notes | 2.900% senior notes | American Tower Corporation
Debt Instrument [Line Items]
Long-term debt, stated interest rate (as a percent)			2.90%		2.90%
Senior note public offering, amount			$ 750,000,000
Proceeds from issuance of debt			$ 1,483,400,000
Debt, interest accrual period			360 days
Secured debt | Series 2015-1 notes | American Tower subsidiary
Debt Instrument [Line Items]
Current portion of long-term obligations					$ 350,000,000

LONG-TERM OBLIGATIONS - SCHED_2

LONG-TERM OBLIGATIONS - SCHEDULE OF LINES OF CREDIT (Details) - American Tower Corporation $ in Millions	Feb. 13, 2020	Mar. 31, 2020USD ($)renewal_period
Credit Facility
Line of Credit Facility [Line Items]
Optional renewal periods | renewal_period		2
2019 Multicurrency Credit Facility | Credit Facility
Line of Credit Facility [Line Items]
Outstanding Principal Balance		$ 965.4
Undrawn letters of credit		$ 3.8
Current commitment fee (as a percent)		0.11%
2019 Multicurrency Credit Facility | Credit Facility | Current margin over LIBOR
Line of Credit Facility [Line Items]
Current margin over LIBOR (as a percent)		1.125%
2019 Credit Facility | Credit Facility
Line of Credit Facility [Line Items]
Outstanding Principal Balance		$ 1,415
Undrawn letters of credit		$ 6.1
Current commitment fee (as a percent)		0.11%
2019 Credit Facility | Credit Facility | Current margin over LIBOR
Line of Credit Facility [Line Items]
Current margin over LIBOR (as a percent)		1.125%
2019 Term Loan | Unsecured debt
Line of Credit Facility [Line Items]
Outstanding Principal Balance		$ 1,000
2019 Term Loan | Unsecured debt | Current margin over LIBOR
Line of Credit Facility [Line Items]
Current margin over LIBOR (as a percent)		1.125%
2020 Term Loan | Unsecured debt
Line of Credit Facility [Line Items]
Outstanding Principal Balance		$ 750
2020 Term Loan | Unsecured debt | Current margin over LIBOR
Line of Credit Facility [Line Items]
Current margin over LIBOR (as a percent)	0.65%	0.65%

FAIR VALUE MEASUREMENTS - ASSET

FAIR VALUE MEASUREMENTS - ASSETS AND LIABILITIES MEASURED AT FAIR VALUE ON A RECURRING BASIS (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Level 1
Assets:
Embedded derivative in lease agreement	$ 0	$ 0
Liabilities:
Redeemable noncontrolling interests	0	0
Level 1 | Interest rate swap agreements
Assets:
Interest rate swap agreements	0	0
Liabilities:
Interest rate swap agreements	0	0
Fair value of debt related to interest rate swap	35.4	3.3
Level 2
Assets:
Embedded derivative in lease agreement	0	0
Liabilities:
Redeemable noncontrolling interests	0	0
Level 2 | Interest rate swap agreements
Assets:
Interest rate swap agreements	34.8	9
Liabilities:
Interest rate swap agreements	0.1	7.5
Fair value of debt related to interest rate swap	0	0
Level 3
Assets:
Embedded derivative in lease agreement	10.5	10.7
Liabilities:
Redeemable noncontrolling interests	541.4	1,096.5
Level 3 | Interest rate swap agreements
Assets:
Interest rate swap agreements	0	0
Liabilities:
Interest rate swap agreements	0	0
Fair value of debt related to interest rate swap	$ 0	$ 0

FAIR VALUE MEASUREMENTS - NARRA

FAIR VALUE MEASUREMENTS - NARRATIVE (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments	$ 3.7	$ 18.1
Long-term obligations	24,577.4		$ 24,055.4
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		25,000
Estimate of Fair Value Measurement | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	17,900		17,500
Estimate of Fair Value Measurement | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 7,100		$ 7,500

