Crown Castle (CCI) 10-K 22 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 17, 2021	Jun. 30, 2020
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-16441
Entity Registrant Name	CROWN CASTLE INTERNATIONAL CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0470458
Entity Address, Address Line One	1220 Augusta Drive
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77057-2261
City Area Code	713
Local Phone Number	570-3000
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	CCI
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 69.4
Entity Common Stock, Shares Outstanding		431,311,859
Entity Central Index Key	0001051470
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
ICFR Auditor Attestation Flag	true

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 232	$ 196
Restricted cash	144	137
Receivables, net of allowance of $17 and $18, respectively	431	596
Prepaid expenses	95	107
Other current assets	202	168
Total current assets	1,104	1,204
Deferred site rental receivables	1,408	1,424
Property and equipment, net	15,162	14,666
Operating lease right-of-use assets	6,464	6,133
Goodwill	10,078	10,078
Site rental contracts and tenant relationships, net	4,365	4,764
Other intangible assets, net	68	72
Other assets, net	119	116
Total assets	38,768	38,457
LIABILITIES AND EQUITY
Accounts payable	230	334
Accrued interest	199	169
Deferred revenues	704	657
Other accrued liabilities	378	361
Current maturities of debt and other obligations	129	100
Current portion of operating lease liabilities	329	299
Total current liabilities	1,969	1,920
Debt and other long-term obligations	19,151	18,021
Operating lease liabilities	5,808	5,511
Other long-term liabilities	2,379	2,516
Total liabilities	29,307	27,968
CCIC stockholders' equity:
Common stock, $0.01 par value; 600 shares authorized; shares issued and outstanding: December 31, 2020—431 and December 31, 2019—416	4	4
6.875% Mandatory Convertible Preferred Stock, Series A, $0.01 par value; 20 shares authorized; shares issued and outstanding: December 31, 2020—0 and December 31, 2019—2; aggregate liquidation value: December 31, 2020—$0 and December 31, 2019—$1,650	0	0
Additional paid-in capital	17,933	17,855
Accumulated other comprehensive income (loss)	(4)	(5)
Dividends/distributions in excess of earnings	(8,472)	(7,365)
Total equity	9,461	10,489
Total liabilities and equity	$ 38,768	$ 38,457

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Allowance for doubtful accounts receivable, current	$ 17	$ 18
6.875% Mandatory Convertible Preferred Stock, Par or Stated Value Per Share (dollars per share)	$ 0.01	$ 0.01
6.875% Mandatory Convertible Preferred Stock, Shares Authorized	20	20
6.875% Mandatory Convertible Preferred Stock, shares issued	0	2
Convertible Preferred Stock, shares outstanding	0	2
Mandatory redemption and aggregate liquidation value, 6.875% Mandatory Convertible Preferred Stock	$ 0	$ 1,650
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	600	600
Common stock, shares issued	431	416
Common stock, shares outstanding	431	416

Consolidated Statement of Opera

Consolidated Statement of Operations and Comprehensive Income (Loss) - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Net revenues:
Site rental revenues		$ 5,320		$ 5,093	$ 4,796
Services and other		520		670	574
Net Revenues		5,840		5,763	5,370
Costs of Operations:
Site rental	[1]	1,521		1,462	1,410
Services and other	[1]	448		524	434
Selling, general and administrative		678		614	563
Asset write-down charges		74		19	26
Acquisition and integration costs		10		13	27
Depreciation, amortization and accretion		1,608		1,572	1,527
Total operating expenses		4,339		4,204	3,987
Other Operating (Income) Expense		(362)		0	0
Operating income (loss)		1,863		1,559	1,383
Interest expense and amortization of deferred financing costs		689		683	642
Gains (losses) on retirement of long-term obligations	[2]	(95)		(2)	(106)
Interest income		2		6	5
Other income (expense)		(5)		1	1
Income (Loss) Attributable to Parent, before Tax, Total		1,076		881	641
Benefit (provision) for income taxes		(20)		(21)	(19)
Net income (loss) attributable to CCIC stockholders		1,056		860	622
Dividends, Preferred Stock		57		113	113
Net income (loss) attributable to CCIC common stockholders		999		747	509
Net income (loss)		1,056		860	622
Other comprehensive income (loss):
Foreign currency translation adjustments		1		0	(1)
Total other comprehensive income (loss)		1	[3]	0	(1)	[3]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		$ 1,057		$ 860	$ 621
Net income (loss) attributable to CCIC common stockholders, per common share:
Basic (in dollars per share)		$ 2.36		$ 1.80	$ 1.23
Diluted (in dollars per share)		$ 2.35		$ 1.79	$ 1.23
Weighted-average common shares outstanding:
Basic (in shares)		423		416	413
Diluted (in shares)		425		418	415
[1]	Exclusive of depreciation, amortization and accretion shown separately.
[2]	Inclusive of the write-off of the respective deferred financing costs.
[3]	See the consolidated statement of operations and comprehensive income (loss) for the components of "total other comprehensive income (loss)."

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)		$ 1,056	$ 860	$ 622
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation, amortization and accretion		1,608	1,572	1,527
(Gains) losses on retirement of long-term obligations	[1]	95	2	106
Amortization of deferred financing costs and other non-cash interest, net		6	1	7
Stock-based compensation expense		138	117	103
Asset write-down charges		74	19	26
Deferred income tax (benefit) provision		3	2	2
Other non-cash adjustments, net		5	(2)	2
Changes in assets and liabilities, excluding the effects of acquisitions:
Increase (decrease) in accrued interest		31	21	16
Increase (decrease) in accounts payable		(77)	19	37
Increase (decrease) in other liabilities		(65)	254	271
Decrease (increase) in receivables		166	(96)	(105)
Decrease (increase) in other assets		15	(71)	(114)
Net cash provided by (used for) operating activities		3,055	2,698	2,500
Cash flows from investing activities:
Capital expenditures		1,624	2,057	1,739
Payments for acquisitions, net of cash acquired		107	17	42
Other investing activities, net		(10)	(7)	(12)
Net cash provided by (used for) investing activities		(1,741)	(2,081)	(1,793)
Cash flows from financing activities:
Proceeds from issuance of long-term debt		3,733	1,894	2,742
Principal payments on debt and other long-term obligations		105	86	105
Purchases and redemptions of long-term debt		2,490	12	2,346
Borrowings under revolving credit facility		2,430	2,110	1,820
Payments under revolving credit facility		2,665	2,660	1,725
Net issuances (repayments) under commercial paper program		130	155	0
Payments for financing costs		38	24	31
Net proceeds from issuance of common stock		0	0	841
Purchases of common stock		76	44	34
Dividends/distributions paid on common stock		2,105	1,912	1,782
Dividends/distributions paid on preferred stock		85	113	113
Net cash provided by (used for) financing activities		(1,271)	(692)	(733)
Net increase (decrease) in cash, cash equivalents, and restricted cash from continuing operations		43	(75)	(26)
Effect of exchange rate changes on cash		0	0	(1)
Cash, Cash Equivalents and Restricted Cash - Beginning of Period		338	413	440
Cash, Cash Equivalents and Restricted Cash - End of Period		$ 381	$ 338	$ 413
[1]	Inclusive of the write-off of the respective deferred financing costs.

Consolidated Statement of Chang

Consolidated Statement of Changes in Member's Equity - USD ($) shares in Millions, $ in Millions		Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital	Foreign Currency Translation Adjustments	Dividends/Distributions in Excess of Earnings	6.875% Mandatory Convertible Preferred Stock [Member]	Common Class A [Member]	Common Class A [Member]Common Stock [Member]	Common Class A [Member]Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding			2
Accumulated other Comprehensive Income (Loss), Net of Tax						$ (4)
Balance, value at Dec. 31, 2017		$ 11,925	$ 0	$ 4	$ 16,844		$ (4,919)
Balance, (in shares) at Dec. 31, 2017				406
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity, net of forfeitures, value		116			116
Stock-based compensation related activity, net of forfeitures, shares				1
Purchases and retirement of capital stock, value		(34)			(34)
Stock Issued During Period, Shares, New Issues										8
Stock Issued During Period, Value, New Issues									$ 841		$ 841
Foreign currency translation adjustments		(1)
Other Comprehensive Income (Loss), Net of Tax	[1]	(1)				(1)
Common stock dividends/distributions		(1,785)					(1,785)
Preferred stock dividends/distributions		(113)					(113)
Net income (loss) attributable to CCIC stockholders		622					622
Balance, value at Dec. 31, 2018		11,571	$ 0	$ 4	17,767		(6,195)
Balance, (in shares) at Dec. 31, 2018				415
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding			2
Accumulated other Comprehensive Income (Loss), Net of Tax						(5)
Stock-based compensation related activity, net of forfeitures, value		132			132
Stock-based compensation related activity, net of forfeitures, shares				1
Purchases and retirement of capital stock, value		(44)			(44)
Foreign currency translation adjustments		0
Other Comprehensive Income (Loss), Net of Tax		0
Common stock dividends/distributions		(1,917)					(1,917)
Preferred stock dividends/distributions		(113)					(113)
Net income (loss) attributable to CCIC stockholders		860					860
Balance, value at Dec. 31, 2019		$ 10,489	$ 0	$ 4	17,855		(7,365)
Balance, (in shares) at Dec. 31, 2019		416		416
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding		2	2
Accumulated other Comprehensive Income (Loss), Net of Tax		$ (5)				(5)
Stock-based compensation related activity, net of forfeitures, value		154			154
Stock-based compensation related activity, net of forfeitures, shares				1
Purchases and retirement of capital stock, value		(76)			(76)
Conversion of Stock, Shares Converted								(2)
Foreign currency translation adjustments		1
Other Comprehensive Income (Loss), Net of Tax	[1]	1				1
Common stock dividends/distributions		(2,106)					(2,106)
Preferred stock dividends/distributions		(57)					(57)
Net income (loss) attributable to CCIC stockholders		1,056					1,056
Balance, value at Dec. 31, 2020		$ 9,461	$ 0	$ 4	$ 17,933		$ (8,472)
Balance, (in shares) at Dec. 31, 2020		431		431
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable preferred stock into Common Stock, shares				14
Convertible Preferred Stock, shares outstanding		0	0
Accumulated other Comprehensive Income (Loss), Net of Tax		$ (4)				$ (4)
[1]	See the consolidated statement of operations and comprehensive income (loss) for the components of "total other comprehensive income (loss)."

Statement of Cash Flows, Supple

Statement of Cash Flows, Supplemental Information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Cash Flow, Supplemental Disclosures [Text Block]	Supplemental Cash Flow Information The following table is a summary of the supplemental cash flow information during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, 2020 2019 2018 Supplemental disclosure of cash flow information: Cash payments related to operating lease liabilities (a) $ 538 $ 541 $ — Interest paid 653 661 619 Income taxes paid 19 16 17 Supplemental disclosure of non-cash investing and financing activities: New ROU assets obtained in exchange for operating lease liabilities 627 431 — Increase in accounts payable for purchases of property and equipment 27 2 29 Purchase of property and equipment under finance leases and installment land purchases 33 33 40 (a) Excludes the Company's contingent payments pursuant to operating leases, which are recorded as expense in the period such contingencies are resolved. The reconciliation of cash, cash equivalents, and restricted cash reported within various lines on the consolidated balance sheet to amounts reported in the consolidated statement of cash flows is shown below. As of December 31, 2020 2019 2018 Cash and cash equivalents $ 232 $ 196 $ 277 Restricted cash, current 144 137 131 Restricted cash reported within other assets, net 5 5 5 Cash, cash equivalents and restricted cash $ 381 $ 338 $ 413

Statement of Cash Flows, Supp_2

Statement of Cash Flows, Supplemental Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information and Non-cash Investing and Financing Activities	The following table is a summary of the supplemental cash flow information during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, 2020 2019 2018 Supplemental disclosure of cash flow information: Cash payments related to operating lease liabilities (a) $ 538 $ 541 $ — Interest paid 653 661 619 Income taxes paid 19 16 17 Supplemental disclosure of non-cash investing and financing activities: New ROU assets obtained in exchange for operating lease liabilities 627 431 — Increase in accounts payable for purchases of property and equipment 27 2 29 Purchase of property and equipment under finance leases and installment land purchases 33 33 40 (a) Excludes the Company's contingent payments pursuant to operating leases, which are recorded as expense in the period such contingencies are resolved.
Schedule of Cash, Cash Equivalents and Restricted Cash [Table Text Block]	The reconciliation of cash, cash equivalents, and restricted cash reported within various lines on the consolidated balance sheet to amounts reported in the consolidated statement of cash flows is shown below. As of December 31, 2020 2019 2018 Cash and cash equivalents $ 232 $ 196 $ 277 Restricted cash, current 144 137 131 Restricted cash reported within other assets, net 5 5 5 Cash, cash equivalents and restricted cash $ 381 $ 338 $ 413

Statement of Cash Flows, Supp_3

Statement of Cash Flows, Supplemental Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash payments related to operating lease liabilities	[1]	$ 538	$ 541	$ 0
Interest paid		653	661
Interest paid				619
Income taxes paid (refund)		19	16	17
New ROU assets obtained in exchange for operating lease liabilities		627	431	0
Increase (Decrease) in accounts payable for purchases of property and equipment		27	2	29
Purchase of property and equipment under capital leases and installment purchases		33	33	40
Cash and cash equivalents		232	196	277
Restricted cash		144	137	131
Restricted Cash, Noncurrent		5	5	5
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 381	$ 338	$ 413
[1]	Excludes the Company's contingent payments pursuant to operating leases, which are recorded as expense in the period such contingencies are resolved.

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Basis of Presentation [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Crown Castle International Corp. and its predecessor, as applicable (together, "CCIC"), and their subsidiaries, collectively referred to herein as the "Company." All significant intercompany balances and transactions have been eliminated in consolidation. As used herein, the term "including," and any variation thereof, means "including without limitation." The use of the word "or" herein is not exclusive. Unless the context suggests otherwise, references to "U.S." are to the United States of America and Puerto Rico, collectively. The Company owns, operates and leases shared communications infrastructure that is geographically dispersed throughout the U.S., including (1) towers and other structures, such as rooftops (collectively, "towers"), and (2) fiber primarily supporting small cell networks ("small cells") and fiber solutions. The Company's towers, fiber and small cells assets are collectively referred to herein as "communications infrastructure," and the Company's customers on its communications infrastructure are referred to herein as "tenants." The Company's core business is providing access, including space or capacity, to its shared communications infrastructure via long-term contracts in various forms, including lease, license, sublease and service agreements (collectively, "tenant contracts"). The Company's operating segments consist of (1) Towers and (2) Fiber. See note 14. Approximately 53% of the Company's towers are leased or subleased or operated and managed under master leases, subleases, and other agreements with AT&T and T-Mobile, including agreements assumed by T-Mobile following its merger with Sprint, completed on April 1, 2020. The Company has the option to purchase these towers at the end of their respective lease terms. The Company has no obligation to exercise such purchase options. Additional information concerning these towers is as follows: ◦ 22% of the Company's towers are leased or subleased or operated and managed under a master prepaid lease or other related agreements with AT&T for a weighted-average initial term of approximately 28 years, weighted on Towers site rental gross margin. The Company has the option to purchase the leased and subleased towers from AT&T at the end of the respective lease or sublease terms for aggregate option payments of approximately $4.2 billion, which payments, if such option is exercised, would be due between 2032 and 2048. ◦ 16% of the Company's towers are leased or subleased or operated and managed for an initial period of 32 years (through May 2037) under master leases, subleases, or other agreements with T-Mobile (which T-Mobile assumed in connection with its merger with Sprint). The Company has the option to purchase in 2037 all (but not less than all) of such leased and subleased towers from T-Mobile for approximately $2.3 billion. ◦ 15% of the Company's towers are leased or subleased or operated and managed under a master prepaid lease or other related agreements with T-Mobile for a weighted-average initial term of approximately 28 years, weighted on Towers site rental gross margin. The Company has the option to purchase the leased and subleased towers from T-Mobile at the end of the respective lease or sublease terms for aggregate option payments of approximately $2.0 billion, which payments, if such option is exercised, would be due between 2035 and 2049. In addition, through the acquisition of the rights to approximately 7,100 towers ("T-Mobile Acquisition"), there are another 1% of the Company's towers subject to a lease and sublease or other related arrangements with AT&T. The Company has the option to purchase these towers that it does not otherwise already own at the end of their respective lease terms for aggregate option payments of up to approximately $405 million, which payments, if such option is exercised, would be due prior to 2032 (less than $10 million would be due before 2025). As part of the Company's effort to provide comprehensive communications infrastructure solutions, as an ancillary business, the Company also offers certain services primarily relating to its Towers segment, predominately consisting of (1) site development services primarily relating to existing or new tenant equipment installations, including: site acquisition, architectural and engineering, or zoning and permitting (collectively, "site development services") and (2) tenant equipment installation or subsequent augmentations (collectively, "installation services"). The Company operates as a REIT for U.S. federal income tax purposes. In addition, the Company has certain taxable REIT subsidiaries ("TRSs"). See note 9.

