Crown Castle (CCI) 10-K 26 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 21, 2018	Jun. 30, 2017
Entity Information [Line Items]
Entity Registrant Name	CROWN CASTLE INTERNATIONAL CORP
Entity Central Index Key	1,051,470
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		406,906,992
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 36.5

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 314,094	$ 567,599
Restricted cash	121,065	124,547
Receivables, net of allowance of $13,746 and $11,314, respectively	397,585	373,532
Prepaid expenses	162,366	128,721
Other current assets	138,670	130,362
Total current assets	1,133,780	1,324,761
Deferred site rental receivables	1,300,338	1,317,658
Property and equipment, net	12,932,885	9,805,315
Goodwill	10,021,468	5,757,676
Site rental contracts and customer relationships, net	5,626,435	3,298,778
Other intangible assets, net	335,324	351,294
Long-term prepaid rent and other assets, net	879,340	819,610
Total assets	32,229,570	22,675,092
LIABILITIES AND EQUITY
Accounts payable	248,817	188,516
Accrued interest	131,790	97,019
Deferred revenues	457,116	353,005
Other accrued liabilities	339,108	221,066
Current maturities of debt and other obligations	115,251	101,749
Total current liabilities	1,292,082	961,355
Debt and other long-term obligations	16,044,369	12,069,393
Other long-term liabilities	2,554,037	2,087,229
Total liabilities	19,890,488	15,117,977
Commitments and contingencies (see note 14)
CCIC stockholders' equity:
Common stock, $0.01 par value; 600,000,000 shares authorized; shares issued and outstanding: December 31, 2017—406,280,673 and December 31, 2016—360,536,659	4,063	3,605
6.875% Mandatory Convertible Preferred Stock, Series A, $0.01 par value; 20,000,000 shares authorized; shares issued and outstanding: December 31, 2017—1,649,998 and December 31, 2016—0; aggregate liquidation value: December 31, 2017—$1,649,998 and December 31, 2016—$0	17	0
Additional paid-in capital	16,843,607	10,938,236
Accumulated other comprehensive income (loss)	(3,989)	(5,888)
Dividends/distributions in excess of earnings	(4,504,616)	(3,378,838)
Total equity	12,339,082	7,557,115
Total liabilities and equity	$ 32,229,570	$ 22,675,092

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts receivable, current	$ 13,746,000	$ 11,314,000
6.875% Mandatory Convertible Preferred Stock, Par or Stated Value Per Share (dollars per share)	$ 0.01
6.875% Mandatory Convertible Preferred Stock, Shares Authorized	20,000,000	0
6.875% Mandatory Convertible Preferred Stock, shares issued	1,649,998	0
Convertible Preferred Stock, shares outstanding	1,649,998	0
Mandatory redemption and aggregate liquidation value, 6.875% Mandatory Convertible Preferred Stock	$ 1,650,000	$ 0
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	406,280,673	360,536,659
Common stock, shares outstanding	406,280,673	360,536,659

Consolidated Statement of Opera

Consolidated Statement of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Net revenues:
Site rental		$ 3,669,191	$ 3,233,307		$ 3,018,413
Network services and other		686,414	687,918		645,438
Net revenues		4,355,605	3,921,225		3,663,851
Costs of Operations:
Site rental	[1]	1,143,914	1,023,350		963,869
Network services and other	[1]	419,787	417,171		357,557
General and administrative		426,698	371,031		310,921
Asset write-down charges		17,322	34,453		33,468
Acquisition and integration costs		61,431	17,453		15,678
Depreciation, amortization and accretion		1,242,408	1,108,551		1,036,178
Total operating expenses		3,311,560	2,972,009		2,717,671
Operating income (loss)		1,044,045	949,216		946,180
Interest expense and amortization of deferred financing costs		(590,682)	(515,032)		(527,128)
Gains (losses) on retirement of long-term obligations		(3,525)	(52,291)	[2]	(4,157)	[3]
Interest income		18,761	796		1,906
Other income (expense)		1,994	(8,835)		57,028
Income (loss) from continuing operations before income taxes		470,593	373,854		473,829
Benefit (provision) for income taxes		(26,043)	(16,881)		51,457
Income (Loss) from Continuing Operations		444,550	356,973		525,286
Income (Loss) from Discontinued Operations, Net of Tax		0	0		19,690	[4],[5],[6]
Net Gain (Loss) from Disposal of Discontinued Operations, Net of Tax		0	0		979,359
Income (Loss) from Discontinued Operations, Net of Tax		0	0		999,049
Income (loss) from continuing operations		444,550	356,973		1,524,335
Less: Net income (loss) attributable to the noncontrolling interest		0	0		3,343
Net income (loss) attributable to CCIC stockholders		444,550	356,973		1,520,992
Dividends on preferred stock		(58,294)	(32,991)		(43,988)
Net income (loss) attributable to CCIC common stockholders		386,256	323,982		1,477,004
Net income (loss) from continuing operations		444,550	356,973		1,524,335
Derivative instruments, net of taxes
Interest rate swaps reclassified into results of operations, net of taxes		0	0		18,725
Foreign currency translation adjustments		1,899	(1,490)		(14,137)
Amounts reclassified into discontinued operations for foreign currency translation adjustments		0	0		(25,678)
Total other comprehensive income (loss)	[7]	1,899	(1,490)		(21,090)
Comprehensive income (loss) attributable to CCIC stockholders		$ 446,449	$ 355,483		$ 1,503,245
Net income (loss) attributable to CCIC common stockholders, per common share:
Basic (in dollars per share)		$ 1.01	$ 0.95		$ 4.44
Diluted (in dollars per share)		$ 1.01	$ 0.95		$ 4.42
Weighted-average common shares outstanding (in thousands):
Basic (in shares)		381,740	340,349		333,002
Diluted (in shares)		383,221	340,879		334,062
Dividends/distributions declared per share of common stock		$ 3.90	$ 3.61		$ 3.35
Discontinued Operations [Member]
Net income (loss) attributable to CCIC common stockholders, per common share:
Basic (in dollars per share)		0	0		2.99
Diluted (in dollars per share)		$ 0	$ 0		$ 2.98
Continuing Operations [Member]
Costs of Operations:
Net income (loss) attributable to CCIC common stockholders		$ 386,256	$ 323,982		$ 481,298
Net income (loss) attributable to CCIC common stockholders, per common share:
Basic (in dollars per share)		$ 1.01	$ 0.95		$ 1.45
Diluted (in dollars per share)		$ 1.01	$ 0.95		$ 1.44
[1]	Exclusive of depreciation, amortization and accretion shown separately.
[2]	Inclusive of $33.8 million related to the write off of deferred financing costs
[3]	Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.
[4]	CCAL results are through May 28, 2015, which was the closing date of the Company's sale of CCAL.
[5]	Exclusive of the gain (loss) from disposal of discontinued operations, net of tax, as presented on the consolidated statement of operations.
[6]	No interest expense has been allocated to discontinued operations.
[7]	See the consolidated statement of operations and comprehensive income (loss) for the components of "total other comprehensive income (loss)" and note 9 with respect to the reclassification adjustment.

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Cash flows from operating activities:
Income (Loss) from Continuing Operations	$ 444,550	$ 356,973		$ 525,286
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation, amortization and accretion	1,242,408	1,108,551		1,036,178
(Gains) losses on retirement of long-term obligations	3,525	52,291	[1]	4,157	[2]
Gains (Losses) on Settled Swaps	328	2,608		(54,475)
Amortization of deferred financing costs and other non-cash interest	9,368	14,333		37,126
Stock-based compensation expense	91,647	79,338		60,773
Asset write-down charges	17,322	34,453		33,468
Deferred income tax (benefit) provision	14,888	8,603		(60,618)
Other non-cash adjustments, net	(1,648)	2,451		(8,915)
Changes in assets and liabilities, excluding the effects of acquisitions:
Increase (decrease) in accrued interest	34,771	30,044		32
Increase (decrease) in accounts payable	(34,067)	10,600		(5,287)
Increase (decrease) in deferred revenues, deferred ground lease payables, other accrued liabilities and other liabilities	175,522	195,998		325,880
Decrease (increase) in receivables	60,859	(58,664)		12,668
Decrease (increase) in prepaid expenses, deferred site rental receivables, long-term prepaid rent, restricted cash and other assets	(15,287)	(55,315)		(112,248)
Net cash provided by (used for) operating activities	2,044,186	1,782,264		1,794,025
Cash flows from investing activities:
Payment for acquisitions of businesses, net of cash acquired	(9,260,135)	(556,854)		(1,102,179)
Capital expenditures	(1,228,071)	(873,883)		(908,892)
Receipts from Foreign Currency Swaps	(328)	8,141		54,475
Other investing activities, net	(5,487)	12,364		(3,138)
Net cash provided by (used for) investing activities	(10,494,021)	(1,410,232)		(1,959,734)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	3,092,323	5,201,010		1,000,000
Net proceeds from issuance of common stock	4,221,329	1,325,865		0
Net proceeds from issuance of preferred stock	1,607,759	0		0
Principal payments on debt and other long-term obligations	(118,880)	(95,787)		(102,866)
Purchases and redemptions of long-term debt	0	(4,044,834)		(1,069,337)
Purchases of common stock	(23,307)	(24,936)		(29,657)
Borrowings under revolving credit facility	2,820,000	3,440,000		1,790,000
Payments under revolving credit facility	(1,840,000)	(4,565,000)		(1,360,000)
Payments for financing costs	(29,240)	(41,533)		(19,642)
Net (increase) decrease in restricted cash	3,808	(7,931)		16,458
Dividends/distributions paid on common stock	(1,508,705)	(1,239,158)		(1,116,444)
Dividends paid on preferred stock	(29,935)	(43,988)		(43,988)
Net cash provided by (used for) financing activities	8,195,152	(96,292)		(935,476)
Net Cash Provided by (Used in) Continuing Operations	(254,683)	275,740		(1,101,185)
Cash Provided by (Used in) Operating Activities, Discontinued Operations	0	0		2,700
Cash Provided by (Used in) Investing Activities, Discontinued Operations	0	113,150		1,103,577
Net Cash Provided by (Used in) Discontinued Operations	0	113,150		1,106,277
Effect of exchange rate changes on cash	1,178	(101)		(1,902)
Cash and Cash Equivalents, at Carrying Value, Including Discontinued Operations Period Start	567,599	178,810		175,620	[3]
Cash and Cash Equivalents, at Carrying Value, Including Discontinued Operations Period End	$ 314,094	$ 567,599		$ 178,810
[1]	Inclusive of $33.8 million related to the write off of deferred financing costs
[2]	Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.
[3]	Inclusive of cash and cash equivalents included in discontinued operations.

Consolidated Statement of Conve

Consolidated Statement of Convertible Preferred Stock and Equity - USD ($)		Total		4.50% Mandatory Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital	Foreign Currency Translation Adjustments		Derivative Instruments	Dividends/Distributions in Excess of Earnings	Noncontrolling Interest	AOCI Attributable to Parent [Member]		6.875% Mandatory Convertible Preferred Stock [Member]	6.875% Mandatory Convertible Preferred Stock [Member]	6.875% Mandatory Convertible Preferred Stock [Member]Preferred Stock [Member]	6.875% Mandatory Convertible Preferred Stock [Member]Additional Paid-in Capital	Common Stock [Member]	Common Stock [Member]Additional Paid-in Capital	4.50% Mandatory Convertible Preferred Stock [Member]Preferred Stock [Member]	Discontinued Operations, Disposed of by Sale [Member]	Discontinued Operations [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding																0				9,775,000
Accumulated other Comprehensive Income (Loss), Net of Tax		$ 15,820,000
Balance, value at Dec. 31, 2014		6,737,228,000			$ 3,339,000	$ 9,512,396,000	$ 34,545,000		$ (18,725,000)	$ (2,815,428,000)	$ 21,003,000					$ 0				$ 98,000
Balance, (in shares) at Dec. 31, 2014					333,856,632
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation related activity, net of forfeitures, value		65,840,000			$ 2,000	65,838,000
Stock-based compensation related activity, net of forfeitures, shares					251,554
Purchases and retirement of capital stock, value		(29,657,000)			$ (3,000)	(29,654,000)
Purchases and retirement of capital stock, shares					(336,526)
Other Comprehensive Income (Loss), Net of Tax	[1]	(21,090,000)					(38,943,000)		18,725,000		(872,000)	$ (20,218,000)
Derivative instruments reclassified into results of operations, net of tax		18,725,000
Noncontrolling Interest, Period Increase (Decrease)																					$ (23,474,000)
Common stock dividends/distributions										(1,119,973,000)
Dividends, Preferred Stock										(43,988,000)
Preferred stock dividends		(43,988,000)				0
Income (loss) from continuing operations		1,524,335,000								1,520,992,000	3,343,000
Balance, value at Dec. 31, 2015		7,089,221,000			$ 3,338,000	9,548,580,000	(4,398,000)		0	(2,458,397,000)	0					$ 0				$ 98,000
Balance, (in shares) at Dec. 31, 2015					333,771,660
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding																0				9,775,000
Accumulated other Comprehensive Income (Loss), Net of Tax		(4,398,000)
Stock-based compensation related activity, net of forfeitures, value		86,273,000			$ 2,000	86,271,000
Stock-based compensation related activity, net of forfeitures, shares					263,782
Purchases and retirement of capital stock, value		(24,936,000)			$ (3,000)	(24,933,000)
Purchases and retirement of capital stock, shares					(289,531)
Conversion of redeemable preferred stock into Common Stock, shares					11,612,684
Stock Issued During Period, Value, Conversion of Convertible Securities					$ 116,000
Conversion of Stock, Shares Converted				(9,775,000)
Conversion of Stock, Amount Converted				$ (98,000)
Stock Issued During Period, Shares, New Issues					15,178,064
Proceeds from Issuance of Common Stock		1,325,865,000			$ 152,000	1,325,713,000
Other Comprehensive Income (Loss), Net of Tax		(1,490,000)	[1]				(1,490,000)	[1]	0			(1,490,000)	[1]
Proceeds and Excess Tax Benefit from Share-based Compensation						2,623,000																$ 2,623,000
Other Adjustments to Additional Paid in Capital | Conversion of Preferred Stock [Member]		(18,000)
Noncontrolling Interest, Increase from Business Combination		0									0
Derivative instruments reclassified into results of operations, net of tax		0
Common stock dividends/distributions		(1,244,423,000)								(1,244,423,000)
Dividends, Preferred Stock		(32,991,000)								(32,991,000)
Income (loss) from continuing operations		356,973,000								356,973,000	0
Balance, value at Dec. 31, 2016		$ 7,557,115,000			$ 3,605,000	10,938,236,000	(5,888,000)		0	(3,378,838,000)	0					$ 0				$ 0
Balance, (in shares) at Dec. 31, 2016		360,536,659			360,536,659
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding		0														0				0
Accumulated other Comprehensive Income (Loss), Net of Tax		$ (5,888,000)
Stock-based compensation related activity, net of forfeitures, value		99,988,000			$ 10,000	99,978,000
Stock-based compensation related activity, net of forfeitures, shares					861,028
Purchases and retirement of capital stock, value		(23,307,000)			$ (3,000)	(23,304,000)
Purchases and retirement of capital stock, shares					(259,331)
Conversion of redeemable preferred stock into Common Stock, shares					17
Stock Issued During Period, Value, Conversion of Convertible Securities					$ 0
Conversion of Stock, Shares Converted														(2,000)
Stock Issued During Period, Shares, New Issues					45,142,300									1,650,000,000
Net Proceeds from Issuances of Stock, Value					$ 451,000									$ 17,000	$ 1,607,759,000		$ 1,607,742,000	$ 4,221,329,000	$ 4,220,878,000
Other Comprehensive Income (Loss), Net of Tax	[1]	1,899,000					1,899,000					$ 1,899,000
Other Adjustments to Additional Paid in Capital | Recognition of Excess Tax Benefits		77,000				77,000
Other Adjustments to Additional Paid in Capital | Conversion of Preferred Stock [Member]						0
Derivative instruments reclassified into results of operations, net of tax		0
Common stock dividends/distributions		(1,512,034,000)								(1,512,034,000)
Dividends, Preferred Stock		(58,294,000)								(58,294,000)
Income (loss) from continuing operations		444,550,000								444,550,000	0
Balance, value at Dec. 31, 2017		$ 12,339,082,000			$ 4,063,000	$ 16,843,607,000	$ (3,989,000)		$ 0	$ (4,504,616,000)	$ 0					$ 17,000				$ 0
Balance, (in shares) at Dec. 31, 2017		406,280,673			406,280,673
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Convertible Preferred Stock, shares outstanding		1,649,998														1,649,998,000				0
Accumulated other Comprehensive Income (Loss), Net of Tax		$ (3,989,000)
[1]	See the consolidated statement of operations and comprehensive income (loss) for the components of "total other comprehensive income (loss)" and note 9 with respect to the reclassification adjustment.