INCOME TAXES - NARRATIVE (Detai

INCOME TAXES - NARRATIVE (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact the ETR	$ 144,300,000	$ 158,100,000
Unrecognized tax benefits, increase resulting from current period tax positions	1,200,000
Unrecognized Tax Benefits, Decrease Resulting from Foreign Currency Translation	12,400,000
Unrecognized tax benefits, decrease from acquisition	2,900,000
Unrecognized tax benefits, income tax penalties and interest accrued	28,000,000	$ 26,600,000
Minimum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	0
Maximum
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible	$ 47,800,000

INCOME TAXES - SCHEDULE OF PENA

INCOME TAXES - SCHEDULE OF PENALTIES AND INCOME TAX RELATED EXPENSES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Penalties and income tax-related interest expense	$ 1.7	$ 1.1

STOCK-BASED COMPENSATION - NARR

STOCK-BASED COMPENSATION - NARRATIVE (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
ESPP, discount rate (as a percent)	15.00%
Total unrecognized compensation expense	$ 0.1
Stock-based compensation expense	$ 47.7	$ 42.5
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected recognition of stock award compensation expense weighted average period ( less than one year for stock options)	3 years
Granted (in shares)	432,104
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years	3 years
Total unrecognized compensation expense	$ 11.6
Expected recognition of stock award compensation expense weighted average period ( less than one year for stock options)	2 years
Granted (in shares)	93,332	114,823	131,311	282,774
Stock-based compensation expense	$ 12.9
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	0.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of potential target shares	200.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected recognition of stock award compensation expense weighted average period ( less than one year for stock options)	1 year
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issuable under stock incentive plan (in shares)	6,400,000
2007 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Total unrecognized compensation expense	$ 189.6
2007 Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
2007 Plan | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years

STOCK-BASED COMPENSATION - SUMM

STOCK-BASED COMPENSATION - SUMMARY OF STOCK-BASED COMPENSATION EXPENSE (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 47.7		$ 42.5
Stock-based compensation expense capitalized as property and equipment	0.5		0.5
Stock-based compensation expense Property
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	0.6		0.6
Service
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	0.3		0.3
Stock-based compensation expense SG&A
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 46.8	$ 41.6	$ 41.6

STOCK-BASED COMPENSATION - SU_2

STOCK-BASED COMPENSATION - SUMMARY OF THE COMPANY'S OPTION ACTIVITY (Details)	3 Months Ended
	Mar. 31, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding as of January 1, 2020 (in shares)	3,060,242
Granted (in shares)	0
Exercised (in shares)	(130,706)
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding as of March 31, 2020 (in shares)	2,929,536

STOCK-BASED COMPENSATION - SU_3

STOCK-BASED COMPENSATION - SUMMARY OF THE COMPANY'S RESTRICTED STOCK UNIT ACTIVITY (Details) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2019
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding as of January 1, 2020 (in shares)	1,454,350
Granted (in shares)	432,104
Vested (in shares)	(592,390)
Forfeited (in shares)	(11,730)
Outstanding as of March 31, 2020 (in shares)	1,282,334
Vested and deferred as of March 31, 2020 (in shares)	0				19,810
PSUs
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding as of January 1, 2020 (in shares)	528,908
Granted (in shares)	93,332	114,823	131,311	282,774
Vested (in shares)	(205,434)
Forfeited (in shares)	0
Outstanding as of March 31, 2020 (in shares)	416,806
Vested and deferred as of March 31, 2020 (in shares)	77,340
Vesting period	3 years	3 years	3 years	3 years