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The following is a discussion of the Company's significant accounting policies in effect for the year ended December 31, 2020. Restricted Cash Restricted cash represents (1) the cash held in reserve by the indenture trustees pursuant to the indenture governing certain of the Company's debt instruments, (2) cash securing performance obligations such as letters of credit, as well as (3) any other cash whose use is limited by contractual provisions. The restriction of rental cash receipts is a critical feature of certain of the Company's debt instruments, due to the applicable indenture trustee's ability to utilize the restricted cash for the payment of (1) debt service costs, (2) ground rents, (3) real estate or personal property taxes, (4) insurance premiums related to towers, (5) other assessments by governmental authorities and potential environmental remediation costs, or (6) a portion of advance rents from tenants. The restricted cash in excess of required reserve balances is subsequently released to the Company in accordance with the terms of the indentures. See note 16 for a reconciliation of cash, cash equivalents and restricted cash. Receivables Allowance An allowance for doubtful accounts is recorded as an offset to accounts receivable. The Company uses judgment in estimating this allowance and considers historical collections, current credit status, or contractual provisions. Additions to the allowance for doubtful accounts are charged either to "Site rental costs of operations" or to "Services and other costs of operations," as appropriate, and deductions from the allowance are recorded when specific accounts receivable are written off as uncollectible. Lease Accounting Effective January 1, 2019, the Company adopted new guidance on the recognition, measurement, presentation and disclosure of leases (commonly referred to as "ASC 842" or the "new lease standard") using a modified retrospective approach as of the effective date without adjusting the comparative periods. General. The Company evaluates whether a contract meets the definition of a lease whenever a contract grants a party the right to control the use of an identified asset for a period of time in exchange for consideration. To the extent the identified asset is able to be shared among multiple parties, the Company has determined that one party does not have control of the identified asset and the contract is not considered a lease. The Company accounts for contracts that do not meet the definition of a lease under other relevant accounting guidance (such as ASC 606 for revenue from contracts with customers). Lessee. For its Tower segment, the Company's lessee arrangements primarily consist of ground leases for land under towers. Ground leases for land are specific to each site, generally contain an initial term of five to 10 years and are renewable (and cancelable after a notice period) at the Company's option. The Company also enters into term easements and ground leases in which it prepays the entire term. For its Fiber segment, the Company's lessee arrangements primarily include leases of fiber assets to support the Company's small cells and fiber solutions. The majority of the Company's lease agreements have certain termination rights that provide for cancellation after a notice period and multiple renewal options exercisable at the Company's option. The Company includes renewal option periods in its calculation of the estimated lease term when it determines the options are reasonably certain to be exercised. When such renewal options are deemed to be reasonably certain, the estimated lease term determined under ASC 842 will be greater than the non-cancelable term of the contractual arrangement. Although certain renewal periods are included in the estimated lease term, the Company would have the ability to terminate or elect to not renew a particular lease if business conditions warrant such a decision. The Company classifies its lessee arrangements at inception as either operating leases or finance leases. A lease is classified as a finance lease if at least one of the following criteria is met: (1) the lease transfers ownership of the underlying asset to the lessee, (2) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) the lease term is for a major part of the remaining economic life of the underlying asset, (4) the present value of the sum of the lease payments equals or exceeds substantially all of the fair value of the underlying asset, or (5) the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. A lease is classified as an operating lease if none of the five criteria described above for finance lease classification is met. Right-of-use ("ROU") assets associated with operating leases are included in "Operating lease right-of-use assets" on the Company's consolidated balance sheet. Current and long-term portions of lease liabilities related to operating leases are included in "Current portion of operating lease liabilities" and "Operating lease liabilities" on the Company's consolidated balance sheet, respectively. ROU assets represent the Company's right to use an underlying asset for the estimated lease term and lease liabilities represent the Company's present value of its future lease payments. In assessing its leases and determining its lease liability at lease commencement or upon modification, the Company is not able to readily determine the rate implicit for its lessee arrangements, and thus uses its incremental borrowing rate on a collateralized basis to determine the present value of the lease payments. The Company's ROU assets are measured as the balance of the lease liability plus any prepaid or accrued lease payments and any unamortized initial direct costs. For both the Towers and Fiber segments, operating lease expenses are recognized on a ratable basis, regardless of whether the payment terms require the Company to make payments annually, quarterly, monthly, or for the entire term in advance. Certain of the Company's ground lease and fiber lease agreements contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the change in consumer price index ("CPI")). If the payment terms include fixed escalator provisions, the effect of such increases is recognized on a straight-line basis. The Company calculates the straight-line expense over the tenant contract's estimated lease term, including any renewal option periods that the Company deems reasonably certain to be exercised. Lease agreements may also contain provisions for a contingent payment based on (1) the revenues derived from the communications infrastructure located on the leased asset, (2) the change in CPI or (3) the usage of the leased asset. The Company's contingent payments are considered variable lease payments and are (1) not included in the initial measurement of the ROU asset or lease liability due to the uncertainty of the payment amount and (2) recorded as expense in the period such contingencies are resolved. ROU assets associated with finance leases are included in "Property and equipment, net" on the Company's consolidated balance sheet. Lease liabilities associated with finance leases are included in "Current maturities of debt and other obligations" and "Debt and other long-term obligations" on the Company's consolidated balance sheet. For both its Towers and Fiber segments, the Company measures the lease liability for finance leases using the effective interest method. The initial lease liability is increased to reflect interest on the liability and decreased to reflect payments made during the period. Interest on the lease liability is determined each period during the lease term as the amount that results in a constant periodic discount rate on the remaining balance of the liability. The Company measures ROU assets for finance leases on a ratable basis over the applicable lease term. The Company reviews the carrying value of its ROU assets for impairment, similar to its other long-lived assets, whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable. The Company could record impairments in the future if there are changes in (1) long-term market conditions, (2) expected future operating results or (3) the utility of the assets that negatively impact the fair value of its ROU assets. Lessor. The Company's lessor arrangements primarily include tenant contracts for dedicated space (including dedicated fiber) on its shared communications infrastructure. The Company classifies its leases at inception as operating, direct financing or sales-type leases. A lease is classified as a sales-type lease if at least one of the following criteria is met: (1) the lease transfers ownership of the underlying asset to the lessee, (2) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) the lease term is for a major part of the remaining economic life of the underlying asset, (4) the present value of the sum of the lease payments equals or exceeds substantially all of the fair value of the underlying assets or (5) the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. Furthermore, when none of the above criteria is met, a lease is classified as a direct financing lease if both of the following criteria are met: (1) the present value of the of the sum of the lease payments and any residual value guaranteed by the lessee, that is not already reflected in the lease payments, equals or exceeds the fair value of the underlying asset and (2) it is probable that the lessor will collect the lease payments plus any amount necessary to satisfy a residual value guarantee. A lease is classified as an operating lease if it does not qualify as a sales-type or direct financing lease. Currently, the Company classifies all of its lessor arrangements as operating leases. Site rental revenues from the Company’s lessor arrangements are recognized on a straight-line, ratable basis over the fixed, non-cancelable term of the relevant tenant contract, regardless of whether the payments from the tenant are received in equal monthly amounts during the life of a tenant contract. Certain of the Company's tenant contracts contain fixed escalation clauses (such as fixed-dollar or fixed-percentage increases) or inflation-based escalation clauses (such as those tied to the change in CPI). If the payment terms call for fixed escalations, upfront payments, or rent-free periods, the rental revenue is recognized on a straight-line basis over the fixed, non-cancelable term of the agreement. When calculating straight-line site rental revenues, the Company considers all fixed elements of tenant contractual escalation provisions. Certain of the Company's arrangements with tenants in its Fiber segment contain both lease and non-lease components. In such circumstances, the Company has determined (1) the timing and pattern of transfer for the lease and non-lease component are the same and (2) the stand-alone lease component would be classified as an operating lease. As such, the Company has aggregated certain non-lease components with lease components and has determined that the lease components (generally dedicated fiber) represent the predominant component of the arrangement. Property and Equipment Property and equipment is stated at cost, net of accumulated depreciation. Property and equipment includes land owned in fee and perpetual easements for land, which have no definite life. Depreciation is computed utilizing the straight-line method at rates based upon the estimated useful lives of the various classes of assets. Depreciation of communications infrastructure is generally computed with a useful life equal to the shorter of 20 years or the term of the underlying ground lease (including optional renewal periods). Additions and permanent improvements to the Company's communications infrastructure are capitalized, while maintenance and repairs are expensed. Labor and interest costs incurred directly related to the construction of certain property and equipment are capitalized during the construction phase of projects. For the years ended December 31, 2020, 2019 and 2018, the Company had $270 million, $246 million and $212 million in capitalized labor costs, respectively. The carrying value of property and equipment is reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Abandonments and write-offs of property and equipment are recorded to "Asset write-down charges" on the Company's consolidated statement of operations and comprehensive income (loss) and were $77 million, $17 million and $22 million for the years ended December 31, 2020, 2019 and 2018, respectively. Asset write-down charges for the year ended December 31, 2020 included the write-off of property and equipment of approximately $63 million which, following the Sprint Cancellation, was deemed to have no alternative future use. See note 15 for further information regarding the Sprint Cancellation. Asset Retirement Obligations Pursuant to its ground lease, easement and leased facility agreements, the Company records obligations to perform asset retirement activities, including requirements to remove communications infrastructure or remediate the space on which certain of its communications infrastructure is located. The Company does not record an obligation for asset retirement activities related to its fiber, as a settlement date is indeterminable and therefore a reasonable estimation of fair value cannot be made. Asset retirement obligations are included in "Other long-term liabilities" on the Company's consolidated balance sheet. The liability accretes as a result of the passage of time and the related accretion expense is included in "Depreciation, amortization and accretion" on the Company's consolidated statement of operations and comprehensive income (loss). The associated asset retirement costs are capitalized as an additional carrying amount of the related long-lived asset and depreciated over the useful life of such asset. Goodwill Goodwill represents the excess of the purchase price for an acquired business over the allocated value of the related net assets. The Company tests goodwill for impairment on an annual basis, regardless of whether adverse events or changes in circumstances have occurred. The annual test begins with goodwill and all intangible assets being allocated to applicable reporting units. The Company's reporting units are the same as its operating segments (Towers and Fiber). The Company then performs a qualitative assessment to determine whether it is "more likely than not" that the fair value of the reporting units is less than its carrying amount. If the Company concludes it is "more likely than not" that the fair value of a reporting unit is less than its carrying amount, it is necessary to perform a quantitative goodwill impairment test. The quantitative goodwill impairment test compares the estimated fair value of the reporting unit and the carrying value of the reporting unit. If the carrying amount of a reporting unit is greater than its fair value, an impairment loss shall be recognized in an amount equal to such excess, limited to the total amount of goodwill allocated to the reporting unit. The Company performed its most recent annual goodwill impairment test as of October 1, 2020, which resulted in no impairments. See "Recently Adopted Accounting Pronouncements" for a discussion of the recently adopted new guidance related to goodwill impairment evaluation. Intangible Assets Intangible assets are included in "Site rental contracts and tenant relationships, net" and "Other intangible assets, net" on the Company's consolidated balance sheet and predominately consist of the estimated fair value of site rental contracts and tenant relationships or other contractual rights, such as trademarks, that are recorded in conjunction with acquisitions. The site rental contracts and tenant relationships intangible assets are comprised of (1) the current term of the existing leases, (2) the high rate of tenant retention, and (3) any associated relationships that are expected to generate value following the expiration of all renewal periods under existing leases. The useful lives of intangible assets are estimated based on the period over which the intangible asset is expected to benefit the Company and gives consideration to the expected useful life of other assets to which the useful life may relate. Amortization expense for intangible assets is computed using the straight-line method over the estimated useful life of each of the intangible assets. The useful life of the site rental contracts and tenant relationships intangible asset is limited by the maximum depreciable life of the communications infrastructure (20 years), as a result of the interdependency of the communications infrastructure and site rental leases. In contrast, the site rental contracts and tenant relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of tenant retention experienced to date. Thus, while site rental contracts and tenant relationships are valued based upon the fair value, which includes assumptions regarding both (1) tenants' exercise of optional renewals contained in the acquired leases and (2) renewals of the acquired leases past the contractual term including exercisable options, the site rental contracts and tenant relationships are amortized over a period not to exceed 20 years. The carrying value of other intangible assets with finite useful lives will be reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. The Company has a dual grouping policy for purposes of determining the unit of account for testing impairment of the site rental contracts and tenant relationships intangible assets. First, the Company pools the site rental contracts and tenant relationships with the related communications infrastructure assets into portfolio groups for purposes of determining the unit of account for impairment testing. Second and separately, the Company evaluates the site rental contracts and tenant relationships by significant tenant or by tenant grouping for individually insignificant tenants, as appropriate. If the sum of the estimated future cash flows (undiscounted) expected to result from the use or eventual disposition of an asset is less than the carrying amount of the asset, an impairment loss is recognized. Measurement of an impairment loss is based on the fair value of the asset. Deferred Credits Deferred credits are included in "Deferred revenues" and "Other long-term liabilities" on the Company's consolidated balance sheet and consist of the estimated fair value of below-market tenant leases for contractual interests with tenants on acquired communications infrastructure, which are amortized to site rental revenues. Fair value for these deferred credits represents the difference between (1) the stated contractual payments to be made pursuant to the in-place lease and (2) management's estimate of fair market lease rates for each corresponding lease. Deferred credits are measured over a period equal to the estimated remaining economic lease term considering renewal provisions or economics associated with those renewal provisions, to the extent applicable. Deferred credits are amortized over their respected estimated lease terms at the time of acquisition. Deferred Financing Costs Third-party costs incurred to obtain financing, with the exception of costs incurred related to revolving lines of credit, are deferred and are included as a direct deduction from the carrying amount of the related debt liability in "Debt and other long-term obligations" on the Company's consolidated balance sheet. Third party costs incurred to obtain financing through a revolving line of credit are deferred and are included in "Other assets, net" on the Company's consolidated balance sheet. Revenue Recognition The Company generates site rental revenues from its core business by providing tenants with access, including space or capacity, to its shared communications infrastructure via long-term tenant contracts in various forms, including lease, license, sublease and service agreements. Providing such access over the length of the tenant contract term represents the Company’s sole performance obligation under its tenant contracts. Site rental revenues. Site rental revenues from the Company's tenant contracts are recognized on a straight-line, ratable basis over the fixed, non-cancelable term of the relevant tenant contract, which generally ranges from five to 15 years for wireless tenants and three to 20 years for the Company's fiber solutions tenants (including from organizations with high-bandwidth and multi-location demands), regardless of whether the payments from the tenant are received in equal monthly amounts during the life of the tenant contract. Certain of the Company's tenant contracts contain (1) fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the CPI), (2) multiple renewal periods exercisable at the tenant's option and (3) only limited termination rights at the applicable tenant's option through the current term. If the payment terms call for fixed escalations, upfront payments, or rent-free periods, the revenue is recognized on a straight-line basis over the fixed, non-cancelable term of the agreement. When calculating straight-line rental revenues, the Company considers all fixed elements of tenant contractual escalation provisions, even if such escalation provisions contain a variable element in addition to a minimum. The Company's assets related to straight-line site rental revenues include current amounts of $152 million and $114 million included in "Other current assets" and non-current amounts of $1.4 billion and $1.4 billion included in "Deferred site rental receivables" for the years ended December 31, 2020 and 2019, respectively. Amounts billed or received prior to being earned are deferred and reflected in "Deferred revenues" and "Other long-term liabilities." Amounts to which the Company has an unconditional right to payment, which are related to both satisfied or partially satisfied performance obligations, are recorded within "Receivables, net" on the Company's consolidated balance sheet. Services and other revenues. As part of the Company’s effort to provide comprehensive communications infrastructure solutions, as an ancillary business, the Company offers certain services primarily relating to its Towers segment, predominately consisting of (1) site development services and (2) installation services. Upon contract commencement, the Company assesses its services to tenants and identifies performance obligations for each promise to provide a distinct service. The Company may have multiple performance obligations for site development services, which primarily include: structural analysis, zoning, permitting and construction drawings. For each of the above performance obligations, services revenues are recognized at completion of the applicable performance obligation, which represents the point at which the Company believes it has transferred goods or services to the tenant. The revenue recognized is based on an allocation of the transaction price among the performance obligations in a respective contract based on estimated standalone selling price. The volume and mix of site development services may vary among contracts and may include a combination of some or all of the above performance obligations. Payments generally are due within 45 to 60 days and generally do not contain variable-consideration provisions. The transaction price for the Company's tower installation services consists of amounts for (1) permanent improvements to the Company's towers that represent a lease component and (2) the performance of the service. Amounts under the Company's tower installation service agreements that represent a lease component are recognized as site rental revenues on a straight-line basis over the length of the associated estimated lease term. For the performance of the installation service, the Company has one performance obligation, which is satisfied at the time of the applicable installation or augmentation and recognized as services and other revenues. Since performance obligations are typically satisfied prior to receiving payment from tenants, the unconditional right to payment is recorded within "Receivables, net" on the Company’s condensed consolidated balance sheet. The vast majority of the Company’s services generally have a duration of one year or less. Additional information on revenues. As of January 1, 2020 and December 31, 2020, a total of $2.9 billion and $2.8 billion of unrecognized revenue, respectively, was reported in "Deferred revenues" and "Other non-current liabilities" on the Company's consolidated balance sheet. During the year ended December 31, 2020, approximately $575 million of the January 1, 2020 unrecognized revenue balance was recognized as revenue. As of January 1, 2019, a total of $2.7 billion of unrecognized revenue was reported in "Deferred revenues" and "Other non-current liabilities" on the Company's consolidated balance sheet. During the year ended December 31, 2019, approximately $510 million of the January 1, 2019 unrecognized revenue balance was recognized as revenue. See note 3 for further discussion regarding the Company’s revenues. Costs of Operations Approximately half of the Company's site rental costs of operations expenses consist of Towers ground lease expenses, and the remainder includes fiber access expenses, property taxes, repairs and maintenance expenses, employee compensation or related benefit costs, or utilities. Generally, the ground leases for land are specific to each site and are for an initial term of five years and are renewable for pre-determined periods. The Company also enters into term easements and ground leases in which it prepays the entire term in advance. Fiber access expenses primarily consist of leases of fiber assets and other access agreements to facilitate the Company's communications infrastructure. Ground lease and fiber access expenses are recognized on a ratable basis, regardless of whether the payment terms require the Company to make payments annually, quarterly, monthly, or for the entire term in advance. Certain of the Company's ground lease and fiber access agreements contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the change in CPI). If the payment terms include fixed escalator provisions, the effect of such increases is recognized on a straight-line basis. The Company's liability related to straight-line expense is included in "Operating lease right-of-use assets" on the Company's consolidated balance sheet. The Company's assets related to prepaid agreements is included in "Prepaid expenses" and "Operating lease right-of-use assets" on the Company's consolidated balance sheet. Services and other costs of operations predominately consist of third-party service providers such as contractors and professional services firms and, to a lesser extent, internal labor costs. The Company recognized $20 million as costs of operations during the year ended December 31, 2020 as a result of a reduction in staffing completed during the fourth quarter of 2020. Such costs were comprised of employee severance payments and termination benefits and primarily impacted the Company's Fiber segment. Acquisitions and Integration Costs Direct or incremental costs related to a potential or completed business combination transaction are expensed as incurred. Such costs are predominately comprised of severance, retention bonuses payable to employees of an acquired enterprise, temporary employees to assist with the integration of the acquired operations, fees paid for services (such as consulting, accounting, legal, or engineering reviews), and any other costs directly associated with the transaction. These business combination costs are included in "Acquisition and integration costs" on the Company's consolidated statement of operations and comprehensive income (loss). For those transactions accounted for as asset acquisitions, these costs are capitalized as part of the purchase price. Stock-Based Compensation Restricted Stock Units. The Company records stock-based compensation expense only for those unvested restricted stock units ("RSUs") for which the requisite service is expected to be rendered. The cumulative effect of a change in the estimated number of RSUs for which the requisite service is expected to be or has been rendered is recognized in the period of the change in the estimate. To the extent that the requisite service is rendered, compensation cost for accounting purposes is not reversed; rather, it is recognized regardless of whether or not the awards vest. A discussion of the Company's valuation techniques and related assumptions and estimates used to measure the Company's stock-based compensation is as follows: Valuation. The fair value of RSUs without market conditions is determined based on the number of shares relating to such RSUs and the quoted price of the Company's common stock at the date of grant. The Company estimates the fair value of RSUs with market conditions granted using a Monte Carlo simulation. The Company's determination of the fair value of RSUs with market conditions on the date of grant is affected by its common stock price as well as assumptions regarding a number of highly complex or subjective variables. The determination of fair value using a Monte Carlo simulation requires the input of subjective assumptions, and other reasonable assumptions could provide differing results. Amortization Method. The Company amortizes the fair value of all RSUs on a straight-line basis for each separately vesting tranche of the award (graded vesting schedule) over the requisite service periods. Expected Volatility. The Company estimates the volatility of its common stock at the date of grant based on the historical volatility of its common stock. Expected Dividend Rate. The expected dividend rate at the date of grant is based on the then-current dividend yield. Risk-Free Rate. The Company bases the risk-free rate on the implied yield currently available on U.S. Treasury issues with an equivalent remaining term equal to the expected life of the award. Forfeitures. The Company uses historical data and management's judgment about the future employee turnover rates to estimate the number of shares for which the requisite service period will not be rendered. Interest Expense and Amortization of Deferred Financing Costs The components of interest expense and amortization of deferred financing costs are as follows: Years Ended December 31, 2020 2019 2018 Interest expense on debt obligations $ 683 $ 682 $ 635 Amortization of deferred financing costs and adjustments on long-term debt, net 23 21 21 Capitalized interest (17) (20) (15) Other — — 1 Total $ 689 $ 683 $ 642 The Company amortizes deferred financing costs, discounts and premiums over the estimated term of the related borrowing using the effective interest yield method. Deferred financing costs and discounts are generally presented as a direct reduction to the related debt obligation on the Company's consolidated balance sheet. Income Taxes The Company operates as a REIT for U.S. federal income tax purposes. As a REIT, the Company is generally entitled to a deduction for dividends that it pays and therefore is not subject to U.S. federal corporate income tax on its net taxable income that is currently distributed to its stockholders. The Company also may be subject to certain federal, state, local and foreign taxes on its income and assets, including (1) taxes on any undistributed income, (2) taxes related to the TRSs, (3) franchise taxes, (4) property taxes, and (5) transfer taxes. In

Revenue (Notes)

Revenue (Notes)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenues The following table is a summary of the contracted amounts owed to the Company by tenants pursuant to tenant contracts in effect as of December 31, 2020. As of December 31, 2020, the weighted-average remaining term of tenant contracts is approximately five years, exclusive of renewals exercisable at the tenant's option. Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total Contracted amounts (a) $ 4,354 $ 4,153 $ 3,564 $ 2,875 $ 2,380 $ 9,560 $ 26,886 (a) Based on the nature of the contract, tenant contracts are accounted for pursuant to relevant lease accounting (ASC 842) or revenue accounting (ASC 606) guidance. Excludes amounts related to services, as those contracts generally have a duration of one year or less. See notes 2 and 13 for further discussion regarding the Company's lessor arrangements and note 14 for further information regarding the Company's operating segments.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment The major classes of property and equipment are summarized in the table below. Estimated Useful Lives As of December 31, 2020 2019 Land (a) — $ 2,171 $ 2,080 Buildings 40 years 147 147 Communications infrastructure assets 1-20 years 22,027 20,521 Information technology assets and other 2-7 years 557 506 Construction in process — 1,063 1,080 Total gross property and equipment 25,965 24,334 Less: accumulated depreciation (10,803) (9,668) Total property and equipment, net $ 15,162 $ 14,666 (a) Includes land owned through fee interests and perpetual easements.

Intangible Assets, Goodwill and

Intangible Assets, Goodwill and Other	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill There were no changes in the carrying value of goodwill during the years ended December 31, 2020 and 2019. Intangibles The following is a summary of the Company's intangible assets. As of December 31, 2020 As of December 31, 2019 Gross Carrying Value Accumulated Amortization Net Book Value Gross Carrying Value Accumulated Amortization Net Book Value Site rental contracts and tenant relationships $ 7,797 $ (3,432) $ 4,365 $ 7,761 $ (2,997) $ 4,764 Other intangible assets 143 (75) 68 143 (71) 72 Total $ 7,940 $ (3,507) $ 4,433 $ 7,904 $ (3,068) $ 4,836 Amortization expense related to intangible assets is classified as follows on the Company's consolidated statement of operations and comprehensive income (loss): For Years Ended December 31, Classification 2020 2019 2018 Depreciation, amortization and accretion $ 439 $ 428 $ 428 Site rental costs of operations (a) — — 17 Total amortization expense $ 439 $ 428 $ 445 (a) Amortization expense of intangible assets classified as "Site rental costs of operations" on the Company's consolidated statement of operations and comprehensive income (loss) for the year ended December 31, 2018 represented amortization of below-market leases. Effective January 1, 2019, the Company adopted ASC 842 and these below-market leases were de-recognized and reclassified from "Other intangible assets, net" to the "Operating lease right-of-use assets" on the Company's consolidated balance sheet. The estimated annual amortization expense related to intangible assets for the years ending December 31, 2021 to 2025 is as follows: Years Ending December 31, 2021 2022 2023 2024 2025 Estimated annual amortization $ 444 $ 444 $ 442 $ 393 $ 371

Other Liabilities (Notes)

Other Liabilities (Notes)	12 Months Ended
	Dec. 31, 2020
Other Liabilities [Abstract]
Other Liabilities	Other long-term liabilities The following is a summary of the components of "Other long-term liabilities" as presented on the Company's consolidated balance sheet. See also note 2. December 31, 2020 2019 Deferred rental revenues $ 1,707 $ 1,814 Deferred credits, net 375 434 Asset retirement obligation 259 227 Deferred income tax liabilities 11 8 Other long-term liabilities 27 33 Total $ 2,379 $ 2,516 Pursuant to its ground lease, easement and leased facility agreements, the Company has the obligation to perform certain asset retirement activities, including requirements upon contract termination to remove communications infrastructure or remediate the space on which its communications infrastructure is located. Accretion expense related to liabilities for retirement obligations amounted to $18 million, $15 million and $14 million for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, the estimated undiscounted future cash outlay for asset retirement obligations was approximately $1.0 billion. See note 2. For the year ended December 31, 2018, the Company recorded $18 million as a decrease to "Site rental costs of operations" for the amortization of above-market leases for land under the Company's towers. Effective January 1, 2019, the Company adopted ASC 842 and these above-market leases were de-recognized and reclassified from "Other long-term liabilities" into the "Operating lease right-of-use assets" on the Company's consolidated balance sheet. For the years ended December 31, 2020, 2019 and 2018, the Company recognized $58 million, $65 million and $69 million, respectively, in "Site rental revenues" related to the amortization of below-market tenant leases. The following table summarizes the estimated annual amounts related to below-market tenant leases expected to be amortized into site rental revenues for the years ending December 31, 2021 to 2025 are as follows: Years Ending December 31, 2021 2022 2023 2024 2025 Below-market tenant leases $ 53 $ 48 $ 45 $ 41 $ 33 Other accrued liabilities Other accrued liabilities included accrued payroll and other accrued compensation of $192 million and $174 million, respectively, as of December 31, 2020 and 2019.