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2017
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 licenses, subleases and lease agreements (collectively, "contracts"). Approximately 53% of the Company's towers are leased or subleased or operated and managed under master leases, subleases, or other agreements with AT&T, Sprint, and T-Mobile. 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: ◦ Approximately 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 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 exercised, would be due between 2032 and 2048. ◦ Approximately 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 Sprint. The Company has the option to purchase in 2037 all (but not less than all) of the leased and subleased Sprint towers from Sprint for approximately $2.3 billion . ◦ Approximately 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 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 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 approximately 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 exercised, would be due between 2018 and 2032 (less than $10 million would be due before 2025). As part of the Company's effort to provide comprehensive communications infrastructure solutions, the Company also offers certain network services relating to its communications infrastructure, consisting of (1) site development services primarily relating to existing or new tenant equipment installations on its towers and small cells, 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 real estate investment trust ("REIT") for U.S. federal income tax purposes. In addition, the Company has certain taxable REIT subsidiaries ("TRSs"). See note 11 . The preparation of financial statements in conformity with U.S. generally accepted accounting principles ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities as of the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. As a result of the 2017 Acquisitions of fiber assets as described in note 4, the Company has changed the name of the "Small Cells" operating segment to "Fiber." The Company changed the name of this segment to reflect its strategy of utilizing the same fiber assets to provide both small cells and fiber solutions to its customers. The name change did not impact the composition or the previously-reported operating results of the Fiber segment. As such, the Company's operating segments are now referred to as "Towers" and "Fiber." See note 16.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies 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. The Company has classified the increases and decreases in restricted cash as (1) cash provided by financing activities for cash held by indenture trustees based on consideration of the terms of the related indebtedness, although the cash flows have aspects of both financing activities and operating activities, (2) cash provided by investing activities for cash securing performance obligations and restricted cash that is acquired in acquisitions, or (3) cash provided by operating activities for the other remaining restricted cash. The following table is a summary of the impact of restricted cash on the statement of cash flows. For the years ended December 31, 2017 2016 2015 Net cash provided by (used from) operating activities $ 847 $ (4,547 ) $ 3,974 Net cash provided by (used from) investing activities $ (26 ) $ 10,541 $ (3,752 ) Net cash provided by (used from) financing activities $ 3,808 $ (7,931 ) $ 16,458 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 "network 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 General. The Company classifies its leases at inception as either operating leases or capital leases. A lease is classified as a capital lease if at least one of the following criteria is met, subject to certain exceptions noted below: (1) the lease transfers ownership of the leased assets to the lessee, (2) there is a bargain purchase option, (3) the lease term is equal to 75% or more of the economic life of the leased assets, or (4) the present value of the minimum lease payments equals or exceeds 90% of the fair value of the leased assets. Lessee. Leases for land are evaluated for capital lease treatment if at least one of the first two criteria mentioned in the immediately preceding paragraph is present relating to the leased assets. When the Company, as lessee, classifies a lease as a capital lease, it records an asset in an amount equal to the present value of the minimum lease payments under the lease at the beginning of the lease term. Applicable operating leases are recognized on a straight-line basis as discussed under "costs of operations" below. Lessor. If the Company is the lessor of leased property that is part of a larger whole (including a portion of space on a tower) and for which fair value is not objectively determinable, then such a lease is accounted for as an operating lease. As applicable, operating leases are recognized on a straight-line basis as discussed under "Revenue Recognition." See also " Recent Accounting Pronouncements Not Yet Adopted " below for further discussion. 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. When the Company purchases fee ownership or perpetual easements for the land previously subject to ground lease, the Company reduces the value recorded as land by the amount of any associated deferred ground lease payable or unamortized above-market leases. 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 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, renewals, and improvements 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, 2017 , 2016 , and 2015 , the Company had $91.9 million , $86.1 million , and $36.7 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 $14.3 million , $26.9 million , and $27.0 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. 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 upon which the Company's communications infrastructure resides. 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 it is concluded that 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 the two-step goodwill impairment test. The two-step goodwill impairment test begins with a comparison of the estimated fair value of the reporting unit and the carrying value of the reporting unit. The first step, commonly referred to as a "step-one impairment test," is a screen for potential impairment while the second step measures the amount of impairment if there is an indication from the first step that one exists. The Company's measurement of the fair value for goodwill is based on an estimate of discounted expected future cash flows of the reporting unit. The Company performed its most recent annual goodwill impairment test as of October 1, 2017 , which resulted in no impairments. Intangible Assets Intangible assets are included in "site rental contracts and customer relationships, net" and "other intangible assets, net" on the Company's consolidated balance sheet and predominately consist of the estimated fair value of the following items recorded in conjunction with acquisitions: (1) site rental contracts and customer relationships, (2) below-market leases for land interest under the acquired communications infrastructure, or (3) other contractual rights such as trademarks. The site rental contracts and customer relationships intangible assets are comprised of (1) the current term of the existing leases, (2) the expected exercise of the renewal provisions contained within the existing leases, which automatically occur under contractual provisions, or (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 customer 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 customer relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of renewals experienced to date. Thus, while site rental contracts and customer 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 customer relationships are amortized over a period not to exceed 20 years as a result of the useful life being limited by the depreciable life of the communications infrastructure. 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 customer relationships intangible assets. First, the Company pools the site rental contracts and customer 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 customer 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 the following items recorded in conjunction with acquisitions: (1) below-market tenant leases for contractual interests with tenants on acquired communications infrastructure, which are amortized to site rental revenues and (2) above-market leases for land interests under the Company's communications infrastructure, which are amortized to site rental cost of operations. 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 "long-term prepaid rent and other assets, net" on the Company's consolidated balance sheet. Revenue Recognition Site rental revenues are recognized on a monthly basis over the fixed, non-cancelable term of the relevant contract (generally ranging from five to 15 years for site rental revenues derived from wireless customers and three to 20 years for site rental revenues derived from the Company's fiber solutions business (including from organizations with high-bandwidth and multi-location demands)), regardless of whether the payments from the tenant are received in equal monthly amounts. Certain of the Company's contracts contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the consumer price index ("CPI")). 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 $86.0 million and $67.2 million included in "other current assets" and non-current amounts of $1.3 billion and $1.3 billion included in "deferred site rental receivables" for the years ended December 31, 2017 and 2016 , respectively. Amounts billed or received prior to being earned are deferred and reflected in "deferred revenues" and "other long-term liabilities." Network services revenues are recognized after completion of the applicable service. Nearly all of the installation services are billed on a cost-plus profit basis and site development services are billed on a fixed fee basis. In jurisdictions where the Company determines that it is the principal taxpayer, taxes and surcharges are recorded on a gross basis. In jurisdictions where the Company determines that it is acting as a collection agent for the government authority (for example, in collecting sales taxes or value-added taxes collected from customers), such amounts are presented on a net basis. See also " Recent Accounting Pronouncements Not Yet Adopted " below for further discussion. Costs of Operations Approximately 55% 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 monthly 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 CPI). If the payment terms include fixed escalation provisions, the effect of such increases is recognized on a straight-line basis. The Company calculates the straight-line expense using a time period that equals or exceeds the remaining depreciable life of the communications infrastructure asset. Further, when a tenant has exercisable renewal options that would compel the Company to exercise existing renewal options, the Company has straight-lined the expense over a sufficient portion of such renewals to coincide with the final termination of the tenant's renewal options. The Company's non-current liability related to straight-line expense is included in "other long-term liabilities" on the Company's consolidated balance sheet. The Company's assets related to prepaid agreements is included in "prepaid expenses" and "long-term prepaid rent and other assets, net" on the Company's consolidated balance sheet. Network 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. Acquisition and Integration Costs All direct or incremental costs related to a business combination are expensed as incurred. Costs include severance, retention bonuses payable to employees of an acquired enterprise, temporary employees to assist with the integration of the acquired operations, or fees paid for services such as consulting, accounting, legal, or engineering reviews. These business combination costs are included in "acquisition and integration costs" on the Company's consolidated statement of operations and comprehensive income (loss). See note 4 for a discussion of the Company's recent acquisitions. 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, 2017 2016 2015 Interest expense on debt obligations $ 581,314 $ 500,699 $ 490,002 Amortization of deferred financing costs and adjustments on long-term debt, net 19,035 19,087 21,048 Amortization of interest rate swaps — — 18,725 Capitalized interest (11,545 ) (7,010 ) (4,805 ) Other 1,878 2,256 2,158 Total $ 590,682 $ 515,032 $ 527,128 The Company amortizes deferred financing costs, discounts, premiums, and purchase price adjustments on long-term debt over the estimated term of the related borrowing using the effective interest yield method. Discounts or purchase price adjustments 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 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) alternative minimum taxes (repealed effective January 1, 2018), (2) taxes on any undistributed income, (3) taxes related to the TRSs, (4) franchise taxes, (5) property taxes, and (6) transfer taxes. In addition, the Company could in 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. During the fourth quarter of 2015, the Company completed the necessary steps to include small cells that were previously included in one or more wholly-owned TRSs in the REIT effective January 2016. As a result, during the fourth quarter of 2015, the Company de-recognized the related net deferred tax liabilities. Effective January 4, 2016, the Company's small cells that were previously included in one or more TRSs were included in the REIT. See note 11 . 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) most likely will be 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. The Company will be subject to a federal corporate level tax rate (currently 21%) on the gain recognized from the sale of assets occurring within a specified period (generally 5 years) after the REIT conversion up to the amount of the built in gain that existed on January 1, 2014, which is based upon the fair market value of those assets in excess of the Company's tax basis on January 1, 2014. 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 December 31, 2017 and 2016 , the Company has not recorded any penalties related to its income tax positions. See note 11. 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 year ended December 31, 2017 , 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 RSUs as determined under the treasury stock method and (2) conversion of the Company's 6.875% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share ("6.875% Convertible Preferred Stock"), as determined under the if-converted method. For the years ended December 31, 2016 and December 31, 2015, diluted 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 RSUs as determined under the treasury stock method and (2) conversion of the Company's then outstanding 4.50% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share ("4.50% Convertible Preferred Stock"), as determined under the if-converted method. A reconciliation of the numerators and denominators of the basic and diluted per share computations is as follows: Years Ended December 31, 2017 2016 2015 Net income (loss) from continuing operations $ 444,550 $ 356,973 $ 525,286 Dividends on preferred stock (58,294 ) (32,991 ) (43,988 ) Net income (loss) from continuing operations attributable to CCIC common stockholders for basic and diluted computations $ 386,256 $ 323,982 $ 481,298 Income (loss) from discontinued operations, net of tax — — 999,049 Less: Net income (loss) attributable to the noncontrolling interest — — 3,343 Net income (loss) from discontinued operations attributable to CCIC common stockholders for basic and diluted computations — — 995,706 Weighted-average number of common shares outstanding (in thousands): Basic weighted-average number of common stock outstanding 381,740 340,349 333,002 Effect of assumed dilution from potential common shares relating to RSUs 1,481 530 1,060 Diluted weighted-average number of common shares outstanding 383,221 340,879 334,062 Net income (loss) attributable to CCIC common stockholders, per common share: Income (loss) from continuing operations, basic $ 1.01 $ 0.95 $ 1.45 Income (loss) from discontinued operations, basic $ — $ — $ 2.99 Net income (loss) attributable to CCIC common stockholders, basic $ 1.01 $ 0.95 $ 4.44 Income (loss) from continuing operations, diluted $ 1.01 $ 0.95 $ 1.44 Income (loss) from discontinued operations, diluted $ — $ — $ 2.98 Net income (loss) attributable to CCIC common stockholders, diluted $ 1.01 $ 0.95 $ 4.42 For the year ended December 31, 2017 , 15.0 million common share equivalents related to the 6.875% Convertible Preferred Stock were excluded from the dilutive common shares because the impact of the conversion of such preferred stock would be anti-dilutive based on the Company's common stock price as of December 31, 2017 . For the year ended December 31, 2015, 11.4 million common share equivalents related to the then outstanding 4.50% Convertible Preferred Stock were excluded from the dilutive common shares because the impact of the conversion of such preferred stock would be anti-dilutive based on the Company's common stock price at the end of such year. See notes 12 and 13 . 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. The fair value of cash and cash equivalents and restricted cash approximate the carrying value. The Company determines the fair value of its debt securities based on indicative quotes (that is non-binding quotes) from brokers that require judgment to interpret market information including implied credit spreads for similar borrowings on recent trades or bid/ask prices or quotes from active markets if applicable. Foreign currency swaps are valued at settlement amounts using observable exchange rates and, if material, reflect an adjustment for the Company's and contract counterparty's credit risk. There were no changes since December 31, 2016 in the Company's valuation techniques used to measure fair values. See note 10 for a further discussion of fair values. Swaps Interest Rate Swaps. The Company had previously entered into interest rate swaps to manage or reduce its interest rate risk, including the use of (1) forward-starting interest rate swaps to hedge its exposure to variability in future cash flows attributable to changes in LIBOR on anticipated financings, including refinancings and potential future borrowings or (2) interest rate swaps to hedge the interest rate variability on a portion of the Company's floating rate debt. Derivative financial instruments were entered into for periods that matched the related underlying exposures. The Company can elect whether or not to designate derivative financial instruments as accounting hedges. The Company can also enter into derivative financial instruments that are not designated as accounting hedges. As of December 31, 2017 , the Company does not have any interest rate swaps. Derivatives were recognized on the consolidated balance sheet at fair value. If the derivative was designated as a cash flow hedge, the effective portion of the change in the fair value of the derivative was recorded as a separate component of stockholders' equity, captioned "accumulated other comprehensive income (loss)" on the Company's consolidated balance sheet, and recognized as increases or decreases to "interest expense and amortization of deferred financing costs" on the Company's consolidated statement of operations and comprehensive income (loss) when the hedged item affects earnings. If a hedge ceased to qualify

Discontinued Operations (Notes)

Discontinued Operations (Notes)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Discontinued Operations On May 14, 2015, the Company entered into a definitive agreement to sell CCAL to a consortium of investors led by Macquarie Infrastructure and Real Assets (collectively, "Buyer"). On May 28, 2015, the Company completed the sale. At closing, the Company received net proceeds of approximately $ 1.1 billion after accounting for the Company's 77.6% ownership interest, repayment of intercompany debt owed to the Company by CCAL and estimated transaction fees and expenses, exclusive of the impact of foreign currency swaps related to the CCAL sale (see note 9 ). As part of the sale of CCAL, in January 2016, the Company received an installment payment from the Buyer totaling approximately $ 124 million , inclusive of the impact of the related foreign currency swap (see note 9 ). During the second quarter 2015, the Company used net proceeds from the sale of CCAL to repay portions of outstanding borrowings under the Company's then outstanding senior secured credit facility ("2012 Credit Facility"). See note 8 . The Company entered into foreign currency swaps to manage and reduce its foreign currency risk associated with the sale of CCAL. These swaps are not included in discontinued operations. See note 9 . Prior to the sale of CCAL, it had historically been a separate operating segment of the Company. The sale of CCAL is treated as discontinued operations for all periods presented pursuant to ASU 2014-08, which the Company adopted on January 1, 2015. The sale of CCAL represented a strategic shift of the Company to focus on its U.S. operations. The gain from disposal of CCAL is included in discontinued operations on the consolidated statement of operations. The tables below set forth the results of operations related to discontinued operations for the year ended December 31, 2015 . Year Ended December 31, 2015 (b)(c) Total revenues $ 65,293 Total cost of operations (a) 17,498 Depreciation, amortization and accretion 10,168 Total other expenses 10,481 Pre-tax income from discontinued operations 27,146 Benefit (provision) from income taxes (7,456 ) Net income (loss) from discontinued operations (d) $ 19,690 (a) Exclusive of depreciation, amortization, and accretion shown separately. (b) No interest expense has been allocated to discontinued operations. (c) CCAL results are through May 28, 2015, which was the closing date of the Company's sale of CCAL. (d) Exclusive of the gain (loss) from disposal of discontinued operations, net of tax, as presented on the consolidated statement of operations. The Company recorded a gain on the sale of CCAL during the year ended December 31, 2015, which was comprised of the following items: Cash received from sale of CCAL (a) $ 1,139,369 Installment payment receivable due January 2016 (a) 117,384 Total proceeds from sale of CCAL $ 1,256,753 Adjusted for: Net assets and liabilities related to discontinued operations (b)(c) 258,575 Transaction fees and expenses 23,059 Foreign currency translation reclassification adjustments (d) (25,678 ) Pre-tax gain (loss) from disposal of discontinued operations 1,000,797 Income taxes related to the sale of CCAL (21,438 ) Gain (loss) from disposal of discontinued operations $ 979,359 (a) Exclusive of foreign currency swaps and based on exchange rates as of May 28, 2015, which was the closing date of the Company's sale of CCAL. See note 9 . The impact of fluctuations in the exchange rate subsequent to the closing date are reflected as a component of "other income (expense)" on the Company's consolidated statement of operations. (b) Represents net assets attributable to CCIC, net of the disposition of noncontrolling interest of $ 23.5 million . (c) Inclusive of $ 11.1 million of cash. (d) Represents foreign currency translation adjustments previously included in "accumulated other comprehensive income (loss)" on the consolidated balance sheet and reclassified to "net gain (loss) from disposal of discontinued operations, net of tax" on the consolidated statement of operations and comprehensive income (loss).

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2017
Acquisitions
Acquisitions	Acquisitions 2015 Sunesys Acquisition During April 2015, the Company entered into a definitive agreement to acquire Quanta Fiber Networks, Inc. ("Sunesys") for approximately $ 1.0 billion in cash, subject to certain limited adjustments ("Sunesys Acquisition"). On August 4, 2015, the Company closed the Sunesys Acquisition. The results of operations from Sunesys have been included in the Company's consolidated statement of operations since the date of acquisition. Prior to the closing, Sunesys was a wholly owned subsidiary of Quanta Services, Inc. and a fiber services provider that owned or had rights to nearly 10,000 route miles of fiber in major metropolitan markets across the U.S., including Los Angeles, Philadelphia, Chicago, Atlanta, Silicon Valley, and northern New Jersey. Approximately 60% of Sunesys' fiber route miles were located in the top 10 basic trading areas. The Company utilized borrowings under the 2012 Credit Facility and cash on hand to fund the cash consideration of approximately $ 1.0 billion . See note 8 . The final purchase price allocation for the Sunesys Acquisition is shown below. Final Purchase Price Allocation Current assets $ 15,306 Property and equipment 444,394 Goodwill (a) 331,775 Other intangible assets, net 254,079 Current liabilities (20,233 ) Other non-current liabilities (37,356 ) Net assets acquired (b) $ 987,965 (a) The final purchase price allocation for the Sunesys Acquisition resulted in the recognition of goodwill based on the Company's expectation to leverage the Sunesys fiber footprint to support new small cells. The Sunesys fiber is complementary to the Company's existing fiber assets and is located where the Company expects to see wireless carrier network investments. (b) Assets acquired in the Sunesys Acquisition are included in the Company's REIT and as such, no deferred taxes were recorded in connection with the Sunesys Acquisition. Net revenues and net income (loss) attributable to the Sunesys Acquisition are included in the Company's consolidated statements of operations and comprehensive income (loss), since the date the acquisition was completed. For the years ended December 31, 2017 , 2016 and 2015 , the Sunesys Acquisition contributed consolidated net revenues of $121.7 million , $112.6 million and $41.4 million , respectively. 2016 TDC Acquisition In April 2016, the Company acquired Tower Development Corporation ("TDC"), a portfolio of approximately 330 towers, for approximately $461.0 million in cash ("TDC Acquisition"). The Company financed the acquisition with cash on hand, cash from borrowings under the Company's senior unsecured revolving credit facility ("2016 Revolver"), and cash from equity issuances under the ATM Program (see note 12 ). The final purchase price allocation was primarily comprised of customer relationships of approximately $140 million , property and equipment of approximately $107 million , and goodwill of approximately $211 million . 2017 FiberNet Acquisition On November 1, 2016, the Company announced that it had entered into a definitive agreement to acquire FPL FiberNet Holdings, LLC and certain other subsidiaries of NextEra Energy, Inc. (collectively, "FiberNet") for approximately $1.5 billion in cash, subject to certain limited adjustments ("FiberNet Acquisition"). FiberNet is a fiber services provider in Florida and Texas that, as of the agreement date, owned or had rights to approximately 11,500 route miles of fiber installed or under construction, inclusive of approximately 6,000 route miles in top metro markets. On January 17, 2017 , the Company closed the FiberNet Acquisition, which was financed using proceeds from its November 2016 Common Stock Offering (as defined in note 12) and borrowings under the 2016 Revolver (see note 8). The preliminary purchase price allocation for the FiberNet Acquisition is shown below and is based upon a preliminary valuation which is subject to change as the Company obtains additional information with respect to fixed assets, intangible assets and certain liabilities. Preliminary Purchase Price Allocation Current assets $ 52,274 Property and equipment 438,478 Goodwill (a) 777,563 Other intangible assets, net (b) 327,338 Other non-current assets 2,449 Current liabilities (41,120 ) Other non-current liabilities (36,152 ) Net assets acquired (c) $ 1,520,830 (a) The preliminary purchase price allocation for the FiberNet Acquisition resulted in the recognition of goodwill based on: • the Company's expectation to leverage the FiberNet fiber footprint to support new small cells and fiber solutions, • the complementary nature of the FiberNet fiber to the Company's existing fiber assets and its location in top metro markets where the Company expects to see wireless carrier network investments, • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. (b) Predominantly comprised of site rental contracts and customer relationships. (c) The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the FiberNet Acquisition. 2017 Wilcon Acquisition On April 17, 2017 , the Company announced that it had entered into a definitive agreement to acquire Wilcon Holdings LLC ("Wilcon") from Pamlico Holdings and other unit holders of Wilcon for approximately $600 million in cash, subject to certain limited adjustments ("Wilcon Acquisition"). Wilcon is a fiber services provider that owns approximately 1,900 route miles of fiber, primarily in Los Angeles and San Diego. On June 26, 2017 , the Company closed the Wilcon Acquisition, which was financed using proceeds from the May 2017 Common Stock Offering (as defined in note 12) and the 4.750% Senior Notes (as defined in note 8) offering. The preliminary purchase price of approximately $600 million was primarily comprised of other intangible assets (predominantly comprised of site rental contracts and customer relationships) of approximately $140 million , property and equipment of approximately $150 million , goodwill of approximately $360 million , offset by deferred revenues of approximately $40 million . The preliminary purchase price allocation for the Wilcon Acquisition resulted in the recognition of goodwill based on (1) the Company's expectation to leverage the Wilcon fiber footprint to support new small cells and fiber solutions, (2) the complementary nature of the Wilcon fiber to the Company's existing fiber assets and its location primarily in Los Angeles and San Diego, where the Company expects to see wireless carrier network investments, (3) the Company's belief that the acquired fiber assets are well positioned to benefit from the continued growth trends in the demand for data, and (4) other intangibles not qualified for separate recognition, including the assembled workforce. The preliminary purchase price allocation for the Wilcon Acquisition is based upon a preliminary valuation which is subject to change as the Company obtains additional information with respect to fixed assets, intangible assets and certain liabilities. 2017 Lightower Acquisition On July 18, 2017 , the Company announced that it had entered into a definitive agreement to acquire LTS Group Holdings LLC ("Lightower") from Berkshire Partners, Pamlico Capital and other investors for approximately $7.1 billion in cash, subject to certain limited adjustments ("Lightower Acquisition"). Lightower owns or has rights to approximately 32,000 route miles of fiber located primarily in top metro markets in the Northeast, including Boston, New York and Philadelphia. On November 1, 2017 , the Company closed the Lightower Acquisition, which was financed using (1) cash on hand, including proceeds from the July 2017 Equity Offerings (as defined in note 12) and the August 2017 Senior Notes (as defined in note 8) offering, and (2) borrowings under the 2016 Revolver. The preliminary purchase price allocation for the Lightower Acquisition is shown below and is based upon a preliminary valuation which is subject to change as the Company obtains additional information with respect to fixed assets, intangible assets and certain liabilities. Preliminary Purchase Price Allocation Current assets $ 104,643 Property and equipment 2,197,466 Goodwill (a) 3,116,010 Other intangible assets, net (b) 2,177,090 Other non-current assets 28,834 Current liabilities (172,399 ) Other non-current liabilities (299,667 ) Net assets acquired (c) $ 7,151,977 (a) The preliminary purchase price allocation for the Lightower Acquisition resulted in the recognition of goodwill based on: • the Company's expectation to leverage the Lightower fiber footprint to support new small cells and fiber solutions , • the complementary nature of the Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments , • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. (b) Predominantly comprised of site rental contracts and customer relationships. (c) The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the Lightower Acquisition. Actual and Pro Forma Financial Information Net revenues and net income (loss) attributable to acquisitions completed during the year ended December 31, 2017 are included in the Company's consolidated statements of operations and comprehensive income (loss), since the respective date each acquisition was completed. For the year ended December 31, 2017, the FiberNet Acquisition, Wilcon Acquisition and Lightower Acquisition (collectively, "2017 Acquisitions") resulted in an increase to consolidated net revenues of $314.1 million . The unaudited pro forma financial results for the years ended December 31, 2017 and 2016 combine the historical results of the Company, along with the historical results of the 2017 Acquisitions for the respective periods. The following table presents the unaudited pro forma consolidated results of operations of the Company as if each acquisition was completed as of January 1, 2016 for the periods presented below. The unaudited pro forma amounts are presented for illustrative purposes only and are not necessarily indicative of future consolidated results of operations. Twelve Months Ended December 31, 2017 2016 Net revenues $ 5,050,166 $ 4,864,852 Income (loss) before income taxes 541,389 (b)(c) 367,326 (b)(c)(d) Benefit (provision) for income taxes (28,960 ) (a) (20,968 ) (a) Net income (loss) $ 512,429 (b)(c) $ 346,358 (b)(c)(d) Basic net income (loss) attributable to CCIC common stockholders, per common share $ 0.89 (c)(e) $ 0.51 (c)(e) Diluted net income (loss) attributable to CCIC common stockholders, per common share $ 0.88 (c)(e) $ 0.51 (c)(e) (a) For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to the benefit (provision) for income tax as a result of the Company's REIT status. The vast majority of the assets and related income from the FiberNet Acquisition, the Wilcon Acquisition, and the Lightower Acquisition are included in the Company's REIT. The remaining assets are included in the Company's TRS. For purposes of the unaudited pro forma financial results, an adjustment has been made to reflect the additional tax impact of the income related to the TRS assets. (b) For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to depreciation and amortization of $247.1 million and $315.9 million , respectively, related to property and equipment and intangibles recorded as a result of the 2017 Acquisitions. (c) Pro forma amounts include the impact of the interest expense and common stock share issuances associated with the related debt and equity financings for the 2017 Acquisitions (see above and notes 8 and 12). (d) Amounts are inclusive of a total of $120 million of Lightower stock-based compensation expense and acquisition and integration costs. (e) Pro forma amounts include the impact of the preferred stock dividends related to the Mandatory Convertible Preferred Stock Offering (as defined in note 12) for the Lightower Acquisition (see above and note 12).