REDEEMABLE NONCONTROLLING INT_3

REDEEMABLE NONCONTROLLING INTERESTS - NARRATIVE (Details)	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2019INR (₨)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019INR (₨)	Dec. 31, 2019USD ($)	Mar. 31, 2020₨ / shares	Mar. 31, 2020USD ($)	Dec. 31, 2018	Apr. 21, 2016
Noncontrolling Interest [Line Items]
Temporary equity, redemption price per share (in dollars per share) | ₨ / shares						₨ 216
Purchase of redeemable noncontrolling interest		$ 524,400,000	$ 425,700,000	₨ 29,400,000,000	$ 425,700,000
Redemption consideration value	₨ 24,800,000,000						$ 328,000,000
Percentage of ownership after transaction		92.00%
ATC, TIPL
Noncontrolling Interest [Line Items]
Ownership interest percentage				63.00%	63.00%		79.00%
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)							21.00%	37.00%
Eure-et-Loir
Noncontrolling Interest [Line Items]
Ownership interest percentage							51.00%
Noncontrolling interest, ownership percentage by noncontrolling owners (as a percent)							49.00%
Redeemable noncontrolling interest carrying amount							$ 2,700,000
Ghana and Uganda Subsidiaries
Noncontrolling Interest [Line Items]
Purchase of redeemable noncontrolling interest		$ 524,400,000
Ownership interest percentage				51.00%	51.00%		100.00%
Payments for repurchase of redeemable noncontrolling interest, interest portion		$ 1,400,000
Tata Teleservices Limited
Noncontrolling Interest [Line Items]
Percentage of ownership before transaction	100.00%
Tata Teleservices Limited | ATC, TIPL
Noncontrolling Interest [Line Items]
Percentage of ownership before transaction				50.00%	50.00%
IDFC | ATC, TIPL
Noncontrolling Interest [Line Items]
Percentage of ownership before transaction				100.00%	100.00%
Viom Transaction
Noncontrolling Interest [Line Items]
Percentage of interests acquired									51.00%

REDEEMABLE NONCONTROLLING INT_4

REDEEMABLE NONCONTROLLING INTERESTS - CHANGE IN REDEEMABLE NONCONTROLLING INTEREST (Details) $ in Millions, ₨ in Billions	3 Months Ended		12 Months Ended
	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019INR (₨)	Dec. 31, 2019USD ($)
Noncontrolling Interest [Abstract]
Balance as of January 1,	$ 1,096.5	$ 1,004.8		$ 1,004.8
Net income (loss) attributable to noncontrolling interests	7.7	(3.7)
Adjustment to noncontrolling interest redemption value	(6.3)	3.7
Purchase of redeemable noncontrolling interest	(524.4)	(425.7)	₨ (29.4)	(425.7)
Foreign currency translation adjustment attributable to noncontrolling interests	(32.1)	9.9
Balance as of March 31,	$ 541.4	$ 589		$ 1,096.5

EQUITY - NARRATIVE (Details)

EQUITY - NARRATIVE (Details) € in Millions	3 Months Ended		12 Months Ended		108 Months Ended
	Mar. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)shares	Mar. 31, 2020USD ($)shares	Dec. 31, 2017USD ($)	Mar. 31, 2011USD ($)
Class of Stock [Line Items]
Proceeds from stock options	$ 11,100,000	$ 27,200,000
Treasury stock activity (in shares) | shares	213,352
Treasury stock repurchased	$ 45,100,000
Accrued treasury stock repurchases	$ 5,400,000			$ 0	$ 5,400,000
Shares repurchased (in shares) | shares	10,864			10,651	10,864
Shares repurchased	$ 1,271,500,000			$ 1,226,400,000	$ 1,271,500,000
Accrued dividend RSU	8,600,000				$ 8,600,000
Paid dividend RSU	7,600,000	$ 6,600,000
ATC Europe
Class of Stock [Line Items]
Dividends			€ 24.5	$ 27,000,000
2011 Buyback
Class of Stock [Line Items]
Stock repurchase program, authorized amount							$ 1,500,000,000
Treasury stock activity (in shares) | shares					14,310,549
Treasury stock repurchased					$ 1,500,000,000
2017 Buyback
Class of Stock [Line Items]
Stock repurchase program, authorized amount						$ 2,000,000,000
Treasury stock repurchased	$ 45,100,000