Debt and Other Obligations

Debt and Other Obligations	12 Months Ended
	Dec. 31, 2020
Debt and Other Obligations [Abstract]
Debt Disclosure	Debt and Other Obligations See note 17 for a discussion of the Company's issuance of the February 2021 Senior Notes (as defined in note 17) and the use of the net proceeds therefrom. The table below sets forth the Company's debt and other obligations as of December 31, 2020. Original Contractual Outstanding Balance as of December 31, Stated 2020 2019 2020 (a) 3.849% Secured Notes Dec. 2012 Apr. 2023 $ 997 $ 995 3.9 % Secured Notes, Series 2009-1, Class A-2 July 2009 Aug. 2029 60 67 9.0 % Tower Revenue Notes, Series 2015-1 May 2015 May 2042 (b)(c) 299 298 3.2 % Tower Revenue Notes, Series 2018-1 July 2018 July 2043 (b)(c) 248 248 3.7 % Tower Revenue Notes, Series 2015-2 May 2015 May 2045 (b)(c) 695 694 3.7 % Tower Revenue Notes, Series 2018-2 July 2018 July 2048 (b)(c) 743 742 4.2 % Finance leases and other obligations Various Various (d) 236 227 Various (d) Total secured debt 3,278 3,271 2016 Revolver Jan. 2016 June 2024 290 (e) 525 1.3 % (f) 2016 Term Loan A Jan. 2016 June 2024 2,252 2,310 1.3 % (f) Commercial Paper Notes Various (g) Various (g) 285 155 0.5 % 3.400% Senior Notes Feb./May 2016 Feb. 2021 — 850 N/A 2.250% Senior Notes Sept. 2016 Sept. 2021 — 698 N/A 4.875% Senior Notes Apr. 2014 Apr. 2022 — 846 N/A 5.250% Senior Notes Oct. 2012 Jan. 2023 1,646 1,644 5.3 % 3.150% Senior Notes Jan. 2018 July 2023 746 744 3.2 % 3.200% Senior Notes Aug. 2017 Sept. 2024 745 744 3.2 % 1.350% Senior Notes June 2020 July 2025 494 — 1.4 % 4.450% Senior Notes Feb. 2016 Feb. 2026 894 893 4.5 % 3.700% Senior Notes May 2016 June 2026 745 744 3.7 % 4.000% Senior Notes Feb. 2017 Mar. 2027 496 495 4.0 % 3.650% Senior Notes Aug. 2017 Sept. 2027 994 993 3.7 % 3.800% Senior Notes Jan. 2018 Feb. 2028 991 990 3.8 % 4.300% Senior Notes Feb. 2019 Feb. 2029 593 592 4.3 % 3.100% Senior Notes Aug. 2019 Nov. 2029 544 543 3.1 % 3.300% Senior Notes Apr. 2020 July 2030 737 — 3.3 % 2.250% Senior Notes June 2020 Jan. 2031 1,088 — 2.3 % 4.750% Senior Notes May 2017 May 2047 344 344 4.8 % 5.200% Senior Notes Feb. 2019 Feb. 2049 395 395 5.2 % 4.000% Senior Notes Aug. 2019 Nov. 2049 345 345 4.0 % 4.150% Senior Notes Apr. 2020 July 2050 489 — 4.2 % 3.250% Senior Notes June 2020 Jan. 2051 889 — 3.3 % Total unsecured debt $ 16,002 $ 14,850 Total debt and other obligations $ 19,280 $ 18,121 Less: current maturities and short-term debt and other current obligations $ 129 $ 100 Non-current portion of long-term debt and other long-term obligations $ 19,151 $ 18,021 (a) Represents the weighted-average stated interest rate. (b) The Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") and Tower Revenue Notes, Series 2018-1 and 2018-2 ("July 2018 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes." (c) If the respective series of Tower Revenue Notes are not paid in full on or prior to an applicable anticipated repayment date, then Excess Cash Flow (as defined in the indenture governing the terms of such notes) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes, and additional interest (of an additional approximately 5% per annum) will accrue on the respective Tower Revenue Notes. As of December 31, 2019, the Tower Revenue Notes have principal amounts of $300 million, $250 million, $700 million and $750 million, with anticipated repayment dates in 2022, 2023, 2025 and 2028, respectively. (d) The Company's finance leases and other obligations relate to land, fiber, vehicles, and other assets and bear interest rates ranging up to 10% and mature in periods ranging from less than one year to approximately 25 years. (e) As of December 31, 2020, the undrawn availability under the 2016 Revolver was $4.7 billion. (f) Both the 2016 Revolver and 2016 Term Loan A bear interest, at our option, at either (1) LIBOR plus a credit spread ranging from 0.875% to 1.750% per annum or (2) an alternate base rate plus a credit spread ranging from 0.000% to 0.750% per annum, in each case, with the applicable credit spread based on the Company's senior unsecured debt rating. The Company pays a commitment fee ranging from 0.125% to 0.350%, based on the Company's senior unsecured debt rating, per annum on the undrawn available amount under the 2016 Revolver. (g) The maturities of the Commercial Paper Notes, as defined below, when outstanding, may vary but may not exceed 397 days from the date of issue. The credit agreement governing the Company's 2016 Credit Facility contains financial maintenance covenants. The Company is currently in compliance with these financial maintenance covenants, and based upon current expectations, the Company believes it will continue to comply with its financial maintenance covenants. In addition, certain of the Company's debt agreements also contain restrictive covenants that place restrictions on CCIC or its subsidiaries and may limit the Company's ability to, among other things, incur additional debt and liens, purchase the Company's securities, make capital expenditures, dispose of assets, undertake transactions with affiliates, make other investments, pay dividends or distribute excess cash flow. Bank Debt In January 2016, the Company established the 2016 Credit Facility, which was originally comprised of (1) a $2.5 billion 2016 Revolver maturing in January 2021, (2) a $2.0 billion 2016 Term Loan A maturing in January 2021 and (3) a $1.0 billion senior unsecured 364-day revolving credit facility ("364-Day Facility") maturing in January 2017. The Company used the net proceeds from the 2016 Credit Facility (1) to repay the then outstanding 2012 Credit Facility and (2) for general corporate purposes. In February 2016, the Company used a portion of the net proceeds from the February 2016 Senior Notes (as defined below) offering to repay in full all outstanding borrowings under the then outstanding 364-Day Facility. In February 2017, the Company entered into an amendment to the 2016 Credit Facility to (1) incur additional term loans in an aggregate principal amount of $500 million and (2) extend the maturity of both the 2016 Term Loan A and the 2016 Revolver to January 2022. In August 2017, the Company entered into an amendment to the 2016 Credit Facility to (1) increase commitments on the 2016 Revolver by $1.0 billion, for total 2016 Revolver commitments of $3.5 billion, and (2) extend the maturity of the Credit Facility to August 2022. In June 2018, the Company entered into an amendment to the 2016 Credit Facility to (1) increase commitments on the 2016 Revolver by $750 million, for total 2016 Revolver commitments of $4.25 billion, and (2) extend the maturity of the Credit Facility from August 2022 to June 2023. In April 2019, the Company established a commercial paper program ("CP Program"), pursuant to which the Company may issue short-term, unsecured commercial paper notes ("Commercial Paper Notes"). Commercial Paper Notes may be issued, repaid and re-issued from time to time, with an aggregate principal amount of Commercial Paper Notes outstanding under the CP Program at any time not to exceed $1.0 billion. The net proceeds of the Commercial Paper Notes are expected to be used for general corporate purposes. The Commercial Paper Notes are issued under customary terms in the commercial paper market and are issued at a discount from par or, alternatively, can be issued at par and bear varying interest rates on a fixed or floating basis. For the year ended December 31, 2020, the Company had net issuances of $285 million under the CP Program. At any point in time, the Company intends to maintain available commitments under its 2016 Revolver in an amount at least equal to the amount of Commercial Paper Notes outstanding. While any outstanding commercial paper issuances generally have short-term maturities, the Company classifies the outstanding issuances as long-term based on its ability and intent to refinance the outstanding issuances on a long-term basis. In June 2019, the Company entered into an amendment to the 2016 Credit Facility to (1) increase commitments on the 2016 Revolver by $750 million, for total 2016 Revolver commitments of $5.0 billion, and (2) extend the maturity of the Credit Facility from June 2023 to June 2024. Securitized Debt The Tower Revenue Notes and the Secured Notes, Series 2009-1, Class A-2 ("2009 Securitized Notes") (collectively, "Securitized Debt") are obligations of special purpose entities and their direct and indirect subsidiaries (each an "issuer"), all of which are wholly-owned, indirect subsidiaries of CCIC. The Tower Revenue Notes and 2009 Securitized Notes are governed by separate indentures. The May 2015 Tower Revenue Notes and July 2018 Tower Revenue Notes (each as defined below) are governed by one indenture and consist of multiple series of notes, each with its own anticipated repayment date. In May 2015, the Company issued $1.0 billion aggregate principal amount of Senior Secured Tower Revenue Notes ("May 2015 Tower Revenue Notes"), which were issued pursuant to the existing indenture and have similar terms and security as the Company's then outstanding Tower Revenue Notes. The May 2015 Tower Revenue Notes consist of (1) $300 million aggregate principal amount of 3.222% senior secured tower revenue notes with an anticipated repayment date of May 2022 and a final maturity date of May 2042 and (2) $700 million aggregate principal amount of 3.663% senior secured tower revenue notes with an anticipated repayment date of May 2025 and a final maturity date of May 2045. The Company primarily used the net proceeds of the May 2015 Tower Revenue Notes, together with proceeds received from the Company's sale of the formerly 77.6% owned subsidiary that operated towers in Australia ("CCAL"), to (1) repay $250 million aggregate principal amount of the previously outstanding August 2010 Tower Revenue Notes, which had an anticipated repayment date of August 2015, (2) repay all of the then outstanding WCP Secured Wireless Site Contracts Revenue Notes, Series 2010-1 ("WCP Securitized Notes"), (3) repay portions of outstanding borrowings under the 2012 Credit Facility and (4) pay related fees and expenses. In July 2018, the Company issued $1.0 billion aggregate principal amount of Senior Secured Tower Revenue Notes ("July 2018 Tower Revenue Notes"), which were issued pursuant to the existing indenture and have similar terms and security as the Company's existing Tower Revenue Notes. The July 2018 Tower Revenue Notes consist of (1) $250 million aggregate principal amount of 3.720% senior secured tower revenue notes with an anticipated repayment date of July 2023 and a final maturity of July 2043 and (2) $750 million aggregate principal amount of 4.241% senior secured tower revenue notes with an anticipated repayment date of July 2028 and a final maturity of July 2048. The Company used the net proceeds of the July 2018 Tower Revenue Notes, together with cash on hand, to repay all of the previously outstanding Tower Revenue Notes, Series 2010-6 and to pay related fees and expenses. In addition to the July 2018 Tower Revenue Notes described above, in connection with Exchange Act risk retention requirements ("Risk Retention Rules"), an indirect subsidiary of the Company issued and a majority-owned affiliate of the Company purchased approximately $53 million of the Senior Secured Tower Revenue Notes, Series 2018-1, Class R-2028 to retain an eligible horizontal residual interest (as defined in the Risk Retention Rules) in an amount equal to at least 5% of the fair value of the July 2018 Tower Revenue Notes. The Securitized Debt is paid solely from the cash flows generated by the operation of the towers held directly and indirectly by the issuers of the respective Securitized Debt. The Securitized Debt is secured by, among other things, (1) a security interest in substantially all of the applicable issuers' assignable personal property, (2) a pledge of the equity interests in each applicable issuer and (3) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses). The governing instruments of two indirect subsidiaries ("Crown Atlantic" and "Crown GT") of the issuers of the Tower Revenue Notes generally prevent them from issuing debt and granting liens on their assets without the approval of a subsidiary of Verizon Communications. Consequently, while distributions paid by Crown Atlantic and Crown GT will service the Tower Revenue Notes, the Tower Revenue Notes are not obligations of, nor are the Tower Revenue Notes secured by the cash flows or any other assets of, Crown Atlantic and Crown GT. As of December 31, 2020, the Securitized Debt was collateralized with personal property and equipment with an aggregate net book value of approximately $920 million, exclusive of Crown Atlantic and Crown GT personal property and equipment. The excess cash flows from the issuers of the Securitized Debt, after the payment of principal, interest, reserves, expenses and management fees, are distributed to the Company in accordance with the terms of the indentures. If the Debt Service Coverage Ratio ("DSCR") (as defined in the applicable governing loan agreement) as of the end of any calendar quarter falls to a certain level, then all excess cash flow of the issuers of the applicable debt instrument will be deposited into a reserve account instead of being released to the Company. The funds in the reserve account will not be released to the Company until the DSCR exceeds a certain level for two consecutive calendar quarters. If the DSCR falls below a certain level as of the end of any calendar quarter, then all cash on deposit in the reserve account along with future excess cash flows of the issuers will be applied to prepay the debt with applicable prepayment consideration. The Company may repay the May 2015 Tower Revenue Notes or the 2009 Securitized Notes in whole or in part at any time after the second anniversary of the applicable issuance date and the July 2018 Tower Revenue Notes from the date of issuance, provided in each case that such prepayment is accompanied by any applicable prepayment consideration. The Securitized Debt has covenants and restrictions customary for rated securitizations, including provisions prohibiting the issuers from incurring additional indebtedness or further encumbering their assets. Bonds—Senior Notes In April 2020, the Company issued $1.25 billion aggregate principal amount of senior unsecured notes ("April 2020 Senior Notes"), which consisted of (1) $750 million aggregate principal amount of 3.300% senior unsecured notes due July 2030 and (2) $500 million aggregate principal amount of 4.150% senior unsecured notes due July 2050. The Company used the net proceeds of the April 2020 Senior Notes offering to repay outstanding borrowings under the 2016 Revolver. In June 2020, the Company issued $2.5 billion aggregate principal amount of senior unsecured notes ("June 2020 Senior Notes"), which consisted of (1) $500 million aggregate principal amount of 1.350% senior unsecured notes due July 2025, (2) $1.1 billion aggregate principal amount of 2.250% senior unsecured notes due January 2031 and (3) $900 million aggregate principal amount of 3.250% senior unsecured notes due January 2051. The Company used the net proceeds of the June 2020 Senior Notes offering, together with available cash, to redeem all of the previously outstanding 3.400% Senior Notes, 2.250% Senior Notes and 4.875% Senior Notes. In February 2019, the Company issued $1.0 billion aggregate principal amount of senior unsecured notes ("February 2019 Senior Notes"), which consisted of (1) $600 million aggregate principal amount of 4.300% senior unsecured notes due February 2029 and (2) $400 million aggregate principal amount of 5.200% senior unsecured notes due February 2049. The Company used the net proceeds of the February 2019 Senior Notes offering to repay a portion of the outstanding borrowings under the 2016 Revolver. In August 2019, the Company issued $900 million aggregate principal amount of senior unsecured notes ("August 2019 Senior Notes"), which consisted of (1) $550 million aggregate principal amount of 3.100% senior unsecured notes due November 2029 and (2) $350 million aggregate principal amount of 4.000% senior unsecured notes due November 2049. The Company used the net proceeds of the August 2019 Senior Notes offering to repay outstanding borrowings under the 2016 Revolver and CP Program. In January 2018, the Company issued $750 million aggregate principal amount of 3.150% senior unsecured notes due July 2023 and $1.0 billion aggregate principal amount of 3.800% senior unsecured notes due February 2028 (collectively, "January 2018 Senior Notes"). The Company used the net proceeds of the January 2018 Senior Notes offering to repay (1) in full the January 2010 Tower Revenue Notes and (2) a portion of the outstanding borrowings under the 2016 Revolver. In February 2017, the Company issued $500 million aggregate principal amount of 4.000% senior unsecured notes due March 2027 ("4.000% Senior Notes"). The Company used the net proceeds from the 4.000% Senior Notes offering to repay a portion of the outstanding borrowings under the 2016 Revolver. In May 2017, the Company issued $350 million aggregate principal amount of 4.750% senior unsecured notes due May 2047 ("4.750% Senior Notes"). The Company used the net proceeds from the 4.750% Senior Notes offering to partially fund the 2017 acquisition of Wilcon Holdings LLC and to repay a portion of the outstanding borrowings under the 2016 Revolver. In August 2017, the Company issued $1.75 billion aggregate principal amount of senior unsecured notes ("August 2017 Senior Notes"), which consisted of (1) $750 million aggregate principal amount of 3.200% senior unsecured notes due September 2024 ("3.200% Senior Notes") and (2) $1.0 billion aggregate principal amount of 3.650% senior unsecured notes due September 2027 ("3.650% Senior Notes"). The Company used the net proceeds from the August 2017 Senior Notes offering to partially fund the 2017 acquisition of LTS Group Holdings LLC and pay related fees and expenses. In February 2016, the Company issued $1.5 billion aggregate principal amount of senior unsecured notes ("February 2016 Senior Notes"), which consisted of (1) $600 million aggregate principal amount of 3.400% senior notes due February 2021 ("3.400% Senior Notes") and (2) $900 million aggregate principal amount of 4.450% senior unsecured notes due February 2026 ("4.450% Senior Notes"). The Company used the net proceeds from the February 2016 Senior Notes offering, together with cash on hand, to (1) repay in full all outstanding borrowings under the then outstanding 364-Day Facility and (2) repay $500 million of outstanding borrowings under the 2016 Revolver. In May 2016, the Company issued $1.0 billion aggregate principal amount of senior unsecured notes ("May 2016 Senior Notes"), which consisted of (1) $250 million aggregate principal amount of additional 3.400% Senior Notes pursuant to the same indenture as the 3.400% Senior Notes issued in the February 2016 Senior Notes offering and (2) $750 million aggregate principal amount of 3.700% senior unsecured notes due June 2026 ("3.700% Senior Notes"). The Company used the net proceeds from the May 2016 Senior Notes offering to repay in full the Tower Revenue Notes, Series 2010-2 and Series 2010-5, each issued by certain of its subsidiaries, and to repay a portion of the outstanding borrowings under the 2016 Revolver. In September 2016, the Company issued $700 million aggregate principal amount of 2.250% senior unsecured notes ("2.250% Senior Notes") due September 2021. The Company used the net proceeds from the 2.250% Senior Notes offering to (1) repay $500 million aggregate principal amount of 2.381% secured notes due 2017 ("2.381% Secured Notes") issued by certain of its subsidiaries and (2) repay a portion of the outstanding borrowings under the 2016 Revolver. In April 2014, the Company issued $850 million aggregate principal amount of 4.875% senior unsecured notes due April 2022 ("4.875% Senior Notes"). The net proceeds from the offering were approximately $839 million, after the deduction of associated fees. The Company utilized the net proceeds from the 4.875% Senior Notes offering (1) to repay $300 million of the January 2010 Tower Revenue Notes with an anticipated repayment date of January 2015 and (2) to redeem all of the then outstanding 7.125% senior unsecured notes due 2019. In October 2012, the Company issued $1.65 billion aggregate principal amount of 5.250% senior unsecured notes due 2023 ("5.250% Senior Notes"). The Company used the net proceeds from the 5.250% Senior Notes offering to partially fund the T-Mobile Acquisition. Each of the 5.250% Senior Notes, 4.450% Senior Notes, May 2016 Senior Notes, 4.000% Senior Notes, 4.750% Senior Notes, August 2017 Senior Notes, January 2018 Senior Notes, February 2019 Senior Notes, August 2019 Senior Notes, April 2020 Senior Notes and June 2020 Senior Notes (collectively, "Senior Notes") are senior unsecured obligations of the Company and rank equally with all of the Company's existing and future senior unsecured indebtedness, including obligations under the 2016 Credit Facility, and senior to all of the Company's future subordinated indebtedness. The Senior Notes are structurally subordinated to all existing and future liabilities and obligations of the Company's subsidiaries. The Company's subsidiaries are not guarantors of the Senior Notes. CCIC may redeem any of the Senior Notes in whole or in part at any time at a price equal to 100% of the principal amount to be redeemed, plus a make whole premium, if applicable, and accrued and unpaid interest, if any, to the date of redemption. Bonds—Secured Notes In December 2012, the Company issued $1.0 billion aggregate principal amount of 3.849% secured notes due 2023 ("3.849% Secured Notes"). The 3.849% Secured Notes were issued and are guaranteed by the same subsidiaries of CCIC that had previously issued and guaranteed the 7.750% senior unsecured notes due 2017 ("7.750% Secured Notes"). The 3.849% Secured Notes are secured by a pledge of the equity interests of such subsidiaries. The 3.849% Secured Notes are not guaranteed by and are not obligations of CCIC or any of its subsidiaries other than the issuers and guarantors of the 3.849% Secured Notes. The 3.849% Secured Notes will be paid solely from the cash flows generated from operations of the towers held directly and indirectly by the issuers and the guarantors of such notes. The Company used the net proceeds from the issuance of the 3.849% Secured Notes to repurchase and redeem the then outstanding 7.750% Secured Notes and a portion of the then outstanding 9.000% senior notes due 2011. The 3.849% Secured Notes may be redeemed at any time at a price equal to 100% of the principal amount, plus a make whole premium, and accrued and unpaid interest, if any to the redemption date. Previously Outstanding Indebtedness See above for a discussion of the Company's recent redemptions and repayments of debt. Scheduled Principal Payments and Final Maturities The following are the scheduled principal payments and final maturities of the total debt and other long-term obligations of the Company outstanding as of December 31, 2020, which do not consider the principal payments that will commence following the anticipated repayment dates on the Tower Revenue Notes. If the Tower Revenue Notes are not paid in full on or prior to their respective anticipated repayment dates, as applicable, then the Excess Cash Flow (as defined in the indenture) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes and additional interest (of an additional approximately 5% per annum) will accrue on the Tower Revenue Notes. Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total Cash Obligations Unamortized Adjustments, Net Total Debt and Other Obligations Outstanding Scheduled principal payments and final maturities $ 415 $ 154 $ 3,608 $ 2,941 $ 525 $ 11,780 $ 19,423 $ (143) $ 19,280 Debt Purchases and Redemptions The following is a summary of the purchases and redemptions of debt during the years ended December 31, 2020, 2019 and 2018. Year Ended December 31, 2020 Principal Amount Cash Paid (a) Gains (losses) (b) 3.400% Senior Notes $ 850 $ 863 $ (13) 2.250% Senior Notes 700 714 (16) 4.875% Senior Notes 850 913 (66) Total $ 2,400 $ 2,490 $ (95) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs. Year Ended December 31, 2019 Principal Amount Cash Paid (a) Gains (losses) (b) Secured Notes, Series 2009-1, Class A-1 $ 12 $ 12 $ (1) 2016 Term Loan A — — (1) Total $ 12 $ 12 $ (2) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs. Year Ended December 31, 2018 Principal Amount Cash Paid (a) Gains (losses) (b) Tower Revenue Notes, Series 2010-3 $ 1,250 $ 1,318 $ (71) 2016 Term Loan A — — (3) Tower Revenue Notes, Series 2010-6 1,000 1,028 (32) Total $ 2,250 $ 2,346 $ (106) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs.

Fair Value Disclosures

Fair Value Disclosures	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair Value Disclosures The following table shows the estimated fair values of the Company's financial instruments, along with the carrying amounts of the related assets (liabilities). See also note 2. Level in Fair Value Hierarchy December 31, 2020 December 31, 2019 Carrying Fair Carrying Fair Assets: Cash and cash equivalents 1 $ 232 $ 232 $ 196 $ 196 Restricted cash, current and non-current 1 149 149 142 142 Liabilities: Total debt and other obligations 2 19,280 21,302 18,121 19,170

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income (loss) from continuing operations before income taxes by geographic area is summarized in the table below. Years Ended December 31, 2020 2019 2018 Domestic $ 1,046 $ 850 $ 618 Foreign (a) 30 31 23 Total $ 1,076 $ 881 $ 641 (a) Inclusive of income (loss) before income taxes from Puerto Rico. The benefit (provision) for income taxes consists of the following: Years Ended December 31, 2020 2019 2018 Current: Federal $ (6) $ (6) $ (5) Foreign (6) (8) (7) State (5) (5) (5) Total current (17) (19) (17) Deferred: Foreign (3) (2) (2) Total deferred (3) (2) (2) Total tax benefit (provision) $ (20) $ (21) $ (19) A reconciliation between the benefit (provision) for income taxes and the amount computed by applying the federal statutory income tax rate to the income (loss) before income taxes is as follows: Years Ended December 31, 2020 2019 2018 Benefit (provision) for income taxes at statutory rate $ (225) $ (185) $ (135) Tax effect of foreign income (losses) — 1 1 Tax adjustment related to REIT operations 219 178 128 State tax (provision) benefit, net of federal (5) (5) (4) Foreign tax (9) (10) (9) Total $ (20) $ (21) $ (19) The components of the net deferred income tax assets and liabilities are as follows: December 31, 2020 2019 Deferred income tax liabilities: Property and equipment $ 7 $ 6 Deferred site rental receivable 7 7 Total deferred income tax liabilities 14 13 Deferred income tax assets: Intangible assets 3 3 Net operating loss carryforwards (a) 15 18 Straight-line rent expense liability 3 3 Accrued liabilities 6 5 Other 2 2 Valuation allowances — — Total deferred income tax assets, net 29 31 Net deferred income tax asset (liabilities) $ 15 $ 18 (a) Balance results from the Company's foreign NOLs. Due to the Company's REIT status, no federal or state NOLs result in the Company recording a deferred income tax asset. See further discussion surrounding the Company's NOL balances below. The Company operates as a REIT for U.S. federal income tax purposes. The components of the net deferred income tax assets (liabilities) are as follows: December 31, 2020 December 31, 2019 Classification Gross Valuation Net Gross Valuation Net Federal $ 25 $ — $ 25 $ 25 $ — $ 25 State 1 — 1 1 — 1 Foreign (11) — (11) (8) — (8) Total $ 15 $ — $ 15 $ 18 $ — $ 18 At December 31, 2020, the Company had U.S. federal and state NOLs of approximately $1.5 billion and $0.6 billion , respectively, which are available to offset future taxable income. These amounts include approximately $237 million of losses related to stock-based compensation. The Company also has foreign NOLs of $40 million. If not utilized, the Company's U.S. federal NOLs expire starting in 2025 and ending in 2036, the state NOLs expire starting in 2021 and ending in 2036, and the foreign NOLs expire starting in 2023 and ending in 2036. The utilization of the NOLs is subject to certain limitations. The Company's U.S. federal and state income tax returns generally remain open to examination by taxing authorities until three years after the applicable NOLs have been used or expired. The remaining valuation allowance relates to certain foreign net deferred tax assets (primarily NOLs). As of December 31, 2020, there were no unrecognized tax benefits that would impact the effective tax rate, if recognized. From time to time, the Company is subject to examinations by various tax authorities in jurisdictions in which the Company has business operations. At this time, the Company is not subject to an Internal Revenue Service examination. The Australian Taxation Office is conducting an audit of the tax consequences for Australian tax purposes of the Company's sale of CCAL. The primary focus of the audit relates to the Company's asset valuation methodology and whether the Company should be subject to Australian capital gains tax on its sale of CCAL. The Company believes its valuation methodology is appropriate, that it is not subject to such tax, and that the ultimate resolution of the audit will not be material to the Company’s financial position. In addition, the Company regularly assesses the likelihood of additional assessments in each of the tax jurisdictions in which it has business operations. The Company has no uncertain tax positions as of December 31, 2020. Additionally, the

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Stockholders' Equity	Equity 2018 "At-The-Market" Stock Offering Program In April 2018, the Company established an "at-the-market" stock offering program through which it may issue and sell shares of its common stock having an aggregate gross sales price of up to $750 million ("2018 ATM Program"). Sales under the 2018 ATM Program may be made by means of ordinary brokers' transactions on the NYSE or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or, subject to our specific instructions, at negotiated prices. The Company intends to use the net proceeds from any sales under the 2018 ATM Program for general corporate purposes, which may include (1) the funding of future acquisitions or investments or (2) the repayment or repurchase of any outstanding indebtedness. The Company has not sold any shares of common stock under the 2018 ATM Program. As of December 31, 2020, the Company had $750 million of gross sales of common stock availability remaining under the 2018 ATM Program. Convertible Preferred Stock Conversion In July and August 2020, all of the approximately 2 million shares of the Company's previously outstanding 6.875% Mandatory Convertible Preferred Stock were converted into approximately 14 million shares of the Company's common stock at a conversion rate (based on the applicable market value of the common stock and subject to certain anti-dilutive adjustments) of 8.8043 shares of common stock per each share of 6.875% Mandatory Convertible Preferred Stock. March 2018 Common Stock Offering In March 2018, the Company completed an offering of 8 million shares of its common stock, which generated net proceeds of $841 million ("March 2018 Equity Financing"). The Company used the net proceeds from the March 2018 Equity Financing for general corporate purposes, including repayment of outstanding indebtedness. Declaration and Payment of Dividends During the year ended December 31, 2020, the following dividends/distributions were declared or paid: Equity Type Declaration Date Record Date Payment Date Dividends Per Share Aggregate Common Stock February 20, 2020 March 13, 2020 March 31, 2020 $ 1.20 $ 504 (a) Common Stock May 14, 2020 June 12, 2020 June 30, 2020 $ 1.20 $ 504 (a) Common Stock August 6, 2020 September 15, 2020 September 30, 2020 $ 1.20 $ 521 (a) Common Stock October 21, 2020 December 15, 2020 December 31, 2020 $ 1.33 $ 577 (a) 6.875% Convertible Preferred Stock December 9, 2019 January 15, 2020 February 3, 2020 $ 17.1875 $ 28 6.875% Convertible Preferred Stock March 12, 2020 April 15, 2020 May 1, 2020 $ 17.1875 $ 28 6.875% Convertible Preferred Stock June 19, 2020 July 15, 2020 August 3, 2020 $ 17.1875 $ 28 (a) Inclusive of dividends accrued for holders of unvested RSUs, which will be paid when and if the RSUs vest. See also note 17 for a discussion of the Company's common stock dividend declared in February 2021. Tax Treatment of Dividends The following table summarizes, for income tax purposes, the nature of dividends paid during 2020 on the Company's common stock and previously outstanding 6.875% Convertible Preferred Stock. Equity Type Payment Date Cash Distribution (per share) Ordinary Taxable Dividend (per share) Qualified Taxable Dividend (per share) (a) Section 199A Dividend (per share) Non-Taxable Distribution (per share) Common Stock March 31, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock June 30, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock September 30, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock December 31, 2020 $ 1.33 $ 0.874 $ 0.012 $ 0.862 $ 0.456 6.875% Convertible Preferred Stock February 3, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — 6.875% Convertible Preferred Stock May 1, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — 6.875% Convertible Preferred Stock August 3, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — (a) Qualified taxable dividend and section 199A dividend amounts are included in ordinary taxable dividend amounts. Purchases of the Company's Common Stock During the years ended December 31, 2020, 2019 and 2018, the Company purchased 0.5 million, 0.4 million and 0.3 million shares of common stock, respectively, utilizing $76 million, $44 million and $34 million in cash, respectively.