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment The major classes of property and equipment are as follows: Estimated Useful Lives As of December 31, 2017 2016 Land (a) — $ 1,859,431 $ 1,747,335 Buildings 40 years 119,313 110,641 Communications infrastructure assets 1-20 years 17,183,482 13,825,394 Information technology assets and other 2-7 years 372,339 278,489 Construction in process — 898,621 456,675 Total gross property and equipment 20,433,186 16,418,534 Less: accumulated depreciation (7,500,301 ) (6,613,219 ) Total property and equipment, net $ 12,932,885 $ 9,805,315 (a) Includes land owned in fee and perpetual easements. Depreciation expense for the years ended December 31, 2017 , 2016 and 2015 was $914.9 million , $832.7 million and $774.9 million , respectively. Capital leases and associated leasehold improvements related to gross property and equipment, and accumulated depreciation was $4.3 billion and $1.7 billion , respectively, as of December 31, 2017 . See notes 1 and 2 , including discussion of the Company's prepaid master lease agreements.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The changes in the carrying value of goodwill for the years ended December 31, 2017 and December 31, 2016 were as follows: Balance as of December 31, 2015 $ 5,513,551 Additions due to TDC Acquisition (a) 210,905 Adjustments due to other acquisitions, purchase price allocations and other, net 33,220 Balance as of December 31, 2016 $ 5,757,676 Additions due to FiberNet Acquisition (b) 777,563 Additions due to Wilcon Acquisition (b) 357,606 Additions due to Lightower Acquisition (b) 3,116,010 Adjustments due to other acquisitions, purchase price allocations and other, net 12,613 Balance as of December 31, 2017 $ 10,021,468 (a) The final purchase price allocation for the TDC Acquisition resulted in the recognition of goodwill in the Towers segment because of the anticipated growth opportunity in the acquired tower portfolio. See note 4 . (b) The preliminary purchase price allocation for the FiberNet Acquisition, Wilcon Acquisition and Lightower Acquisition resulted in the recognition of goodwill in the Fiber segment based on: • the Company's expectation to leverage the FiberNet, Wilcon and Lightower fiber footprint to support new small cell and fiber solutions , • the complementary nature of the FiberNet, Wilcon and Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments , • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. See note 4 . Intangibles The following is a summary of the Company's intangible assets. See note 4 for further discussion of the Company's acquisitions. As of December 31, 2017 As of December 31, 2016 Gross Carrying Value (a) Accumulated Amortization Net Book Value Gross Carrying Value Accumulated Amortization Net Book Value Site rental contracts and customer relationships $ 7,782,934 $ (2,156,499 ) $ 5,626,435 $ 5,146,301 $ (1,847,523 ) $ 3,298,778 Other intangible assets 502,891 (167,567 ) 335,324 497,091 (145,797 ) 351,294 Total $ 8,285,825 $ (2,324,066 ) $ 5,961,759 $ 5,643,392 $ (1,993,320 ) $ 3,650,072 (a) During the year ended December 31, 2017 , intangible assets additions (primarily site rental contracts and customer relationships) from acquisitions had a weighted average amortization period of approximately 17 years. 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 2017 2016 2015 Depreciation, amortization and accretion $ 314,447 $ 264,656 $ 251,443 Site rental costs of operations 18,373 19,367 20,420 Total amortization expense $ 332,820 $ 284,023 $ 271,863 The estimated annual amortization expense related to intangible assets (inclusive of those recorded as an increase to "site rental costs of operations") for the years ending December 31, 2018 to 2022 is as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Estimated annual amortization $ 445,849 $ 444,889 $ 444,589 $ 444,155 $ 443,688

Other Liabilities (Notes)

Other Liabilities (Notes)	12 Months Ended
	Dec. 31, 2017
Other Liabilities [Abstract]
Other Liabilities	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, 2017 2016 Deferred rental revenues $ 1,076,845 $ 983,263 Deferred ground lease payable 559,556 517,281 Above market leases for land interests, net 201,542 224,126 Deferred credits, net 531,856 207,992 Asset retirement obligation 173,733 146,100 Deferred income tax liabilities 5,192 8,075 Other long-term liabilities 5,313 392 Total $ 2,554,037 $ 2,087,229 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 upon which its communications infrastructure resides. Accretion expense related to liabilities for retirement obligations amounted to $13.1 million , $11.3 million and $9.9 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. As of December 31, 2017 and 2016 , liabilities for retirement obligations were $173.7 million and $146.1 million , respectively, representing the net present value of the estimated expected future cash outlay. As of December 31, 2017 , the estimated undiscounted future cash outlay for asset retirement obligations was approximately $1.2 billion . See note 2 . For the years ended December 31, 2017 , 2016 and 2015 , the Company recorded $19.3 million , $21.0 million and $22.5 million , respectively, as a decrease to "site rental costs of operations" for the amortization of above-market leases for land interests under the Company's towers. The estimated amortization expense related to above-market leases for land interests under the Company's towers recorded to site rental costs of operations for the years ending December 31, 2018 to 2022 is as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Above-market leases for land interests $ 18,277 $ 17,674 $ 16,769 $ 15,667 $ 14,580 For the years ended December 31, 2017 , 2016 and 2015 , the Company recognized $37.3 million , $33.6 million and $32.8 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, 2018 to 2022 are as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Below-market tenant leases $ 65,104 $ 59,145 $ 53,050 $ 49,745 $ 44,910 Other accrued liabilities Other accrued liabilities included accrued payroll and other accrued compensation of $ 141.0 million and $ 100.9 million , respectively, as of December 31, 2017 and 2016 .

Debt and Other Obligations

Debt and Other Obligations	12 Months Ended
	Dec. 31, 2017
Debt and Other Obligations [Abstract]
Debt and Other Obligations	Debt and Other Obligations See note 19 for a discussion of the Company's issuance of the January 2018 Senior Notes (as defined in note 19) and the application of the net proceeds therefrom. The table below sets forth the Company's debt and other obligations as of December 31, 2017 . Original Issue Date Contractual Maturity Date Outstanding Balance as of December 31, Stated Interest Rate as of December 31, 2017 2016 2017 (a) Bank debt – variable rate: 2016 Revolver Jan. 2016 Aug. 2022 $ 980,000 (b) $ — 2.6 % (c) 2016 Term Loan A Jan. 2016 Aug. 2022 2,396,588 1,954,173 2.6 % (c) Total bank debt 3,376,588 1,954,173 Securitized debt – fixed rate: Secured Notes, Series 2009-1, Class A-1 Jul. 2009 Aug. 2019 (d) 31,813 51,416 6.3 % Secured Notes, Series 2009-1, Class A-2 Jul. 2009 Aug. 2029 (d) 69,500 68,737 9.0 % Tower Revenue Notes, Series 2010-3 Jan. 2010 Jan. 2040 (e)(f) 1,246,106 1,244,237 6.1 % Tower Revenue Notes, Series 2010-6 Aug. 2010 Aug. 2040 (e)(f) 995,354 993,557 4.9 % Tower Revenue Notes, Series 2015-1 May 2015 May 2042 (e)(f) 297,211 296,573 3.2 % Tower Revenue Notes, Series 2015-2 May 2015 May 2045 (e)(f) 692,325 691,285 3.7 % Total securitized debt 3,332,309 3,345,805 Bonds – fixed rate: 5.250% Senior Notes Oct. 2012 Jan. 2023 1,639,207 1,637,099 5.3 % 3.849% Secured Notes Dec. 2012 Apr. 2023 992,663 991,279 3.8 % 4.875% Senior Notes Apr. 2014 Apr. 2022 842,090 840,322 4.9 % 3.400% Senior Notes Feb./May 2016 Feb. 2021 849,859 849,698 3.4 % 4.450% Senior Notes Feb. 2016 Feb. 2026 891,145 890,118 4.5 % 3.700% Senior Notes May 2016 June 2026 742,727 741,908 3.7 % 2.250% Senior Notes Sept. 2016 Sept. 2021 695,383 693,893 2.3 % 4.000% Senior Notes Feb. 2017 Mar. 2027 493,833 — 4.0 % 4.750% Senior Notes May 2017 May 2047 343,209 — 4.8 % 3.200% Senior Notes Aug. 2017 Sept. 2024 741,859 — 3.2 % 3.650% Senior Notes Aug. 2017 Sept. 2027 990,965 — 3.7 % Total bonds 9,222,940 6,644,317 Other: Capital leases and other obligations Various Various (g) 227,783 226,847 Various Total debt and other obligations 16,159,620 12,171,142 Less: current maturities and short-term debt and other current obligations 115,251 101,749 Non-current portion of long-term debt and other long-term obligations $ 16,044,369 $ 12,069,393 (a) Represents the weighted-average stated interest rate. (b) As of December 31, 2017 , the undrawn availability under the 2016 Revolver was $2.5 billion . See note 19. (c) The 2016 Revolver and senior unsecured term loan A facility ("2016 Term Loan A") bear interest at a rate per annum equal to LIBOR plus a credit spread ranging from 1.125% to 2.000% , based on the Company's senior unsecured debt rating. The Company pays a commitment fee of approximately 0.200% per annum on the undrawn available amount under the 2016 Revolver. (d) The Secured Notes, Series 2009-1, Class A-1 and Secured Notes, Series 2009-1, Class A-2 are collectively referred to herein as "2009 Securitized Notes." (e) The Tower Revenue Notes, Series 2010-3 ("January 2010 Tower Revenue Notes"), Tower Revenue Notes, Series 2010-6 ("August 2010 Tower Revenue Notes") and Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes." (f) 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) 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, 2017, the Tower Revenue Notes have principal amounts of $2.3 billion , $300.0 million and $700.0 million , with anticipated repayment dates in 2020, 2022 and 2025, respectively. See note 19. (g) The Company's capital 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 30 years. 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 completed 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 $500.0 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 the commitments under the 2016 Revolver by $1.0 billion , for total commitments of $3.5 billion , and (2) extend the maturity of both the 2016 Term Loan A and the 2016 Revolver to August 2022 . Securitized Debt The Tower Revenue Notes and the 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 January 2010 Tower Revenue Notes, August 2010 Tower Revenue Notes and May 2015 Tower Revenue Notes are governed by one indenture and consist of multiple series of notes, each with its own anticipated repayment date. The net proceeds of the January 2010 Tower Revenue Notes and August 2010 Tower Revenue Notes were primarily used to repay the portion of the 2005 Tower Revenue Notes and 2006 Tower Revenue Notes not previously purchased. In April 2014, the Company utilized a portion of the net proceeds from the 4.875% Senior Notes (as defined below) offering to repay $300.0 million of the January 2010 Tower Revenue Notes which had an anticipated repayment date of January 2015. The net proceeds of the May 2015 Tower Revenue Notes, together with proceeds received from the Company's sale of CCAL, were primarily used to (1) repay $250.0 million aggregate principal amount of 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. 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, 2017 , the Securitized Debt was collateralized with personal property and equipment with an aggregate net book value of approximately $1.1 billion , 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 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, provided 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. See note 19 for a discussion of the redemption of the January 2010 Tower Revenue Notes. Bonds—Senior Notes In February 2017 , the Company issued $500.0 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 $350.0 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 Wilcon Acquisition 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) $750.0 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 Lightower Acquisition 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) $600.0 million aggregate principal amount of 3.400% senior notes due February 2021 ("3.400% Senior Notes") and (2) $900.0 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 $500.0 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) $250.0 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) $750.0 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 $700.0 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 $500.0 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 $ 850.0 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 $ 839.0 million , after the deduction of associated fees. The Company utilized the net proceeds from the 4.875% Senior Notes offering (1) to repay $300.0 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 February 2016 Senior Notes, May 2016 Senior Notes, 2.250% Senior Notes, 4.875% Senior Notes, 5.250% Senior Notes, 4.000% Senior Notes, 4.750% Senior Notes, August 2017 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 2012 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. Contractual Maturities The following are the scheduled contractual maturities of the total debt or other long-term obligations outstanding at December 31, 2017 . These maturities reflect contractual maturity dates and 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, 2018 2019 2020 2021 2022 Thereafter Total Cash Obligations Unamortized Adjustments, Net Total Debt and Other Obligations Outstanding Scheduled contractual maturities $ 116,045 $ 167,458 $ 155,051 $ 1,824,568 $ 3,701,737 $ 10,296,901 $ 16,261,760 $ (102,140 ) $ 16,159,620 Debt Purchases and Redemptions The following is a summary of the purchases and redemptions of debt during the years ended December 31, 2017 , 2016 and 2015 . Year Ending December 31, 2017 Principal Amount Cash Paid Gains (losses) (a) 2016 Term Loan A $ — $ — $ (3,525 ) (a) The losses related to write off of deferred financing costs. Year Ending December 31, 2016 Principal Amount Cash Paid (a) Gains (losses) (b) Revolving Credit Facility under 2012 Credit Facility $ — $ — $ (1,930 ) Tranche A Term Loans under 2012 Credit Facility 629,375 629,375 (1,498 ) Tranche B Term Loans under 2012 Credit Facility 2,247,015 2,247,015 (27,122 ) Tower Revenue Notes, Series 2010-2 350,000 352,796 (3,338 ) Tower Revenue Notes, Series 2010-5 300,000 307,176 (8,129 ) 2.381% Secured Notes 500,000 508,472 (10,274 ) Total $ 4,026,390 $ 4,044,834 $ (52,291 ) (a) Exclusive of accrued interest. (b) Inclusive of $33.8 million related to the write off of deferred financing costs. Year Ending December 31, 2015 Principal Amount Cash Paid (a) Gains (losses) (b) Tower Revenue Notes, Series 2010-4 $ 250,000 $ 250,000 $ (159 ) WCP Securitized Notes 252,830 252,830 2,105 Tranche B Term Loans under 2012 Credit Facility 564,137 564,137 (6,127 ) Other 2,394 2,370 24 Total $ 1,069,361 $ 1,069,337 $ (4,157 ) (a) Exclusive of accrued interest. (b) Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.

Swaps

Swaps	12 Months Ended
	Dec. 31, 2017
Summary of Derivative Instruments [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Swaps Foreign Currency Swaps During May 2015, the Company entered into two previously outstanding foreign currency swaps to manage and reduce its foreign currency risk related to its sale of CCAL (see note 3 ). The Company does not enter into foreign currency swaps for speculative or trading purposes. The foreign currency swaps were originally comprised of the following: Item Swapped Notional Amount Forward Rate Start Date End Date Pay Amount Receive Amount Fair Value at December 31, 2017 May 2015 cash receipt from sale of CCAL A$1,400,000 0.8072 May 2015 June 2015 Australian Dollar US Dollar N/A (a) Installment payment from Buyer A$155,000 0.79835 May 2015 January 2016 Australian Dollar US Dollar N/A (b) (a) In conjunction with closing the CCAL sale on May 28, 2015, the Company cash settled the swap with a notional value of Australian dollar $ 1.4 billion and recorded a gain on foreign currency swaps of $ 54.5 million , which is included as a component of "other income (expense)" on the Company's consolidated statement of operations. (b) As of December 31, 2015 , the Company marked-to-market the swap with a notional value of Australian dollar $ 155.0 million and recorded (1) an asset within "other current assets" on the Company's consolidated balance sheet and (2) a corresponding gain on foreign currency swaps , which is included as a component of "other income (expense)" on the Company's consolidated statement of operations. In January 2016, the then outstanding swap related to the installment payment received from the Buyer was settled. In total, the Company recorded a gain on foreign currency swaps of $ 65.2 million for the year ended December 31, 2015 , respectively. This gain is included as a component of "other income (expense)" on the Company's consolidated statement of operations.

Fair Value Disclosures

Fair Value Disclosures	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures
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, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and cash equivalents 1 $ 314,094 $ 314,094 $ 567,599 $ 567,599 Restricted cash 1 126,065 126,065 129,547 129,547 Liabilities: Debt and other obligations 2 $ 16,159,620 $ 16,643,725 $ 12,171,142 $ 12,660,013

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Income Taxes	Income Taxes Income (loss) from continuing operations before income taxes by geographic area is as follows: Years Ended December 31, 2017 2016 2015 Domestic $ 450,771 $ 349,041 $ 461,293 Foreign (a) 19,822 24,813 12,536 Total $ 470,593 $ 373,854 $ 473,829 (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, 2017 2016 2015 Current: Federal $ (2,816 ) $ (227 ) $ 495 Foreign (6,050 ) (6,820 ) (5,675 ) State (2,289 ) (1,231 ) (3,981 ) Total current (11,155 ) (8,278 ) (9,161 ) Deferred: Federal (17,743 ) (7,968 ) 44,716 Foreign 2,883 (601 ) (1,048 ) State (28 ) (34 ) 16,950 Total deferred (14,888 ) (8,603 ) 60,618 Total tax benefit (provision) $ (26,043 ) $ (16,881 ) $ 51,457 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, 2017 2016 2015 Benefit (provision) for income taxes at statutory rate $ (164,707 ) $ (130,849 ) $ (165,840 ) Tax effect of foreign income (losses) (430 ) 1,215 (527 ) Tax adjustment related to REIT operations 158,812 121,092 186,649 Tax adjustment related to the inclusion of small cells in the REIT (a) — — 33,759 Expenses for which no federal tax benefit was recognized (42 ) (43 ) (414 ) Valuation allowances 21 (21 ) 3,000 State tax (provision) benefit, net of federal (2,115 ) (1,085 ) 1,210 Foreign tax (3,168 ) (7,421 ) (6,723 ) Effects of tax law change (b) (14,628 ) — — Other 214 231 343 Total $ (26,043 ) $ (16,881 ) $ 51,457 (a) During the fourth quarter of 2015, the Company de-recognized the net deferred tax liabilities related to the Company's small cells previously included in one or more TRSs in conjunction with the inclusion of small cells in the REIT in January 2016. (b) Pursuant to the Tax Cuts and Jobs Act, which was signed into law in December 2017, the Company was required to write down its net federal deferred tax asset in the amount of $16.8 million as a result of the reduction in the federal corporate tax rate offset by a benefit of $2.2 million related to the refund of the Company's alternative minimum tax credit carryforward. The components of the net deferred income tax assets and liabilities are as follows: December 31, 2017 2016 Deferred income tax liabilities: Property and equipment $ 4,940 $ 3,945 Deferred site rental receivable 6,907 6,192 Total deferred income tax liabilities 11,847 10,137 Deferred income tax assets: Intangible assets 4,460 22,377 Net operating loss carryforwards 20,800 21,143 Deferred ground lease payable 2,060 1,646 Accrued liabilities 5,161 5,511 Receivables allowance 317 383 Other 1,431 1,726 Valuation allowances (1,172 ) (6,627 ) Total deferred income tax assets, net 33,057 46,159 Net deferred income tax asset (liabilities) $ 21,210 $ 36,022 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, 2017 December 31, 2016 Classification Gross Valuation Allowance Net Gross Valuation Allowance Net Federal $ 25,260 $ — $ 25,260 $ 42,948 $ (21 ) $ 42,927 State 1,142 — 1,142 1,170 — 1,170 Foreign (4,020 ) (1,172 ) (5,192 ) (1,469 ) (6,606 ) (8,075 ) Total $ 22,382 $ (1,172 ) $ 21,210 $ 42,649 $ (6,627 ) $ 36,022 At December 31, 2017 , 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 $237.0 million of losses related to stock-based compensation. The Company also has foreign NOLs of $53.2 million . If not utilized, the Company's U.S. federal NOLs expire starting in 2024 and ending in 2036 , the state NOLs expire starting in 2018 and ending in 2036 , and the foreign NOLs expire starting in 2022 and ending in 2037 . 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, 2017 , there were no unrecognized tax benefits that would impact the effective tax rate, if recognized. The aggregate changes in the balance of unrecognized tax benefits are as follows: Years Ended December 31, 2017 2016 Balance at beginning of year $ 3,080 $ 6,770 Additions based on prior year tax positions — 116 Reductions as a result of the lapse of statute limitations (3,080 ) (3,806 ) Balance at end of year $ — $ 3,080 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 Company regularly assesses the likelihood of additional assessments in each of the tax jurisdictions. The Company believes it has adequately provided for uncertain tax positions and does not believe assessments, if any, arising from current or future examination or audits will have a material effect on the Company's financial statements. As of December 31, 2017 , the Company's deferred tax assets are included in "long-term prepaid rent and other assets, net" and the Company's deferred tax liabilities are included in "other long-term liabilities" on the Company's consolidated balance sheet.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Stockholders' Equity	Equity "At-The-Market" Stock Offering Program The Company maintains an "at-the-market" stock offering program ("ATM Program") through which it may, from time to time, issue and sell shares of its common stock having an aggregate cumulative gross sales price of up to $500.0 million to or through sales agents. Sales, if any, under the ATM Program may be made by means of ordinary brokers' transactions on the New York Stock Exchange or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or, subject to specific instructions of the Company, at negotiated prices. The Company intends to use the net proceeds from any sales under the ATM Program for general corporate purposes, which may include the funding of future acquisitions or investments and the repayment or repurchase of any outstanding indebtedness. During the year ended December 31, 2017, 0.2 million shares of common stock were sold under the ATM Program, generating net proceeds of $22.0 million after giving effect to sales commissions of $0.2 million. During the year ended December 31, 2016 , 3.8 million shares of common stock were sold under the ATM Program, generating net proceeds of $323.8 million after giving effect to sales agent commissions of $3.3 million . The net proceeds from the sales under the ATM Program were used, in part, to fund the TDC Acquisition. As of December 31, 2017, the Company had approximately $150 million of gross sales of common stock availability remaining under the ATM Program. May 2017 Common Stock Offering On May 1, 2017 , the Company completed an offering of 4.75 million shares of its common stock, which generated net proceeds of approximately $442.0 million ("May 2017 Common Stock Offering"). The Company used the net proceeds of the May 2017 Common Stock Offering to partially fund the Wilcon Acquisition. July 2017 Equity Offerings On July 26, 2017 , the Company completed an offering of 40.15 million shares of common stock, including certain additional shares sold pursuant to the underwriters' option, which generated net proceeds of approximately $3.8 billion ("July 2017 Common Stock Offering"). The Company used the net proceeds of the July 2017 Common Stock Offering to partially fund the Lightower Acquisition and pay related fees and expenses. On July 26, 2017 , the Company completed an offering of 1.65 million shares of the Company's 6.875% Convertible Preferred Stock, at $1,000 per share, including certain additional shares sold pursuant to the underwriters' option, which generated net proceeds of approximately $1.6 billion ("Mandatory Convertible Preferred Stock Offering"). The Company used the net proceeds from the Mandatory Convertible Preferred Stock Offering to partially fund the Lightower Acquisition and pay related fees and expenses. The holders of the 6.875% Convertible Preferred Stock are entitled to receive cumulative dividends, when and if declared by the Company's board of directors, at the rate of 6.875% on the liquidation preference of $1,000 per share. The dividends may be paid in cash or, subject to certain limitations, in shares of the Company's common stock or any combination of cash and shares of common stock on February 1, May 1, August 1 and November 1 of each year, commencing on November 1, 2017 and to, and including, August 1, 2020. The terms of the 6.875% Convertible Preferred Stock provide that, unless accumulated dividends have been paid or set aside for payment on all outstanding shares of 6.875% Convertible Preferred Stock for all past dividend periods, no dividends may be declared or paid on common stock. Unless converted earlier, each outstanding share of the 6.875% Convertible Preferred Stock will automatically convert into shares of the Company's common stock on August 1, 2020 into between 8.6806 and 10.4167 shares of the Company's common stock, depending on the applicable market value of the common stock and subject to certain anti-dilution adjustments. At any time prior to August 1, 2020, holders of the 6.875% Convertible Preferred Stock may elect to convert all or a portion of their shares into common stock at the minimum conversion rate of 8.6806 , subject to certain anti-dilution adjustments. The July 2017 Common Stock Offering and Mandatory Convertible Preferred Stock Offering are collectively referred to herein as "July 2017 Equity Offerings." Convertible Preferred Stock Conversion In October and November 2016, all of the approximately 9.8 million shares of the Company's then outstanding 4.50% Convertible Preferred Stock converted to approximately 11.6 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 1.1880 common shares per each share of 4.50% Convertible Preferred Stock. November 2016 Common Stock Offering In November 2016, the Company completed an equity offering of approximately 11.4 million shares of common stock, which generated net proceeds of approximately $1.0 billion ("November 2016 Common Stock Offering"). The Company utilized proceeds from such offering to partially fund the FiberNet Acquisition. Declaration and Payment of Dividends During the year ended December 31, 2017 , the following dividends were declared or paid: Equity Type Declaration Date Record Date Payment Date Dividends Per Share Aggregate Payment Amount (In millions) Common Stock February 17, 2017 March 17, 2017 March 31, 2017 $ 0.950 $ 343.3 (a) Common Stock May 18, 2017 June 16, 2017 June 30, 2017 $ 0.950 $ 350.3 (a) Common Stock August 3, 2017 September 15, 2017 September 29, 2017 $ 0.950 $ 389.6 (a) Common Stock October 15, 2017 December 15, 2017 December 29, 2017 $ 1.050 $ 428.8 (a) 6.875% Convertible Preferred Stock September 21, 2017 October 15, 2017 November 1, 2017 $ 18.142 $ 29.9 6.875% Convertible Preferred Stock December 15, 2017 January 15, 2018 February 1, 2018 $ 17.188 $ 28.4 (a) Inclusive of dividends accrued for holders of unvested RSUs, which will be paid when and if the RSUs vest. See note 19 for further discussion of common stock dividends. Tax Treatment of Dividends The following table summarizes, for income tax purposes, the nature of dividends paid during 2017 on the Company's common stock and 6.875% Convertible Preferred Stock. Equity Type Payment Date Dividends Per Share Ordinary Taxable Dividend Per Share Qualified Taxable Dividend Per Share (a) Long-Term Capital Gain Distribution Per Share Non-Taxable Distribution (per share) Common Stock March 31, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock June 30, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock September 29, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock December 29, 2017 $ 1.050 $ 1.050 $ 0.384 $ — $ — 6.875% Convertible Preferred Stock November 1, 2017 $ 18.142 $ 18.142 $ 6.629 $ — $ — (a) Qualified taxable dividend amounts are included in ordinary taxable dividend amounts. The Company has determined that none of the distributions to the Company's shareholders for the tax year ended December 31, 2017 consisted of an alternative minimum tax adjustment. Purchases of the Company's Common Stock During each of the years ended December 31, 2017 , 2016 and 2015 , the Company purchased 0.3 million shares of common stock utilizing $23.3 million , $24.9 million and $29.7 million in cash, respectively.