EQUITY - DISTRIBUTIONS (Details

EQUITY - DISTRIBUTIONS (Details) - USD ($) $ / shares in Units, $ in Millions	Apr. 29, 2020	Mar. 12, 2020	Jan. 14, 2020	Dec. 11, 2019	Apr. 26, 2019	Mar. 07, 2019	Jan. 14, 2019	Dec. 05, 2018	Mar. 31, 2020	Mar. 31, 2019
Dividends Payable [Line Items]
Aggregate Payment Amount on common stock									$ 454.9	$ 377.1
Common Stock, $0.01 par value
Dividends Payable [Line Items]
Distribution per share, common stock (in dollars per share)		$ 1.08		$ 1.01		$ 0.90		$ 0.84
Aggregate Payment Amount on common stock			$ 447.3		$ 397.8		$ 370.5
Common Stock, $0.01 par value | Subsequent Event
Dividends Payable [Line Items]
Aggregate Payment Amount on common stock	$ 478.8

EARNINGS PER COMMON SHARE - SCH

EARNINGS PER COMMON SHARE - SCHEDULE OF EARNINGS PER BASIC AND DILUTED BY COMMON CLASS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income attributable to American Tower Corporation common stockholders	$ 415	$ 397.4
Basic weighted average common shares outstanding (in shares)	443,055	441,351
Dilutive securities (in shares)	2,777	3,270
Diluted weighted average common shares outstanding (in shares)	445,832	444,621
Basic net income attributable to American Tower Corporation common stockholders per common share (in dollars per share)	$ 0.94	$ 0.90
Diluted net income attributable to American Tower Corporation common stockholders per common share (in dollars per share)	$ 0.93	$ 0.89

EARNINGS PER COMMON SHARE - S_2

EARNINGS PER COMMON SHARE - SCHEDULE OF SHARES EXCLUDED FROM COMPUTATION OF EARNINGS PER SHARE (Details) - shares shares in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from dilutive effect (in shares)	86	105

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - NARRATIVE (Details) ₨ in Millions, $ in Millions	Dec. 05, 2016INR (₨)	Dec. 05, 2016USD ($)	Mar. 27, 2015USD ($)communications_siterenewal_period	Mar. 31, 2020USD ($)communications_sitecommunication_siterenewal_period
INDIA
Loss Contingencies [Line Items]
Foreign income tax assessment	₨ 4,750	$ 69.8
Verizon Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units (in number of communication sites) | 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 (in numbers of terms) | renewal_period			8
Renewal term			5 years
AT&T Transaction
Loss Contingencies [Line Items]
Capital leased assets, number of units (in number of communication sites) | communications_site				2,200
Aggregate purchase option price for towers | $				$ 960.4
Successive terms to renew lease (in numbers of terms) | renewal_period				5
Renewal term				5 years
Operating lease, term of contract				27 years
Number of sites acquired life to date | communication_site				228

ACQUISITIONS - SCHEDULE OF MERG

ACQUISITIONS - SCHEDULE OF MERGER AND ACQUISITION RELATED COSTS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combinations [Abstract]
Acquisition and merger related expenses	$ 7.6	$ 2
Integration costs	$ 6.6	$ 4.1