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement, Noncash Expense [Abstract]
Stock-based Compensation	Stock-based Compensation Stock Compensation Plans Pursuant to a stockholder approved plan, the Company has and is permitted to grant stock-based awards to certain employees, consultants or non-employee directors of the Company and its subsidiaries or affiliates. As of December 31, 2020, the Company has 8 million shares available for future issuance pursuant to its 2013 Long-Term Incentive Plan ("LTI Plan"). Of the shares remaining available for future issuance, approximately 2 million shares may be issued pursuant to outstanding RSUs granted under the LTI Plan. Restricted Stock Units The Company issues RSUs to certain executives and employees. Each RSU represents a contingent right to receive one share of the Company's common stock subject to satisfaction of the applicable vesting terms. The RSUs granted to certain executives and employees include (1) annual performance awards that generally include provisions for forfeiture by the employee if certain market performance of the Company's common stock is not achieved, (2) new hire or promotional awards that generally contain only service-based vesting conditions, and (3) other awards related to specific business initiatives or compensation objectives including retention and merger integration. Generally, such awards vest over periods of approximately three years. The following is a summary of the RSU activity during the year ended December 31, 2020. RSUs (In millions) Outstanding at the beginning of year 2.8 Granted 1.0 Vested (1.3) Forfeited (0.1) Outstanding at end of year 2.4 The Company granted approximately one million RSUs to the Company's executives and certain other employees for each of the years ended December 31, 2020, 2019 and 2018. The weighted-average grant-date fair value per share of the grants for the years ended December 31, 2020, 2019 and 2018 was $160.78, $106.55 and $91.52 per share, respectively. The weighted-average requisite service period for the RSUs granted during 2020 was approximately 2.4 years. Of the approximately one million RSUs granted during the year ended December 31, 2020, (1) approximately 0.6 million RSUs were subject to time-based vesting conditions, vesting over a three-year period and (2) approximately 0.4 million RSUs were granted to the Company's executives and certain other employees and may vest on the third anniversary of the grant date based upon (a) the Company's total shareholder returns (defined as share price appreciation plus the value of dividends paid during the performance period) and (b) the Company's total shareholder return compared to that of the companies in the Standard & Poor's 500 Index. Certain RSU agreements contain provisions that result in forfeiture by the employee of any unvested shares in the event that the Company's common stock does not achieve certain performance targets. To the extent that the requisite service is rendered, compensation cost for accounting purposes is not reversed; rather, it is recognized regardless of whether or not the market performance target is achieved. The following table summarizes the assumptions used in the Monte Carlo simulation to determine the grant-date fair value for the RSUs with market conditions granted during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, 2020 2019 2018 Risk-free rate 1.4 % 2.5 % 2.4 % Expected volatility 19 % 18 % 18 % Expected dividend rate 3.5 % 4.0 % 3.8 % The Company recognized aggregate stock-based compensation expense related to RSUs of $111 million, $96 million and $90 million for the years ended December 31, 2020, 2019 and 2018, respectively. The aggregate unrecognized compensation (net of estimated forfeitures) related to RSUs at December 31, 2020 is $110 million and is estimated to be recognized over a weighted-average period of less than one year. The following table is a summary of the RSUs vested during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, Total Shares Fair Value on (In millions 2020 1 $ 220 2019 1 135 2018 1 107 Stock-based Compensation The following table discloses the components of stock-based compensation expense. Years Ended December 31, 2020 2019 2018 Stock-based compensation expense: Site rental costs of operations $ 16 $ 19 $ 17 Services and other costs of operations 8 7 8 Selling, general and administrative expenses 109 90 83 Total stock-based compensation $ 133 $ 116 $ 108

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies SEC Investigation In September 2019, the Company received a subpoena from the SEC requesting certain documents from 2015 through the present, primarily related to the Company's long-standing capitalization and expense policies for tenant upgrades and installations in its services business. Prior to receiving this subpoena, the Company previously provided information to the SEC related to certain services-related transactions. The Company responded to the requests and cooperated fully with the SEC's investigation. On January 26, 2021, the SEC notified the Company that it had concluded its investigation, and based on the information the SEC had as of that date, the SEC staff did not intend to recommend an enforcement action by the Commission. Shareholder Litigation In February and March 2020, putative securities class action suits were filed in the United States District Court for the District of New Jersey against the Company and certain of its current officers. The lawsuits were filed against the Company on behalf of investors that purchased or otherwise acquired stock of the Company between February 26, 2018 and February 26, 2020. The allegations concern allegedly false or misleading statements or other alleged failures to disclose information about the Company’s business, operations and prospects. The plaintiffs seek monetary damages and the award of plaintiffs’ costs and expenses incurred. In December 2020, the cases were consolidated as In re Crown Castle International Corp. Securities Litigation , No. 2:20-cv-02156 in the United States District Court for the District of New Jersey. The Company is currently unable to determine the likelihood of an outcome or estimate a range of reasonably possible losses, if any. The Company believes the putative class action is without merit and intends to defend itself vigorously. During the quarter ended June 30, 2020, derivative lawsuits were filed in the United States District Court for the District of Delaware, against the Company's current directors and certain of its current officers and the Company as a nominal defendant. Each complaint alleges, among other things, breaches of fiduciary duties, waste of corporate assets, unjust enrichment, and false or misleading statements. The derivative plaintiffs seek, among other things, unspecified monetary damages, costs and expenses, restitution from the defendants, and an order requiring the Company to implement certain corporate governance reforms. As a nominal defendant, no monetary relief is sought against the Company itself. In June 2020, the derivative lawsuits were consolidated as In re Crown Castle International Corp. Derivative Litigation , C.A. No. 20-00606-MN in the United States District Court for the District of Delaware. The consolidated derivative action is currently stayed pending the resolution of any motion to dismiss In re Crown Castle International Corp. Securities Litigation in the United States District Court for the District of New Jersey. Durham Lawsuits The Company has received notices of claims and has been named as one of several defendants in lawsuits stemming from an April 2019 gas leak explosion in Durham, North Carolina, which occurred near an area where the Company's subcontractors were installing fiber. The explosion resulted in two fatalities, physical injuries (some of which were serious), and property damage to surrounding buildings and businesses. Currently, the Company is unable to determine the likelihood of an outcome or estimate a range of possible losses, if any, related to these lawsuits. New York State Department of Transportation In 2019, the State of New York passed legislation authorizing the Department of Transportation ("NYSDOT") to enter into agreements with any fiber provider for the use and occupancy of the state right-of-way for fiber optic lines. The legislation authorizes the NYSDOT to charge a fee of up to fair market value for such use and occupancy. To date, the Company has paid fees relating to newly deployed fiber lines but has not been required to pay, and has not recognized any costs in connection with, any fees relating to previously deployed fiber lines. The Company believes that the legislation violates both federal and state law and is evaluating its legal options regarding any use and occupancy fees that may be assessed on previously deployed fiber. Currently, the Company is unable to determine the likelihood of an outcome or reasonably estimate the amount of fees, if any, that it may be required to pay as a result of the legislation. Other Matters The Company is involved in various other claims, assessments, lawsuits or proceedings arising in the ordinary course of business. While there are uncertainties inherent in the ultimate outcome of such other matters and it is impossible to presently determine the ultimate costs or losses that may be incurred, if any, management believes the adverse resolution of such uncertainties and the incurrence of such costs should not have a material adverse effect on the Company's condensed consolidated financial position or results of operations. Additionally, the Company and certain of its subsidiaries are contingently liable for commitments or performance guarantees arising in the ordinary course of business, including certain letters of credit or surety bonds. See note 13 for a discussion of the operating lease commitments. In addition, see note 1 for a discussion of the Company's option to purchase approximately 53% of its towers at the end of their respective lease terms. The Company has no obligation to exercise such purchase options.

Leases (Notes)

Leases (Notes)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases [Text Block]	Leases Lessor Tenant Leases See note 3 for further information regarding the contractual amounts owed to the Company pursuant to tenant contracts in effect as of December 31, 2020 and other information. Lessee Operating Leases The components of the Company's operating lease expense are as follows: Years Ended December 31, 2020 2019 (d) Lease cost: Operating lease expense (a) $ 640 $ 632 Variable lease expense (b) 153 149 Total lease expense (c) $ 793 $ 781 (a) Represents the Company's operating lease expense related to its ROU assets for the twelve months ended December 31, 2020 and 2019. (b) Represents the Company's expense related to contingent payments for operating leases (such as payments based on revenues derived from the communications infrastructure located on the leased asset) for the twelve months ended December 31, 2020 and 2019. Such contingencies are recognized as expense in the period they are resolved. (c) Excludes those direct operating expenses accounted for pursuant to accounting guidance outside the scope of ASC 842. (d) Amounts for the year ended December 31, 2019 reflect a revision from the Company's 2019 Annual Report on Form 10-K relating to an immaterial classification error of certain operating lease expenses. In connection with this revision, the Company reclassified $16 million from operating lease expense to variable lease expense for the year ended December 31, 2019; total lease expense for the year ended December 31, 2019 remained unchanged. Lessee Finance Leases The vast majority of the Company's finance leases are related to the towers subject to prepaid master lease agreements with AT&T and T-Mobile, including agreements assumed by T-Mobile in connection with its merger with Sprint, and are recorded as "Property and equipment, net" on the consolidated balance sheet. See note 1 for further discussion of the Company's prepaid master lease agreements. Finance leases and associated leasehold improvements related to gross property and equipment and accumulated depreciation were $4.4 billion and $2.3 billion, respectively, as of December 31, 2020. Finance leases and associated leasehold improvements related to gross property and equipment and accumulated depreciation were $4.4 billion and $2.1 billion, respectively, as of December 31, 2019. For the twelve months ended December 31, 2020 and 2019, the Company recorded $211 million and $216 million, respectively, to "Depreciation, amortization and accretion" related to finance leases. Other Lessee Information As of December 31, 2020, the Company's weighted-average remaining lease term and weighted-average discount rate for operating leases were 17 years and 3.7%, respectively. The following table is a summary of the Company's maturities of operating lease liabilities as of December 31, 2020: Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total undiscounted lease payments Less: Imputed interest Total operating lease liabilities Operating leases (a) $ 546 $ 543 $ 538 $ 532 $ 518 $ 5,842 $ 8,519 $ (2,382) $ 6,137 (a) Excludes the Company's contingent payments for operating leases (such as payments based on revenues derived from the communications infrastructure located on the leased asset) as such arrangements are excluded from the Company's operating lease liability. Such contingencies are recognized as expense in the period they are resolved.

Operating Segments and Concentr

Operating Segments and Concentrations of Credit Risk	12 Months Ended
	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating Segments and Concentrations of Credit Risks	Operating Segments and Concentrations of Credit Risk Operating Segments The Company's operating segments consist of (1) Towers and (2) Fiber. The Towers segment provides access, including space or capacity, to the Company's approximately 40,000 towers geographically dispersed throughout the U.S. The Towers segment also reflects certain ancillary services relating to the Company's towers, predominately consisting of site development services and installation services. The Fiber segment provides access, including space or capacity, to the Company's approximately 80,000 route miles of fiber primarily supporting small cell networks and fiber solutions geographically dispersed throughout the U.S. The measurements of profit or loss used by the Company's chief operating decision maker ("CODM") to evaluate the performance of its operating segments are (1) segment site rental gross margin, (2) segment services and other gross margin and (3) segment operating profit. The Company defines segment site rental gross margin as segment site rental revenues less segment site rental cost of operations, which excludes stock-based compensation expense and prepaid lease purchase price adjustments recorded in consolidated cost of operations. The Company defines segment services and other gross margin as segment services and other revenues less segment services and other cost of operations, which excludes stock-based compensation expense recorded in consolidated cost of operations. The Company defines segment operating profit as segment site rental gross margin plus segment services and other gross margin, and segment other operating (income) expense, less selling, general and administrative expenses attributable to the respective segment. All of these measurements of profit or loss are exclusive of depreciation, amortization and accretion, which are shown separately. Costs that are directly attributable to Towers and Fiber are assigned to those respective segments. Additionally, certain costs are shared across segments and are reflected in the Company's segment measures through allocations that management believes to be reasonable. The "Other" column (1) represents amounts excluded from specific segments, such as asset write-down charges, acquisition and integration costs, depreciation, amortization and accretion, amortization of prepaid lease purchase price adjustments, interest expense and amortization of deferred financing costs, gains (losses) on retirement of long-term obligations, net gain (loss) on interest rate swaps, gains (losses) on foreign currency swaps, interest income, other income (expense), income (loss) from discontinued operations, and stock-based compensation expense, and (2) reconciles segment operating profit to income (loss) before income taxes, as the amounts are not utilized in assessing each segment’s performance. The "Other" total assets balance includes corporate assets such as cash and cash equivalents which have not been allocated to specific segments. There are no significant revenues resulting from transactions between the Company's operating segments. Year Ended December 31, 2020 Towers Fiber Other Consolidated Segment site rental revenues $ 3,497 $ 1,823 $ 5,320 Segment services and other revenues 500 20 520 Segment revenues 3,997 1,843 5,840 Segment site rental cost of operations 866 620 1,486 Segment services and other cost of operations 429 12 441 Segment cost of operations (a)(b) 1,295 632 1,927 Segment site rental gross margin 2,631 1,203 3,834 Segment services and other gross margin 71 8 79 Segment selling, general and administrative expenses (b) 100 186 286 Segment other operating (income) expense (c) — (362) (362) Segment operating profit (loss) 2,602 1,387 3,989 Other selling, general and administrative expenses (b) $ 283 283 Stock-based compensation expense 133 133 Depreciation, amortization and accretion 1,608 1,608 Interest expense and amortization of deferred financing costs 689 689 Other (income) expenses to reconcile to income (loss) before income taxes (d) 200 200 Income (loss) before income taxes $ 1,076 Capital expenditures $ 335 $ 1,232 $ 57 $ 1,624 Total assets (at year end) $ 22,242 $ 15,746 $ 780 $ 38,768 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2020 excludes (1) stock-based compensation expense of $24 million and (2) prepaid lease purchase price adjustments of $18 million. For the year ended December 31, 2020, segment selling, general and administrative expenses exclude stock-based compensation expense of $109 million. (c) See note 15 for further information. (d) See consolidated statement of operations for further information. Year Ended December 31, 2019 Towers Fiber Other Consolidated Segment site rental revenues $ 3,389 $ 1,704 $ 5,093 Segment services and other revenues 653 17 670 Segment revenues 4,042 1,721 5,763 Segment site rental cost of operations 864 559 1,423 Segment services and other cost of operations 506 11 517 Segment cost of operations (a)(b) 1,370 570 1,940 Segment site rental gross margin 2,525 1,145 3,670 Segment services and other gross margin 147 6 153 Segment selling, general and administrative expenses (b) 96 195 291 Segment operating profit (loss) 2,576 956 3,532 Other selling, general and administrative expenses (b) $ 233 233 Stock-based compensation expense 116 116 Depreciation, amortization and accretion 1,572 1,572 Interest expense and amortization of deferred financing costs 683 683 Other (income) expenses to reconcile to income (loss) before income taxes (c) 47 47 Income (loss) before income taxes $ 881 Capital expenditures $ 543 $ 1,473 $ 41 $ 2,057 Total assets (at year end) $ 22,357 $ 15,389 $ 711 $ 38,457 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2019 excludes (1) stock-based compensation expense of $26 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2019, segment selling, general and administrative expenses exclude stock-based compensation expense of $90 million. (c) See consolidated statement of operations for further information. Year Ended December 31, 2018 Towers Fiber Other Consolidated Segment site rental revenues $ 3,196 $ 1,600 $ 4,796 Segment services and other revenues 558 16 574 Segment revenues 3,754 1,616 5,370 Segment site rental cost of operations 848 525 1,373 Segment services and other cost of operations 415 11 426 Segment cost of operations (a)(b) 1,263 536 1,799 Segment site rental gross margin 2,348 1,075 3,423 Segment services and other gross margin 143 5 148 Segment selling, general and administrative expenses (b) 110 179 289 Segment operating profit (loss) 2,381 901 3,282 Other selling, general and administrative expenses (b) $ 191 191 Stock-based compensation expense 108 108 Depreciation, amortization and accretion 1,527 1,527 Interest expense and amortization of deferred financing costs 642 642 Other (income) expenses to reconcile to income (loss) before income taxes (c) 173 173 Income (loss) before income taxes $ 641 Capital expenditures $ 440 $ 1,264 $ 35 $ 1,739 Total assets (at year end) $ 17,644 $ 14,512 $ 606 $ 32,762 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2018 excludes (1) stock-based compensation expense of $25 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2018, segment selling, general and administrative expenses exclude stock-based compensation expense of $83 million. (c) See consolidated statement of operations for further information. Major Tenants The following table summarizes the percentage of the consolidated revenues for those tenants accounting for more than 10% of the consolidated revenues. Years Ended December 31, 2020 (a) 2019 2018 T-Mobile 36 % 22 % 19 % AT&T 22 % 21 % 20 % Verizon Wireless 19 % 19 % 20 % Sprint — % 14 % 15 % Total 77 % 76 % 74 % (a) For the year ended December 31, 2020, revenues attributable to T-Mobile includes revenues previously derived from Sprint. On April 1, 2020, T-Mobile and Sprint announced the completion of their previously disclosed merger. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents, restricted cash and trade receivables. The Company mitigates its risk with respect to cash and cash equivalents by maintaining such deposits at high credit quality financial institutions and monitoring the credit ratings of those institutions. The Company's restricted cash is predominately held and directed by a trustee (see note 2). The Company derives the largest portion of its revenues from tenants in the wireless industry. The Company also has a concentration in its volume of business with T-Mobile, AT&T and Verizon Wireless or their agents that accounts for a significant portion of the Company's revenues, receivables and deferred site rental receivables. The Company mitigates its concentrations of credit risk with respect to trade receivables by actively monitoring the creditworthiness of its tenants, the use of tenant leases with contractually determinable payment terms or proactive management of past due balances.

Other Operating Income

Other Operating Income	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other Operating Income	Other Operating Income During the fourth quarter of 2020, T-Mobile notified the Company that it was cancelling approximately 5,700 small cell nodes initially contracted with Sprint ("Sprint Cancellation") prior to its merger with T-Mobile. The majority of the cancelled small cells were not yet constructed and, upon completion, would have been located at the same locations as other T-Mobile small cells. The Sprint Cancellation resulted in T-Mobile accelerating payment of all contractual rental obligations associated with the approximately 5,700 small cells as well as the payment of capital costs incurred to date. The Company received approximately $308 million from T-Mobile pursuant to the Sprint Cancellation, and recognized receipt of this payment as "Other operating income" on its consolidated statement of operations and comprehensive income (loss) for the year ended December 31, 2020. Additionally, the Company previously received upfront payments from Sprint for certain of the small cells subject to the Sprint Cancellation, which the Company previously recorded as "Deferred revenues" and "Other long-term liabilities" on its consolidated balance sheet. As a result of the Sprint Cancellation, during the fourth quarter of 2020, the Company recognized the unamortized portion of such upfront payments, or approximately $54 million, as "Other operating income" on its consolidated statement of operations and comprehensive income (loss) for the year ended December 31, 2020. See also note 2 for a discussion of the Company's separate evaluation and write-off of property and equipment previously recorded related to the cancelled small cells.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events February 2021 Senior Notes Offering On February 16, 2021, the Company issued $3.25 billion aggregate principal amount of senior unsecured notes ("February 2021 Senior Notes"), which consisted of (1) $1.0 billion aggregate principal amount of 1.050% senior unsecured notes due July 2026, (2) $1.0 billion aggregate principal amount of 2.100% senior unsecured notes due April 2031 and (3) $1.25 billion aggregate principal amount of 2.900% senior unsecured notes due April 2041. The Company used a portion of the net proceeds from the February 2021 Senior Notes offering to repay a portion of the outstanding Commercial Paper Notes at their maturity date and a portion of outstanding borrowings under the 2016 Term Loan A. The Company intends to use the remainder of the net proceeds from the February 2021 Senior Notes offering to (1) redeem all of the outstanding 5.250% Senior Notes on March 10, 2021 (the designated redemption date) and (2) repay an additional portion of the outstanding Commercial Paper Notes at their maturity date. Common Stock Dividend On February 18, 2021, the Company's board of directors declared a quarterly cash dividend of $1.33 per common share. The quarterly dividend will be payable on March 31, 2021, to common stockholders of record as of March 15, 2021.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
Schedule II Valuation and Qualifying Accounts
Schedule II - Valuation and Qualifying Accounts Disclosure [Text Block]	Additions Deductions Balance at Charged to Credited to Written Off Effect of Other Adjustments Balance at Allowance for Doubtful Accounts Receivable: 2020 $ 18 $ 4 $ — $ (5) $ — $ — $ 17 2019 $ 14 $ 7 $ — $ (3) $ — $ — $ 18 2018 $ 14 $ 4 $ — $ (4) $ — $ — $ 14 Additions Deductions Balance at Charged Charged to Credited to Credited to Other Balance at Deferred Tax Valuation Allowance: 2020 $ — $ — $ — $ — $ — $ — $ — 2019 $ 1 $ — $ — $ (1) $ — $ — $ — 2018 $ 1 $ — $ — $ — $ — $ — $ 1

Schedule III - Schedule of Real

Schedule III - Schedule of Real Estate and Depreciation (Notes)	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block]	Description Encumbrances Initial Cost to Company Cost Capitalized Subsequent to Acquisition Gross Amount Carried at Close of Current Period Accumulated Depreciation at Close of Current Period Date of Construction Date Acquired Life on Which Depreciation in Latest Income Statement is Computed Communications infrastructure (a) $ 3,295 (b) (c) (c) $ 25,441 $ (10,478) Various Various Up to 20 years (a) Includes approximately 40,000 towers and 80,000 route miles of fiber. No single asset exceeds 5% of the aggregate gross amounts at which the assets were carried at the close of the period set forth in the table above. (b) Encumbrances are reported at face value, without contemplating the effect of deferred financing costs, discounts or premiums. Certain of the Company's debt is secured by (1) a security interest in substantially all of the applicable issuers' assignable personal property, (2) a pledge of the equity interests in each applicable issuer and (3) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses). (c) The Company has omitted this information, as it would be impracticable to compile such information on an asset-by-asset basis. 2020 2019 Gross amount at beginning $ 23,854 $ 21,840 Additions during period: Acquisitions through foreclosure — — Other acquisitions (a) 68 4 Communications infrastructure construction and improvements 1,438 1,878 Purchase of land interests 64 53 Sustaining capital expenditures 66 84 Other (b) 47 101 Total additions 1,683 2,120 Deductions during period: Cost of real estate sold or disposed (96) (45) Other — (61) Total deductions (96) (106) Balance at end $ 25,441 $ 23,854 (a) Includes acquisitions of communications infrastructure. (b) Predominately relates to the purchase of property and equipment under finance leases and installment land purchases. 2020 2019 Gross amount of accumulated depreciation at beginning $ (9,382) $ (8,338) Additions during period: Depreciation (1,114) (1,087) Total additions (1,114) (1,087) Deductions during period: Amount for assets sold or disposed 18 24 Other — 19 Total deductions 18 43 Balance at end $ (10,478) $ (9,382)