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [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, 2017 , the Company has 11.2 million shares available for future issuance pursuant to its 2013 Long-Term Incentive Plan ("LTI Plan"). Of these shares remaining available for future issuance, approximately 3.0 million 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 common stock subject to satisfaction of the applicable vesting terms. The RSUs granted to certain executives and employees include (1) annual performance awards that often 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 conditions, or (3) other awards related to specific business initiatives or compensation objectives including retention and merger integration. Generally, such awards vest over periods of approximately 3 years. The following is a summary of the RSU activity during the year ended December 31, 2017 . RSUs (In thousands) Outstanding at the beginning of year 2,677 Granted 1,359 Vested (747 ) Forfeited (321 ) Outstanding at end of year 2,968 The Company granted approximately 1.3 million , 1.3 million and 1.0 million RSUs to the Company's executives and certain other employees for each of the years ended December 31, 2017 , 2016 and 2015 , respectively. The weighted-average grant-date fair value per share of the grants for the years ended December 31, 2017 , 2016 and 2015 was $73.52 , $68.53 and $69.96 per share, respectively. The weighted-average requisite service period for the RSUs granted during 2017 was approximately 2.5 years. The approximately 1.3 million RSUs granted during the year ended December 31, 2017 , were comprised of (1) approximately 0.7 million RSUs that time vest over a three-year period and (2) approximately 0.6 million RSUs to the Company's executives and certain other employees which may vest on the third anniversary of the grant date based upon the Company's total shareholder returns (defined as share price appreciation plus the value of dividends paid during the performance period) compared to that of selected peer companies. 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 awards granted during the years ended December 31, 2017 , 2016 and 2015 , respectively, with market conditions. Years Ended December 31, 2017 2016 2015 Risk-free rate 1.5 % 0.9 % 1.0 % Expected volatility 18 % 19 % 19 % Expected dividend rate 4.4 % 4.2 % 4.2 % The Company recognized aggregate stock-based compensation expense related to RSUs of $88.7 million , $76.3 million and $57.1 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The aggregate unrecognized compensation (net of estimated forfeitures) related to RSUs at December 31, 2017 is $72.9 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 awards vested during the years ended December 31, 2017 , 2016 and 2015 . Years Ended December 31, Total Shares Vested Fair Value on Vesting Date (In thousands of shares) 2017 747 $ 67,241 2016 828 71,325 2015 946 83,244 Stock-based Compensation The following table discloses the components of stock-based compensation expense. Years Ended December 31, 2017 2016 2015 Stock-based compensation expense: Site rental costs of operations $ 14,942 $ 14,371 $ 8,969 Network services and other costs of operations 4,961 7,717 5,370 General and administrative expenses 76,532 74,450 52,809 Total stock-based compensation $ 96,435 $ 96,538 $ 67,148

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company is involved in various claims, lawsuits, or proceedings arising in the ordinary course of business. While there are uncertainties inherent in the ultimate outcome of such matters and it is impossible to presently determine the ultimate costs or losses that may be incurred, if any, management believes the resolution of such uncertainties and the incurrence of such costs should not have a material adverse effect on the Company's 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 15 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

Leases	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Leases	Operating Leases Tenant Leases The following table is a summary of the rental cash payments owed to the Company, as a lessor, by tenants pursuant to contractual agreements in effect as of December 31, 2017 . Generally, the Company's leases with its tenants provide for (1) annual escalations, (2) multiple renewal periods at the tenant's option, and (3) only limited termination rights at the applicable tenant's option through the current term. As of December 31, 2017 , the weighted-average remaining term of tenant leases is approximately five years, exclusive of renewals at the tenant's option. The tenants' rental payments included in the table below are through the current terms with a maximum current term of 20 years and do not assume exercise of tenant renewal options. Years Ending December 31, 2018 2019 2020 2021 2022 Thereafter Total Tenant leases $ 3,401,845 $ 3,277,019 $ 3,160,514 $ 3,028,825 $ 2,805,519 $ 5,628,294 $ 21,302,016 Operating Leases The following table is a summary of rental cash payments owed by the Company, as lessee, to landlords pursuant to contractual agreements in effect as of December 31, 2017 . The Company is obligated under non-cancelable operating leases for land interests under 76% of its towers. The majority of these lease agreements have (1) certain termination rights that provide for cancellation after a notice period, (2) multiple renewal options at the Company's option, and (3) annual escalations. Lease agreements may also contain provisions for a contingent payment based on revenues or the gross margin derived from the communications infrastructure located on the leased land interest. Approximately 75% and approximately 90% of the Company's Towers site rental gross margins for the year ended December 31, 2017 are derived from towers where the land interest under the tower is owned or leased with final expiration dates of greater than 20 years and ten years, respectively, inclusive of renewals at the Company's option. The operating lease payments included in the table below include payments for certain renewal periods at the Company's option up to the estimated communications infrastructure useful life of 20 years and an estimate of contingent payments based on revenues and gross margins derived from existing tenant leases. Years Ending December 31, 2018 2019 2020 2021 2022 Thereafter Total Operating leases $ 635,321 $ 632,775 $ 622,587 $ 617,951 $ 609,796 $ 7,941,187 $ 11,059,617 Rental expense from operating leases was $710.2 million , $677.9 million , and $657.1 million , respectively, for the years ended December 31, 2017 , 2016 , and 2015 . The rental expense was inclusive of contingent payments based on revenues or gross margin derived from the communications infrastructure located on the leased land interests of $100.1 million , $96.9 million , and $91.8 million , respectively, for the years ended December 31, 2017 , 2016 , and 2015 .

Operating Segments and Concentr

Operating Segments and Concentrations of Credit Risk	12 Months Ended
	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Segments and Concentrations of Credit Risks	Operating Segments and Concentrations of Credit Risk Operating Segments As a result of the 2017 Acquisitions of fiber assets (see note 4), the Company changed the name of the "Small Cells" operating segment to "Fiber." The Company changed the name of this segment to reflect its strategy of utilizing the same fiber assets to provide both small cells and fiber solutions to its customers. The name change did not impact the composition or previously-reported operating results of the Fiber segment. As such, the Company's operating segments are now referred to as "Towers" and "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 network services relating to the Company's towers, consisting of site development services and installation services. The Fiber segment provides access, including space or capacity, to the Company's approximately 60,000 route miles of fiber primarily supporting small cells and fiber solutions. The measurement of profit or loss used by the Company's chief operating decision maker ("CODM") to evaluate the results of operations of its operating segments are (1) segment site rental gross margin, (2) segment network 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 network services and other gross margin as segment network services and other revenues less segment network 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 network services and other gross margin, less general and administrative expenses attributable to the respective segment. Costs that are directly attributable to Towers and Fiber are assigned to those respective segments. The "Other" column (1) represents amounts excluded from specific segments, such as restructuring charges (credits), 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, impairment of available-for-sale securities, interest income, other income (expense), cumulative effect of a change in accounting principle, 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, 2017 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,899,554 $ 769,637 $ 3,669,191 Segment network services and other revenues 636,532 49,882 686,414 Segment revenues 3,536,086 819,519 4,355,605 Segment site rental cost of operations 844,795 264,059 1,108,854 Segment network services and other cost of operations 374,134 40,691 414,825 Segment cost of operations (a) 1,218,929 304,750 1,523,679 Segment site rental gross margin 2,054,759 505,578 2,560,337 Segment network services and other gross margin 262,398 9,191 271,589 Segment general and administrative expenses (a) 93,662 89,048 167,455 350,165 Segment operating profit (loss) 2,223,495 425,721 (167,455 ) 2,481,761 Stock-based compensation expense 96,435 96,435 Depreciation, amortization and accretion 1,242,408 1,242,408 Interest expense and amortization of deferred financing costs 590,682 590,682 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 81,643 81,643 Income (loss) from continuing operations before income taxes $ 470,593 Capital expenditures $ 418,476 $ 782,409 $ 27,186 $ 1,228,071 Total assets (at year end) $ 17,940,893 $ 13,669,636 $ 619,041 $ 32,229,570 Total goodwill (at year end) $ 5,127,259 $ 4,894,209 $ — $ 10,021,468 (a) Segment cost of operations excludes (1) stock-based compensation expense of $19.9 million for the year ended December 31, 2017 and (2) prepaid lease purchase price adjustments of $20.1 million for the year ended December 31, 2017 . Segment general and administrative expenses exclude stock-based compensation expense of $76.5 million for the year ended December 31, 2017 . (b) See consolidated statement of operations for further information. Year Ended December 31, 2016 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,830,708 $ 402,599 $ 3,233,307 Segment network services and other revenues 603,689 84,229 687,918 Segment revenues 3,434,397 486,828 3,921,225 Segment site rental cost of operations 840,209 147,459 987,668 Segment network services and other cost of operations 344,595 64,859 409,454 Segment cost of operations (a) 1,184,804 212,318 1,397,122 Segment site rental gross margin 1,990,499 255,140 2,245,639 Segment network services and other gross margin 259,094 19,370 278,464 Segment general and administrative expenses (a) 92,903 60,676 143,001 296,580 Segment operating profit (loss) 2,156,690 213,834 (143,001 ) 2,227,523 Stock-based compensation expense 96,538 96,538 Depreciation, amortization and accretion 1,108,551 1,108,551 Interest expense and amortization of deferred financing costs 515,032 515,032 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 133,548 133,548 Income (loss) from continuing operations before income taxes $ 373,854 Capital expenditures $ 429,526 $ 409,710 $ 34,647 $ 873,883 Total assets (at year end) $ 18,394,572 $ 3,440,600 $ 839,920 $ 22,675,092 Total goodwill (at year end) $ 5,114,639 $ 643,037 $ — $ 5,757,676 (a) Segment cost of operations excludes (1) stock-based compensation expense of $22.1 million for the year ended December 31, 2016 and (2) prepaid lease purchase price adjustments of $21.3 million for the year ended December 31, 2016 . Segment general and administrative expenses exclude stock-based compensation expense of $74.5 million for the year ended December 31, 2016 . (b) See consolidated statement of operations for further information. Year Ended December 31, 2015 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,734,045 $ 284,368 $ 3,018,413 Segment network services and other revenues 591,655 53,783 645,438 Segment revenues 3,325,700 338,151 3,663,851 Segment site rental cost of operations 827,175 107,195 934,370 Segment network services and other cost of operations 309,025 43,162 352,187 Segment cost of operations (a) 1,136,200 150,357 1,286,557 Segment site rental gross margin 1,906,870 177,173 2,084,043 Segment network services and other gross margin 282,630 10,621 293,251 Segment general and administrative expenses (a) 91,899 38,379 127,833 258,111 Segment operating profit (loss) 2,097,601 149,415 (127,833 ) 2,119,183 Stock-based compensation expense 67,148 67,148 Depreciation, amortization and accretion 1,036,178 1,036,178 Interest expense and amortization of deferred financing costs 527,128 527,128 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 14,900 14,900 Income (loss) from continuing operations before income taxes $ 473,829 Capital expenditures $ 564,753 $ 314,882 $ 29,257 $ 908,892 Total assets (at year end) $ 17,974,847 $ 3,511,956 $ 450,163 $ 21,936,966 Total goodwill (at year end) $ 4,863,847 $ 649,704 $ — $ 5,513,551 (a) Segment cost of operations excludes (1) stock-based compensation expense of $14.3 million for the year ended December 31, 2015 and (2) prepaid lease purchase price adjustments of $20.5 million for the year ended December 31, 2015 . Segment general and administrative expenses exclude stock-based compensation expense of $52.8 million for the year ended December 31, 2015 . (b) See consolidated statement of operations for further information. Major Customers The following table summarizes the percentage of the consolidated revenues for those customers accounting for more than 10% of the consolidated revenues. Years Ended December 31, 2017 2016 2015 AT&T 25 % 27 % 27 % T-Mobile 22 % 23 % 22 % Verizon Wireless 22 % 22 % 21 % Sprint 17 % 16 % 19 % Total 86 % 88 % 89 % 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 customers in the wireless industry. The Company also has a concentration in its volume of business with AT&T, T-Mobile, Verizon Wireless and Sprint 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.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table is a summary of the supplemental cash flow information during the years ended December 31, 2017 , 2016 and 2015 . Years Ended December 31, 2017 2016 2015 Supplemental disclosure of cash flow information: Interest paid $ 546,543 $ 470,655 $ 489,970 Income taxes paid 16,427 13,821 28,771 Supplemental disclosure of non-cash investing and financing activities: Increase (decrease) in accounts payable for purchases of property and equipment 2,279 17,922 (7,042 ) Purchase of property and equipment under capital leases and installment land purchases 31,999 52,322 60,270 Installment payment receivable for sale of CCAL (see note 3) — — 117,384 Preferred stock dividends accrued but not paid (see note 12) 28,359 — 10,997

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) Summary quarterly financial information for the years ended December 31, 2017 and 2016 is as follows: Three Months Ended (a) March 31 June 30 September 30 December 31 2017: Net revenues $ 1,015,942 $ 1,038,335 $ 1,063,238 $ 1,238,090 Operating income (loss) 256,549 258,500 260,567 268,429 Gains (losses) on retirement of long-term obligations (3,525 ) — — — Benefit (provision) for income taxes (4,369 ) (4,538 ) (2,383 ) (14,753 ) Net income (loss) attributable to CCIC stockholders 119,138 112,114 115,194 98,104 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 0.33 $ 0.31 $ 0.22 $ 0.17 Diluted $ 0.33 $ 0.31 $ 0.21 $ 0.17 Three Months Ended (a) March 31 June 30 September 30 December 31 2016: Net revenues $ 934,384 $ 962,409 $ 992,016 $ 1,032,416 Operating income (loss) 211,739 231,185 244,254 262,038 Gains (losses) on retirement of long-term obligations (30,550 ) (11,467 ) (10,274 ) — Benefit (provision) for income taxes (3,872 ) (3,884 ) (5,041 ) (4,084 ) Net income (loss) attributable to CCIC stockholders 47,840 86,058 98,366 124,709 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 0.11 $ 0.22 $ 0.26 $ 0.35 Diluted $ 0.11 $ 0.22 $ 0.26 $ 0.35 (a) The sum of quarterly information may not agree to year to date information due to rounding.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events [Text Block]	19. Subsequent Events January 2018 Senior Notes On January 16, 2018 , the Company issued $1.75 billion aggregate principal amount of senior unsecured notes ("January 2018 Senior Notes"), which consisted of (1) $750.0 million aggregate principal amount of 3.150% senior unsecured notes due July 2023 ("3.150% Senior Notes") and (2) $1.0 billion aggregate principal amount of 3.800% senior unsecured notes due February 2028 ("3.650% 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. Common Stock Dividend On February 21, 2018 , the Company declared a quarterly common stock dividend of $1.05 per share, which was approved by the Company's board of directors. The common stock dividend will be paid on March 30, 2018 to common stockholders of record as of March 16, 2018 .

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Schedule II Valuation and Qualifying Accounts
Schedule II - Valuation and Qualifying Accounts Disclosure [Text Block]	Additions Deductions Balance at Beginning of Year Charged to Operations Credited to Operations Written Off Effect of Exchange Rate Changes Other Adjustments Balance at End of Year Allowance for Doubtful Accounts Receivable: 2017 $ 11,314 $ 4,360 $ — $ (4,591 ) $ — $ 2,663 (a) $ 13,746 2016 $ 9,574 $ 4,873 $ — $ (3,133 ) $ — $ — $ 11,314 2015 $ 10,037 $ 2,958 $ — $ (3,421 ) $ — $ — $ 9,574 (a) Represents the allowance for doubtful accounts reflected in the preliminary purchase price allocations for the 2017 Acquisitions. See note 4. Additions Deductions Balance at Beginning of Year Charged to Operations Charged to Additional Paid-in Capital and Other Comprehensive Income Credited to Operations Credited to Additional Paid-in Capital and Other Comprehensive Income Other Adjustments (a) Balance at End of Year Deferred Tax Valuation Allowance: 2017 $ 6,627 $ 59 $ — $ (5,514 ) $ — $ — $ 1,172 2016 $ 1,994 $ 586 $ — $ (2,236 ) $ — $ 6,283 $ 6,627 2015 $ 21,038 $ 164 $ — $ (3,000 ) $ — $ (16,208 ) $ 1,994 (a) Inclusive of (1) the effects of acquisitions and (2) the inclusion of small cells in the REIT in January 2016.

Schedule III - Schedule of Real

Schedule III - Schedule of Real Estate and Depreciation (Notes)	12 Months Ended
	Dec. 31, 2017
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, 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 40,080 towers (1) $ 4,580,581 (2) (3) (3) $ 20,109,562 (4) $ (7,303,230 ) Various Various Up to 20 years (1) Amount is exclusive of small cell nodes. No single tower 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. (2) Certain of the Company's debt is secured by (1) a pledge of the equity interests in each applicable issuer and (2) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses). (3) The Company has omitted this information, as it would be impracticable to compile such information on a tower-by-tower basis. (4) Does not include those towers under construction. 2017 2016 Gross amount at beginning $ 16,120,896 $ 15,110,835 Additions during period: Acquisitions through foreclosure — — Other acquisitions (1)(2) 2,787,829 130,139 Communications infrastructure construction and improvements 1,062,589 709,538 Purchase of land interests 80,647 74,579 Sustaining capital expenditures 56,480 55,417 Other (3) 46,537 95,049 Total additions 4,034,082 1,064,722 Deductions during period: Cost of real estate sold or disposed (45,416 ) (54,661 ) Other — — Total deductions: (45,416 ) (54,661 ) Balance at end $ 20,109,562 $ 16,120,896 (1) Inclusive of changes between the final purchase price allocation and the preliminary purchase price allocations. (2) Includes acquisitions of communications infrastructure. (3) Predominately relates to the purchase of property and equipment under capital leases and installment land purchases. 2017 2016 Gross amount of accumulated depreciation at beginning $ (6,446,448 ) $ (5,648,598 ) Additions during period: Depreciation (889,983 ) (810,549 ) Total additions (889,983 ) (810,549 ) Deductions during period: Amount for assets sold or disposed 26,391 24,190 Other 6,810 (11,491 ) Total deductions 33,201 12,699 Balance at end $ (7,303,230 ) $ (6,446,448 )