ACQUISITIONS - NARRATIVE (Detai

ACQUISITIONS - NARRATIVE (Details) € in Millions, $ in Millions	Dec. 31, 2019USD ($)communication_site	Nov. 28, 2019EUR (€)communication_site	Nov. 28, 2019USD ($)communication_site	Mar. 31, 2020USD ($)communication_site	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)communication_site	Apr. 01, 2020communication_site	Dec. 19, 2019communication_site
Business Acquisition [Line Items]
Payment received related to acquisition in France					$ 5.7
Estimated aggregate impact of acquisitions completed, revenue				$ 0.1
Estimated aggregate impact of acquisitions completed, gross margin (less than $0.1 million)				0.1
Post closing adjustments, goodwill				(0.1)
Eaton Towers Holding Limited
Business Acquisition [Line Items]
Number of communications sites acquired (in number of towers) | communication_site	5,800					5,800
Percentage of interests acquired	100.00%					100.00%
Number of markets in which entity operates | communication_site	5					5
Eaton Tower, existing debt assume						$ 2,000
Receivable for reimbursement of taxes						$ 9.7
Post closing adjustments, assets				15.1
Post closing adjustments, liabilities				15
Post closing adjustments, goodwill				$ (0.1)
Entel Acquisition
Business Acquisition [Line Items]
Number of communications sites acquired (in number of towers) | communication_site	2,400			156		2,400		3,200
Aggregate purchase price	$ 800			$ 39.7
Other Acquisitions 2020 | Communication Sites
Business Acquisition [Line Items]
Number of communications sites acquired (in number of towers) | communication_site				37
Aggregate purchase price				$ 11.2
Orange S.A. | Communication Sites
Business Acquisition [Line Items]
Number of communications sites acquired (in number of towers) | communication_site		2,000	2,000
Asset purchase period		5 years	5 years
Orange S.A. | Communication Sites | Subsequent Event
Business Acquisition [Line Items]
Number of communications sites acquired (in number of towers) | communication_site							113
Orange S.A. | Communication Sites | Minimum
Business Acquisition [Line Items]
Aggregate purchase price		€ 500	$ 550.5
Orange S.A. | Communication Sites | Maximum
Business Acquisition [Line Items]
Aggregate purchase price		€ 600	$ 660.5

ACQUISITIONS - SUMMARY OF ALLOC

ACQUISITIONS - SUMMARY OF ALLOCATION OF THE PURCHASE PRICE (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)site	Dec. 31, 2019USD ($)
Asset Acquisition:
Goodwill	$ 5,948.8	$ 6,178.3
Tenant-related intangible assets | Maximum
Asset Acquisition:
Estimated useful lives (in years)	20 years
Network location intangible assets | Maximum
Asset Acquisition:
Estimated useful lives (in years)	20 years
Acquisitions 2020
Asset Acquisition:
Current assets	$ 0.3
Property and equipment	25.9
Other non-current assets	10.6
Current liabilities	(0.9)
Deferred tax liability	0
Other non-current liabilities	(4.6)
Net assets acquired	50.9
Goodwill	0
Fair value of net assets acquired	50.9
Debt assumed	0
Purchase price	$ 50.9
Acquisitions 2020 | Peru
Asset Acquisition:
Number of sites acquired | site	7
Acquisitions 2020 | Tenant-related intangible assets
Asset Acquisition:
Intangible assets	$ 14.1
Acquisitions 2020 | Tenant-related intangible assets | Maximum
Asset Acquisition:
Estimated useful lives (in years)	20 years
Acquisitions 2020 | Network location intangible assets
Asset Acquisition:
Intangible assets	$ 4.2
Acquisitions 2020 | Other intangible assets
Asset Acquisition:
Intangible assets	$ 1.3

ACQUISITIONS - PRO FORMA INFORM

ACQUISITIONS - PRO FORMA INFORMATION (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combinations [Abstract]
Pro forma revenues	$ 1,993.8	$ 1,899.3
Pro forma net income attributable to American Tower Corporation common stockholders	$ 414.9	$ 380.3
Pro forma net income per common share amounts:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.94	$ 0.86
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.93	$ 0.86

BUSINESS SEGMENTS (Details)