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Restricted Cash	Restricted CashRestricted cash represents (1) the cash held in reserve by the indenture trustees pursuant to the indenture governing certain of the Company's debt instruments, (2) cash securing performance obligations such as letters of credit, as well as (3) any other cash whose use is limited by contractual provisions. The restriction of rental cash receipts is a critical feature of certain of the Company's debt instruments, due to the applicable indenture trustee's ability to utilize the restricted cash for the payment of (1) debt service costs, (2) ground rents, (3) real estate or personal property taxes, (4) insurance premiums related to towers, (5) other assessments by governmental authorities and potential environmental remediation costs, or (6) a portion of advance rents from tenants. The restricted cash in excess of required reserve balances is subsequently released to the Company in accordance with the terms of the indentures. See note 16 for a reconciliation of cash, cash equivalents and restricted cash.
Receivables Allowance	Receivables Allowance An allowance for doubtful accounts is recorded as an offset to accounts receivable. The Company uses judgment in estimating this allowance and considers historical collections, current credit status, or contractual provisions. Additions to the allowance for doubtful accounts are charged either to "Site rental costs of operations" or to "Services and other costs of operations," as appropriate, and deductions from the allowance are recorded when specific accounts receivable are written off as uncollectible.
General, Leases [Policy Text Block]	Lease Accounting Effective January 1, 2019, the Company adopted new guidance on the recognition, measurement, presentation and disclosure of leases (commonly referred to as "ASC 842" or the "new lease standard") using a modified retrospective approach as of the effective date without adjusting the comparative periods. General. The Company evaluates whether a contract meets the definition of a lease whenever a contract grants a party the right to control the use of an identified asset for a period of time in exchange for consideration. To the extent the identified asset is able to be shared among multiple parties, the Company has determined that one party does not have control of the identified asset and the contract is not considered a lease. The Company accounts for contracts that do not meet the definition of a lease under other relevant accounting guidance (such as ASC 606 for revenue from contracts with customers).
Lessee, Leases [Policy Text Block]	Lessee. For its Tower segment, the Company's lessee arrangements primarily consist of ground leases for land under towers. Ground leases for land are specific to each site, generally contain an initial term of five to 10 years and are renewable (and cancelable after a notice period) at the Company's option. The Company also enters into term easements and ground leases in which it prepays the entire term. For its Fiber segment, the Company's lessee arrangements primarily include leases of fiber assets to support the Company's small cells and fiber solutions. The majority of the Company's lease agreements have certain termination rights that provide for cancellation after a notice period and multiple renewal options exercisable at the Company's option. The Company includes renewal option periods in its calculation of the estimated lease term when it determines the options are reasonably certain to be exercised. When such renewal options are deemed to be reasonably certain, the estimated lease term determined under ASC 842 will be greater than the non-cancelable term of the contractual arrangement. Although certain renewal periods are included in the estimated lease term, the Company would have the ability to terminate or elect to not renew a particular lease if business conditions warrant such a decision. The Company classifies its lessee arrangements at inception as either operating leases or finance leases. A lease is classified as a finance lease if at least one of the following criteria is met: (1) the lease transfers ownership of the underlying asset to the lessee, (2) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) the lease term is for a major part of the remaining economic life of the underlying asset, (4) the present value of the sum of the lease payments equals or exceeds substantially all of the fair value of the underlying asset, or (5) the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. A lease is classified as an operating lease if none of the five criteria described above for finance lease classification is met. Right-of-use ("ROU") assets associated with operating leases are included in "Operating lease right-of-use assets" on the Company's consolidated balance sheet. Current and long-term portions of lease liabilities related to operating leases are included in "Current portion of operating lease liabilities" and "Operating lease liabilities" on the Company's consolidated balance sheet, respectively. ROU assets represent the Company's right to use an underlying asset for the estimated lease term and lease liabilities represent the Company's present value of its future lease payments. In assessing its leases and determining its lease liability at lease commencement or upon modification, the Company is not able to readily determine the rate implicit for its lessee arrangements, and thus uses its incremental borrowing rate on a collateralized basis to determine the present value of the lease payments. The Company's ROU assets are measured as the balance of the lease liability plus any prepaid or accrued lease payments and any unamortized initial direct costs. For both the Towers and Fiber segments, operating lease expenses are recognized on a ratable basis, regardless of whether the payment terms require the Company to make payments annually, quarterly, monthly, or for the entire term in advance. Certain of the Company's ground lease and fiber lease agreements contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the change in consumer price index ("CPI")). If the payment terms include fixed escalator provisions, the effect of such increases is recognized on a straight-line basis. The Company calculates the straight-line expense over the tenant contract's estimated lease term, including any renewal option periods that the Company deems reasonably certain to be exercised. Lease agreements may also contain provisions for a contingent payment based on (1) the revenues derived from the communications infrastructure located on the leased asset, (2) the change in CPI or (3) the usage of the leased asset. The Company's contingent payments are considered variable lease payments and are (1) not included in the initial measurement of the ROU asset or lease liability due to the uncertainty of the payment amount and (2) recorded as expense in the period such contingencies are resolved. ROU assets associated with finance leases are included in "Property and equipment, net" on the Company's consolidated balance sheet. Lease liabilities associated with finance leases are included in "Current maturities of debt and other obligations" and "Debt and other long-term obligations" on the Company's consolidated balance sheet. For both its Towers and Fiber segments, the Company measures the lease liability for finance leases using the effective interest method. The initial lease liability is increased to reflect interest on the liability and decreased to reflect payments made during the period. Interest on the lease liability is determined each period during the lease term as the amount that results in a constant periodic discount rate on the remaining balance of the liability. The Company measures ROU assets for finance leases on a ratable basis over the applicable lease term. The Company reviews the carrying value of its ROU assets for impairment, similar to its other long-lived assets, whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable. The Company could record impairments in the future if there are changes in (1) long-term market conditions, (2) expected future operating results or (3) the utility of the assets that negatively impact the fair value of its ROU assets.
Lessor, Leases Policy	Lessor. The Company's lessor arrangements primarily include tenant contracts for dedicated space (including dedicated fiber) on its shared communications infrastructure. The Company classifies its leases at inception as operating, direct financing or sales-type leases. A lease is classified as a sales-type lease if at least one of the following criteria is met: (1) the lease transfers ownership of the underlying asset to the lessee, (2) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) the lease term is for a major part of the remaining economic life of the underlying asset, (4) the present value of the sum of the lease payments equals or exceeds substantially all of the fair value of the underlying assets or (5) the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. Furthermore, when none of the above criteria is met, a lease is classified as a direct financing lease if both of the following criteria are met: (1) the present value of the of the sum of the lease payments and any residual value guaranteed by the lessee, that is not already reflected in the lease payments, equals or exceeds the fair value of the underlying asset and (2) it is probable that the lessor will collect the lease payments plus any amount necessary to satisfy a residual value guarantee. A lease is classified as an operating lease if it does not qualify as a sales-type or direct financing lease. Currently, the Company classifies all of its lessor arrangements as operating leases. Site rental revenues from the Company’s lessor arrangements are recognized on a straight-line, ratable basis over the fixed, non-cancelable term of the relevant tenant contract, regardless of whether the payments from the tenant are received in equal monthly amounts during the life of a tenant contract. Certain of the Company's tenant contracts contain fixed escalation clauses (such as fixed-dollar or fixed-percentage increases) or inflation-based escalation clauses (such as those tied to the change in CPI). If the payment terms call for fixed escalations, upfront payments, or rent-free periods, the rental revenue is recognized on a straight-line basis over the fixed, non-cancelable term of the agreement. When calculating straight-line site rental revenues, the Company considers all fixed elements of tenant contractual escalation provisions. Certain of the Company's arrangements with tenants in its Fiber segment contain both lease and non-lease components. In such circumstances, the Company has determined (1) the timing and pattern of transfer for the lease and non-lease component are the same and (2) the stand-alone lease component would be classified as an operating lease. As such, the Company has aggregated certain non-lease components with lease components and has determined that the lease components (generally dedicated fiber) represent the predominant component of the arrangement.
Property and Equipment	Property and Equipment Property and equipment is stated at cost, net of accumulated depreciation. Property and equipment includes land owned in fee and perpetual easements for land, which have no definite life. Depreciation is computed utilizing the straight-line method at rates based upon the estimated useful lives of the various classes of assets. Depreciation of communications infrastructure is generally computed with a useful life equal to the shorter of 20 years or the term of the underlying ground lease (including optional renewal periods). Additions and permanent improvements to the Company's communications infrastructure are capitalized, while maintenance and repairs are expensed. Labor and interest costs incurred directly related to the construction of certain property and equipment are capitalized during the construction phase of projects. For the years ended December 31, 2020, 2019 and 2018, the Company had $270 million, $246 million and $212 million in capitalized labor costs, respectively. The carrying value of property and equipment is reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Abandonments and write-offs of property and equipment are recorded to "Asset write-down charges" on the Company's consolidated statement of operations and comprehensive income (loss) and were $77 million, $17 million and $22 million for the years ended December 31, 2020, 2019 and 2018, respectively. Asset write-down charges for the year ended December 31, 2020 included the write-off of property and equipment of approximately $63 million which, following the Sprint Cancellation, was deemed to have no alternative future use. See note 15 for further information regarding the Sprint Cancellation.
Asset Retirement Obligations	Asset Retirement Obligations Pursuant to its ground lease, easement and leased facility agreements, the Company records obligations to perform asset retirement activities, including requirements to remove communications infrastructure or remediate the space on which certain of its communications infrastructure is located. The Company does not record an obligation for asset retirement activities related to its fiber, as a settlement date is indeterminable and therefore a reasonable estimation of fair value cannot be made. Asset retirement obligations are included in "Other long-term liabilities" on the Company's consolidated balance sheet. The liability accretes as a result of the passage of time and the related accretion expense is included in "Depreciation, amortization and accretion" on the Company's consolidated statement of operations and comprehensive income (loss). The associated asset retirement costs are capitalized as an additional carrying amount of the related long-lived asset and depreciated over the useful life of such asset.
Goodwill	Goodwill Goodwill represents the excess of the purchase price for an acquired business over the allocated value of the related net assets. The Company tests goodwill for impairment on an annual basis, regardless of whether adverse events or changes in circumstances have occurred. The annual test begins with goodwill and all intangible assets being allocated to applicable reporting units. The Company's reporting units are the same as its operating segments (Towers and Fiber). The Company then performs a qualitative assessment to determine whether it is "more likely than not" that the fair value of the reporting units is less than its carrying amount. If the Company concludes it is "more likely than not" that the fair value of a reporting unit is less than its carrying amount, it is necessary to perform a quantitative goodwill impairment test. The quantitative goodwill impairment test compares the estimated fair value of the reporting unit and the carrying value of the reporting unit. If the carrying amount of a reporting unit is greater than its fair value, an impairment loss shall be recognized in an amount equal to such excess, limited to the total amount of goodwill allocated to the reporting unit. The Company performed its most recent annual goodwill impairment test as of October 1, 2020, which resulted in no impairments. See "Recently Adopted Accounting Pronouncements" for a discussion of the recently adopted new guidance related to goodwill impairment evaluation.
Intangible Assets	Intangible Assets Intangible assets are included in "Site rental contracts and tenant relationships, net" and "Other intangible assets, net" on the Company's consolidated balance sheet and predominately consist of the estimated fair value of site rental contracts and tenant relationships or other contractual rights, such as trademarks, that are recorded in conjunction with acquisitions. The site rental contracts and tenant relationships intangible assets are comprised of (1) the current term of the existing leases, (2) the high rate of tenant retention, and (3) any associated relationships that are expected to generate value following the expiration of all renewal periods under existing leases. The useful lives of intangible assets are estimated based on the period over which the intangible asset is expected to benefit the Company and gives consideration to the expected useful life of other assets to which the useful life may relate. Amortization expense for intangible assets is computed using the straight-line method over the estimated useful life of each of the intangible assets. The useful life of the site rental contracts and tenant relationships intangible asset is limited by the maximum depreciable life of the communications infrastructure (20 years), as a result of the interdependency of the communications infrastructure and site rental leases. In contrast, the site rental contracts and tenant relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of tenant retention experienced to date. Thus, while site rental contracts and tenant relationships are valued based upon the fair value, which includes assumptions regarding both (1) tenants' exercise of optional renewals contained in the acquired leases and (2) renewals of the acquired leases past the contractual term including exercisable options, the site rental contracts and tenant relationships are amortized over a period not to exceed 20 years. The carrying value of other intangible assets with finite useful lives will be reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. The Company has a dual grouping policy for purposes of determining the unit of account for testing impairment of the site rental contracts and tenant relationships intangible assets. First, the Company pools the site rental contracts and tenant relationships with the related communications infrastructure assets into portfolio groups for purposes of determining the unit of account for impairment testing. Second and separately, the Company evaluates the site rental contracts and tenant relationships by significant tenant or by tenant grouping for individually insignificant tenants, as appropriate. If the sum of the estimated future cash flows (undiscounted) expected to result from the use or eventual disposition of an asset is less than the carrying amount of the asset, an impairment loss is recognized. Measurement of an impairment loss is based on the fair value of the asset.
Deferred Credits	Deferred Credits Deferred credits are included in "Deferred revenues" and "Other long-term liabilities" on the Company's consolidated balance sheet and consist of the estimated fair value of below-market tenant leases for contractual interests with tenants on acquired communications infrastructure, which are amortized to site rental revenues. Fair value for these deferred credits represents the difference between (1) the stated contractual payments to be made pursuant to the in-place lease and (2) management's estimate of fair market lease rates for each corresponding lease. Deferred credits are measured over a period equal to the estimated remaining economic lease term considering renewal provisions or economics associated with those renewal provisions, to the extent applicable. Deferred credits are amortized over their respected estimated lease terms at the time of acquisition.
Deferred Financing Costs	Deferred Financing CostsThird-party costs incurred to obtain financing, with the exception of costs incurred related to revolving lines of credit, are deferred and are included as a direct deduction from the carrying amount of the related debt liability in "Debt and other long-term obligations" on the Company's consolidated balance sheet. Third party costs incurred to obtain financing through a revolving line of credit are deferred and are included in "Other assets, net" on the Company's consolidated balance sheet.
Revenue Recognition	Revenue Recognition The Company generates site rental revenues from its core business by providing tenants with access, including space or capacity, to its shared communications infrastructure via long-term tenant contracts in various forms, including lease, license, sublease and service agreements. Providing such access over the length of the tenant contract term represents the Company’s sole performance obligation under its tenant contracts. Site rental revenues. Site rental revenues from the Company's tenant contracts are recognized on a straight-line, ratable basis over the fixed, non-cancelable term of the relevant tenant contract, which generally ranges from five to 15 years for wireless tenants and three to 20 years for the Company's fiber solutions tenants (including from organizations with high-bandwidth and multi-location demands), regardless of whether the payments from the tenant are received in equal monthly amounts during the life of the tenant contract. Certain of the Company's tenant contracts contain (1) fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the CPI), (2) multiple renewal periods exercisable at the tenant's option and (3) only limited termination rights at the applicable tenant's option through the current term. If the payment terms call for fixed escalations, upfront payments, or rent-free periods, the revenue is recognized on a straight-line basis over the fixed, non-cancelable term of the agreement. When calculating straight-line rental revenues, the Company considers all fixed elements of tenant contractual escalation provisions, even if such escalation provisions contain a variable element in addition to a minimum. The Company's assets related to straight-line site rental revenues include current amounts of $152 million and $114 million included in "Other current assets" and non-current amounts of $1.4 billion and $1.4 billion included in "Deferred site rental receivables" for the years ended December 31, 2020 and 2019, respectively. Amounts billed or received prior to being earned are deferred and reflected in "Deferred revenues" and "Other long-term liabilities." Amounts to which the Company has an unconditional right to payment, which are related to both satisfied or partially satisfied performance obligations, are recorded within "Receivables, net" on the Company's consolidated balance sheet. Services and other revenues. As part of the Company’s effort to provide comprehensive communications infrastructure solutions, as an ancillary business, the Company offers certain services primarily relating to its Towers segment, predominately consisting of (1) site development services and (2) installation services. Upon contract commencement, the Company assesses its services to tenants and identifies performance obligations for each promise to provide a distinct service. The Company may have multiple performance obligations for site development services, which primarily include: structural analysis, zoning, permitting and construction drawings. For each of the above performance obligations, services revenues are recognized at completion of the applicable performance obligation, which represents the point at which the Company believes it has transferred goods or services to the tenant. The revenue recognized is based on an allocation of the transaction price among the performance obligations in a respective contract based on estimated standalone selling price. The volume and mix of site development services may vary among contracts and may include a combination of some or all of the above performance obligations. Payments generally are due within 45 to 60 days and generally do not contain variable-consideration provisions. The transaction price for the Company's tower installation services consists of amounts for (1) permanent improvements to the Company's towers that represent a lease component and (2) the performance of the service. Amounts under the Company's tower installation service agreements that represent a lease component are recognized as site rental revenues on a straight-line basis over the length of the associated estimated lease term. For the performance of the installation service, the Company has one performance obligation, which is satisfied at the time of the applicable installation or augmentation and recognized as services and other revenues. Since performance obligations are typically satisfied prior to receiving payment from tenants, the unconditional right to payment is recorded within "Receivables, net" on the Company’s condensed consolidated balance sheet. The vast majority of the Company’s services generally have a duration of one year or less. Additional information on revenues. As of January 1, 2020 and December 31, 2020, a total of $2.9 billion and $2.8 billion of unrecognized revenue, respectively, was reported in "Deferred revenues" and "Other non-current liabilities" on the Company's consolidated balance sheet. During the year ended December 31, 2020, approximately $575 million of the January 1, 2020 unrecognized revenue balance was recognized as revenue. As of January 1, 2019, a total of $2.7 billion of unrecognized revenue was reported in "Deferred revenues" and "Other non-current liabilities" on the Company's consolidated balance sheet. During the year ended December 31, 2019, approximately $510 million of the January 1, 2019 unrecognized revenue balance was recognized as revenue. See note 3 for further discussion regarding the Company’s revenues.
Cost of Operations	Costs of Operations Approximately half of the Company's site rental costs of operations expenses consist of Towers ground lease expenses, and the remainder includes fiber access expenses, property taxes, repairs and maintenance expenses, employee compensation or related benefit costs, or utilities. Generally, the ground leases for land are specific to each site and are for an initial term of five years and are renewable for pre-determined periods. The Company also enters into term easements and ground leases in which it prepays the entire term in advance. Fiber access expenses primarily consist of leases of fiber assets and other access agreements to facilitate the Company's communications infrastructure. Ground lease and fiber access expenses are recognized on a ratable basis, regardless of whether the payment terms require the Company to make payments annually, quarterly, monthly, or for the entire term in advance. Certain of the Company's ground lease and fiber access agreements contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the change in CPI). If the payment terms include fixed escalator provisions, the effect of such increases is recognized on a straight-line basis. The Company's liability related to straight-line expense is included in "Operating lease right-of-use assets" on the Company's consolidated balance sheet. The Company's assets related to prepaid agreements is included in "Prepaid expenses" and "Operating lease right-of-use assets" on the Company's consolidated balance sheet. Services and other costs of operations predominately consist of third-party service providers such as contractors and professional services firms and, to a lesser extent, internal labor costs. The Company recognized $20 million as costs of operations during the year ended December 31, 2020 as a result of a reduction in staffing completed during the fourth quarter of 2020. Such costs were comprised of employee severance payments and termination benefits and primarily impacted the Company's Fiber segment.
Acquisitions and Integration Costs	Acquisitions and Integration Costs Direct or incremental costs related to a potential or completed business combination transaction are expensed as incurred. Such costs are predominately comprised of severance, retention bonuses payable to employees of an acquired enterprise, temporary employees to assist with the integration of the acquired operations, fees paid for services (such as consulting, accounting, legal, or engineering reviews), and any other costs directly associated with the transaction. These business combination costs are included in "Acquisition and integration costs" on the Company's consolidated statement of operations and comprehensive income (loss). For those transactions accounted for as asset acquisitions, these costs are capitalized as part of the purchase price.
Stock-Based Compensation	Stock-Based Compensation Restricted Stock Units. The Company records stock-based compensation expense only for those unvested restricted stock units ("RSUs") for which the requisite service is expected to be rendered. The cumulative effect of a change in the estimated number of RSUs for which the requisite service is expected to be or has been rendered is recognized in the period of the change in the estimate. To the extent that the requisite service is rendered, compensation cost for accounting purposes is not reversed; rather, it is recognized regardless of whether or not the awards vest. A discussion of the Company's valuation techniques and related assumptions and estimates used to measure the Company's stock-based compensation is as follows: Valuation. The fair value of RSUs without market conditions is determined based on the number of shares relating to such RSUs and the quoted price of the Company's common stock at the date of grant. The Company estimates the fair value of RSUs with market conditions granted using a Monte Carlo simulation. The Company's determination of the fair value of RSUs with market conditions on the date of grant is affected by its common stock price as well as assumptions regarding a number of highly complex or subjective variables. The determination of fair value using a Monte Carlo simulation requires the input of subjective assumptions, and other reasonable assumptions could provide differing results. Amortization Method. The Company amortizes the fair value of all RSUs on a straight-line basis for each separately vesting tranche of the award (graded vesting schedule) over the requisite service periods. Expected Volatility. The Company estimates the volatility of its common stock at the date of grant based on the historical volatility of its common stock. Expected Dividend Rate. The expected dividend rate at the date of grant is based on the then-current dividend yield. Risk-Free Rate. The Company bases the risk-free rate on the implied yield currently available on U.S. Treasury issues with an equivalent remaining term equal to the expected life of the award. Forfeitures. The Company uses historical data and management's judgment about the future employee turnover rates to estimate the number of shares for which the requisite service period will not be rendered.
Interest Expense and Amortization of Deferred Financing Costs	Interest Expense and Amortization of Deferred Financing Costs The components of interest expense and amortization of deferred financing costs are as follows: Years Ended December 31, 2020 2019 2018 Interest expense on debt obligations $ 683 $ 682 $ 635 Amortization of deferred financing costs and adjustments on long-term debt, net 23 21 21 Capitalized interest (17) (20) (15) Other — — 1 Total $ 689 $ 683 $ 642
Income Taxes	Income Taxes The Company operates as a REIT for U.S. federal income tax purposes. As a REIT, the Company is generally entitled to a deduction for dividends that it pays and therefore is not subject to U.S. federal corporate income tax on its net taxable income that is currently distributed to its stockholders. The Company also may be subject to certain federal, state, local and foreign taxes on its income and assets, including (1) taxes on any undistributed income, (2) taxes related to the TRSs, (3) franchise taxes, (4) property taxes, and (5) transfer taxes. In addition, the Company could under certain circumstances be required to pay an excise or penalty tax, which could be significant in amount, in order to utilize one or more relief provisions under the Internal Revenue Code of 1986, as amended ("Code"), to maintain qualification for taxation as a REIT. Additionally, the Company has included in TRSs certain other assets and operations. Those TRS assets and operations will continue to be subject, as applicable, to federal and state corporate income taxes or to foreign taxes in the jurisdictions in which such assets and operations are located. The Company's foreign assets and operations (including its tower operations in Puerto Rico) are subject to foreign income taxes in the jurisdictions in which such assets and operations are located, regardless of whether they are included in a TRS or not. For its REIT conversion and certain subsequent acquisitions into the REIT, the Company will be subject to a federal corporate level tax rate (currently 21%) on any gain recognized from the sale of assets occurring within a specified period (generally 5 years) after the transfer date up to the amount of the built in gain that existed on the transfer date, which is based upon the fair market value of those assets in excess of the Company's tax basis on the transfer date. This gain can be offset by any remaining federal net operating loss carryforwards ("NOLs"). For the Company's TRSs, the Company accounts for income taxes using an asset and liability approach, which requires the recognition of deferred income tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company's financial statements or tax returns. Deferred income tax assets and liabilities are determined based on the temporary differences between the financial statement and tax bases of assets and liabilities using enacted tax rates. A valuation allowance is provided on deferred tax assets if it is determined that it is "more likely than not" that the asset will not be realized. The Company records a valuation allowance against deferred tax assets when it is "more likely than not" that some portion or all of the deferred tax asset will not be realized. The Company reviews the recoverability of deferred tax assets each quarter and based upon projections of future taxable income, reversing deferred tax liabilities or other known events that are expected to affect future taxable income, records a valuation allowance for assets that do not meet the "more likely than not" realization threshold. Valuation allowances may be reversed if related deferred tax assets are deemed realizable based upon changes in facts and circumstances that impact the recoverability of the asset. The Company recognizes a tax position if it is "more likely than not" that it will be sustained upon examination. The tax position is measured at the largest amount that is greater than 50 percent likely of being realized upon ultimate settlement. The Company reports penalties and tax-related interest expense as a component of the benefit (provision) for income taxes. As of
Per Share Information	Per Share Information Basic net income (loss) attributable to CCIC common stockholders, per common share, excludes dilution and is computed by dividing net income (loss) attributable to CCIC common stockholders by the weighted-average number of common shares outstanding during the period. For the years ended December 31, 2020, 2019 and 2018, diluted net income (loss) attributable to CCIC common stockholders, per common share, is computed by dividing net income (loss) attributable to CCIC common stockholders by the weighted-average number of common shares outstanding during the period, plus any potential dilutive common share equivalents, including shares issuable upon (1) the vesting of restricted stock units as determined under the treasury stock method and (2) conversion of the Company's previously outstanding 6.875% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share ("6.875% Convertible Preferred Stock"), as applicable, as determined under the if-converted method. A reconciliation of the numerators and denominators of the basic and diluted per share computations is shown in the table below. Years Ended December 31, 2020 2019 2018 Net income (loss) attributable to CCIC stockholders $ 1,056 $ 860 $ 622 Dividends/distributions on preferred stock (57) (113) (113) Net income (loss) attributable to CCIC common stockholders for basic and diluted computations $ 999 $ 747 $ 509 Weighted-average number of common shares outstanding (in millions): Basic weighted-average number of common stock outstanding 423 416 413 Effect of assumed dilution from potential issuance of common shares relating to RSUs 2 2 2 Diluted weighted-average number of common shares outstanding 425 418 415 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 2.36 $ 1.80 $ 1.23 Diluted $ 2.35 $ 1.79 $ 1.23 Dividends/distributions declared per share of common stock $ 4.93 $ 4.58 $ 4.28
Fair Values	Fair Values The Company's assets and liabilities recorded at fair value are categorized based upon a fair value hierarchy that ranks the quality and reliability of the information used to determine fair value. The three levels of the fair value hierarchy are (1) Level 1 — quoted prices (unadjusted) in active and accessible markets, (2) Level 2 — observable prices that are based on inputs not quoted in active markets but corroborated by market data, and (3) Level 3 — unobservable inputs and are not corroborated by market data. The Company evaluates fair value hierarchy level classifications quarterly, and transfers between levels are effective at the end of the quarterly period.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In January 2017, the Financial Accounting Standards Board ("FASB") issued new guidance to simplify the accounting for goodwill impairment by removing the second step of the existing goodwill impairment test. As a result of the guidance, goodwill impairment, if any, will be measured during the quantitative impairment test as the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Additionally, the guidance does not change the option to complete a qualitative assessment prior to performing a quantitative impairment test. The Company adopted the guidance during its most recent annual goodwill impairment test on October 1, 2020. The adoption of this guidance did not impact the Company's consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted No new accounting pronouncements issued but not yet adopted are expected to have a material impact on the Company's consolidated financial statements.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Components of Interest Expense and Amortization of Deferred Financing Costs	The components of interest expense and amortization of deferred financing costs are as follows: Years Ended December 31, 2020 2019 2018 Interest expense on debt obligations $ 683 $ 682 $ 635 Amortization of deferred financing costs and adjustments on long-term debt, net 23 21 21 Capitalized interest (17) (20) (15) Other — — 1 Total $ 689 $ 683 $ 642
Reconciliation of the Numerators and Denominators of the Basic and Diluted Per Share Computations	A reconciliation of the numerators and denominators of the basic and diluted per share computations is shown in the table below. Years Ended December 31, 2020 2019 2018 Net income (loss) attributable to CCIC stockholders $ 1,056 $ 860 $ 622 Dividends/distributions on preferred stock (57) (113) (113) Net income (loss) attributable to CCIC common stockholders for basic and diluted computations $ 999 $ 747 $ 509 Weighted-average number of common shares outstanding (in millions): Basic weighted-average number of common stock outstanding 423 416 413 Effect of assumed dilution from potential issuance of common shares relating to RSUs 2 2 2 Diluted weighted-average number of common shares outstanding 425 418 415 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 2.36 $ 1.80 $ 1.23 Diluted $ 2.35 $ 1.79 $ 1.23 Dividends/distributions declared per share of common stock $ 4.93 $ 4.58 $ 4.28

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	The following table is a summary of the contracted amounts owed to the Company by tenants pursuant to tenant contracts in effect as of December 31, 2020. As of December 31, 2020, the weighted-average remaining term of tenant contracts is approximately five years, exclusive of renewals exercisable at the tenant's option. Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total Contracted amounts (a) $ 4,354 $ 4,153 $ 3,564 $ 2,875 $ 2,380 $ 9,560 $ 26,886 (a) Based on the nature of the contract, tenant contracts are accounted for pursuant to relevant lease accounting (ASC 842) or revenue accounting (ASC 606) guidance. Excludes amounts related to services, as those contracts generally have a duration of one year or less.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Major Classes of Property and Equipment	The major classes of property and equipment are summarized in the table below. Estimated Useful Lives As of December 31, 2020 2019 Land (a) — $ 2,171 $ 2,080 Buildings 40 years 147 147 Communications infrastructure assets 1-20 years 22,027 20,521 Information technology assets and other 2-7 years 557 506 Construction in process — 1,063 1,080 Total gross property and equipment 25,965 24,334 Less: accumulated depreciation (10,803) (9,668) Total property and equipment, net $ 15,162 $ 14,666 (a) Includes land owned through fee interests and perpetual easements.