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Restricted Cash	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. The Company has classified the increases and decreases in restricted cash as (1) cash provided by financing activities for cash held by indenture trustees based on consideration of the terms of the related indebtedness, although the cash flows have aspects of both financing activities and operating activities, (2) cash provided by investing activities for cash securing performance obligations and restricted cash that is acquired in acquisitions, or (3) cash provided by operating activities for the other remaining restricted cash. The following table is a summary of the impact of restricted cash on the statement of cash flows. For the years ended December 31, 2017 2016 2015 Net cash provided by (used from) operating activities $ 847 $ (4,547 ) $ 3,974 Net cash provided by (used from) investing activities $ (26 ) $ 10,541 $ (3,752 ) Net cash provided by (used from) financing activities $ 3,808 $ (7,931 ) $ 16,458
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 "network 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 General. The Company classifies its leases at inception as either operating leases or capital leases. A lease is classified as a capital lease if at least one of the following criteria is met, subject to certain exceptions noted below: (1) the lease transfers ownership of the leased assets to the lessee, (2) there is a bargain purchase option, (3) the lease term is equal to 75% or more of the economic life of the leased assets, or (4) the present value of the minimum lease payments equals or exceeds 90% of the fair value of the leased assets.
Lease, Policy	Lessee. Leases for land are evaluated for capital lease treatment if at least one of the first two criteria mentioned in the immediately preceding paragraph is present relating to the leased assets. When the Company, as lessee, classifies a lease as a capital lease, it records an asset in an amount equal to the present value of the minimum lease payments under the lease at the beginning of the lease term. Applicable operating leases are recognized on a straight-line basis as discussed under "costs of operations" below. Lessor. If the Company is the lessor of leased property that is part of a larger whole (including a portion of space on a tower) and for which fair value is not objectively determinable, then such a lease is accounted for as an operating lease. As applicable, operating leases are recognized on a straight-line basis as discussed under "Revenue Recognition."
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. When the Company purchases fee ownership or perpetual easements for the land previously subject to ground lease, the Company reduces the value recorded as land by the amount of any associated deferred ground lease payable or unamortized above-market leases. 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 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, renewals, and improvements 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, 2017 , 2016 , and 2015 , the Company had $91.9 million , $86.1 million , and $36.7 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 $14.3 million , $26.9 million , and $27.0 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.
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 upon which the Company's communications infrastructure resides. 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 it is concluded that 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 the two-step goodwill impairment test. The two-step goodwill impairment test begins with a comparison of the estimated fair value of the reporting unit and the carrying value of the reporting unit. The first step, commonly referred to as a "step-one impairment test," is a screen for potential impairment while the second step measures the amount of impairment if there is an indication from the first step that one exists. The Company's measurement of the fair value for goodwill is based on an estimate of discounted expected future cash flows of the reporting unit. The Company performed its most recent annual goodwill impairment test as of October 1, 2017 , which resulted in no impairments.
Intangible Assets	Intangible Assets Intangible assets are included in "site rental contracts and customer relationships, net" and "other intangible assets, net" on the Company's consolidated balance sheet and predominately consist of the estimated fair value of the following items recorded in conjunction with acquisitions: (1) site rental contracts and customer relationships, (2) below-market leases for land interest under the acquired communications infrastructure, or (3) other contractual rights such as trademarks. The site rental contracts and customer relationships intangible assets are comprised of (1) the current term of the existing leases, (2) the expected exercise of the renewal provisions contained within the existing leases, which automatically occur under contractual provisions, or (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 customer 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 customer relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of renewals experienced to date. Thus, while site rental contracts and customer 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 customer relationships are amortized over a period not to exceed 20 years as a result of the useful life being limited by the depreciable life of the communications infrastructure. 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 customer relationships intangible assets. First, the Company pools the site rental contracts and customer 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 customer 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 the following items recorded in conjunction with acquisitions: (1) below-market tenant leases for contractual interests with tenants on acquired communications infrastructure, which are amortized to site rental revenues and (2) above-market leases for land interests under the Company's communications infrastructure, which are amortized to site rental cost of operations. 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 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 "long-term prepaid rent and other assets, net" on the Company's consolidated balance sheet.
Revenue Recognition	Revenue Recognition Site rental revenues are recognized on a monthly basis over the fixed, non-cancelable term of the relevant contract (generally ranging from five to 15 years for site rental revenues derived from wireless customers and three to 20 years for site rental revenues derived from the Company's fiber solutions business (including from organizations with high-bandwidth and multi-location demands)), regardless of whether the payments from the tenant are received in equal monthly amounts. Certain of the Company's contracts contain fixed escalation clauses (such as fixed dollar or fixed percentage increases) or inflation-based escalation clauses (such as those tied to the consumer price index ("CPI")). 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 $86.0 million and $67.2 million included in "other current assets" and non-current amounts of $1.3 billion and $1.3 billion included in "deferred site rental receivables" for the years ended December 31, 2017 and 2016 , respectively. Amounts billed or received prior to being earned are deferred and reflected in "deferred revenues" and "other long-term liabilities." Network services revenues are recognized after completion of the applicable service. Nearly all of the installation services are billed on a cost-plus profit basis and site development services are billed on a fixed fee basis. In jurisdictions where the Company determines that it is the principal taxpayer, taxes and surcharges are recorded on a gross basis. In jurisdictions where the Company determines that it is acting as a collection agent for the government authority (for example, in collecting sales taxes or value-added taxes collected from customers), such amounts are presented on a net basis.
Cost of Operations	Costs of Operations Approximately 55% 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 monthly 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 CPI). If the payment terms include fixed escalation provisions, the effect of such increases is recognized on a straight-line basis. The Company calculates the straight-line expense using a time period that equals or exceeds the remaining depreciable life of the communications infrastructure asset. Further, when a tenant has exercisable renewal options that would compel the Company to exercise existing renewal options, the Company has straight-lined the expense over a sufficient portion of such renewals to coincide with the final termination of the tenant's renewal options. The Company's non-current liability related to straight-line expense is included in "other long-term liabilities" on the Company's consolidated balance sheet. The Company's assets related to prepaid agreements is included in "prepaid expenses" and "long-term prepaid rent and other assets, net" on the Company's consolidated balance sheet. Network 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.
Acquisition and Integration Costs	Acquisition and Integration Costs All direct or incremental costs related to a business combination are expensed as incurred. Costs include severance, retention bonuses payable to employees of an acquired enterprise, temporary employees to assist with the integration of the acquired operations, or fees paid for services such as consulting, accounting, legal, or engineering reviews. These business combination costs are included in "acquisition and integration costs" on the Company's consolidated statement of operations and comprehensive income (loss). See note 4 for a discussion of the Company's recent acquisitions.
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, 2017 2016 2015 Interest expense on debt obligations $ 581,314 $ 500,699 $ 490,002 Amortization of deferred financing costs and adjustments on long-term debt, net 19,035 19,087 21,048 Amortization of interest rate swaps — — 18,725 Capitalized interest (11,545 ) (7,010 ) (4,805 ) Other 1,878 2,256 2,158 Total $ 590,682 $ 515,032 $ 527,128 The Company amortizes deferred financing costs, discounts, premiums, and purchase price adjustments on long-term debt over the estimated term of the related borrowing using the effective interest yield method. Discounts or purchase price adjustments are generally presented as a direct reduction to the related debt obligation on the Company's consolidated balance sheet.
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 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) alternative minimum taxes (repealed effective January 1, 2018), (2) taxes on any undistributed income, (3) taxes related to the TRSs, (4) franchise taxes, (5) property taxes, and (6) transfer taxes. In addition, the Company could in 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. During the fourth quarter of 2015, the Company completed the necessary steps to include small cells that were previously included in one or more wholly-owned TRSs in the REIT effective January 2016. As a result, during the fourth quarter of 2015, the Company de-recognized the related net deferred tax liabilities. Effective January 4, 2016, the Company's small cells that were previously included in one or more TRSs were included in the REIT. See note 11 . 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) most likely will be 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. The Company will be subject to a federal corporate level tax rate (currently 21%) on the gain recognized from the sale of assets occurring within a specified period (generally 5 years) after the REIT conversion up to the amount of the built in gain that existed on January 1, 2014, which is based upon the fair market value of those assets in excess of the Company's tax basis on January 1, 2014. 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 December 31, 2017 and 2016 , the Company has not recorded any penalties related to its income tax positions.
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 year ended December 31, 2017 , 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 RSUs as determined under the treasury stock method and (2) conversion of the Company's 6.875% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share ("6.875% Convertible Preferred Stock"), as determined under the if-converted method. For the years ended December 31, 2016 and December 31, 2015, diluted 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 RSUs as determined under the treasury stock method and (2) conversion of the Company's then outstanding 4.50% Mandatory Convertible Preferred Stock, Series A, par value $0.01 per share ("4.50% Convertible Preferred Stock"), as determined under the if-converted method. A reconciliation of the numerators and denominators of the basic and diluted per share computations is as follows: Years Ended December 31, 2017 2016 2015 Net income (loss) from continuing operations $ 444,550 $ 356,973 $ 525,286 Dividends on preferred stock (58,294 ) (32,991 ) (43,988 ) Net income (loss) from continuing operations attributable to CCIC common stockholders for basic and diluted computations $ 386,256 $ 323,982 $ 481,298 Income (loss) from discontinued operations, net of tax — — 999,049 Less: Net income (loss) attributable to the noncontrolling interest — — 3,343 Net income (loss) from discontinued operations attributable to CCIC common stockholders for basic and diluted computations — — 995,706 Weighted-average number of common shares outstanding (in thousands): Basic weighted-average number of common stock outstanding 381,740 340,349 333,002 Effect of assumed dilution from potential common shares relating to RSUs 1,481 530 1,060 Diluted weighted-average number of common shares outstanding 383,221 340,879 334,062 Net income (loss) attributable to CCIC common stockholders, per common share: Income (loss) from continuing operations, basic $ 1.01 $ 0.95 $ 1.45 Income (loss) from discontinued operations, basic $ — $ — $ 2.99 Net income (loss) attributable to CCIC common stockholders, basic $ 1.01 $ 0.95 $ 4.44 Income (loss) from continuing operations, diluted $ 1.01 $ 0.95 $ 1.44 Income (loss) from discontinued operations, diluted $ — $ — $ 2.98 Net income (loss) attributable to CCIC common stockholders, diluted $ 1.01 $ 0.95 $ 4.42 For the year ended December 31, 2017 , 15.0 million common share equivalents related to the 6.875% Convertible Preferred Stock were excluded from the dilutive common shares because the impact of the conversion of such preferred stock would be anti-dilutive based on the Company's common stock price as of December 31, 2017 . For the year ended December 31, 2015, 11.4 million common share equivalents related to the then outstanding 4.50% Convertible Preferred Stock were excluded from the dilutive common shares because the impact of the conversion of such preferred stock would be anti-dilutive based on the Company's common stock price at the end of such year.
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. The fair value of cash and cash equivalents and restricted cash approximate the carrying value. The Company determines the fair value of its debt securities based on indicative quotes (that is non-binding quotes) from brokers that require judgment to interpret market information including implied credit spreads for similar borrowings on recent trades or bid/ask prices or quotes from active markets if applicable. Foreign currency swaps are valued at settlement amounts using observable exchange rates and, if material, reflect an adjustment for the Company's and contract counterparty's credit risk. There were no changes since December 31, 2016 in the Company's valuation techniques used to measure fair values. See note 10 for a further discussion of fair values.
Derivative Instruments	Swaps Interest Rate Swaps. The Company had previously entered into interest rate swaps to manage or reduce its interest rate risk, including the use of (1) forward-starting interest rate swaps to hedge its exposure to variability in future cash flows attributable to changes in LIBOR on anticipated financings, including refinancings and potential future borrowings or (2) interest rate swaps to hedge the interest rate variability on a portion of the Company's floating rate debt. Derivative financial instruments were entered into for periods that matched the related underlying exposures. The Company can elect whether or not to designate derivative financial instruments as accounting hedges. The Company can also enter into derivative financial instruments that are not designated as accounting hedges. As of December 31, 2017 , the Company does not have any interest rate swaps. Derivatives were recognized on the consolidated balance sheet at fair value. If the derivative was designated as a cash flow hedge, the effective portion of the change in the fair value of the derivative was recorded as a separate component of stockholders' equity, captioned "accumulated other comprehensive income (loss)" on the Company's consolidated balance sheet, and recognized as increases or decreases to "interest expense and amortization of deferred financing costs" on the Company's consolidated statement of operations and comprehensive income (loss) when the hedged item affects earnings. If a hedge ceased to qualify for hedge accounting, any change in the fair value of the derivative since the date it ceased to qualify was recorded to "net gain (loss) on interest rate swaps." However, any amounts previously recorded to "accumulated other comprehensive income (loss)" would remain there until the original forecasted transaction affected earnings. In situations where it becomes probable that the hedged forecasted transaction will not occur, any gains or losses that have been recorded to "accumulated other comprehensive income (loss)" are immediately reclassified to earnings. Foreign Currency Swaps. During 2015, the Company entered into foreign currency swaps to manage and reduce its foreign currency risk related to the May 2015 sale of the Company's formerly 77.6% owned subsidiary that operated towers in Australia ("CCAL") (see note 3 ). The derivatives were recognized on the consolidated balance sheet at fair value as of December 31, 2015. These swaps were not designated as accounting hedges and as such, the corresponding gain (loss) on the fair value adjustment is included as a component of "other income (expense)" on the Company's consolidated statement of operations and comprehensive income (loss). See note 9 . In January 2016, the then outstanding swap related to the installment payment received from the Buyer (as defined in note 3 ) was cash settled.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements No accounting pronouncements adopted during the year ended December 31, 2017 had a material impact on the Company's consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In May 2014, the FASB released updated guidance regarding the recognition of revenue from contracts with customers, exclusive of those contracts within lease accounting. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (1) identify the contracts with the customer; (2) identify the performance obligations in the contract; (3) determine the contract price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when (or as) the entity satisfies a performance obligation. This guidance is effective for the Company on January 1, 2018, following the FASB's July 2015 decision to defer the effective date of the standard by one year. This guidance is required to be applied, at the Company's election, either (1) retrospectively to each prior reporting period presented, or (2) with the cumulative effect being recognized at the date of initial application. The Company will adopt the guidance effective January 1, 2018 with the cumulative effect being recognized at the date of initial application, and the adoption of this guidance will not have a material impact on its consolidated financial statements. In February 2016, the FASB issued new guidance on the recognition, measurement, presentation and disclosure of leases. The new guidance requires lessees to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments for all leases with a term greater than 12 months. The accounting for lessors remains largely unchanged from existing guidance. This guidance is effective for the Company as of January 1, 2019 and is required to be applied using a modified retrospective approach for all leases existing at, or entered into after, the beginning of the earliest comparative period presented. Although early adoption is permitted, the Company does not expect to early adopt the new guidance prior to January 1, 2019. With regard to the application of this guidance to the Towers segment, the Company expects that (1) its Towers lessee arrangements will continue to be classified as operating leases under the new guidance; (2) this guidance will have a material impact on its consolidated balance sheet due to the addition of right-of-use assets and lease liabilities for all lessee arrangements with a term greater than 12 months; and (3) there will not be a material impact to its consolidated statement of operations and consolidated statement of cash flows. With regard to the application of this guidance to the Fiber segment, the Company (1) has established and is progressing through the various steps of a cross-functional project plan to assess the impact of the standard; (2) expects this guidance to have a material impact on its consolidated balance sheet due to the addition of right-of-use assets and lease liabilities for all lessee arrangements with a term greater than 12 months; and (3) continues to assess additional impacts to its consolidated financial statements, including the consolidated statement of operations and the consolidated statement of cash flows. In November 2016, the FASB issued new guidance which requires an entity's statement of cash flows to explain the change in restricted cash and restricted cash equivalents in addition to cash and cash equivalents. This new guidance also requires an entity that includes cash, cash equivalents, restricted cash and restricted cash equivalents on multiple lines on its balance sheet to present a reconciliation between its statement of cash flows and its balance sheet. The guidance is effective for the Company on January 1, 2018, and is required to be applied retrospectively to each prior reporting period presented. The Company will adopt this guidance effective January 1, 2018, and believes that the impact of the new guidance will be limited to certain changes in presentation on the consolidated statement of cash flows. In January 2017, the FASB issued new guidance which clarifies the definition of a business in order to assist companies in evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The guidance is effective for the Company as of January 1, 2018, and is required to be applied prospectively. The Company will adopt this guidance effective January 1, 2018 and will apply the new guidance to prospective transactions. The adoption of this guidance will not have a material impact on the Company's consolidated financial statements. In January 2017, the 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 step-one 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 step-one impairment test. The guidance is effective for the Company as of January 1, 2020. Early adoption is permitted. The Company is currently evaluating the impact of the guidance, including the impact on its consolidated financial statements. In February 2017, the FASB issued new guidance which clarifies the scope and application of accounting for the de-recognition of non-financial assets and in substance non-financial assets, including sales and partial sales of real estate assets. The new guidance also eliminates the existing industry specific guidance for partial sales of real estate and requires full gain recognition upon partial sales of real estate. The guidance is effective for the Company as of January 1, 2018. The Company will adopt this guidance effective January 1, 2018, and the adoption of this guidance will not have a material impact on its consolidated financial statements.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Significant Accounting Policies [Abstract]
Schedule of Restricted Cash and Cash Equivalents	The following table is a summary of the impact of restricted cash on the statement of cash flows. For the years ended December 31, 2017 2016 2015 Net cash provided by (used from) operating activities $ 847 $ (4,547 ) $ 3,974 Net cash provided by (used from) investing activities $ (26 ) $ 10,541 $ (3,752 ) Net cash provided by (used from) financing activities $ 3,808 $ (7,931 ) $ 16,458
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, 2017 2016 2015 Interest expense on debt obligations $ 581,314 $ 500,699 $ 490,002 Amortization of deferred financing costs and adjustments on long-term debt, net 19,035 19,087 21,048 Amortization of interest rate swaps — — 18,725 Capitalized interest (11,545 ) (7,010 ) (4,805 ) Other 1,878 2,256 2,158 Total $ 590,682 $ 515,032 $ 527,128
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 as follows: Years Ended December 31, 2017 2016 2015 Net income (loss) from continuing operations $ 444,550 $ 356,973 $ 525,286 Dividends on preferred stock (58,294 ) (32,991 ) (43,988 ) Net income (loss) from continuing operations attributable to CCIC common stockholders for basic and diluted computations $ 386,256 $ 323,982 $ 481,298 Income (loss) from discontinued operations, net of tax — — 999,049 Less: Net income (loss) attributable to the noncontrolling interest — — 3,343 Net income (loss) from discontinued operations attributable to CCIC common stockholders for basic and diluted computations — — 995,706 Weighted-average number of common shares outstanding (in thousands): Basic weighted-average number of common stock outstanding 381,740 340,349 333,002 Effect of assumed dilution from potential common shares relating to RSUs 1,481 530 1,060 Diluted weighted-average number of common shares outstanding 383,221 340,879 334,062 Net income (loss) attributable to CCIC common stockholders, per common share: Income (loss) from continuing operations, basic $ 1.01 $ 0.95 $ 1.45 Income (loss) from discontinued operations, basic $ — $ — $ 2.99 Net income (loss) attributable to CCIC common stockholders, basic $ 1.01 $ 0.95 $ 4.44 Income (loss) from continuing operations, diluted $ 1.01 $ 0.95 $ 1.44 Income (loss) from discontinued operations, diluted $ — $ — $ 2.98 Net income (loss) attributable to CCIC common stockholders, diluted $ 1.01 $ 0.95 $ 4.42

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	Cash received from sale of CCAL (a) $ 1,139,369 Installment payment receivable due January 2016 (a) 117,384 Total proceeds from sale of CCAL $ 1,256,753 Adjusted for: Net assets and liabilities related to discontinued operations (b)(c) 258,575 Transaction fees and expenses 23,059 Foreign currency translation reclassification adjustments (d) (25,678 ) Pre-tax gain (loss) from disposal of discontinued operations 1,000,797 Income taxes related to the sale of CCAL (21,438 ) Gain (loss) from disposal of discontinued operations $ 979,359 (a) Exclusive of foreign currency swaps and based on exchange rates as of May 28, 2015, which was the closing date of the Company's sale of CCAL. See note 9 . The impact of fluctuations in the exchange rate subsequent to the closing date are reflected as a component of "other income (expense)" on the Company's consolidated statement of operations. (b) Represents net assets attributable to CCIC, net of the disposition of noncontrolling interest of $ 23.5 million . (c) Inclusive of $ 11.1 million of cash. (d) Represents foreign currency translation adjustments previously included in "accumulated other comprehensive income (loss)" on the consolidated balance sheet and reclassified to "net gain (loss) from disposal of discontinued operations, net of tax" on the consolidated statement of operations and comprehensive income (loss). Year Ended December 31, 2015 (b)(c) Total revenues $ 65,293 Total cost of operations (a) 17,498 Depreciation, amortization and accretion 10,168 Total other expenses 10,481 Pre-tax income from discontinued operations 27,146 Benefit (provision) from income taxes (7,456 ) Net income (loss) from discontinued operations (d) $ 19,690 (a) Exclusive of depreciation, amortization, and accretion shown separately. (b) No interest expense has been allocated to discontinued operations. (c) CCAL results are through May 28, 2015, which was the closing date of the Company's sale of CCAL. (d) Exclusive of the gain (loss) from disposal of discontinued operations, net of tax, as presented on the consolidated statement of operations.

Acquisitions Acquisitions (Tabl

Acquisitions Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Information [Table Text Block]	The unaudited pro forma financial results for the years ended December 31, 2017 and 2016 combine the historical results of the Company, along with the historical results of the 2017 Acquisitions for the respective periods. The following table presents the unaudited pro forma consolidated results of operations of the Company as if each acquisition was completed as of January 1, 2016 for the periods presented below. The unaudited pro forma amounts are presented for illustrative purposes only and are not necessarily indicative of future consolidated results of operations. Twelve Months Ended December 31, 2017 2016 Net revenues $ 5,050,166 $ 4,864,852 Income (loss) before income taxes 541,389 (b)(c) 367,326 (b)(c)(d) Benefit (provision) for income taxes (28,960 ) (a) (20,968 ) (a) Net income (loss) $ 512,429 (b)(c) $ 346,358 (b)(c)(d) Basic net income (loss) attributable to CCIC common stockholders, per common share $ 0.89 (c)(e) $ 0.51 (c)(e) Diluted net income (loss) attributable to CCIC common stockholders, per common share $ 0.88 (c)(e) $ 0.51 (c)(e) (a) For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to the benefit (provision) for income tax as a result of the Company's REIT status. The vast majority of the assets and related income from the FiberNet Acquisition, the Wilcon Acquisition, and the Lightower Acquisition are included in the Company's REIT. The remaining assets are included in the Company's TRS. For purposes of the unaudited pro forma financial results, an adjustment has been made to reflect the additional tax impact of the income related to the TRS assets. (b) For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to depreciation and amortization of $247.1 million and $315.9 million , respectively, related to property and equipment and intangibles recorded as a result of the 2017 Acquisitions. (c) Pro forma amounts include the impact of the interest expense and common stock share issuances associated with the related debt and equity financings for the 2017 Acquisitions (see above and notes 8 and 12). (d) Amounts are inclusive of a total of $120 million of Lightower stock-based compensation expense and acquisition and integration costs. (e) Pro forma amounts include the impact of the preferred stock dividends related to the Mandatory Convertible Preferred Stock Offering (as defined in note 12) for the Lightower Acquisition (see above and note 12).
Sunesys [Member]
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The final purchase price allocation for the Sunesys Acquisition is shown below. Final Purchase Price Allocation Current assets $ 15,306 Property and equipment 444,394 Goodwill (a) 331,775 Other intangible assets, net 254,079 Current liabilities (20,233 ) Other non-current liabilities (37,356 ) Net assets acquired (b) $ 987,965 (a) The final purchase price allocation for the Sunesys Acquisition resulted in the recognition of goodwill based on the Company's expectation to leverage the Sunesys fiber footprint to support new small cells. The Sunesys fiber is complementary to the Company's existing fiber assets and is located where the Company expects to see wireless carrier network investments. (b) Assets acquired in the Sunesys Acquisition are included in the Company's REIT and as such, no deferred taxes were recorded in connection with the Sunesys Acquisition.
Lightower Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The preliminary purchase price allocation for the Lightower Acquisition is shown below and is based upon a preliminary valuation which is subject to change as the Company obtains additional information with respect to fixed assets, intangible assets and certain liabilities. Preliminary Purchase Price Allocation Current assets $ 104,643 Property and equipment 2,197,466 Goodwill (a) 3,116,010 Other intangible assets, net (b) 2,177,090 Other non-current assets 28,834 Current liabilities (172,399 ) Other non-current liabilities (299,667 ) Net assets acquired (c) $ 7,151,977 (a) The preliminary purchase price allocation for the Lightower Acquisition resulted in the recognition of goodwill based on: • the Company's expectation to leverage the Lightower fiber footprint to support new small cells and fiber solutions , • the complementary nature of the Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments , • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. (b) Predominantly comprised of site rental contracts and customer relationships. (c) The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the Lightower Acquisition
FiberNet Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The preliminary purchase price allocation for the FiberNet Acquisition is shown below and is based upon a preliminary valuation which is subject to change as the Company obtains additional information with respect to fixed assets, intangible assets and certain liabilities. Preliminary Purchase Price Allocation Current assets $ 52,274 Property and equipment 438,478 Goodwill (a) 777,563 Other intangible assets, net (b) 327,338 Other non-current assets 2,449 Current liabilities (41,120 ) Other non-current liabilities (36,152 ) Net assets acquired (c) $ 1,520,830 (a) The preliminary purchase price allocation for the FiberNet Acquisition resulted in the recognition of goodwill based on: • the Company's expectation to leverage the FiberNet fiber footprint to support new small cells and fiber solutions, • the complementary nature of the FiberNet fiber to the Company's existing fiber assets and its location in top metro markets where the Company expects to see wireless carrier network investments, • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. (b) Predominantly comprised of site rental contracts and customer relationships. (c) The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the FiberNet Acquisition.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Major Classes of Property and Equipment	The major classes of property and equipment are as follows: Estimated Useful Lives As of December 31, 2017 2016 Land (a) — $ 1,859,431 $ 1,747,335 Buildings 40 years 119,313 110,641 Communications infrastructure assets 1-20 years 17,183,482 13,825,394 Information technology assets and other 2-7 years 372,339 278,489 Construction in process — 898,621 456,675 Total gross property and equipment 20,433,186 16,418,534 Less: accumulated depreciation (7,500,301 ) (6,613,219 ) Total property and equipment, net $ 12,932,885 $ 9,805,315 (a) Includes land owned in fee and perpetual easements.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Finite-Lived Intangible Assets [Line Items]
Schedule of Goodwill	Goodwill The changes in the carrying value of goodwill for the years ended December 31, 2017 and December 31, 2016 were as follows: Balance as of December 31, 2015 $ 5,513,551 Additions due to TDC Acquisition (a) 210,905 Adjustments due to other acquisitions, purchase price allocations and other, net 33,220 Balance as of December 31, 2016 $ 5,757,676 Additions due to FiberNet Acquisition (b) 777,563 Additions due to Wilcon Acquisition (b) 357,606 Additions due to Lightower Acquisition (b) 3,116,010 Adjustments due to other acquisitions, purchase price allocations and other, net 12,613 Balance as of December 31, 2017 $ 10,021,468 (a) The final purchase price allocation for the TDC Acquisition resulted in the recognition of goodwill in the Towers segment because of the anticipated growth opportunity in the acquired tower portfolio. See note 4 . (b) The preliminary purchase price allocation for the FiberNet Acquisition, Wilcon Acquisition and Lightower Acquisition resulted in the recognition of goodwill in the Fiber segment based on: • the Company's expectation to leverage the FiberNet, Wilcon and Lightower fiber footprint to support new small cell and fiber solutions , • the complementary nature of the FiberNet, Wilcon and Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments , • the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and • other intangibles not qualified for separate recognition, including the assembled workforce. See note 4 .
Intangible Assets	The following is a summary of the Company's intangible assets. See note 4 for further discussion of the Company's acquisitions. As of December 31, 2017 As of December 31, 2016 Gross Carrying Value (a) Accumulated Amortization Net Book Value Gross Carrying Value Accumulated Amortization Net Book Value Site rental contracts and customer relationships $ 7,782,934 $ (2,156,499 ) $ 5,626,435 $ 5,146,301 $ (1,847,523 ) $ 3,298,778 Other intangible assets 502,891 (167,567 ) 335,324 497,091 (145,797 ) 351,294 Total $ 8,285,825 $ (2,324,066 ) $ 5,961,759 $ 5,643,392 $ (1,993,320 ) $ 3,650,072
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 2017 2016 2015 Depreciation, amortization and accretion $ 314,447 $ 264,656 $ 251,443 Site rental costs of operations 18,373 19,367 20,420 Total amortization expense $ 332,820 $ 284,023 $ 271,863
Site Rental Contracts and Customer Relationships [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Schedule of Estimated Annual Amortization Expense	The estimated annual amortization expense related to intangible assets (inclusive of those recorded as an increase to "site rental costs of operations") for the years ending December 31, 2018 to 2022 is as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Estimated annual amortization $ 445,849 $ 444,889 $ 444,589 $ 444,155 $ 443,688