BUSINESS SEGMENTS (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)segment	Sep. 30, 2019segment	Mar. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments divided | segment			2
Number of reportable segments | segment	6	6	5
Segment revenues	$ 1,993.1			$ 1,813.4
Selling, general, administrative and development expense	217.8			198.1
OPERATING INCOME	736.8			614.9
Stock-based compensation expense	47.7			42.5
Depreciation, amortization and accretion	472.3			436.9
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	439.7			441.6
Total assets	40,789.1	$ 42,801.6		38,926.8
Operating Expense
Segment Reporting Information [Line Items]
Stock-based compensation expense	0.9			0.9
Stock-based compensation expense Services
Segment Reporting Information [Line Items]
Stock-based compensation expense	46.8	$ 41.6		41.6
Operating Segments
Segment Reporting Information [Line Items]
Segment revenues	1,993.1			1,813.4
Segment operating expenses	551.1			542.5
Segment gross margin	1,442			1,270.9
Selling, general, administrative and development expense	127.3			117.8
OPERATING INCOME	1,314.7			1,153.1
Operating Segments | Property
Segment Reporting Information [Line Items]
Segment revenues	1,973.2			1,786
Segment operating expenses	543.5			532.4
Segment gross margin	1,429.7			1,253.6
Selling, general, administrative and development expense	123.8			114.4
OPERATING INCOME	1,305.9			1,139.2
Total assets	40,276.7			38,532.4
Operating Segments | Property, US
Segment Reporting Information [Line Items]
Segment revenues	1,089.9			986.3
Segment operating expenses	190			191.3
Segment gross margin	899.9			795
Selling, general, administrative and development expense	42			41.7
OPERATING INCOME	857.9			753.3
Total assets	22,486.9			22,160.9
Operating Segments | Property, Asia
Segment Reporting Information [Line Items]
Segment revenues	286.6			288.9
Segment operating expenses	164			178
Segment gross margin	122.6			110.9
Selling, general, administrative and development expense	32.6			26.6
OPERATING INCOME	90			84.3
Total assets	4,986			5,427.6
Operating Segments | Property, Africa
Segment Reporting Information [Line Items]
Segment revenues	225.5			144
Segment operating expenses	77.7			53.5
Segment gross margin	147.8			90.5
Selling, general, administrative and development expense	17.1			13.2
OPERATING INCOME	130.7			77.3
Total assets	4,510.3			2,085.5
Operating Segments | Property, Europe
Segment Reporting Information [Line Items]
Segment revenues	34.5			33.5
Segment operating expenses	6.6			6.2
Segment gross margin	27.9			27.3
Selling, general, administrative and development expense	5.5			5.2
OPERATING INCOME	22.4			22.1
Total assets	1,554.5			1,552
Operating Segments | Property, Latin America
Segment Reporting Information [Line Items]
Segment revenues	336.7			333.3
Segment operating expenses	105.2			103.4
Segment gross margin	231.5			229.9
Selling, general, administrative and development expense	26.6			27.7
OPERATING INCOME	204.9			202.2
Total assets	6,739			7,306.4
Operating Segments | Services
Segment Reporting Information [Line Items]
Segment revenues	19.9			27.4
Segment operating expenses	7.6			10.1
Segment gross margin	12.3			17.3
Selling, general, administrative and development expense	3.5			3.4
OPERATING INCOME	8.8			13.9
Total assets	29			43.8
Other
Segment Reporting Information [Line Items]
Selling, general, administrative and development expense	43.7			38.7
Stock-based compensation expense	47.7			42.5
Depreciation, amortization and accretion	472.3			436.9
Other expense	311.3			193.4
Total assets	$ 483.4			$ 350.6

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($)	Apr. 21, 2020	Apr. 03, 2020	Mar. 31, 2020
Senior notes | 2.800% senior notes
Subsequent Event [Line Items]
Long-term debt, stated interest rate (as a percent)			2.80%
Subsequent Event | Unsecured debt | April 2020 Term Loan
Subsequent Event [Line Items]
Senior note public offering, amount	$ 1,190,000,000	$ 1,140,000,000
Subsequent Event | Unsecured debt | April 2020 Term Loan | Current margin over LIBOR
Subsequent Event [Line Items]
Current margin over LIBOR (as a percent)	1.75%
Subsequent Event | Unsecured debt | April 2020 Term Loan | Base Rate
Subsequent Event [Line Items]
Current margin over LIBOR (as a percent)	0.75%

Uncategorized Items - amt-20200

Label	Element	Value
Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (24,700,000)
Accounting Standards Update 2016-02 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (24,700,000)