Intangible Assets, Goodwill a_2

Intangible Assets, Goodwill and Other (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	The following is a summary of the Company's intangible assets. As of December 31, 2020 As of December 31, 2019 Gross Carrying Value Accumulated Amortization Net Book Value Gross Carrying Value Accumulated Amortization Net Book Value Site rental contracts and tenant relationships $ 7,797 $ (3,432) $ 4,365 $ 7,761 $ (2,997) $ 4,764 Other intangible assets 143 (75) 68 143 (71) 72 Total $ 7,940 $ (3,507) $ 4,433 $ 7,904 $ (3,068) $ 4,836
Schedule of Amortization Expense	Amortization expense related to intangible assets is classified as follows on the Company's consolidated statement of operations and comprehensive income (loss): For Years Ended December 31, Classification 2020 2019 2018 Depreciation, amortization and accretion $ 439 $ 428 $ 428 Site rental costs of operations (a) — — 17 Total amortization expense $ 439 $ 428 $ 445
Schedule of Estimated Annual Amortization Expense	The estimated annual amortization expense related to intangible assets for the years ending December 31, 2021 to 2025 is as follows: Years Ending December 31, 2021 2022 2023 2024 2025 Estimated annual amortization $ 444 $ 444 $ 442 $ 393 $ 371

Other Liabilities (Tables)

Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Other Liabilities [Abstract]
Other Noncurrent Liabilities	The following is a summary of the components of "Other long-term liabilities" as presented on the Company's consolidated balance sheet. See also note 2. December 31, 2020 2019 Deferred rental revenues $ 1,707 $ 1,814 Deferred credits, net 375 434 Asset retirement obligation 259 227 Deferred income tax liabilities 11 8 Other long-term liabilities 27 33 Total $ 2,379 $ 2,516
Amortization of below-market tenant leases	The following table summarizes the estimated annual amounts related to below-market tenant leases expected to be amortized into site rental revenues for the years ending December 31, 2021 to 2025 are as follows: Years Ending December 31, 2021 2022 2023 2024 2025 Below-market tenant leases $ 53 $ 48 $ 45 $ 41 $ 33

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	12 Months Ended
	Dec. 31, 2020
Debt and Other Obligations [Abstract]
Schedule of Long-Term Debt Instruments	The table below sets forth the Company's debt and other obligations as of December 31, 2020. Original Contractual Outstanding Balance as of December 31, Stated 2020 2019 2020 (a) 3.849% Secured Notes Dec. 2012 Apr. 2023 $ 997 $ 995 3.9 % Secured Notes, Series 2009-1, Class A-2 July 2009 Aug. 2029 60 67 9.0 % Tower Revenue Notes, Series 2015-1 May 2015 May 2042 (b)(c) 299 298 3.2 % Tower Revenue Notes, Series 2018-1 July 2018 July 2043 (b)(c) 248 248 3.7 % Tower Revenue Notes, Series 2015-2 May 2015 May 2045 (b)(c) 695 694 3.7 % Tower Revenue Notes, Series 2018-2 July 2018 July 2048 (b)(c) 743 742 4.2 % Finance leases and other obligations Various Various (d) 236 227 Various (d) Total secured debt 3,278 3,271 2016 Revolver Jan. 2016 June 2024 290 (e) 525 1.3 % (f) 2016 Term Loan A Jan. 2016 June 2024 2,252 2,310 1.3 % (f) Commercial Paper Notes Various (g) Various (g) 285 155 0.5 % 3.400% Senior Notes Feb./May 2016 Feb. 2021 — 850 N/A 2.250% Senior Notes Sept. 2016 Sept. 2021 — 698 N/A 4.875% Senior Notes Apr. 2014 Apr. 2022 — 846 N/A 5.250% Senior Notes Oct. 2012 Jan. 2023 1,646 1,644 5.3 % 3.150% Senior Notes Jan. 2018 July 2023 746 744 3.2 % 3.200% Senior Notes Aug. 2017 Sept. 2024 745 744 3.2 % 1.350% Senior Notes June 2020 July 2025 494 — 1.4 % 4.450% Senior Notes Feb. 2016 Feb. 2026 894 893 4.5 % 3.700% Senior Notes May 2016 June 2026 745 744 3.7 % 4.000% Senior Notes Feb. 2017 Mar. 2027 496 495 4.0 % 3.650% Senior Notes Aug. 2017 Sept. 2027 994 993 3.7 % 3.800% Senior Notes Jan. 2018 Feb. 2028 991 990 3.8 % 4.300% Senior Notes Feb. 2019 Feb. 2029 593 592 4.3 % 3.100% Senior Notes Aug. 2019 Nov. 2029 544 543 3.1 % 3.300% Senior Notes Apr. 2020 July 2030 737 — 3.3 % 2.250% Senior Notes June 2020 Jan. 2031 1,088 — 2.3 % 4.750% Senior Notes May 2017 May 2047 344 344 4.8 % 5.200% Senior Notes Feb. 2019 Feb. 2049 395 395 5.2 % 4.000% Senior Notes Aug. 2019 Nov. 2049 345 345 4.0 % 4.150% Senior Notes Apr. 2020 July 2050 489 — 4.2 % 3.250% Senior Notes June 2020 Jan. 2051 889 — 3.3 % Total unsecured debt $ 16,002 $ 14,850 Total debt and other obligations $ 19,280 $ 18,121 Less: current maturities and short-term debt and other current obligations $ 129 $ 100 Non-current portion of long-term debt and other long-term obligations $ 19,151 $ 18,021 (a) Represents the weighted-average stated interest rate. (b) The Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") and Tower Revenue Notes, Series 2018-1 and 2018-2 ("July 2018 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes." (c) If the respective series of Tower Revenue Notes are not paid in full on or prior to an applicable anticipated repayment date, then Excess Cash Flow (as defined in the indenture governing the terms of such notes) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes, and additional interest (of an additional approximately 5% per annum) will accrue on the respective Tower Revenue Notes. As of December 31, 2019, the Tower Revenue Notes have principal amounts of $300 million, $250 million, $700 million and $750 million, with anticipated repayment dates in 2022, 2023, 2025 and 2028, respectively. (d) The Company's finance leases and other obligations relate to land, fiber, vehicles, and other assets and bear interest rates ranging up to 10% and mature in periods ranging from less than one year to approximately 25 years. (e) As of December 31, 2020, the undrawn availability under the 2016 Revolver was $4.7 billion. (f) Both the 2016 Revolver and 2016 Term Loan A bear interest, at our option, at either (1) LIBOR plus a credit spread ranging from 0.875% to 1.750% per annum or (2) an alternate base rate plus a credit spread ranging from 0.000% to 0.750% per annum, in each case, with the applicable credit spread based on the Company's senior unsecured debt rating. The Company pays a commitment fee ranging from 0.125% to 0.350%, based on the Company's senior unsecured debt rating, per annum on the undrawn available amount under the 2016 Revolver.
Schedule of Maturities of Long-term Debt	The following are the scheduled principal payments and final maturities of the total debt and other long-term obligations of the Company outstanding as of December 31, 2020, which do not consider the principal payments that will commence following the anticipated repayment dates on the Tower Revenue Notes. If the Tower Revenue Notes are not paid in full on or prior to their respective anticipated repayment dates, as applicable, then the Excess Cash Flow (as defined in the indenture) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes and additional interest (of an additional approximately 5% per annum) will accrue on the Tower Revenue Notes. Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total Cash Obligations Unamortized Adjustments, Net Total Debt and Other Obligations Outstanding Scheduled principal payments and final maturities $ 415 $ 154 $ 3,608 $ 2,941 $ 525 $ 11,780 $ 19,423 $ (143) $ 19,280
Schedule of Extinguishment of Debt	The following is a summary of the purchases and redemptions of debt during the years ended December 31, 2020, 2019 and 2018. Year Ended December 31, 2020 Principal Amount Cash Paid (a) Gains (losses) (b) 3.400% Senior Notes $ 850 $ 863 $ (13) 2.250% Senior Notes 700 714 (16) 4.875% Senior Notes 850 913 (66) Total $ 2,400 $ 2,490 $ (95) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs. Year Ended December 31, 2019 Principal Amount Cash Paid (a) Gains (losses) (b) Secured Notes, Series 2009-1, Class A-1 $ 12 $ 12 $ (1) 2016 Term Loan A — — (1) Total $ 12 $ 12 $ (2) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs. Year Ended December 31, 2018 Principal Amount Cash Paid (a) Gains (losses) (b) Tower Revenue Notes, Series 2010-3 $ 1,250 $ 1,318 $ (71) 2016 Term Loan A — — (3) Tower Revenue Notes, Series 2010-6 1,000 1,028 (32) Total $ 2,250 $ 2,346 $ (106) (a) Exclusive of accrued interest. (b) Inclusive of the write-off of the respective deferred financing costs.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Estimated Fair Values and Carrying Amounts of Assets and Liabilities	The following table shows the estimated fair values of the Company's financial instruments, along with the carrying amounts of the related assets (liabilities). See also note 2. Level in Fair Value Hierarchy December 31, 2020 December 31, 2019 Carrying Fair Carrying Fair Assets: Cash and cash equivalents 1 $ 232 $ 232 $ 196 $ 196 Restricted cash, current and non-current 1 149 149 142 142 Liabilities: Total debt and other obligations 2 19,280 21,302 18,121 19,170

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations Before Income Taxes	Income (loss) from continuing operations before income taxes by geographic area is summarized in the table below. Years Ended December 31, 2020 2019 2018 Domestic $ 1,046 $ 850 $ 618 Foreign (a) 30 31 23 Total $ 1,076 $ 881 $ 641 (a) Inclusive of income (loss) before income taxes from Puerto Rico.
Benefit (Provision) for Income Taxes	The benefit (provision) for income taxes consists of the following: Years Ended December 31, 2020 2019 2018 Current: Federal $ (6) $ (6) $ (5) Foreign (6) (8) (7) State (5) (5) (5) Total current (17) (19) (17) Deferred: Foreign (3) (2) (2) Total deferred (3) (2) (2) Total tax benefit (provision) $ (20) $ (21) $ (19)
Effective Tax Rate	A reconciliation between the benefit (provision) for income taxes and the amount computed by applying the federal statutory income tax rate to the income (loss) before income taxes is as follows: Years Ended December 31, 2020 2019 2018 Benefit (provision) for income taxes at statutory rate $ (225) $ (185) $ (135) Tax effect of foreign income (losses) — 1 1 Tax adjustment related to REIT operations 219 178 128 State tax (provision) benefit, net of federal (5) (5) (4) Foreign tax (9) (10) (9) Total $ (20) $ (21) $ (19)
Components of Deferred Tax Assets and Liabilities	The components of the net deferred income tax assets and liabilities are as follows: December 31, 2020 2019 Deferred income tax liabilities: Property and equipment $ 7 $ 6 Deferred site rental receivable 7 7 Total deferred income tax liabilities 14 13 Deferred income tax assets: Intangible assets 3 3 Net operating loss carryforwards (a) 15 18 Straight-line rent expense liability 3 3 Accrued liabilities 6 5 Other 2 2 Valuation allowances — — Total deferred income tax assets, net 29 31 Net deferred income tax asset (liabilities) $ 15 $ 18 (a) Balance results from the Company's foreign NOLs. Due to the Company's REIT status, no federal or state NOLs result in the Company recording a deferred income tax asset. See further discussion surrounding the Company's NOL balances below.
Jurisdictional Components of Deferred Tax Assets and Liabilities	The components of the net deferred income tax assets (liabilities) are as follows: December 31, 2020 December 31, 2019 Classification Gross Valuation Net Gross Valuation Net Federal $ 25 $ — $ 25 $ 25 $ — $ 25 State 1 — 1 1 — 1 Foreign (11) — (11) (8) — (8) Total $ 15 $ — $ 15 $ 18 $ — $ 18

Stockholders' Equity Stockholde

Stockholders' Equity Stockholders Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Dividends Declared [Abstract]
Dividends Declared	During the year ended December 31, 2020, the following dividends/distributions were declared or paid: Equity Type Declaration Date Record Date Payment Date Dividends Per Share Aggregate Common Stock February 20, 2020 March 13, 2020 March 31, 2020 $ 1.20 $ 504 (a) Common Stock May 14, 2020 June 12, 2020 June 30, 2020 $ 1.20 $ 504 (a) Common Stock August 6, 2020 September 15, 2020 September 30, 2020 $ 1.20 $ 521 (a) Common Stock October 21, 2020 December 15, 2020 December 31, 2020 $ 1.33 $ 577 (a) 6.875% Convertible Preferred Stock December 9, 2019 January 15, 2020 February 3, 2020 $ 17.1875 $ 28 6.875% Convertible Preferred Stock March 12, 2020 April 15, 2020 May 1, 2020 $ 17.1875 $ 28 6.875% Convertible Preferred Stock June 19, 2020 July 15, 2020 August 3, 2020 $ 17.1875 $ 28 (a) Inclusive of dividends accrued for holders of unvested RSUs, which will be paid when and if the RSUs vest.
Tax Treatment of Dividends Paid [Table Text Block]	The following table summarizes, for income tax purposes, the nature of dividends paid during 2020 on the Company's common stock and previously outstanding 6.875% Convertible Preferred Stock. Equity Type Payment Date Cash Distribution (per share) Ordinary Taxable Dividend (per share) Qualified Taxable Dividend (per share) (a) Section 199A Dividend (per share) Non-Taxable Distribution (per share) Common Stock March 31, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock June 30, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock September 30, 2020 $ 1.20 $ 0.788 $ 0.010 $ 0.778 $ 0.412 Common Stock December 31, 2020 $ 1.33 $ 0.874 $ 0.012 $ 0.862 $ 0.456 6.875% Convertible Preferred Stock February 3, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — 6.875% Convertible Preferred Stock May 1, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — 6.875% Convertible Preferred Stock August 3, 2020 $ 17.1875 $ 17.1875 $ 0.2265 $ 16.9610 $ — (a) Qualified taxable dividend and section 199A dividend amounts are included in ordinary taxable dividend amounts.

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement, Noncash Expense [Abstract]
Summary of Restricted Stock Awards Activity	The following is a summary of the RSU activity during the year ended December 31, 2020. RSUs (In millions) Outstanding at the beginning of year 2.8 Granted 1.0 Vested (1.3) Forfeited (0.1) Outstanding at end of year 2.4
Summary of the Assumptions Used in the Monte Carlo Simulation to Determine the Grant-Date Fair Value	The following table summarizes the assumptions used in the Monte Carlo simulation to determine the grant-date fair value for the RSUs with market conditions granted during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, 2020 2019 2018 Risk-free rate 1.4 % 2.5 % 2.4 % Expected volatility 19 % 18 % 18 % Expected dividend rate 3.5 % 4.0 % 3.8 %
Summary of Restricted Stock Vested	The following table is a summary of the RSUs vested during the years ended December 31, 2020, 2019 and 2018. Years Ended December 31, Total Shares Fair Value on (In millions 2020 1 $ 220 2019 1 135 2018 1 107
Stock Based Compensation Expense	The following table discloses the components of stock-based compensation expense. Years Ended December 31, 2020 2019 2018 Stock-based compensation expense: Site rental costs of operations $ 16 $ 19 $ 17 Services and other costs of operations 8 7 8 Selling, general and administrative expenses 109 90 83 Total stock-based compensation $ 133 $ 116 $ 108

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	The following table is a summary of the Company's maturities of operating lease liabilities as of December 31, 2020: Years Ending December 31, 2021 2022 2023 2024 2025 Thereafter Total undiscounted lease payments Less: Imputed interest Total operating lease liabilities Operating leases (a) $ 546 $ 543 $ 538 $ 532 $ 518 $ 5,842 $ 8,519 $ (2,382) $ 6,137 (a) Excludes the Company's contingent payments for operating leases (such as payments based on revenues derived from the communications infrastructure located on the leased asset) as such arrangements are excluded from the Company's operating lease liability. Such contingencies are recognized as expense in the period they are resolved.
Lease, Cost [Table Text Block]	The components of the Company's operating lease expense are as follows: Years Ended December 31, 2020 2019 (d) Lease cost: Operating lease expense (a) $ 640 $ 632 Variable lease expense (b) 153 149 Total lease expense (c) $ 793 $ 781 (a) Represents the Company's operating lease expense related to its ROU assets for the twelve months ended December 31, 2020 and 2019. (b) Represents the Company's expense related to contingent payments for operating leases (such as payments based on revenues derived from the communications infrastructure located on the leased asset) for the twelve months ended December 31, 2020 and 2019. Such contingencies are recognized as expense in the period they are resolved. (c) Excludes those direct operating expenses accounted for pursuant to accounting guidance outside the scope of ASC 842. (d) Amounts for the year ended December 31, 2019 reflect a revision from the Company's 2019 Annual Report on Form 10-K relating to an immaterial classification error of certain operating lease expenses. In connection with this revision, the Company reclassified $16 million from operating lease expense to variable lease expense for the year ended December 31, 2019; total lease expense for the year ended December 31, 2019 remained unchanged.

Operating Segments and Concen_2

Operating Segments and Concentrations of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Year Ended December 31, 2020 Towers Fiber Other Consolidated Segment site rental revenues $ 3,497 $ 1,823 $ 5,320 Segment services and other revenues 500 20 520 Segment revenues 3,997 1,843 5,840 Segment site rental cost of operations 866 620 1,486 Segment services and other cost of operations 429 12 441 Segment cost of operations (a)(b) 1,295 632 1,927 Segment site rental gross margin 2,631 1,203 3,834 Segment services and other gross margin 71 8 79 Segment selling, general and administrative expenses (b) 100 186 286 Segment other operating (income) expense (c) — (362) (362) Segment operating profit (loss) 2,602 1,387 3,989 Other selling, general and administrative expenses (b) $ 283 283 Stock-based compensation expense 133 133 Depreciation, amortization and accretion 1,608 1,608 Interest expense and amortization of deferred financing costs 689 689 Other (income) expenses to reconcile to income (loss) before income taxes (d) 200 200 Income (loss) before income taxes $ 1,076 Capital expenditures $ 335 $ 1,232 $ 57 $ 1,624 Total assets (at year end) $ 22,242 $ 15,746 $ 780 $ 38,768 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2020 excludes (1) stock-based compensation expense of $24 million and (2) prepaid lease purchase price adjustments of $18 million. For the year ended December 31, 2020, segment selling, general and administrative expenses exclude stock-based compensation expense of $109 million. (c) See note 15 for further information. (d) See consolidated statement of operations for further information.	Year Ended December 31, 2019 Towers Fiber Other Consolidated Segment site rental revenues $ 3,389 $ 1,704 $ 5,093 Segment services and other revenues 653 17 670 Segment revenues 4,042 1,721 5,763 Segment site rental cost of operations 864 559 1,423 Segment services and other cost of operations 506 11 517 Segment cost of operations (a)(b) 1,370 570 1,940 Segment site rental gross margin 2,525 1,145 3,670 Segment services and other gross margin 147 6 153 Segment selling, general and administrative expenses (b) 96 195 291 Segment operating profit (loss) 2,576 956 3,532 Other selling, general and administrative expenses (b) $ 233 233 Stock-based compensation expense 116 116 Depreciation, amortization and accretion 1,572 1,572 Interest expense and amortization of deferred financing costs 683 683 Other (income) expenses to reconcile to income (loss) before income taxes (c) 47 47 Income (loss) before income taxes $ 881 Capital expenditures $ 543 $ 1,473 $ 41 $ 2,057 Total assets (at year end) $ 22,357 $ 15,389 $ 711 $ 38,457 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2019 excludes (1) stock-based compensation expense of $26 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2019, segment selling, general and administrative expenses exclude stock-based compensation expense of $90 million. (c) See consolidated statement of operations for further information.	Year Ended December 31, 2018 Towers Fiber Other Consolidated Segment site rental revenues $ 3,196 $ 1,600 $ 4,796 Segment services and other revenues 558 16 574 Segment revenues 3,754 1,616 5,370 Segment site rental cost of operations 848 525 1,373 Segment services and other cost of operations 415 11 426 Segment cost of operations (a)(b) 1,263 536 1,799 Segment site rental gross margin 2,348 1,075 3,423 Segment services and other gross margin 143 5 148 Segment selling, general and administrative expenses (b) 110 179 289 Segment operating profit (loss) 2,381 901 3,282 Other selling, general and administrative expenses (b) $ 191 191 Stock-based compensation expense 108 108 Depreciation, amortization and accretion 1,527 1,527 Interest expense and amortization of deferred financing costs 642 642 Other (income) expenses to reconcile to income (loss) before income taxes (c) 173 173 Income (loss) before income taxes $ 641 Capital expenditures $ 440 $ 1,264 $ 35 $ 1,739 Total assets (at year end) $ 17,644 $ 14,512 $ 606 $ 32,762 Total goodwill (at year end) $ 5,127 $ 4,951 $ — $ 10,078 (a) Exclusive of depreciation, amortization and accretion shown separately. (b) Segment cost of operations for the year ended December 31, 2018 excludes (1) stock-based compensation expense of $25 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2018, segment selling, general and administrative expenses exclude stock-based compensation expense of $83 million. (c) See consolidated statement of operations for further information.
A Summary of the Percentage of the Consolidated Revenues for Those Customers Accounting for More than 10% of the Consolidated Revenues	The following table summarizes the percentage of the consolidated revenues for those tenants accounting for more than 10% of the consolidated revenues. Years Ended December 31, 2020 (a) 2019 2018 T-Mobile 36 % 22 % 19 % AT&T 22 % 21 % 20 % Verizon Wireless 19 % 19 % 20 % Sprint — % 14 % 15 % Total 77 % 76 % 74 % (a) For the year ended December 31, 2020, revenues attributable to T-Mobile includes revenues previously derived from Sprint. On April 1, 2020, T-Mobile and Sprint announced the completion of their previously disclosed merger.