Other Liabilities (Tables)

Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 Deferred rental revenues $ 1,076,845 $ 983,263 Deferred ground lease payable 559,556 517,281 Above market leases for land interests, net 201,542 224,126 Deferred credits, net 531,856 207,992 Asset retirement obligation 173,733 146,100 Deferred income tax liabilities 5,192 8,075 Other long-term liabilities 5,313 392 Total $ 2,554,037 $ 2,087,229
Schedule of Above Market Leases	The estimated amortization expense related to above-market leases for land interests under the Company's towers recorded to site rental costs of operations for the years ending December 31, 2018 to 2022 is as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Above-market leases for land interests $ 18,277 $ 17,674 $ 16,769 $ 15,667 $ 14,580
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, 2018 to 2022 are as follows: Years Ending December 31, 2018 2019 2020 2021 2022 Below-market tenant leases $ 65,104 $ 59,145 $ 53,050 $ 49,745 $ 44,910

Debt and Other Obligations (Tab

Debt and Other Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Debt and Other Obligations [Abstract]
Schedule of Long-Term Debt Instruments	Original Issue Date Contractual Maturity Date Outstanding Balance as of December 31, Stated Interest Rate as of December 31, 2017 2016 2017 (a) Bank debt – variable rate: 2016 Revolver Jan. 2016 Aug. 2022 $ 980,000 (b) $ — 2.6 % (c) 2016 Term Loan A Jan. 2016 Aug. 2022 2,396,588 1,954,173 2.6 % (c) Total bank debt 3,376,588 1,954,173 Securitized debt – fixed rate: Secured Notes, Series 2009-1, Class A-1 Jul. 2009 Aug. 2019 (d) 31,813 51,416 6.3 % Secured Notes, Series 2009-1, Class A-2 Jul. 2009 Aug. 2029 (d) 69,500 68,737 9.0 % Tower Revenue Notes, Series 2010-3 Jan. 2010 Jan. 2040 (e)(f) 1,246,106 1,244,237 6.1 % Tower Revenue Notes, Series 2010-6 Aug. 2010 Aug. 2040 (e)(f) 995,354 993,557 4.9 % Tower Revenue Notes, Series 2015-1 May 2015 May 2042 (e)(f) 297,211 296,573 3.2 % Tower Revenue Notes, Series 2015-2 May 2015 May 2045 (e)(f) 692,325 691,285 3.7 % Total securitized debt 3,332,309 3,345,805 Bonds – fixed rate: 5.250% Senior Notes Oct. 2012 Jan. 2023 1,639,207 1,637,099 5.3 % 3.849% Secured Notes Dec. 2012 Apr. 2023 992,663 991,279 3.8 % 4.875% Senior Notes Apr. 2014 Apr. 2022 842,090 840,322 4.9 % 3.400% Senior Notes Feb./May 2016 Feb. 2021 849,859 849,698 3.4 % 4.450% Senior Notes Feb. 2016 Feb. 2026 891,145 890,118 4.5 % 3.700% Senior Notes May 2016 June 2026 742,727 741,908 3.7 % 2.250% Senior Notes Sept. 2016 Sept. 2021 695,383 693,893 2.3 % 4.000% Senior Notes Feb. 2017 Mar. 2027 493,833 — 4.0 % 4.750% Senior Notes May 2017 May 2047 343,209 — 4.8 % 3.200% Senior Notes Aug. 2017 Sept. 2024 741,859 — 3.2 % 3.650% Senior Notes Aug. 2017 Sept. 2027 990,965 — 3.7 % Total bonds 9,222,940 6,644,317 Other: Capital leases and other obligations Various Various (g) 227,783 226,847 Various Total debt and other obligations 16,159,620 12,171,142 Less: current maturities and short-term debt and other current obligations 115,251 101,749 Non-current portion of long-term debt and other long-term obligations $ 16,044,369 $ 12,069,393 (a) Represents the weighted-average stated interest rate. (b) As of December 31, 2017 , the undrawn availability under the 2016 Revolver was $2.5 billion . See note 19. (c) The 2016 Revolver and senior unsecured term loan A facility ("2016 Term Loan A") bear interest at a rate per annum equal to LIBOR plus a credit spread ranging from 1.125% to 2.000% , based on the Company's senior unsecured debt rating. The Company pays a commitment fee of approximately 0.200% per annum on the undrawn available amount under the 2016 Revolver. (d) The Secured Notes, Series 2009-1, Class A-1 and Secured Notes, Series 2009-1, Class A-2 are collectively referred to herein as "2009 Securitized Notes." (e) The Tower Revenue Notes, Series 2010-3 ("January 2010 Tower Revenue Notes"), Tower Revenue Notes, Series 2010-6 ("August 2010 Tower Revenue Notes") and Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes." (f) 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) 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, 2017, the Tower Revenue Notes have principal amounts of $2.3 billion , $300.0 million and $700.0 million , with anticipated repayment dates in 2020, 2022 and 2025, respectively. See note 19. (g) The Company's capital 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 30 years.
Schedule of Maturities of Long-term Debt	Contractual Maturities The following are the scheduled contractual maturities of the total debt or other long-term obligations outstanding at December 31, 2017 . These maturities reflect contractual maturity dates and 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, 2018 2019 2020 2021 2022 Thereafter Total Cash Obligations Unamortized Adjustments, Net Total Debt and Other Obligations Outstanding Scheduled contractual maturities $ 116,045 $ 167,458 $ 155,051 $ 1,824,568 $ 3,701,737 $ 10,296,901 $ 16,261,760 $ (102,140 ) $ 16,159,620
Schedule of Extinguishment of Debt	The following is a summary of the purchases and redemptions of debt during the years ended December 31, 2017 , 2016 and 2015 . Year Ending December 31, 2017 Principal Amount Cash Paid Gains (losses) (a) 2016 Term Loan A $ — $ — $ (3,525 ) (a) The losses related to write off of deferred financing costs. Year Ending December 31, 2016 Principal Amount Cash Paid (a) Gains (losses) (b) Revolving Credit Facility under 2012 Credit Facility $ — $ — $ (1,930 ) Tranche A Term Loans under 2012 Credit Facility 629,375 629,375 (1,498 ) Tranche B Term Loans under 2012 Credit Facility 2,247,015 2,247,015 (27,122 ) Tower Revenue Notes, Series 2010-2 350,000 352,796 (3,338 ) Tower Revenue Notes, Series 2010-5 300,000 307,176 (8,129 ) 2.381% Secured Notes 500,000 508,472 (10,274 ) Total $ 4,026,390 $ 4,044,834 $ (52,291 ) (a) Exclusive of accrued interest. (b) Inclusive of $33.8 million related to the write off of deferred financing costs. Year Ending December 31, 2015 Principal Amount Cash Paid (a) Gains (losses) (b) Tower Revenue Notes, Series 2010-4 $ 250,000 $ 250,000 $ (159 ) WCP Securitized Notes 252,830 252,830 2,105 Tranche B Term Loans under 2012 Credit Facility 564,137 564,137 (6,127 ) Other 2,394 2,370 24 Total $ 1,069,361 $ 1,069,337 $ (4,157 ) (a) Exclusive of accrued interest. (b) Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.

Swaps Foreign Currency Swaps (T

Swaps Foreign Currency Swaps (Tables)	12 Months Ended
	Dec. 31, 2017
Foreign Currency Swaps [Abstract]
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	Item Swapped Notional Amount Forward Rate Start Date End Date Pay Amount Receive Amount Fair Value at December 31, 2017 May 2015 cash receipt from sale of CCAL A$1,400,000 0.8072 May 2015 June 2015 Australian Dollar US Dollar N/A (a) Installment payment from Buyer A$155,000 0.79835 May 2015 January 2016 Australian Dollar US Dollar N/A (b) (a) In conjunction with closing the CCAL sale on May 28, 2015, the Company cash settled the swap with a notional value of Australian dollar $ 1.4 billion and recorded a gain on foreign currency swaps of $ 54.5 million , which is included as a component of "other income (expense)" on the Company's consolidated statement of operations. (b) As of December 31, 2015 , the Company marked-to-market the swap with a notional value of Australian dollar $ 155.0 million and recorded (1) an asset within "other current assets" on the Company's consolidated balance sheet and (2) a corresponding gain on foreign currency swaps , which is included as a component of "other income (expense)" on the Company's consolidated statement of operations. In January 2016, the then outstanding swap related to the installment payment received from the Buyer was settled.

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures
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, 2017 December 31, 2016 Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and cash equivalents 1 $ 314,094 $ 314,094 $ 567,599 $ 567,599 Restricted cash 1 126,065 126,065 129,547 129,547 Liabilities: Debt and other obligations 2 $ 16,159,620 $ 16,643,725 $ 12,171,142 $ 12,660,013

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Income (Loss) from Continuing Operations Before Income Taxes	Income (loss) from continuing operations before income taxes by geographic area is as follows: Years Ended December 31, 2017 2016 2015 Domestic $ 450,771 $ 349,041 $ 461,293 Foreign (a) 19,822 24,813 12,536 Total $ 470,593 $ 373,854 $ 473,829 (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, 2017 2016 2015 Current: Federal $ (2,816 ) $ (227 ) $ 495 Foreign (6,050 ) (6,820 ) (5,675 ) State (2,289 ) (1,231 ) (3,981 ) Total current (11,155 ) (8,278 ) (9,161 ) Deferred: Federal (17,743 ) (7,968 ) 44,716 Foreign 2,883 (601 ) (1,048 ) State (28 ) (34 ) 16,950 Total deferred (14,888 ) (8,603 ) 60,618 Total tax benefit (provision) $ (26,043 ) $ (16,881 ) $ 51,457
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, 2017 2016 2015 Benefit (provision) for income taxes at statutory rate $ (164,707 ) $ (130,849 ) $ (165,840 ) Tax effect of foreign income (losses) (430 ) 1,215 (527 ) Tax adjustment related to REIT operations 158,812 121,092 186,649 Tax adjustment related to the inclusion of small cells in the REIT (a) — — 33,759 Expenses for which no federal tax benefit was recognized (42 ) (43 ) (414 ) Valuation allowances 21 (21 ) 3,000 State tax (provision) benefit, net of federal (2,115 ) (1,085 ) 1,210 Foreign tax (3,168 ) (7,421 ) (6,723 ) Effects of tax law change (b) (14,628 ) — — Other 214 231 343 Total $ (26,043 ) $ (16,881 ) $ 51,457 (a) During the fourth quarter of 2015, the Company de-recognized the net deferred tax liabilities related to the Company's small cells previously included in one or more TRSs in conjunction with the inclusion of small cells in the REIT in January 2016. (b) Pursuant to the Tax Cuts and Jobs Act, which was signed into law in December 2017, the Company was required to write down its net federal deferred tax asset in the amount of $16.8 million as a result of the reduction in the federal corporate tax rate offset by a benefit of $2.2 million related to the refund of the Company's alternative minimum tax credit carryforward.
Components of Deferred Tax Assets and Liabilities	The components of the net deferred income tax assets and liabilities are as follows: December 31, 2017 2016 Deferred income tax liabilities: Property and equipment $ 4,940 $ 3,945 Deferred site rental receivable 6,907 6,192 Total deferred income tax liabilities 11,847 10,137 Deferred income tax assets: Intangible assets 4,460 22,377 Net operating loss carryforwards 20,800 21,143 Deferred ground lease payable 2,060 1,646 Accrued liabilities 5,161 5,511 Receivables allowance 317 383 Other 1,431 1,726 Valuation allowances (1,172 ) (6,627 ) Total deferred income tax assets, net 33,057 46,159 Net deferred income tax asset (liabilities) $ 21,210 $ 36,022
Jurisdictional Components of Deferred Tax Assets and Liabilities	The components of the net deferred income tax assets (liabilities) are as follows: December 31, 2017 December 31, 2016 Classification Gross Valuation Allowance Net Gross Valuation Allowance Net Federal $ 25,260 $ — $ 25,260 $ 42,948 $ (21 ) $ 42,927 State 1,142 — 1,142 1,170 — 1,170 Foreign (4,020 ) (1,172 ) (5,192 ) (1,469 ) (6,606 ) (8,075 ) Total $ 22,382 $ (1,172 ) $ 21,210 $ 42,649 $ (6,627 ) $ 36,022
Schedule of Unrecognized Tax Benefits Roll Forward	The aggregate changes in the balance of unrecognized tax benefits are as follows: Years Ended December 31, 2017 2016 Balance at beginning of year $ 3,080 $ 6,770 Additions based on prior year tax positions — 116 Reductions as a result of the lapse of statute limitations (3,080 ) (3,806 ) Balance at end of year $ — $ 3,080

Stockholders' Equity Stockholde

Stockholders' Equity Stockholders Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Dividends Declared [Abstract]
Dividends Declared	During the year ended December 31, 2017 , the following dividends were declared or paid: Equity Type Declaration Date Record Date Payment Date Dividends Per Share Aggregate Payment Amount (In millions) Common Stock February 17, 2017 March 17, 2017 March 31, 2017 $ 0.950 $ 343.3 (a) Common Stock May 18, 2017 June 16, 2017 June 30, 2017 $ 0.950 $ 350.3 (a) Common Stock August 3, 2017 September 15, 2017 September 29, 2017 $ 0.950 $ 389.6 (a) Common Stock October 15, 2017 December 15, 2017 December 29, 2017 $ 1.050 $ 428.8 (a) 6.875% Convertible Preferred Stock September 21, 2017 October 15, 2017 November 1, 2017 $ 18.142 $ 29.9 6.875% Convertible Preferred Stock December 15, 2017 January 15, 2018 February 1, 2018 $ 17.188 $ 28.4 (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 2017 on the Company's common stock and 6.875% Convertible Preferred Stock. Equity Type Payment Date Dividends Per Share Ordinary Taxable Dividend Per Share Qualified Taxable Dividend Per Share (a) Long-Term Capital Gain Distribution Per Share Non-Taxable Distribution (per share) Common Stock March 31, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock June 30, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock September 29, 2017 $ 0.950 $ 0.950 $ 0.347 $ — $ — Common Stock December 29, 2017 $ 1.050 $ 1.050 $ 0.384 $ — $ — 6.875% Convertible Preferred Stock November 1, 2017 $ 18.142 $ 18.142 $ 6.629 $ — $ — (a) Qualified taxable dividend amounts are included in ordinary taxable dividend amounts.

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Summary of Restricted Stock Awards Activity	The following is a summary of the RSU activity during the year ended December 31, 2017 . RSUs (In thousands) Outstanding at the beginning of year 2,677 Granted 1,359 Vested (747 ) Forfeited (321 ) Outstanding at end of year 2,968
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 awards granted during the years ended December 31, 2017 , 2016 and 2015 , respectively, with market conditions. Years Ended December 31, 2017 2016 2015 Risk-free rate 1.5 % 0.9 % 1.0 % Expected volatility 18 % 19 % 19 % Expected dividend rate 4.4 % 4.2 % 4.2 %
Summary of Restricted Stock Vested	The following table is a summary of the awards vested during the years ended December 31, 2017 , 2016 and 2015 . Years Ended December 31, Total Shares Vested Fair Value on Vesting Date (In thousands of shares) 2017 747 $ 67,241 2016 828 71,325 2015 946 83,244
Stock Based Compensation Expense	The following table discloses the components of stock-based compensation expense. Years Ended December 31, 2017 2016 2015 Stock-based compensation expense: Site rental costs of operations $ 14,942 $ 14,371 $ 8,969 Network services and other costs of operations 4,961 7,717 5,370 General and administrative expenses 76,532 74,450 52,809 Total stock-based compensation $ 96,435 $ 96,538 $ 67,148

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Tenant Leases	Tenant Leases The following table is a summary of the rental cash payments owed to the Company, as a lessor, by tenants pursuant to contractual agreements in effect as of December 31, 2017 . Generally, the Company's leases with its tenants provide for (1) annual escalations, (2) multiple renewal periods at the tenant's option, and (3) only limited termination rights at the applicable tenant's option through the current term. As of December 31, 2017 , the weighted-average remaining term of tenant leases is approximately five years, exclusive of renewals at the tenant's option. The tenants' rental payments included in the table below are through the current terms with a maximum current term of 20 years and do not assume exercise of tenant renewal options. Years Ending December 31, 2018 2019 2020 2021 2022 Thereafter Total Tenant leases $ 3,401,845 $ 3,277,019 $ 3,160,514 $ 3,028,825 $ 2,805,519 $ 5,628,294 $ 21,302,016
Operating Leases	Operating Leases The following table is a summary of rental cash payments owed by the Company, as lessee, to landlords pursuant to contractual agreements in effect as of December 31, 2017 . The Company is obligated under non-cancelable operating leases for land interests under 76% of its towers. The majority of these lease agreements have (1) certain termination rights that provide for cancellation after a notice period, (2) multiple renewal options at the Company's option, and (3) annual escalations. Lease agreements may also contain provisions for a contingent payment based on revenues or the gross margin derived from the communications infrastructure located on the leased land interest. Approximately 75% and approximately 90% of the Company's Towers site rental gross margins for the year ended December 31, 2017 are derived from towers where the land interest under the tower is owned or leased with final expiration dates of greater than 20 years and ten years, respectively, inclusive of renewals at the Company's option. The operating lease payments included in the table below include payments for certain renewal periods at the Company's option up to the estimated communications infrastructure useful life of 20 years and an estimate of contingent payments based on revenues and gross margins derived from existing tenant leases. Years Ending December 31, 2018 2019 2020 2021 2022 Thereafter Total Operating leases $ 635,321 $ 632,775 $ 622,587 $ 617,951 $ 609,796 $ 7,941,187 $ 11,059,617