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts Allowance for Doubtful Accounts (Tables)	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts Disclosure [Text Block]	Additions Deductions Balance at Charged to Credited to Written Off Effect of Other Adjustments Balance at Allowance for Doubtful Accounts Receivable: 2020 $ 18 $ 4 $ — $ (5) $ — $ — $ 17 2019 $ 14 $ 7 $ — $ (3) $ — $ — $ 18 2018 $ 14 $ 4 $ — $ (4) $ — $ — $ 14 Additions Deductions Balance at Charged Charged to Credited to Credited to Other Balance at Deferred Tax Valuation Allowance: 2020 $ — $ — $ — $ — $ — $ — $ — 2019 $ 1 $ — $ — $ (1) $ — $ — $ — 2018 $ 1 $ — $ — $ — $ — $ — $ 1

Schedule III - Schedule of Re_2

Schedule III - Schedule of Real Estate and Depreciation Schedule of Real Estate and Accumulated Depreciation (Tables)	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block]	Description Encumbrances Initial Cost to Company Cost Capitalized Subsequent to Acquisition Gross Amount Carried at Close of Current Period Accumulated Depreciation at Close of Current Period Date of Construction Date Acquired Life on Which Depreciation in Latest Income Statement is Computed Communications infrastructure (a) $ 3,295 (b) (c) (c) $ 25,441 $ (10,478) Various Various Up to 20 years (a) Includes approximately 40,000 towers and 80,000 route miles of fiber. No single asset exceeds 5% of the aggregate gross amounts at which the assets were carried at the close of the period set forth in the table above. (b) Encumbrances are reported at face value, without contemplating the effect of deferred financing costs, discounts or premiums. Certain of the Company's debt is secured by (1) a security interest in substantially all of the applicable issuers' assignable personal property, (2) a pledge of the equity interests in each applicable issuer and (3) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses). (c) The Company has omitted this information, as it would be impracticable to compile such information on an asset-by-asset basis. 2020 2019 Gross amount at beginning $ 23,854 $ 21,840 Additions during period: Acquisitions through foreclosure — — Other acquisitions (a) 68 4 Communications infrastructure construction and improvements 1,438 1,878 Purchase of land interests 64 53 Sustaining capital expenditures 66 84 Other (b) 47 101 Total additions 1,683 2,120 Deductions during period: Cost of real estate sold or disposed (96) (45) Other — (61) Total deductions (96) (106) Balance at end $ 25,441 $ 23,854 (a) Includes acquisitions of communications infrastructure. (b) Predominately relates to the purchase of property and equipment under finance leases and installment land purchases. 2020 2019 Gross amount of accumulated depreciation at beginning $ (9,382) $ (8,338) Additions during period: Depreciation (1,114) (1,087) Total additions (1,114) (1,087) Deductions during period: Amount for assets sold or disposed 18 24 Other — 19 Total deductions 18 43 Balance at end $ (10,478) $ (9,382)

Basis of Presentation (Details)

Basis of Presentation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
AT&T [Member]
Purchase Option, Percentage of Towers	22.00%
T-Mobile [Member]
Purchase Option, Percentage of Towers	15.00%
Sprint assumed by T-Mobile [Member]
Purchase Option, Percentage of Towers	16.00%
Subject to Capital Lease with TMO or AT&T [Member]
Purchase Option, Percentage of Towers	53.00%
AT&T Prior to 2025 [Member]
Purchase Option Price	$ 10
AT&T lease or sublease in accordance with TMO Agreement [Member]
Purchase Option Price	$ 405
Tower count as a percentage of total towers	1.00%
T-Mobile [Member]
Purchase Option Price	$ 2,000
Period of tower lease	28 years
Sprint assumed by T-Mobile [Member]
Purchase Option Price	$ 2,300
Period of tower lease	32 years
AT&T [Member]
Purchase Option Price	$ 4,200
Period of tower lease	28 years

Accounting Policies (Details)

Accounting Policies (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Capitalized Labor Costs	$ 270	$ 246	$ 212
Asset write-down charges	$ 74	19	26
Revenue Recognition Non-cancelable Term - Fiber	three to 20 years
Deferred site rental receivables	$ 1,408	1,424
Revenue, Remaining Performance Obligation, Amount	2,800	2,900	2,700
Contract with Customer, Liability, Revenue Recognized	575	510
Employee Severance Payments	20
Interest expense on debt obligations	683	682	635
Amortization of deferred financing costs and adjustments on long-term debt, net	23	21	21
Capitalized interest	(17)	(20)	(15)
Other	0	0	1
Interest expense and amortization of deferred financing costs	$ 689	683	642
Percentage of tax position that is likely of being realized upon ultimate settlement	50.00%
Net income (loss) attributable to CCIC stockholders	$ 1,056	860	622
Dividends, Preferred Stock	(57)	(113)	(113)
Net Income (Loss) Available to Common Stockholders, Basic	$ 999	$ 747	$ 509
Basic (in shares)	423	416	413
Diluted (in shares)	425	418	415
Basic (in dollars per share)	$ 2.36	$ 1.80	$ 1.23
Diluted (in dollars per share)	2.35	1.79	1.23
Common Stock, Dividends, Per Share, Declared	$ 4.93	$ 4.58	$ 4.28
Portion of company site rental costs that are Towers ground lease expenses	50.00%
Ground Lease Agreement Initial Term	five to 10 years
Useful life of site rental contracts and customer relationships (years)	20 years
Revenue Recognition Non-cancelable Lease Term	five to 15 years
Revenue, Performance Obligation, Description of Payment Terms	45 to 60 days
Minimum [Member]
Ground Lease Agreement Initial Term	five years
Maximum [Member]
Ground Lease Agreement Initial Term	10 years
Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share (in shares)		14	15
Restricted Stock Units (RSUs) [Member]
Effect of assumed dilution from potential common shares relating to stock options and restricted stock awards	2	2	2
Sprint Cancellation [Member]
Asset write-down charges	$ 63
Property, Plant and Equipment [Member]
Asset write-down charges	77	$ 17	$ 22
Other Current Assets [Member]
Deferred site rental receivables, current	152	114
Deferred Revenue [Domain]
Deferred site rental receivables	$ 1,400	$ 1,400
Communication Infrastructure [Member]
Property, Plant and Equipment, Useful Life	20 years
Communication Infrastructure [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	1 year
Communication Infrastructure [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	20 years
Towers [Member]
Property, Plant and Equipment, Useful Life	20 years

Revenue (Details)

Revenue (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Weighted Average Remaining Term Of Tenant Leases at the Tenant's Option	5
Contracted revenues, Year 1	$ 4,354	[1]
Contracted revenues, Year 2	4,153	[1]
Contracted revenues, Year 3	3,564	[1]
Contracted revenues, Year 4	2,875	[1]
Contracted revenues, Year 5	2,380	[1]
Contracted revenues, Thereafter	9,560	[1]
Contracted revenues	$ 26,886	[1]
[1]	Based on the nature of the contract, tenant contracts are accounted for pursuant to relevant lease accounting (ASC 842) or revenue accounting (ASC 606) guidance. Excludes amounts related to services, as those contracts generally have a duration of one year or less.

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 25,965	$ 24,334
Less: accumulated depreciation		(10,803)	(9,668)
Total property and equipment, net		15,162	14,666
Depreciation expense		1,200	1,100	$ 1,100
Land owned in fee and perpetual easements [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	[1]	2,171	2,080
Buildings [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 147	147
Property, Plant and Equipment, Useful Life		40 years
Communication Infrastructure [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 22,027	20,521
Property, Plant and Equipment, Useful Life		20 years
Information technology assets and other [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 557	506
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 1,063	$ 1,080
Minimum [Member] | Communication Infrastructure [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		1 year
Minimum [Member] | Information technology assets and other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		2 years
Maximum [Member] | Communication Infrastructure [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		20 years
Maximum [Member] | Information technology assets and other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		7 years
[1]	Includes land owned through fee interests and perpetual easements.

Intangible Assets, Goodwill a_3

Intangible Assets, Goodwill and Other (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		$ 7,940	$ 7,904
Accumulated amortization of intangible assets		(3,507)	(3,068)
Finite-Lived Intangible Assets, Net		4,433	4,836
Amortization expense		439	428	$ 445
Estimated annual amortization expense related to intangible assets - Year 1		444
Estimated annual amortization expense related to intangible assets - Year 2		444
Estimated annual amortization expense related to intangible assets - Year 3		442
Estimated annual amortization expense related to intangible assets - Year 4		393
Estimated annual amortization expense related to intangible assets - Year 5		371
Depreciation, Amortization and Accretion [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Amortization expense		439	428	428
Site Rental Costs of Operations [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Amortization expense	[1]	0	0	$ 17
Site Rental Contracts and Customer Relationships [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		7,797	7,761
Accumulated amortization of intangible assets		(3,432)	(2,997)
Finite-Lived Intangible Assets, Net		4,365	4,764
Other Intangible Assets [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		143	143
Accumulated amortization of intangible assets		(75)	(71)
Finite-Lived Intangible Assets, Net		$ 68	$ 72
[1]	Amortization expense of intangible assets classified as "Site rental costs of operations" on the Company's consolidated statement of operations and comprehensive income (loss) for the year ended December 31, 2018 represented amortization of below-market leases. Effective January 1, 2019, the Company adopted ASC 842 and these below-market leases were de-recognized and reclassified from "Other intangible assets, net" to the "Operating lease right-of-use assets" on the Company's consolidated balance sheet.

Other Liabilities (Details)

Other Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Liabilities [Line Items]
Other Liabilities, non-current	$ 2,379	$ 2,516
Asset Retirement Obligation, Accretion Expense	18	15	$ 14
Estimated Future Undiscounted Cash Flows Expected To Be Paid Relating To Asset Retirement Obligations	1,000
Amortization of Above Market Leases			18
Amortization of Below Market Tenant Lease	58	65	$ 69
Below Market Lease, Amortization Income, Year One	53
Below Market Lease, Amortization Income, Year Two	48
Below Market Lease, Amortization Income, Year Three	45
Below Market Lease, Amortization Income, Year Four	41
Below Market Lease, Amortization Income, after Year Five	33
Accrued Payroll and Other Compensation	192	174
Deferred rental revenues [Domain]
Other Liabilities [Line Items]
Other Liabilities, non-current	1,707	1,814
Deferred credits, net [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	375	434
Asset retirement obligation [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	259	227
Deferred tax liability, noncurrent [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	11	8
Other long-term liabilities[Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	$ 27	$ 33

Debt and Other Obligations (Ind

Debt and Other Obligations (Indebtedness) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt and other obligations		$ 19,280		$ 18,121
Less: current maturities and short-term debt and other current obligations		129		100
Non-current portion of long-term debt and other long-term obligations		19,151		18,021
Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		3,278		3,271
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 16,002		14,850
Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.00%
Minimum [Member] | Finance Lease Obligations and Other [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity Date Range		one year
Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.75%
Maximum [Member] | Finance Lease Obligations and Other [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity Date Range		25 years
3.849% Secured Notes [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 997		995
Debt Instrument, Interest Rate, Stated Percentage		3.90%	[1]							3.849%
Debt Instrument, Face Amount										$ 1,000
Fixed Rate Debt 2009 Securitized Notes A-2 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 60		67
Debt Instrument, Interest Rate, Stated Percentage	[1]	9.00%
2015 Tower Revenue Notes 3.222% due 2042 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 300
2015 Tower Revenue Notes 3.222% due 2042 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[2],[3]	$ 299		298
Debt Instrument, Interest Rate, Stated Percentage		3.20%	[1]		3.222%
Debt Instrument, Face Amount								$ 300
2018 Tower Revenue Notes 3.720% due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250
2018 Tower Revenue Notes 3.720% due 2043 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[2],[3]	$ 248		248
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[1]		3.72%
Debt Instrument, Face Amount					$ 250
2015 Tower Revenue Notes 3.663% due 2045 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 700
2015 Tower Revenue Notes 3.663% due 2045 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[2],[3]	$ 695		694
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[1]		3.663%
Debt Instrument, Face Amount								$ 700
2018 Tower Revenue Notes 4.241% due 2048 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 750
2018 Tower Revenue Notes 4.241% due 2048 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[2],[3]	$ 743		742
Debt Instrument, Interest Rate, Stated Percentage		4.20%	[1]		4.241%
Debt Instrument, Face Amount					$ 750
Finance Lease Obligations and Other [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		10.00%
2016 Term Loan A [Member] | Bank Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 2,252		2,310
Debt Instrument, Interest Rate, Stated Percentage	[1],[4]	1.30%
Debt Instrument, Face Amount							$ 2,000
Senior Unsecured 2016 Notes 3.40% [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 0		850
Debt Instrument, Interest Rate, Stated Percentage		3.40%
2.250% Senior Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 0		698
Debt Instrument, Interest Rate, Stated Percentage		2.25%					2.25%
Debt Instrument, Face Amount							$ 700
4.875% Senior Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 0		846
Debt Instrument, Interest Rate, Stated Percentage		4.875%							4.875%
Debt Instrument, Face Amount									$ 850
5.250% Senior Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 1,646		1,644
Debt Instrument, Interest Rate, Stated Percentage		5.30%	[1]							5.25%
Debt Instrument, Face Amount										$ 1,650
3.150% Senior Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 746		744
Debt Instrument, Interest Rate, Stated Percentage		3.20%	[1]		3.15%
Debt Instrument, Face Amount					$ 750
August 2017 Senior Unsecured 3.200% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 745		744
Debt Instrument, Interest Rate, Stated Percentage		3.20%	[1]			3.20%
Debt Instrument, Face Amount						$ 750
Senior Unsecured 2016 Notes 4.450% [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 894		893
Debt Instrument, Interest Rate, Stated Percentage	[1]	4.50%
Senior Unsecured 2016 Notes 3.7% [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 745		744
Debt Instrument, Interest Rate, Stated Percentage	[1]	3.70%
4.000% Senior Unsecured Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 496		495
Debt Instrument, Interest Rate, Stated Percentage		4.00%	[1]			4.00%
Debt Instrument, Face Amount						$ 500
August 2017 Senior Unsecured 3.650% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 994		993
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[1]			3.65%
Debt Instrument, Face Amount						$ 1,000
3.800% Senior Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 991		990
Debt Instrument, Interest Rate, Stated Percentage		3.80%	[1]		3.80%
Debt Instrument, Face Amount					$ 1,000
February 2019 Senior Unsecured 4.300% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 593		$ 592
Debt Instrument, Interest Rate, Stated Percentage		4.30%	[1]	4.30%
Debt Instrument, Face Amount				$ 600
August 2019 Senior Unsecured 3.100% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 544		$ 543
Debt Instrument, Interest Rate, Stated Percentage		3.10%	[1]	3.10%
Debt Instrument, Face Amount				$ 550
4.750% Senior Unsecured Notes [Member] [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 344		344
Debt Instrument, Interest Rate, Stated Percentage		4.80%	[1]			4.75%
Debt Instrument, Face Amount						$ 350
February 2019 Senior Unsecured 5.200% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 395		$ 395
Debt Instrument, Interest Rate, Stated Percentage		5.20%	[1]	5.20%
Debt Instrument, Face Amount				$ 400
August 2019 Senior Unsecured 4.000% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 345		$ 345
Debt Instrument, Interest Rate, Stated Percentage		4.00%	[1]	4.00%
Debt Instrument, Face Amount				$ 350
Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)		5.00%
Secured Debt [Member] | Finance Lease Obligations and Other [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[5]	$ 236		227
June 2020 Senior Unsecured 1.350% Notes [Domain] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 494		0
Debt Instrument, Interest Rate, Stated Percentage	[1]	1.35%
Debt Instrument, Face Amount		$ 500
April 2020 Senior Unsecured 3.300% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 737		0
Debt Instrument, Interest Rate, Stated Percentage	[1]	3.30%
Debt Instrument, Face Amount		$ 750
June 2020 Senior Unsecured 2.250% Notes [Domain] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 1,088		0
Debt Instrument, Interest Rate, Stated Percentage	[1]	2.25%
Debt Instrument, Face Amount		$ 1,100
April 2020 Senior Unsecured 4.150% Notes [Member] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 489		0
Debt Instrument, Interest Rate, Stated Percentage	[1]	4.15%
Debt Instrument, Face Amount		$ 500
June 2020 Senior Unsecured 3.250% Notes [Domain] | Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 889		0
Debt Instrument, Interest Rate, Stated Percentage	[1]	3.25%
Debt Instrument, Face Amount		$ 900
2016 Revolver [Member] | Bank Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	[1],[4]	1.30%
Commercial Paper [Member] | Bank Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	[1]	0.50%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 290		525
Line of Credit Facility, Remaining Borrowing Capacity		$ 4,700
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage		0.125%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage		0.35%
Commercial Paper [Member]
Debt Instrument [Line Items]
Total debt and other obligations	[6]	$ 285		$ 155
Debt Instrument, Maturity Date, Description		397 days
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.875%
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.75%
[1]	Represents the weighted-average stated interest rate.
[2]	If the respective series of Tower Revenue Notes are not paid in full on or prior to an applicable anticipated repayment date, then Excess Cash Flow (as defined in the indenture governing the terms of such notes) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes, and additional interest (of an additional approximately 5% per annum) will accrue on the respective Tower Revenue Notes. As of December 31, 2019, the Tower Revenue Notes have principal amounts of $300 million, $250 million, $700 million and $750 million, with anticipated repayment dates in 2022, 2023, 2025 and 2028, respectively.
[3]	The Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") and Tower Revenue Notes, Series 2018-1 and 2018-2 ("July 2018 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes."
[4]	Both the 2016 Revolver and 2016 Term Loan A bear interest, at our option, at either (1) LIBOR plus a credit spread ranging from 0.875% to 1.750% per annum or (2) an alternate base rate plus a credit spread ranging from 0.000% to 0.750% per annum, in each case, with the applicable credit spread based on the Company's senior unsecured debt rating. The Company pays a commitment fee ranging from 0.125% to 0.350%, based on the Company's senior unsecured debt rating, per annum on the undrawn available amount under the 2016 Revolver.
[5]	The Company's finance leases and other obligations relate to land, fiber, vehicles, and other assets and bear interest rates ranging up to 10% and mature in periods ranging from less than one year to approximately 25 years.
[6]	The maturities of the Commercial Paper Notes, as defined below, when outstanding, may vary but may not exceed 397 days from the date of issue.

Debt and Other Obligations (Tex

Debt and Other Obligations (Textuals) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2012
Debt Instrument [Line Items]
Principal amount		$ 2,400		$ 12	$ 2,250
Debt and Lease Obligation		$ 19,280		18,121
Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)		5.00%
4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt								$ 839
2018 Tower Revenue Notes 3.720% due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250
2018 Tower Revenue Notes 4.241% due 2048 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		750
Secured Debt [Member]
Debt Instrument [Line Items]
Debt and Lease Obligation		$ 3,278		3,271
Secured Debt [Member] | 2.381% Secured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							2.381%
Repayments of Debt							$ 500
Secured Debt [Member] | 3.849% Secured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount										$ 1,000
Debt Instrument, Interest Rate, Stated Percentage		3.90%	[1]							3.849%
Debt and Lease Obligation		$ 997		995
Secured Debt [Member] | July 2018 Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					1,000
Secured Debt [Member] | 2018 Tower Revenue Notes 3.720% due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 250
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[1]		3.72%
Debt and Lease Obligation	[2],[3]	$ 248		248
Secured Debt [Member] | 2018 Tower Revenue Notes 4.241% due 2048 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 750
Debt Instrument, Interest Rate, Stated Percentage		4.20%	[1]		4.241%
Debt and Lease Obligation	[2],[3]	$ 743		742
Secured Debt [Member] | 2018 Tower Revenue Notes Risk Retention Tranche [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 53
Secured Debt [Member] | May 2015 Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount									$ 1,000
Bank Debt [Member] | 2016 Term Loan A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							2,000
Debt Instrument, Interest Rate, Stated Percentage	[1],[4]	1.30%
Debt and Lease Obligation		$ 2,252		2,310
Bank Debt [Member] | Senior Unsecured 364-Day Revolving Credit Facility [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity							1,000
Bank Debt [Member] | 2016 Revolver [Member]
Debt Instrument [Line Items]
Principal amount							500
Debt Instrument, Interest Rate, Stated Percentage	[1],[4]	1.30%
Bonds [Member] | May 2016 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							1,000
Bonds [Member] | 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								$ 850
Debt Instrument, Interest Rate, Stated Percentage		4.875%						4.875%
Debt and Lease Obligation		$ 0		846
Bonds [Member] | 4.000% Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 500
Debt Instrument, Interest Rate, Stated Percentage		4.00%	[1]			4.00%
Debt and Lease Obligation		$ 496		495
Bonds [Member] | 2016 Senior Unsecured Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							1,500
Bonds [Member] | 3.400% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 250
Debt Instrument, Interest Rate, Stated Percentage							3.40%
Bonds [Member] | 3.700% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 750
Debt Instrument, Interest Rate, Stated Percentage							3.70%
Bonds [Member] | 2.250% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 700
Debt Instrument, Interest Rate, Stated Percentage		2.25%					2.25%
Debt and Lease Obligation		$ 0		698
Bonds [Member] | 4.450% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 900
Debt Instrument, Interest Rate, Stated Percentage							4.45%
Bonds [Member] | 4.750% Senior Unsecured Notes [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 350
Debt Instrument, Interest Rate, Stated Percentage		4.80%	[1]			4.75%
Debt and Lease Obligation		$ 344		344
Bonds [Member] | August 2017 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 1,750
Bonds [Member] | August 2017 Senior Unsecured 3.200% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 750
Debt Instrument, Interest Rate, Stated Percentage		3.20%	[1]			3.20%
Debt and Lease Obligation		$ 745		744
Bonds [Member] | August 2017 Senior Unsecured 3.650% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 1,000
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[1]			3.65%
Debt and Lease Obligation		$ 994		993
Bonds [Member] | 3.150% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 750
Debt Instrument, Interest Rate, Stated Percentage		3.20%	[1]		3.15%
Debt and Lease Obligation		$ 746		744
Bonds [Member] | 3.800% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 1,000
Debt Instrument, Interest Rate, Stated Percentage		3.80%	[1]		3.80%
Debt and Lease Obligation		$ 991		990
Bonds [Member] | August 2019 Senior Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				900
Bonds [Member] | August 2019 Senior Unsecured 3.100% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 550
Debt Instrument, Interest Rate, Stated Percentage		3.10%	[1]	3.10%
Debt and Lease Obligation		$ 544		$ 543
Bonds [Member] | August 2019 Senior Unsecured 4.000% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 350
Debt Instrument, Interest Rate, Stated Percentage		4.00%	[1]	4.00%
Debt and Lease Obligation		$ 345		$ 345
Bonds [Member] | February 2019 Senior Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				1,000
Bonds [Member] | February 2019 Senior Unsecured 4.300% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 600
Debt Instrument, Interest Rate, Stated Percentage		4.30%	[1]	4.30%
Debt and Lease Obligation		$ 593		$ 592
Bonds [Member] | February 2019 Senior Unsecured 5.200% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 400
Debt Instrument, Interest Rate, Stated Percentage		5.20%	[1]	5.20%
Debt and Lease Obligation		$ 395		$ 395
Bonds [Member] | June 2020 Senior Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		2,500
Bonds [Member] | June 2020 Senior Unsecured 1.350% Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 500
Debt Instrument, Interest Rate, Stated Percentage	[1]	1.35%
Debt and Lease Obligation		$ 494		0
Bonds [Member] | June 2020 Senior Unsecured 2.250% Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,100
Debt Instrument, Interest Rate, Stated Percentage	[1]	2.25%
Debt and Lease Obligation		$ 1,088		0
Bonds [Member] | June 2020 Senior Unsecured 3.250% Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 900
Debt Instrument, Interest Rate, Stated Percentage	[1]	3.25%
Debt and Lease Obligation		$ 889		0
Bonds [Member] | Senior Unsecured 2016 Notes 3.40% [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.40%
Debt and Lease Obligation		$ 0		850
Bonds [Member] | April 2020 Senior Unsecured 4.150% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 500
Debt Instrument, Interest Rate, Stated Percentage	[1]	4.15%
Debt and Lease Obligation		$ 489		0
Bonds [Member] | April 2020 Senior Notes [Domain] [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,250
Bonds [Member] | 5.250% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount										$ 1,650
Debt Instrument, Interest Rate, Stated Percentage		5.30%	[1]							5.25%
Debt and Lease Obligation		$ 1,646		1,644
Collateral Pledged [Member]
Debt Instrument [Line Items]
Debt Instrument, PPE Collaterized Amount		920
Additional Principal Incurred [Member] | Bank Debt [Member] | 2016 Term Loan A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 500
February 2016 Senior Note Upsizing [Member] | Bonds [Member] | 3.400% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 600
Debt Instrument, Interest Rate, Stated Percentage							3.40%
Commercial Paper [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				1,000
Commercial Paper		285
Debt and Lease Obligation	[5]	285		155
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net				750	$ 750	1,000
Line of Credit Facility, Maximum Borrowing Capacity				5,000	$ 4,250	$ 3,500	$ 2,500
Debt and Lease Obligation		$ 290		$ 525
[1]	Represents the weighted-average stated interest rate.
[2]	If the respective series of Tower Revenue Notes are not paid in full on or prior to an applicable anticipated repayment date, then Excess Cash Flow (as defined in the indenture governing the terms of such notes) of the issuers of such notes will be used to repay principal of the applicable series and class of the Tower Revenue Notes, and additional interest (of an additional approximately 5% per annum) will accrue on the respective Tower Revenue Notes. As of December 31, 2019, the Tower Revenue Notes have principal amounts of $300 million, $250 million, $700 million and $750 million, with anticipated repayment dates in 2022, 2023, 2025 and 2028, respectively.
[3]	The Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") and Tower Revenue Notes, Series 2018-1 and 2018-2 ("July 2018 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes."
[4]	Both the 2016 Revolver and 2016 Term Loan A bear interest, at our option, at either (1) LIBOR plus a credit spread ranging from 0.875% to 1.750% per annum or (2) an alternate base rate plus a credit spread ranging from 0.000% to 0.750% per annum, in each case, with the applicable credit spread based on the Company's senior unsecured debt rating. The Company pays a commitment fee ranging from 0.125% to 0.350%, based on the Company's senior unsecured debt rating, per annum on the undrawn available amount under the 2016 Revolver.
[5]	The maturities of the Commercial Paper Notes, as defined below, when outstanding, may vary but may not exceed 397 days from the date of issue.

Debt and Other Obligations (Sch

Debt and Other Obligations (Scheduled Contractual Maturities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Contractual Maturities - Year 1	$ 415
Contractual Maturities - Year 2	154
Contractual Maturities - Year 3	3,608
Contractual Maturities - Year 4	2,941
Contractual Maturities - Year 5	525
Contractual Maturities - Thereafter	11,780
Total Cash Obligations	19,423
Unamortized Discounts	(143)
Total Debt and Other Obligations Outstanding	$ 19,280
Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)	5.00%

Debt and Other Obligations (Deb

Debt and Other Obligations (Debt Purchases and Repayments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Extinguishment of Debt [Line Items]
Principal amount		$ 2,400	$ 12	$ 2,250
Cash paid	[1]	2,490	12	2,346
Gains (losses) on retirement of long-term obligations	[2]	(95)	(2)	(106)
Fixed Rate Debt 2009 Securitized Notes A-1 [Member]
Extinguishment of Debt [Line Items]
Principal amount			12
Cash paid	[1]		12
Gains (losses) on retirement of long-term obligations	[2]		(1)
3.400% Senior Notes [Member]
Extinguishment of Debt [Line Items]
Principal amount		850
Cash paid	[1]	863
Gains (losses) on retirement of long-term obligations	[2]	(13)
2.250% Senior Notes [Member]
Extinguishment of Debt [Line Items]
Principal amount		700
Cash paid	[1]	714
Gains (losses) on retirement of long-term obligations	[2]	(16)
4.875% Senior Notes [Member]
Extinguishment of Debt [Line Items]
Principal amount		850
Cash paid	[1]	913
Gains (losses) on retirement of long-term obligations	[2]	$ (66)
2016 Term Loan A [Member]
Extinguishment of Debt [Line Items]
Principal amount			0	0
Cash paid	[1]		0	0
Gains (losses) on retirement of long-term obligations	[2]		$ (1)	(3)
Fixed Rate Securitized Debt January 2010 Tower Revenue Notes 3 [Member]
Extinguishment of Debt [Line Items]
Principal amount				1,250
Cash paid	[1]			1,318
Gains (losses) on retirement of long-term obligations	[2]			(71)
Fixed Rate Securitized Debt August 2010 Tower Revenue Notes 6 [Member]
Extinguishment of Debt [Line Items]
Principal amount				1,000
Cash paid	[1]			1,028
Gains (losses) on retirement of long-term obligations	[2]			$ (32)
[1]	Exclusive of accrued interest.
[2]	Inclusive of the write-off of the respective deferred financing costs.

Fair Value Disclosures (Estimat

Fair Value Disclosures (Estimated Fair Values and Carrying Amounts of Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	$ 232	$ 196	$ 277
Cash and cash equivalents, fair value	232	196
Restricted cash, carrying value	149	142
Restricted cash, fair value amount	149	142
Debt and other obligations, carrying amount	19,280	18,121
Debt and other obligations, fair value amount	$ 21,302	$ 19,170

Income Taxes (Income (Loss) fro

Income Taxes (Income (Loss) from Continuing Operations before Income Taxes) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic		$ 1,046	$ 850	$ 618
Foreign	[1]	30	31	23
Income (loss) before income taxes		$ 1,076	$ 881	$ 641
[1]	Inclusive of income (loss) before income taxes from Puerto Rico

Income Taxes (Benefit (Provisio

Income Taxes (Benefit (Provision) for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current Federal	$ (6)	$ (6)	$ (5)
Current Foreign	(6)	(8)	(7)
Current State	(5)	(5)	(5)
Total current	(17)	(19)	(17)
Deferred Foreign	(3)	(2)	(2)
Total deferred	(3)	(2)	(2)
Benefit (provision) for income taxes	$ (20)	$ (21)	$ (19)

Income Taxes Income Taxes Effec

Income Taxes Income Taxes Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign tax	$ (9)	$ (10)	$ (9)
Benefit (provision) for income taxes at statutory rate	(225)	(185)	(135)
Tax effect of foreign income (losses)	0	1	1
Tax adjustment related to REIT operations	(219)	(178)	(128)
State tax (provision) benefit, net of federal	(5)	(5)	(4)
Benefit (provision) for income taxes	$ (20)	$ (21)	$ (19)

Income Taxes (Components of Def

Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Property and equipment		$ 7	$ 6
Deferred site rental receivable		7	7
Total deferred income tax liabilities		14	13
Intangible assets		3	3
Net operating loss carryforwards	[1]	15	18
Straight-line rent expense liability		3	3
Accrued liabilities		6	5
Other		2	2
Valuation allowances		0	0
Total deferred income tax assets, net		29	31
Net deferred income tax assets (liabilities)		$ 15	$ 18
[1]	Balance results from the Company's foreign NOLs. Due to the Company's REIT status, no federal or state NOLs result in the Company recording a deferred income tax asset. See further discussion surrounding the Company's NOL balances below.

Income Taxes (Jurisdictional Co

Income Taxes (Jurisdictional Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Taxes (Jurisdictional components of deferred taxes)
Deferred Tax Assets, Gross	$ 15	$ 18
Valuation allowances	0	0
Net deferred income tax assets (liabilities)	15	18
U.S. Federal [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	1,500
Deferred Tax Assets, Gross	25	25
Valuation allowances	0	0
Net deferred income tax assets (liabilities)	25	25
State and Local Jurisdiction [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	600
Deferred Tax Assets, Gross	1	1
Valuation allowances	0	0
Net deferred income tax assets (liabilities)	1	1
Foreign Tax Authority [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	40
Deferred Tax Assets, Gross	11	8
Valuation allowances	0	0
Deferred Tax Liabilities, Net	(11)	$ (8)
Share-based Payment Arrangement [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	$ 237

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Purchases of common stock, shares	500,000	400,000	300,000
Purchases of common stock, value	$ 76	$ 44	$ 34
At the Market Stock Offering Program, aggregate value of common stock			$ 750
Availability Under ATM	$ 750
Conversion factor, 6.785% Mandatory Convertible Preferred Stock	8.8043
Common Stock [Member] | Conversion of 6.875% Mandatory Convertible Preferred Stock [Domain]
Conversion of Stock, Shares Issued	14,000,000
Common Stock [Member] | March 2018 Equity Financing [Member]
Stock Issued During Period, Shares, New Issues			8,000,000
Proceeds from Issuance of Common Stock			$ 841
6.875% Mandatory Convertible Preferred Stock [Member]
Conversion of Stock, Shares Converted	2,000,000
6.875% Mandatory Convertible Preferred Stock [Member] | Conversion of 6.875% Mandatory Convertible Preferred Stock [Domain]
Conversion of Stock, Shares Converted	2,000,000

Stockholders' Equity Tax Treatm

Stockholders' Equity Tax Treatment of Dividends Paid (Details) - $ / shares		3 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid				$ 17.1875	$ 17.1875	$ 17.1875
Common Stock, Dividends, Per Share, Cash Paid		$ 1.33	$ 1.20	$ 1.20	$ 1.20
Preferred Stock [Member]
Class of Stock [Line Items]
Payment Date				Aug. 3, 2020	May 1, 2020	Feb. 3, 2020
Common Stock [Member]
Class of Stock [Line Items]
Payment Date		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Common Stock [Member]
Class of Stock [Line Items]
Non-Taxable Distribution		$ 0.456	$ 0.412	$ 0.412	$ 0.412
Ordinary Taxable Dividend Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid				17.1875	17.1875	$ 17.1875
Common Stock, Dividends, Per Share, Cash Paid		0.874	0.788	0.788	0.788
Qualified Taxable Dividend Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid	[1]			0.2265	0.2265	0.2265
Common Stock, Dividends, Per Share, Cash Paid	[1]	0.012	0.010	0.010	0.010
Long-Term Capital Gain Distribution Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid				16.9610	16.9610	$ 16.9610
Common Stock, Dividends, Per Share, Cash Paid		$ 0.862	$ 0.778	$ 0.778	$ 0.778
[1]	Qualified taxable dividend and section 199A dividend amounts are included in ordinary taxable dividend amounts.

Stockholders' Equity Declaratio

Stockholders' Equity Declaration and Payment of Dividends (Details) - USD ($) $ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Dec. 31, 2019

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Class of Stock [Line Items]

Dividends, Common Stock, Cash

$ 521

[1]

$ 504

[1]

$ 504

[1]

$ 577

[1]

$ 2,106

$ 1,917

$ 1,785

Common Stock, Dividends, Per Share, Cash Paid

$ 1.33

$ 1.20

$ 1.20

$ 1.20

Preferred Stock, Dividends, Per Share, Cash Paid

$ 17.1875

$ 17.1875

$ 17.1875

Dividends, Preferred Stock, Cash

$ 28

$ 28

$ 28

$ 57

$ 113

$ 113

Common Stock [Member]

Class of Stock [Line Items]

Dividends Payable, Date Declared

Aug. 6, 2020

May 14, 2020

Feb. 20, 2020

Oct. 21, 2020

Dividends Payable, Date of Record

Sep. 15, 2020

Jun. 12, 2020

Mar. 13, 2020

Dec. 15, 2020

Payment Date

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Preferred Stock [Member]

Class of Stock [Line Items]

Dividends Payable, Date Declared

Jun. 19, 2020

Mar. 12, 2020

Dec. 9, 2019

Dividends Payable, Date of Record

Jul. 15, 2020

Apr. 15, 2020

Jan. 15, 2020

Payment Date

Aug. 3, 2020

May 1, 2020

Feb. 3, 2020

[1]

Inclusive of dividends accrued for holders of unvested RSUs, which will be paid when and if the RSUs vest.

Stock-based Compensation (Narra

Stock-based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)	8
Vesting Period	three
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)	2
Shares granted, number of shares	1,000,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, weighted-average grant-date fair value (in dollars per share)	$ 160.78	$ 106.55	$ 91.52
Weighted-average requisite service period (years)	2 years 4 months 24 days
Restricted stock or unit expense	$ 111	$ 96	$ 90
Compensation cost not yet recognized	$ 110
Period for recognition	1 year
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, number of shares	0.4
Time Vesting Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, number of shares	0.6

Stock-based Compensation (Summa

Stock-based Compensation (Summary of Restricted Stock Awards Activity) (Details) - Restricted Stock Units (RSUs) [Member] shares in Millions	12 Months Ended
	Dec. 31, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(1.3)
Shares outstanding at the beginning of the year, number of shares	2.8
Shares outstanding at the end of year, number of shares	2.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	(0.1)

Stock-based Compensation (Sum_2

Stock-based Compensation (Summary of the Assumptions Used in the Monte Carlo Simulation to Determine the Grant-Date Fair Value) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Noncash Expense [Abstract]
Risk-free rate	1.40%	2.50%	2.40%
Expected volatility	19.00%	18.00%	18.00%
Expected dividend rate	3.50%	4.00%	3.80%

Stock-based Compensation (Sum_3

Stock-based Compensation (Summary of Restricted Stock Awards Vested) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Noncash Expense [Abstract]
Total shares vested	1	1	1
Fair value on vesting date	$ 220	$ 135	$ 107

Stock-based Compensation (Stock

Stock-based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Payment Arrangement, Expense	$ 133	$ 116	$ 108
Site Rental Cost of Operations [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Payment Arrangement, Expense	16	19	17
Services and Other Costs of Operations [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Payment Arrangement, Expense	8	7	8
Selling, General and Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Payment Arrangement, Expense	$ 109	$ 90	$ 83

Commitments and Contingencies T

Commitments and Contingencies Tower purchase option (Details)	Dec. 31, 2020
Subject to Capital Lease with TMO or AT&T [Member]
Purchase Option, Percentage of Towers	53.00%

Leases Lessee Operating Leases

Leases Lessee Operating Leases (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Expense	[1]	$ 640	$ 632	[2]
Variable Lease, Cost	[3]	153	149	[2]
Lease, Cost	[4]	793	781	[2]
Operating Lease, Expense	[1]	640	632	[2]
Variable Lease, Cost	[3]	153	149	[2]
Lease, Cost	[4]	$ 793	781	[2]
Revision of Prior Period, Adjustment [Member]
Leases [Abstract]
Lease, Cost			16
Lease, Cost			$ 16
[1]	Represents the Company's operating lease expense related to its ROU assets for the twelve months ended December 31, 2020 and 2019.
[2]	Amounts for the year ended December 31, 2019 reflect a revision from the Company's 2019 Annual Report on Form 10-K relating to an immaterial classification error of certain operating lease expenses. In connection with this revision, the Company reclassified $16 million from operating lease expense to variable lease expense for the year ended December 31, 2019; total lease expense for the year ended December 31, 2019 remained unchanged.
[3]	Represents the Company's expense related to contingent payments for operating leases (such as payments based on revenues derived from the communications infrastructure located on the leased asset) for the twelve months ended December 31, 2020 and 2019. Such contingencies are recognized as expense in the period they are resolved.
[4]	Excludes those direct operating expenses accounted for pursuant to accounting guidance outside the scope of ASC 842.

Leases Lessee Finance Leases (D

Leases Lessee Finance Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Amortization Related to Finance Leases	$ 2,300	$ 2,100
Finance Lease, Right-of-Use Asset, Amortization	211	216
Property, Plant and Equipment [Member]
Gross amount of finance lease ROU asset	$ 4,400	$ 4,400

Leases Other Lessee Information

Leases Other Lessee Information (Details)	Dec. 31, 2020
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	17 years
Lessee, Operating Lease, Discount Rate	3.70%

Leases Maturities of Lease Liab

Leases Maturities of Lease Liabilities (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
Lessee, Operating Lease, Liability, to be Paid, Year One	$ 546
Lessee, Operating Lease, Liability, to be Paid, Year Two	543
Lessee, Operating Lease, Liability, to be Paid, Year Three	538
Lessee, Operating Lease, Liability, to be Paid, Year Four	532
Lessee, Operating Lease, Liability, to be Paid, Year Five	518
Lessee, Operating Lease, Liability, to be Paid, after Year Five	5,842
Lessee, Operating Lease, Liability, to be Paid	8,519
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(2,382)
Operating Lease, Liability	$ 6,137

Operating Segments and Concen_3

Operating Segments and Concentrations of Credit Risk (Major Customers) (Details)	12 Months Ended
	Dec. 31, 2020	[1]	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk, Percentage	77.00%		76.00%	74.00%
AT&T [Member]
Concentration Risk, Percentage	22.00%		21.00%	20.00%
T-Mobile [Member]
Concentration Risk, Percentage	36.00%		22.00%	19.00%
Verizon Wireless [Member]
Concentration Risk, Percentage	19.00%		19.00%	20.00%
Sprint [Member]
Concentration Risk, Percentage	0.00%		14.00%	15.00%
[1]	For the year ended December 31, 2020, revenues attributable to T-Mobile includes revenues previously derived from Sprint. On April 1, 2020, T-Mobile and Sprint announced the completion of their previously disclosed merger.

Operating Segments and Concen_4

Operating Segments and Concentrations of Credit Risk Operating Segment Results (Details) $ in Millions		12 Months Ended
		Dec. 31, 2020USD ($)		Dec. 31, 2019USD ($)		Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Tower Count		40,000
Fiber Miles		80,000
Net Revenues		$ 5,840		$ 5,763		$ 5,370
Segment services and other cost of operations	[1]	448		524		434
Selling, general and administrative		678		614		563
Other Operating (Income) Expense		(362)		0		0
Assets		38,768		38,457
Goodwill		10,078		10,078
Amortization of prepaid lease purchase price adjustments		18		20		20
Stock-based compensation expense		138		117		103
Site rental revenues		5,320		5,093		4,796
Services and other		520		670		574
Site rental	[1]	1,521		1,462		1,410
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Income (Loss) Attributable to Parent, before Tax, Total		1,076		881		641
Capital expenditures		1,624		2,057		1,739
Site rental revenues		5,320		5,093		4,796
Services and other		520		670		574
Site rental	[1]	1,521		1,462		1,410
Stock-based compensation expense		138		117		103
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Income (Loss) Attributable to Parent, before Tax, Total		1,076		881		641
Capital expenditures		1,624		2,057		1,739
Segments [Domain]
Segment Reporting Information [Line Items]
Net Revenues		5,840		5,763		5,370
Segment Services and Other Cost of Operations		441		517		426
Segment cost of operations	[2]	1,927	[3]	1,940	[4]	1,799	[5]
Segment site rental gross margin		3,834		3,670		3,423
Segment services and other gross margin		79		153		148
Selling, general and administrative		283	[3]	233	[4]	191	[5]
Segment General and Administrative Expenses		286	[3]	291	[4]	289	[5]
Other Operating (Income) Expense	[6]	(362)
Segment Operating Profit		3,989		3,532		3,282
Assets		38,768		38,457		32,762
Goodwill		10,078		10,078		10,078
Stock-based compensation expense		133		116		108
Site rental revenues		5,320		5,093		4,796
Services and other		520		670		574
Segment Site Rental Cost of Operations		1,486		1,423		1,373
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Other Expenses	[7]	200		47		173
Income (Loss) Attributable to Parent, before Tax, Total		1,076		881		641
Capital expenditures		1,624		2,057		1,739
Site rental revenues		5,320		5,093		4,796
Services and other		520		670		574
Stock-based compensation expense		133		116		108
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Other Expenses	[7]	200		47		173
Segment Site Rental Cost of Operations		1,486		1,423		1,373
Income (Loss) Attributable to Parent, before Tax, Total		1,076		881		641
Capital expenditures		1,624		2,057		1,739
Towers [Member]
Segment Reporting Information [Line Items]
Net Revenues		3,997		4,042		3,754
Segment services and other cost of operations		429		506		415
Segment cost of operations	[2]	1,295	[3]	1,370	[4]	1,263	[5]
Segment site rental gross margin		2,631		2,525		2,348
Segment services and other gross margin		71		147		143
Selling, general and administrative		100	[3]	96	[4]	110	[5]
Other Operating (Income) Expense	[6]	0
Segment Operating Profit		2,602		2,576		2,381
Assets		22,242		22,357		17,644
Goodwill		5,127		5,127		5,127
Site rental revenues		3,497		3,389		3,196
Services and other		500		653		558
Site rental		866		864		848
Capital expenditures		335		543		440
Site rental revenues		3,497		3,389		3,196
Services and other		500		653		558
Site rental		866		864		848
Capital expenditures		335		543		440
Fiber [Member]
Segment Reporting Information [Line Items]
Net Revenues		1,843		1,721		1,616
Segment services and other cost of operations		12		11		11
Segment cost of operations	[2]	632	[3]	570	[4]	536	[5]
Segment site rental gross margin		1,203		1,145		1,075
Segment services and other gross margin		8		6		5
Selling, general and administrative		186	[3]	195	[4]	179	[5]
Other Operating (Income) Expense	[6]	(362)
Segment Operating Profit		1,387		956		901
Assets		15,746		15,389		14,512
Goodwill		4,951		4,951		4,951
Site rental revenues		1,823		1,704		1,600
Services and other		20		17		16
Site rental		620		559		525
Capital expenditures		1,232		1,473		1,264
Site rental revenues		1,823		1,704		1,600
Services and other		20		17		16
Site rental		620		559		525
Capital expenditures		1,232		1,473		1,264
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Selling, general and administrative		283	[3]	233	[4]	191	[5]
Assets		780		711		606
Goodwill		0		0		0
Stock-based compensation expense		133		116		108
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Other Expenses	[7]	200		47		173
Capital expenditures		57		41		35
Stock-based compensation expense		133		116		108
Depreciation, amortization and accretion		1,608		1,572		1,527
Interest expense and amortization of deferred financing costs		689		683		642
Other Expenses	[7]	200		47		173
Capital expenditures		57		41		35
Segment cost of operations share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		24		26		25
Stock-based compensation expense		24		$ 26		$ 25
Segment G&A share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		109
Stock-based compensation expense		$ 109
[1]	Exclusive of depreciation, amortization and accretion shown separately.
[2]	Exclusive of depreciation, amortization and accretion shown separately.
[3]	Segment cost of operations for the year ended December 31, 2020 excludes (1) stock-based compensation expense of $24 million and (2) prepaid lease purchase price adjustments of $18 million. For the year ended December 31, 2020, segment selling, general and administrative expenses exclude stock-based compensation expense of $109 million.
[4]	Segment cost of operations for the year ended December 31, 2019 excludes (1) stock-based compensation expense of $26 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2019, segment selling, general and administrative expenses exclude stock-based compensation expense of $90 million.
[5]	Segment cost of operations for the year ended December 31, 2018 excludes (1) stock-based compensation expense of $25 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2018, segment selling, general and administrative expenses exclude stock-based compensation expense of $83 million.
[6]	See note 15 for further information.
[7]	See consolidated statement of operations for further information.

Other Income and Expenses (Deta

Other Income and Expenses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Sprint Cancellation [Member]
Small Cell Node Count	5,700
Payment received [Member]
Other Operating Income	$ 308
Unamortized portion of payment received [Member]
Other Operating Income	$ 54

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Feb. 18, 2021	Feb. 16, 2021
February 2021 Senior Notes [Domain]
Subsequent Event [Line Items]
Debt Instrument, Face Amount		$ 3,250,000,000
February 2021 Senior Unsecured 1.050% Notes [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount		$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage		1.05%
February 2021 Senior Unsecured 2.100% Notes [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount		$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.10%
February 2021 Senior Unsecured 2.900% Notes [Domain]
Subsequent Event [Line Items]
Debt Instrument, Face Amount		$ 1,250,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.90%
Dividend Declared [Member]
Subsequent Event [Line Items]
Dividends	$ 1.33

Schedule II - Valuation and Q_3

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 18	$ 14	$ 14
Charged to operations	4	7	4
Credited to operations	(5)	(3)	(4)
Effect of exchange rate changes or Other adjustments	0	0	0
Valuation allowance and reserves, other adjustments	0	0	0
Balance at end of year	17	18	14
Deferred Tax Valuation Allowance [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	0	1	1
Charged to operations	0	0	0
Credited to operations	0	0	0
SEC Schedule, 12-09, Valuation Allowances and Reserves, Addition, Recovery	0	(1)	0
Effect of exchange rate changes or Other adjustments	0	0	0
Valuation allowance and reserves, other adjustments	0	0	0
Balance at end of year	$ 0	$ 0	$ 1

Schedule III - Schedule of Re_3

Schedule III - Schedule of Real Estate and Depreciation (Details) $ in Millions		12 Months Ended
		Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 3,295
Gross Amount of Property Carried		25,441	$ 23,854	$ 21,840
Gross Amount of Accumulated Depreciation Carried		$ (10,478)	(9,382)	$ (8,338)
Tower Count		40,000
Fiber Miles		80,000
Other Acquisitions	[2]	$ 68	4
Communications Infrastructure Construction and Improvements		1,438	1,878
Purchase of land interests		64	53
Sustaining Capital Expenditures		66	84
Other Additions	[3]	47	101
Total Additions		1,683	2,120
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Write-down or Reserve, Amount		(96)	(45)
Cost of Real Estate Sold or Disposed		(96)	(106)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Deduction		0	(61)
Depreciation		(1,114)	(1,087)
Amount of Accumulated Depreciation Sold or Disposed		18	24
Other Deductions to Accumulated Depreciation		0	19
Real Estate Period Deductions to Accumulated Depreciation		$ 18	$ 43
[1]	Encumbrances are reported at face value, without contemplating the effect of deferred financing costs, discounts or premiums. Certain of the Company's debt is secured by (1) a security interest in substantially all of the applicable issuers' assignable personal property, (2) a pledge of the equity interests in each applicable issuer and (3) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses).
[2]	Includes acquisitions of communications infrastructure.
[3]	Predominately relates to the purchase of property and equipment under finance leases and installment land purchases.