Operating Segments and Concen42

Operating Segments and Concentrations of Credit Risk (Tables) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 3,669,191	$ 3,233,307	$ 3,018,413
Amortization of prepaid lease purchase price adjustments	20,100	21,300	20,500
Allocated Share-based Compensation Expense	$ 96,435	$ 96,538	$ 67,148
Concentration Risk, Percentage	86.00%	88.00%	89.00%
Sales Revenue, Services, Net	$ 686,414	$ 687,918	$ 645,438
Revenues	4,355,605	3,921,225	3,663,851
Direct Costs of Leased and Rented Property or Equipment	1,108,854	987,668	934,370
Cost of Services	414,825	409,454	352,187
Direct Operating Costs	1,523,679	1,397,122	1,286,557
Segment site rental gross margin	2,560,337	2,245,639	2,084,043
Segment network services gross margin	271,589	278,464	293,251
Segment General and Administrative Expenses	350,165	296,580	258,111
Segment Operating Profit	2,481,761	2,227,523	2,119,183
Depreciation, amortization and accretion	1,242,408	1,108,551	1,036,178
Interest expense and amortization of deferred financing costs	590,682	515,032	527,128
Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes	81,643	133,548	14,900
Income (Loss) from Continuing Operations Before Income Taxes	470,593	373,854	473,829
Assets	32,229,570	22,675,092	21,936,966
Goodwill	$ 10,021,468	$ 5,757,676	$ 5,513,551
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Year Ended December 31, 2017 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,899,554 $ 769,637 $ 3,669,191 Segment network services and other revenues 636,532 49,882 686,414 Segment revenues 3,536,086 819,519 4,355,605 Segment site rental cost of operations 844,795 264,059 1,108,854 Segment network services and other cost of operations 374,134 40,691 414,825 Segment cost of operations (a) 1,218,929 304,750 1,523,679 Segment site rental gross margin 2,054,759 505,578 2,560,337 Segment network services and other gross margin 262,398 9,191 271,589 Segment general and administrative expenses (a) 93,662 89,048 167,455 350,165 Segment operating profit (loss) 2,223,495 425,721 (167,455 ) 2,481,761 Stock-based compensation expense 96,435 96,435 Depreciation, amortization and accretion 1,242,408 1,242,408 Interest expense and amortization of deferred financing costs 590,682 590,682 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 81,643 81,643 Income (loss) from continuing operations before income taxes $ 470,593 Capital expenditures $ 418,476 $ 782,409 $ 27,186 $ 1,228,071 Total assets (at year end) $ 17,940,893 $ 13,669,636 $ 619,041 $ 32,229,570 Total goodwill (at year end) $ 5,127,259 $ 4,894,209 $ — $ 10,021,468 (a) Segment cost of operations excludes (1) stock-based compensation expense of $19.9 million for the year ended December 31, 2017 and (2) prepaid lease purchase price adjustments of $20.1 million for the year ended December 31, 2017 . Segment general and administrative expenses exclude stock-based compensation expense of $76.5 million for the year ended December 31, 2017 . (b) See consolidated statement of operations for further information.	Year Ended December 31, 2016 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,830,708 $ 402,599 $ 3,233,307 Segment network services and other revenues 603,689 84,229 687,918 Segment revenues 3,434,397 486,828 3,921,225 Segment site rental cost of operations 840,209 147,459 987,668 Segment network services and other cost of operations 344,595 64,859 409,454 Segment cost of operations (a) 1,184,804 212,318 1,397,122 Segment site rental gross margin 1,990,499 255,140 2,245,639 Segment network services and other gross margin 259,094 19,370 278,464 Segment general and administrative expenses (a) 92,903 60,676 143,001 296,580 Segment operating profit (loss) 2,156,690 213,834 (143,001 ) 2,227,523 Stock-based compensation expense 96,538 96,538 Depreciation, amortization and accretion 1,108,551 1,108,551 Interest expense and amortization of deferred financing costs 515,032 515,032 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 133,548 133,548 Income (loss) from continuing operations before income taxes $ 373,854 Capital expenditures $ 429,526 $ 409,710 $ 34,647 $ 873,883 Total assets (at year end) $ 18,394,572 $ 3,440,600 $ 839,920 $ 22,675,092 Total goodwill (at year end) $ 5,114,639 $ 643,037 $ — $ 5,757,676 (a) Segment cost of operations excludes (1) stock-based compensation expense of $22.1 million for the year ended December 31, 2016 and (2) prepaid lease purchase price adjustments of $21.3 million for the year ended December 31, 2016 . Segment general and administrative expenses exclude stock-based compensation expense of $74.5 million for the year ended December 31, 2016 . (b) See consolidated statement of operations for further information.	Year Ended December 31, 2015 Towers Fiber Other Consolidated Total Segment site rental revenues $ 2,734,045 $ 284,368 $ 3,018,413 Segment network services and other revenues 591,655 53,783 645,438 Segment revenues 3,325,700 338,151 3,663,851 Segment site rental cost of operations 827,175 107,195 934,370 Segment network services and other cost of operations 309,025 43,162 352,187 Segment cost of operations (a) 1,136,200 150,357 1,286,557 Segment site rental gross margin 1,906,870 177,173 2,084,043 Segment network services and other gross margin 282,630 10,621 293,251 Segment general and administrative expenses (a) 91,899 38,379 127,833 258,111 Segment operating profit (loss) 2,097,601 149,415 (127,833 ) 2,119,183 Stock-based compensation expense 67,148 67,148 Depreciation, amortization and accretion 1,036,178 1,036,178 Interest expense and amortization of deferred financing costs 527,128 527,128 Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes (b) 14,900 14,900 Income (loss) from continuing operations before income taxes $ 473,829 Capital expenditures $ 564,753 $ 314,882 $ 29,257 $ 908,892 Total assets (at year end) $ 17,974,847 $ 3,511,956 $ 450,163 $ 21,936,966 Total goodwill (at year end) $ 4,863,847 $ 649,704 $ — $ 5,513,551 (a) Segment cost of operations excludes (1) stock-based compensation expense of $14.3 million for the year ended December 31, 2015 and (2) prepaid lease purchase price adjustments of $20.5 million for the year ended December 31, 2015 . Segment general and administrative expenses exclude stock-based compensation expense of $52.8 million for the year ended December 31, 2015 . (b) 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 customers accounting for more than 10% of the consolidated revenues. Years Ended December 31, 2017 2016 2015 AT&T 25 % 27 % 27 % T-Mobile 22 % 23 % 22 % Verizon Wireless 22 % 22 % 21 % Sprint 17 % 16 % 19 % Total 86 % 88 % 89 %
Towers [Member]
Segment Reporting Information [Line Items]
Revenues	$ 2,899,554	$ 2,830,708	$ 2,734,045
Sales Revenue, Services, Net	636,532	603,689	591,655
Revenues	3,536,086	3,434,397	3,325,700
Direct Costs of Leased and Rented Property or Equipment	844,795	840,209	827,175
Cost of Services	374,134	344,595	309,025
Direct Operating Costs	1,218,929	1,184,804	1,136,200
Segment site rental gross margin	2,054,759	1,990,499	1,906,870
Segment network services gross margin	262,398	259,094	282,630
Segment General and Administrative Expenses	93,662	92,903	91,899
Segment Operating Profit	2,223,495	2,156,690	2,097,601
Assets	17,940,893	18,394,572	17,974,847
Goodwill	5,127,259	5,114,639	4,863,847
Small Cells [Member]
Segment Reporting Information [Line Items]
Revenues	769,637	402,599	284,368
Sales Revenue, Services, Net	49,882	84,229	53,783
Revenues	819,519	486,828	338,151
Direct Costs of Leased and Rented Property or Equipment	264,059	147,459	107,195
Cost of Services	40,691	64,859	43,162
Direct Operating Costs	304,750	212,318	150,357
Segment site rental gross margin	505,578	255,140	177,173
Segment network services gross margin	9,191	19,370	10,621
Segment General and Administrative Expenses	89,048	60,676	38,379
Segment Operating Profit	425,721	213,834	149,415
Assets	13,669,636	3,440,600	3,511,956
Goodwill	4,894,209	643,037	649,704
Other [Member]
Segment Reporting Information [Line Items]
Allocated Share-based Compensation Expense	96,435	96,538	67,148
Segment General and Administrative Expenses	167,455	143,001	127,833
Segment Operating Profit	(167,455)	(143,001)	(127,833)
Depreciation, amortization and accretion	1,242,408	1,108,551	1,036,178
Interest expense and amortization of deferred financing costs	590,682	515,032	527,128
Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes	81,643	133,548	14,900
Assets	619,041	839,920	450,163
Goodwill	$ 0	$ 0	$ 0

Supplemental Cash Flow Inform43

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [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, 2017 , 2016 and 2015 . Years Ended December 31, 2017 2016 2015 Supplemental disclosure of cash flow information: Interest paid $ 546,543 $ 470,655 $ 489,970 Income taxes paid 16,427 13,821 28,771 Supplemental disclosure of non-cash investing and financing activities: Increase (decrease) in accounts payable for purchases of property and equipment 2,279 17,922 (7,042 ) Purchase of property and equipment under capital leases and installment land purchases 31,999 52,322 60,270 Installment payment receivable for sale of CCAL (see note 3) — — 117,384 Preferred stock dividends accrued but not paid (see note 12) 28,359 — 10,997

Quarterly Financial Informati44

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information (Unaudited)	Summary quarterly financial information for the years ended December 31, 2017 and 2016 is as follows: Three Months Ended (a) March 31 June 30 September 30 December 31 2017: Net revenues $ 1,015,942 $ 1,038,335 $ 1,063,238 $ 1,238,090 Operating income (loss) 256,549 258,500 260,567 268,429 Gains (losses) on retirement of long-term obligations (3,525 ) — — — Benefit (provision) for income taxes (4,369 ) (4,538 ) (2,383 ) (14,753 ) Net income (loss) attributable to CCIC stockholders 119,138 112,114 115,194 98,104 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 0.33 $ 0.31 $ 0.22 $ 0.17 Diluted $ 0.33 $ 0.31 $ 0.21 $ 0.17 Three Months Ended (a) March 31 June 30 September 30 December 31 2016: Net revenues $ 934,384 $ 962,409 $ 992,016 $ 1,032,416 Operating income (loss) 211,739 231,185 244,254 262,038 Gains (losses) on retirement of long-term obligations (30,550 ) (11,467 ) (10,274 ) — Benefit (provision) for income taxes (3,872 ) (3,884 ) (5,041 ) (4,084 ) Net income (loss) attributable to CCIC stockholders 47,840 86,058 98,366 124,709 Net income (loss) attributable to CCIC common stockholders, per common share: Basic $ 0.11 $ 0.22 $ 0.26 $ 0.35 Diluted $ 0.11 $ 0.22 $ 0.26 $ 0.35 (a) The sum of quarterly information may not agree to year to date information due to rounding.

Schedule II - Valuation and Q45

Schedule II - Valuation and Qualifying Accounts Allowance for Doubtful Accounts (Tables)	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts Disclosure [Text Block]	Additions Deductions Balance at Beginning of Year Charged to Operations Credited to Operations Written Off Effect of Exchange Rate Changes Other Adjustments Balance at End of Year Allowance for Doubtful Accounts Receivable: 2017 $ 11,314 $ 4,360 $ — $ (4,591 ) $ — $ 2,663 (a) $ 13,746 2016 $ 9,574 $ 4,873 $ — $ (3,133 ) $ — $ — $ 11,314 2015 $ 10,037 $ 2,958 $ — $ (3,421 ) $ — $ — $ 9,574 (a) Represents the allowance for doubtful accounts reflected in the preliminary purchase price allocations for the 2017 Acquisitions. See note 4. Additions Deductions Balance at Beginning of Year Charged to Operations Charged to Additional Paid-in Capital and Other Comprehensive Income Credited to Operations Credited to Additional Paid-in Capital and Other Comprehensive Income Other Adjustments (a) Balance at End of Year Deferred Tax Valuation Allowance: 2017 $ 6,627 $ 59 $ — $ (5,514 ) $ — $ — $ 1,172 2016 $ 1,994 $ 586 $ — $ (2,236 ) $ — $ 6,283 $ 6,627 2015 $ 21,038 $ 164 $ — $ (3,000 ) $ — $ (16,208 ) $ 1,994 (a) Inclusive of (1) the effects of acquisitions and (2) the inclusion of small cells in the REIT in January 2016.

Schedule III - Schedule of Re46

Schedule III - Schedule of Real Estate and Depreciation Schedule of Real Estate and Accumulated Depreciation (Tables)	12 Months Ended
	Dec. 31, 2017
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, 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 40,080 towers (1) $ 4,580,581 (2) (3) (3) $ 20,109,562 (4) $ (7,303,230 ) Various Various Up to 20 years (1) Amount is exclusive of small cell nodes. No single tower 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. (2) Certain of the Company's debt is secured by (1) a pledge of the equity interests in each applicable issuer and (2) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses). (3) The Company has omitted this information, as it would be impracticable to compile such information on a tower-by-tower basis. (4) Does not include those towers under construction. 2017 2016 Gross amount at beginning $ 16,120,896 $ 15,110,835 Additions during period: Acquisitions through foreclosure — — Other acquisitions (1)(2) 2,787,829 130,139 Communications infrastructure construction and improvements 1,062,589 709,538 Purchase of land interests 80,647 74,579 Sustaining capital expenditures 56,480 55,417 Other (3) 46,537 95,049 Total additions 4,034,082 1,064,722 Deductions during period: Cost of real estate sold or disposed (45,416 ) (54,661 ) Other — — Total deductions: (45,416 ) (54,661 ) Balance at end $ 20,109,562 $ 16,120,896 (1) Inclusive of changes between the final purchase price allocation and the preliminary purchase price allocations. (2) Includes acquisitions of communications infrastructure. (3) Predominately relates to the purchase of property and equipment under capital leases and installment land purchases. 2017 2016 Gross amount of accumulated depreciation at beginning $ (6,446,448 ) $ (5,648,598 ) Additions during period: Depreciation (889,983 ) (810,549 ) Total additions (889,983 ) (810,549 ) Deductions during period: Amount for assets sold or disposed 26,391 24,190 Other 6,810 (11,491 ) Total deductions 33,201 12,699 Balance at end $ (7,303,230 ) $ (6,446,448 )

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Ground Lease Agreement Initial Term	5
Subject to Capital Lease with Sprint, TMO, or AT&T [Member]
Tower count as a percentage of total towers	53.00%
Leased or Operated Under Sprint Agreement [Member]
Ground Lease Agreement Initial Term	32
Purchase Option Price	$ 2,300
Tower count as a percentage of total towers	16.00%
Leased or Operated Under T-Mobile Agreement [Member]
Ground Lease Agreement Initial Term	28
Tower count as a percentage of total towers	15.00%
T-Mobile [Member]
Purchase Option Price	$ 2,000
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%
AT&T Prior to 2025 in accordance with TMO agreement [Member]
Purchase Option Price	$ 10
CCAL [Member]
Noncontrolling Interest, Ownership Percentage by Parent		77.60%
AT&T [Member]
Ground Lease Agreement Initial Term	28
Purchase Option Price	$ 4,200
Tower count as a percentage of total towers	22.00%

Summary of Significant Accoun48

Summary of Significant Accounting Policies (Details) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2017USD ($)yearsshares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)shares
Fair Value Measurements, Changes in Valuation Techniques	0
Net cash provided by (used from) operating activities	$ 847	$ (4,547)	$ 3,974
Net cash provided by (used from) investing activities	(26)	10,541	(3,752)
Net cash provided by (used from) financing activities	3,808	(7,931)	16,458
Capitalized Labor Costs	$ 91,900	86,100	36,700
Useful life of site rental contracts and customer relationships (years)	20 years
Revenue recognition, non-cancelable lease term, minimum (years) | years	5
Revenue recognition, non-cancelable lease term, maximum (years) | years	15
Portion of company site rental costs that are ground lease expenses	0.5500
Ground Lease Agreement Initial Term	5
Percentage of tax position that is likely of being realized upon ultimate settlement	50.00%
Asset write-down charges	$ 17,322	34,453	33,468
Wireless Infrastructure [Member]
Estimated useful life, maximum, in years	20 years
Wireless Infrastructure [Member] | Maximum [Member]
Estimated useful life, maximum, in years	20 years
Towers [Member]
Estimated useful life, maximum, in years	20 years
Property, Plant and Equipment [Member]
Asset write-down charges	$ 14,300	26,900	$ 27,000
Other Current Assets [Member]
Straight-Line Site Rental Revenues	86,000	67,200
Deferred Revenue [Domain]
Straight-Line Site Rental Revenues	$ 1,300,000	$ 1,300,000
Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share (in shares) | shares	15		11.4

Summary of Significant Accoun49

Summary of Significant Accounting Policies (Interest Expense and Amortization of Deferred Financing Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Interest expense on debt obligations	$ 581,314	$ 500,699	$ 490,002
Amortization of deferred financing costs and adjustments on long-term debt, net	19,035	19,087	21,048
Amortization of interest rate swaps	0	0	18,725
Capitalized Interest	(11,545)	(7,010)	(4,805)
Other Components	1,878	2,256	2,158
Total	$ 590,682	$ 515,032	$ 527,128

Summary of Significant Accoun50

Summary of Significant Accounting Policies (Per Share Information) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income (Loss) from Continuing Operations																	$ 444,550	$ 356,973	$ 525,286
Dividends on preferred stock																	(58,294)	(32,991)	(43,988)
Net income (loss) attributable to CCIC common stockholders																	386,256	323,982	1,477,004
Income (Loss) from Discontinued Operations, Net of Tax																	0	0	999,049
Less: Net income (loss) attributable to the noncontrolling interest																	$ 0	$ 0	$ 3,343
Weighted-average common shares outstanding:
Basic weighted-average number of common stock outstanding																	381,740	340,349	333,002
Diluted weighted-average number of common shares outstanding																	383,221	340,879	334,062
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Basic (in dollars per share)	$ 0.17		$ 0.22		$ 0.31		$ 0.33		$ 0.35		$ 0.26		$ 0.22		$ 0.11		$ 1.01	$ 0.95	$ 4.44
Diluted (in dollars per share)	$ 0.17		$ 0.21		$ 0.31		$ 0.33		$ 0.35		$ 0.26		$ 0.22		$ 0.11		$ 1.01	$ 0.95	$ 4.42
Preferred Stock [Member]
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Antidilutive securities excluded from computation of earnings per share (in shares)																	15,000		11,400
Stock Options and Restricted Stock Awards [Member]
Weighted-average common shares outstanding:
Effect of assumed dilution from potential common shares relating to stock options and restricted stock awards																	1,481	530	1,060
Discontinued Operations, Disposed of by Sale [Member]
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income (loss) attributable to CCIC common stockholders																	$ 0	$ 0	$ 995,706
Discontinued Operations [Member]
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Basic (in dollars per share)																	$ 0	$ 0	$ 2.99
Diluted (in dollars per share)																	$ 0	$ 0	$ 2.98
Continuing Operations [Member]
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income (loss) attributable to CCIC common stockholders																	$ 386,256	$ 323,982	$ 481,298
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Basic (in dollars per share)																	$ 1.01	$ 0.95	$ 1.45
Diluted (in dollars per share)																	$ 1.01	$ 0.95	$ 1.44
[1]	The sum of quarterly information may not agree to year to date information due to rounding.

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015		May 28, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested				$ 1,100,000
Disposal Group, Including Discontinued Operation, Revenue	[1],[2]			65,293
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	[1],[2],[3]			17,498
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	[1],[2]			10,168
Disposal Group, Including Discontinued Operation, Other Expense	[1],[2]			10,481
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	[1],[2]			27,146
Discontinued Operation, Tax Effect of Income (Loss) from Discontinued Operation During Phase-out Period				(7,456)
Income (Loss) from Discontinued Operations, Net of Tax		$ 0	$ 0	19,690	[1],[2],[4]
Cash Proceeds from Divestiture of Interest in Consolidated Subsidiaries	[5]			1,139,369
Installment payment receivable for sale of subsidiary		0	0	117,384
Total Proceeds From Sale of CCAL				1,256,753
Net assets and liabilities related to discontinued operations	[6],[7]			258,575
Transaction fees and expenses				23,059
Foreign Currency Translation Reclassification Adjustments	[8]			(25,678)
Pre-tax Gain (Loss) from Disposal of Discontinued Operations				1,000,797
Income Taxes Related to Sale of CCAL				(21,438)
Net Gain (Loss) from Disposal of Discontinued Operations, Net of Tax		$ 0	0	$ 979,359
CCAL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent				77.60%
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest				$ 23,500
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents						$ 11,100
Inclusive of Foreign Currency Swap
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Installment payment receivable for sale of subsidiary			$ 124,000
Exclusive of Foreign Currency Swap
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Installment payment receivable for sale of subsidiary	[5]					$ 117,384
[1]	CCAL results are through May 28, 2015, which was the closing date of the Company's sale of CCAL.
[2]	No interest expense has been allocated to discontinued operations.
[3]	Exclusive of depreciation, amortization, and accretion shown separately.
[4]	Exclusive of the gain (loss) from disposal of discontinued operations, net of tax, as presented on the consolidated statement of operations.
[5]	Exclusive of foreign currency swaps and based on exchange rates as of May 28, 2015, which was the closing date of the Company's sale of CCAL. See note 9. The impact of fluctuations in the exchange rate subsequent to the closing date are reflected as a component of "other income (expense)" on the Company's consolidated statement of operations.
[6]	Inclusive of $11.1 million of cash.
[7]	Represents net assets attributable to CCIC, net of the disposition of noncontrolling interest of $23.5 million.
[8]	Represents foreign currency translation adjustments previously included in "accumulated other comprehensive income (loss)" on the consolidated balance sheet and reclassified to "net gain (loss) from disposal of discontinued operations, net of tax" on the consolidated statement of operations and comprehensive income (loss).

Acquisitions (Details)

Acquisitions (Details) $ / shares in Units, $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares		Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Depreciation and Amortization			$ 247,100	$ 315,900
Business Acquisition, Pro Forma Revenue			$ 5,050,166	4,864,852
Fiber Miles			60,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		$ 314,100
Business Acquisition, Pro Forma Income (Loss) Before Income Taxes	[1],[2]		$ 541,389	367,326	[3]
Business Combination, Pro Forma Benefit (Provision) for Income Taxes	[4]		(28,960)	(20,968)
Business Acquisition, Pro Forma Net Income (Loss)	[1],[2]		$ 512,429	$ 346,358	[3]
Business Acquisition, Pro Forma Earnings Per Share, Basic | $ / shares	[2]		$ 0.89	$ 0.51
Business Acquisition, Pro Forma Earnings Per Share, Diluted | $ / shares	[2]		$ 0.88	$ 0.51
Business Combination, Pro Forma Stock-Based Compensation, Acquisition and Integration Costs				$ 120,000
FiberNet Acquisition [Member]
Business Acquisition [Line Items]
Consideration transferred			$ 1,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets			52,274
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			438,478
Business Acquisition, Goodwill, Expected Tax Deductible Amount	[5]		777,563
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	[6]		327,338
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			2,449
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities			(41,120)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities			(36,152)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	[7]		$ 1,520,830
Fiber Miles Acquired			11,500
Business Acquisition, Date of Acquisition Agreement			Jan. 17, 2017
Sunesys [Member]
Business Acquisition [Line Items]
Consideration transferred				$ 1,000,000
Fiber Miles				10,000
Percentage of FIber Miles			60.00%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets				$ 15,306
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				444,394
Business Acquisition, Goodwill, Expected Tax Deductible Amount	[8]			331,775
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				254,079
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities				(20,233)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities				(37,356)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	[9]			987,965
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			$ 121,700	$ 112,600		$ 41,400
AT&T [Member]
Business Acquisition [Line Items]
Tower count as a percentage of total towers			22.00%
TDC [Member]
Business Acquisition [Line Items]
Consideration transferred			$ 461,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			107,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount			211,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 140,000
Tower Count			330
Wilcon Acquisition [Member]
Business Acquisition [Line Items]
Consideration transferred			$ 600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			150,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount			360,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 140,000
Fiber Miles Acquired			1,900
Business Acquisition, Date of Acquisition Agreement			Jun. 26, 2017
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			$ 40,000
Lightower Acquisition [Member]
Business Acquisition [Line Items]
Consideration transferred			7,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets			104,643
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			2,197,466
Business Acquisition, Goodwill, Expected Tax Deductible Amount	[10]		3,116,010
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	[11]		2,177,090
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			28,834
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities			(172,399)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities			(299,667)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	[12]		$ 7,151,977
Fiber Miles Acquired			32,000
Business Acquisition, Date of Acquisition Agreement			Nov. 1, 2017
Top Metro Markets [Domain] | FiberNet Acquisition [Member]
Business Acquisition [Line Items]
Fiber Miles Acquired			6,000
[1]	For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to depreciation and amortization of $247.1 million and $315.9 million, respectively, related to property and equipment and intangibles recorded as a result of the 2017 Acquisitions.
[2]	Pro forma amounts include the impact of the interest expense and common stock share issuances associated with the related debt and equity financings for the 2017 Acquisitions (see above and notes 8 and 12).
[3]	Amounts are inclusive of a total of $120 million of Lightower stock-based compensation expense and acquisition and integration costs.
[4]	For the years ended December 31, 2017 and 2016, amounts are inclusive of pro forma adjustments to the benefit (provision) for income tax as a result of the Company's REIT status. The vast majority of the assets and related income from the FiberNet Acquisition, the Wilcon Acquisition, and the Lightower Acquisition are included in the Company's REIT. The remaining assets are included in the Company's TRS. For purposes of the unaudited pro forma financial results, an adjustment has been made to reflect the additional tax impact of the income related to the TRS assets.
[5]	The preliminary purchase price allocation for the FiberNet Acquisition resulted in the recognition of goodwill based on:•the Company's expectation to leverage the FiberNet fiber footprint to support new small cells and fiber solutions,•the complementary nature of the FiberNet fiber to the Company's existing fiber assets and its location in top metro markets where the Company expects to see wireless carrier network investments,•the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and•other intangibles not qualified for separate recognition, including the assembled workforce.
[6]	Predominantly comprised of site rental contracts and customer relationships.
[7]	The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the FiberNet Acquisition
[8]	The final purchase price allocation for the Sunesys Acquisition resulted in the recognition of goodwill based on the Company's expectation to leverage the Sunesys fiber footprint to support new small cells. The Sunesys fiber is complementary to the Company's existing fiber assets and is located where the Company expects to see wireless carrier network investments.
[9]	Assets acquired in the Sunesys Acquisition are included in the Company's REIT and as such, no deferred taxes were recorded in connection with the Sunesys Acquisition.
[10]	The preliminary purchase price allocation for the Lightower Acquisition resulted in the recognition of goodwill based on:•the Company's expectation to leverage the Lightower fiber footprint to support new small cells and fiber solutions,•the complementary nature of the Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments,•the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and•other intangibles not qualified for separate recognition, including the assembled workforce.
[11]	Predominantly comprised of site rental contracts and customer relationships.
[12]	The vast majority of the assets will be included in the Company's REIT. As such, no deferred taxes were recorded in connection with the Lightower Acquisition.

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 20,433,186	$ 16,418,534
Less: accumulated depreciation		(7,500,301)	(6,613,219)
Total property and equipment, net		12,932,885	9,805,315
Depreciation expense		914,900	832,700	$ 774,900
Capital Leased Assets, Gross		4,300,000
Accumulated Depreciation on Capital Lease Assets		1,700,000
Land owned in fee and perpetual easements [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment	[1]	1,859,431	1,747,335
Buildings [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 119,313	110,641
Property, Plant and Equipment, Useful Life		40 years
Wireless Infrastructure [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 17,183,482	13,825,394
Property, Plant and Equipment, Useful Life		20 years
Information technology assets and other [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 372,339	278,489
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 898,621	$ 456,675
Minimum [Member] | Wireless 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] | Wireless 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 in fee and perpetual easements.

Goodwill and Intangible Asset54

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Goodwill and Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		17 years
Goodwill Period Start		$ 5,757,676		$ 5,513,551
Goodwill Period End		10,021,468		5,757,676	$ 5,513,551
Finite-lived intangible assets, gross		8,285,825	[1]	5,643,392
Accumulated amortization of intangible assets		(2,324,066)		(1,993,320)
Finite-lived intangible assets, net		5,961,759		3,650,072
2,017		445,849
2,018		444,889
2,019		444,589
2,020		444,155
2,021		443,688
Site Rental Contracts and Customer Relationships [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		7,782,934	[1]	5,146,301
Accumulated amortization of intangible assets		(2,156,499)		(1,847,523)
Finite-lived intangible assets, net		5,626,435		3,298,778
Other Intangible Assets [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		502,891	[1]	497,091
Accumulated amortization of intangible assets		(167,567)		(145,797)
Finite-lived intangible assets, net		335,324		351,294
Other Acquired Goodwill [Domain]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Additions due to acquisitions		12,613		33,220
FiberNet Acquisition [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Additions due to acquisitions	[2]	777,563
Wilcon Acquisition [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Additions due to acquisitions	[2]	357,606
Lightower Acquisition [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Additions due to acquisitions	[2]	3,116,010
TDC [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Additions due to acquisitions	[3]			210,905
Depreciation, Amortization and Accretion [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Amortization expense		314,447		264,656	251,443
Site Rental Costs of Operations [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Amortization expense		18,373		19,367	20,420
Total Amortization Expense [Member]
Goodwill and Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 332,820		$ 284,023	$ 271,863
[1]	(a)During the year ended December 31, 2017, intangible assets additions (primarily site rental contracts and customer relationships) from acquisitions had a weighted average amortization period of approximately 17 years.
[2]	The preliminary purchase price allocation for the FiberNet Acquisition, Wilcon Acquisition and Lightower Acquisition resulted in the recognition of goodwill in the Fiber segment based on:•the Company's expectation to leverage the FiberNet, Wilcon and Lightower fiber footprint to support new small cell and fiber solutions,•the complementary nature of the FiberNet, Wilcon and Lightower fiber to the Company's existing fiber assets and its location where the Company expects to see wireless carrier network investments,•the Company's belief that the acquired fiber assets are well-positioned to benefit from the continued growth trends in the demand for data, and•other intangibles not qualified for separate recognition, including the assembled workforce. See note 4.
[3]	The final purchase price allocation for the TDC Acquisition resulted in the recognition of goodwill in the Towers segment because of the anticipated growth opportunity in the acquired tower portfolio. See note 4.

Other Liabilities (Details)

Other Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Liabilities [Line Items]
Asset Retirement Obligation, Accretion Expense	$ 13,100	$ 11,300	$ 9,900
Other Liabilities, non-current	2,554,037	2,087,229
Estimated Future Undiscounted Cash Flows Expected To Be Paid Relating To Asset Retirement Obligations	1,200,000
Amortization of Below Market Tenant Lease	37,300	33,600	32,800
Accrued Payroll and Other Compensation	141,000	100,900
Above Market Leases [Member]
Other Liabilities [Line Items]
Amortization of Above Market Leases	19,300	21,000	$ 22,500
Amortization expense, 2018 [Member]
Other Liabilities [Line Items]
Expected amortization of above-market leases by year	18,277
Amortization expense, 2019 [Member]
Other Liabilities [Line Items]
Expected amortization of above-market leases by year	17,674
Amortization expense, 2020 [Member]
Other Liabilities [Line Items]
Expected amortization of above-market leases by year	16,769
Amortization expense, 2021 [Member]
Other Liabilities [Line Items]
Expected amortization of above-market leases by year	15,667
Amortization expense, 2022 [Member] [Domain]
Other Liabilities [Line Items]
Expected amortization of above-market leases by year	14,580
Amortization expense, 2018 [Member]
Other Liabilities [Line Items]
Expected amortization of below-market tenant leases by year	65,104
Amortization expense, 2019 [Member]
Other Liabilities [Line Items]
Expected amortization of below-market tenant leases by year	59,145
Amortization expense, 2020 [Member] [Domain]
Other Liabilities [Line Items]
Expected amortization of below-market tenant leases by year	53,050
Amortization expense, 2021 [Member] [Domain]
Other Liabilities [Line Items]
Expected amortization of below-market tenant leases by year	49,745
Amortization expense, 2022 [Member] [Domain]
Other Liabilities [Line Items]
Expected amortization of below-market tenant leases by year	44,910
customer prepaid rent [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	1,076,845	983,263
deferred ground lease payable [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	559,556	517,281
Above Market Leases [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	201,542	224,126
deferred credits [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	531,856	207,992
asset retirement obligations [Member]
Other Liabilities [Line Items]
Asset Retirement Obligation	173,733	146,100
Deferred Tax Liability, noncurrent [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	5,192	8,075
Other Liabilities [Member]
Other Liabilities [Line Items]
Other Liabilities, non-current	$ 5,313	$ 392

Debt and Other Obligations (Ind

Debt and Other Obligations (Indebtedness) (Details) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

[3]

Jun. 30, 2017

[3]

Mar. 31, 2017

[3]

Dec. 31, 2016

Sep. 30, 2016

[3]

Jun. 30, 2016

[3]

Mar. 31, 2016

[3]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2012

Debt Instrument [Line Items]

Original issue date

Oct. 1, 2012

Total debt and other obligations

$ 16,159,620

$ 12,171,142

$ 16,159,620

$ 12,171,142

Less: current maturities and short-term debt and other current obligations

115,251

101,749

115,251

101,749

Non-current portion of long-term debt and other long-term obligations

16,044,369

12,069,393

16,044,369

12,069,393

Debt Instrument, Interest Rate, Stated Percentage

5.30%

Long-term Debt, Gross

16,261,760

16,261,760

Debt Instrument, Face Amount

$ 1,650,000

Extinguishment of Debt, Amount

4,026,390

$ 1,069,361

Repayments of Other Long-term Debt

4,044,834

[1]

1,069,337

[2]

Gains (losses) on retirement of long-term obligations

0

[3]

$ 0

$ 0

$ (3,525)

0

[3]

$ (10,274)

$ (11,467)

$ (30,550)

(3,525)

(52,291)

[4]

(4,157)

[5]

2016 Term Loan A [Member]

Debt Instrument [Line Items]

Extinguishment of Debt, Amount

0

Repayments of Other Long-term Debt

0

Gains (losses) on retirement of long-term obligations

[6]

$ (3,525)

Fixed Rate Securitized Debt January 2010 Tower Revenue Notes 2 [Member]

Debt Instrument [Line Items]

Extinguishment of Debt, Amount

350,000

Repayments of Other Long-term Debt

[1]

352,796

Gains (losses) on retirement of long-term obligations

[4]

(3,338)

2012 Credit Facility [Member]

Debt Instrument [Line Items]

Line of Credit Facility, Commitment Fee Percentage

0.20%

2012 Revolver [Member]

Debt Instrument [Line Items]

Extinguishment of Debt, Amount

0

Repayments of Other Long-term Debt

[1]

0

Gains (losses) on retirement of long-term obligations

[4]

(1,930)

Bank Debt [Member]

Debt Instrument [Line Items]

Total debt and other obligations

3,376,588

1,954,173

$ 3,376,588

1,954,173

Variable Rate 2012 Term Loans Tranche B [Member]

Debt Instrument [Line Items]

Extinguishment of Debt, Amount

2,247,015

564,137

Repayments of Other Long-term Debt

2,247,015

[1]

564,137

[2]

Gains (losses) on retirement of long-term obligations

(27,122)

[4]

$ (6,127)

[5]

Securitized Debt [Member]

Debt Instrument [Line Items]

Total debt and other obligations

3,332,309

3,345,805

3,332,309

3,345,805

High Yield Bonds [Member]

Debt Instrument [Line Items]

Total debt and other obligations

9,222,940

6,644,317

9,222,940

6,644,317

2016 Revolver [Member]

Debt Instrument [Line Items]

Extinguishment of Debt, Amount

500,000

Line of Credit Facility, Maximum Borrowing Capacity

3,500,000

$ 3,500,000

2016 Revolver [Member] | Bank Debt [Member]

Debt Instrument [Line Items]

Original issue date

Jan. 1, 2016

Contractual maturity date

8/31/2022

Total debt and other obligations

$ 980,000

[7]

0

$ 980,000

[7]

0

Debt Instrument, Interest Rate, Stated Percentage

[8],[9]

2.60%

2.60%

Line of Credit Facility, Maximum Borrowing Capacity

2,500,000

2,500,000

2016 Term Loan A [Member] | Bank Debt [Member]

Debt Instrument [Line Items]

Original issue date

Jan. 1, 2016

Contractual maturity date

8/31/2022

Total debt and other obligations

$ 2,396,588

1,954,173

$ 2,396,588

1,954,173

Debt Instrument, Interest Rate, Stated Percentage

[8],[9]

2.60%

2.60%

Debt Instrument, Face Amount

2,000,000

2,000,000

Fixed Rate Debt 2009 Securitized Notes A-1 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

Jul. 1, 2009

Contractual maturity date

[10]

8/1/2019

Total debt and other obligations

$ 31,813

51,416

$ 31,813

51,416

Debt Instrument, Interest Rate, Stated Percentage

[8]

6.30%

6.30%

Fixed Rate Debt 2009 Securitized Notes A-2 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

Jul. 1, 2009

Contractual maturity date

[10]

8/1/2029

Total debt and other obligations

$ 69,500

68,737

$ 69,500

68,737

Debt Instrument, Interest Rate, Stated Percentage

[8]

9.00%

9.00%

Fixed Rate Securitized Debt January 2010 Tower Revenue Notes 3 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

Jan. 1, 2010

Contractual maturity date

[11],[12]

1/1/2040

Total debt and other obligations

$ 1,246,106

1,244,237

$ 1,246,106

1,244,237

Debt Instrument, Interest Rate, Stated Percentage

[8]

6.10%

6.10%

Fixed Rate Securitized Debt August 2010 Tower Revenue Notes 6 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

Aug. 1, 2010

Contractual maturity date

[11],[12]

8/1/2040

Total debt and other obligations

$ 995,354

993,557

$ 995,354

993,557

Debt Instrument, Interest Rate, Stated Percentage

[8]

4.90%

4.90%

Fixed Rate Securitized Debt May 2015 Tower Revenue Notes [Member] [Domain] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

May 1, 2015

Contractual maturity date

[11],[12]

5/1/2042

Total debt and other obligations

$ 297,211

296,573

$ 297,211

296,573

Debt Instrument, Interest Rate, Stated Percentage

[8]

3.20%

3.20%

Fixed Rate Securitized Debt May 2015 Tower Revenue Notes 2 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Original issue date

May 1, 2015

Contractual maturity date

[11],[12]

5/1/2045

Total debt and other obligations

$ 692,325

691,285

$ 692,325

691,285

Debt Instrument, Interest Rate, Stated Percentage

[8]

3.70%

3.70%

5.250% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Oct. 1, 2012

Contractual maturity date

1/15/2023

Total debt and other obligations

$ 1,639,207

1,637,099

$ 1,639,207

1,637,099

Debt Instrument, Interest Rate, Stated Percentage

[8]

5.30%

5.30%

3.849% Secured Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Dec. 1, 2012

Contractual maturity date

4/15/2023

Total debt and other obligations

$ 992,663

991,279

$ 992,663

991,279

Debt Instrument, Interest Rate, Stated Percentage

[8]

3.80%

3.80%

4.875% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Apr. 1, 2014

Apr. 1, 2014

Contractual maturity date

4/1/2022

Total debt and other obligations

$ 842,090

840,322

$ 842,090

840,322

Debt Instrument, Interest Rate, Stated Percentage

4.90%

[8]

4.90%

[8]

4.90%

Debt Instrument, Face Amount

$ 850,000

$ 850,000

3.400% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Feb. 1, 2016

Contractual maturity date

2/15/2021

Total debt and other obligations

$ 849,859

$ 849,698

$ 849,859

$ 849,698

Debt Instrument, Interest Rate, Stated Percentage

3.40%

[8]

3.40%

3.40%

[8]

3.40%

Debt Instrument, Face Amount

$ 250,000

$ 250,000

4.450% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Feb. 1, 2016

Contractual maturity date

2/15/2026

Total debt and other obligations

$ 891,145

$ 890,118

$ 891,145

$ 890,118

Debt Instrument, Interest Rate, Stated Percentage

4.50%

[8]

4.50%

4.50%

[8]

4.50%

Debt Instrument, Face Amount

$ 900,000

$ 900,000

3.700% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

May 1, 2016

Contractual maturity date

6/15/2026

Total debt and other obligations

$ 742,727

$ 741,908

$ 742,727

$ 741,908

Debt Instrument, Interest Rate, Stated Percentage

3.70%

[8]

3.70%

3.70%

[8]

3.70%

Debt Instrument, Face Amount

$ 750,000

$ 750,000

2.250% Senior Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Sep. 1, 2016

Contractual maturity date

9/1/2021

Total debt and other obligations

$ 695,383

693,893

$ 695,383

693,893

Debt Instrument, Interest Rate, Stated Percentage

[8]

2.30%

2.30%

4.000% Senior Unsecured Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Feb. 1, 2017

Contractual maturity date

3/1/2027

Total debt and other obligations

$ 493,833

0

$ 493,833

0

Debt Instrument, Interest Rate, Stated Percentage

[8]

4.00%

4.00%

Debt Instrument, Face Amount

$ 500,000

$ 500,000

4.750% Senior Unsecured Notes [Member] [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

May 1, 2017

Contractual maturity date

5/1/2047

Total debt and other obligations

$ 343,209

0

$ 343,209

0

Debt Instrument, Interest Rate, Stated Percentage

[8]

4.80%

4.80%

Debt Instrument, Face Amount

$ 350,000

$ 350,000

3.200% Senior Unsecured Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Aug. 1, 2017

Contractual maturity date

9/1/2024

Total debt and other obligations

$ 741,859

0

$ 741,859

0

Debt Instrument, Interest Rate, Stated Percentage

[8]

3.20%

3.20%

3.650% Senior Unsecured Notes [Member] | High Yield Bonds [Member]

Debt Instrument [Line Items]

Original issue date

Aug. 1, 2017

Contractual maturity date

9/1/2027

Total debt and other obligations

$ 990,965

0

$ 990,965

0

Debt Instrument, Interest Rate, Stated Percentage

[8]

3.70%

3.70%

Capital Lease Obligations and Other [Member]

Debt Instrument [Line Items]

Original Debt Issuance Date

Various

Contractual maturity date

[13]

Various

Total debt and other obligations

$ 227,783

$ 226,847

$ 227,783

$ 226,847

Percentage of debt instrument interest rate stated

[8]

Various

Capital Lease Obligations and Other [Member] | Maximum [Member]

Debt Instrument [Line Items]

Debt Instrument, Interest Rate, Stated Percentage

10.00%

10.00%

Fixed Rate Securitized Debt 2010 Tower Revenue Notes [Member]

Debt Instrument [Line Items]

Debt Instrument, Face Amount

$ 2,300,000

$ 2,300,000

Interest rate, increase (decrease)

5.00%

Variable Rate Revolver [Member]

Debt Instrument [Line Items]

Availability on revolver

2,500,000

$ 2,500,000

2015 Tower Revenue Notes 3.222% due 2042 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Total debt and other obligations

300,000

300,000

2015 Tower Revenue Notes 3.663% due 2045 [Member] | Securitized Debt [Member]

Debt Instrument [Line Items]

Total debt and other obligations

$ 700,000

$ 700,000

[1]

Exclusive of accrued interest.

[2]

Exclusive of accrued interest

[3]

The sum of quarterly information may not agree to year to date information due to rounding.

[4]

Inclusive of $33.8 million related to the write off of deferred financing costs

[5]

Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.

[6]

The losses related to write off of deferred financing costs.

[7]

As of December 31, 2017, the undrawn availability under the 2016 Revolver was $2.5 billion.

[8]

Represents the weighted-average stated interest rate.

[9]

The 2016 Revolver and senior unsecured term loan A facility ("2016 Term Loan A") bear interest at a rate per annum equal to LIBOR plus a credit spread ranging from 1.125% to 2.000%, based on the Company's senior unsecured debt rating. The Company pays a commitment fee of approximately 0.200% per annum on the undrawn available amount under the 2016 Revolver.

[10]

(d)The Secured Notes, Series 2009-1, Class A-1 and Secured Notes, Series 2009-1, Class A-2 are collectively referred to herein as "2009 Securitized Notes."

[11]

(e)The Tower Revenue Notes, Series 2010-3 ("January 2010 Tower Revenue Notes"), Tower Revenue Notes, Series 2010-6 ("August 2010 Tower Revenue Notes") and Tower Revenue Notes, Series 2015-1 and 2015-2 ("May 2015 Tower Revenue Notes") are collectively referred to herein as "Tower Revenue Notes."

[12]

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) 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, 2017, the Tower Revenue Notes have principal amounts of $2.3 billion, $300.0 million and $700.0 million, with anticipated repayment dates in 2020, 2022 and 2025, respectively.

[13]

The Company's capital 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 30 years.

Debt and Other Obligations (Tex

Debt and Other Obligations (Textuals) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt and other obligations		$ 16,159,620,000		$ 12,171,142,000
Borrowings under revolving credit facility		2,820,000,000		3,440,000,000	$ 1,790,000,000
Debt Instrument, Face Amount							$ 1,650,000,000
Debt Instrument, Maturity Date							Jan. 1, 2023
Extinguishment of Debt, Amount				4,026,390,000	1,069,361,000
Principal balance outstanding on debt instruments		16,261,760,000
Cash and equivalents		$ 314,094,000		567,599,000
Debt Instrument, Issuance Date							Oct. 1, 2012
Debt Instrument, Interest Rate, Stated Percentage							5.30%
Debt Instrument, Covenant Description		7.0 to 1.0
Variable Rate Revolver [Member]
Debt Instrument [Line Items]
Availability on revolver		$ 2,500,000,000
Fixed Rate Securitized Debt 2010 Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Interest rate, increase (decrease)		5.00%
Debt Instrument, Face Amount		$ 2,300,000,000
Capital Lease Obligations and Other [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 227,783,000		226,847,000
Contractual maturity date, start		1 year
Contractual maturity date, end		30 years
2016 Revolver [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 3,500,000,000
Debt Instrument, Issuance Date		Aug. 1, 2017
Line of Credit Facility, Change in Borrowing Capacity		$ 1,000,000,000
Debt Instrument, Maturity Date		Aug. 1, 2022
Extinguishment of Debt, Amount				500,000,000
2016 Term Loan A [Member]
Debt Instrument [Line Items]
Debt Instrument, Issuance Date		Feb. 1, 2017
Debt Instrument, Maturity Date		Jan. 1, 2022
Securitized Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 3,332,309,000		3,345,805,000
Securitized Debt [Member] | 2015 Tower Revenue Notes 3.222% due 2042 [Member]
Debt Instrument [Line Items]
Total debt and other obligations		300,000,000
Securitized Debt [Member] | 2015 Tower Revenue Notes 3.663% due 2045 [Member]
Debt Instrument [Line Items]
Total debt and other obligations		700,000,000
Bank Debt [Member]
Debt Instrument [Line Items]
Total debt and other obligations		3,376,588,000		1,954,173,000
Bank Debt [Member] | 2016 Revolver [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				2,500,000,000
Total debt and other obligations		$ 980,000,000	[1]	0
Debt Instrument, Issuance Date		Jan. 1, 2016
Debt Instrument, Interest Rate, Stated Percentage	[2],[3]	2.60%
Bank Debt [Member] | 2016 Term Loan A [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 2,396,588,000		1,954,173,000
Debt Instrument, Face Amount				2,000,000,000
Debt Instrument, Issuance Date		Jan. 1, 2016
Debt Instrument, Interest Rate, Stated Percentage	[2],[3]	2.60%
January 2010 Tower Revenue Notes [Member]
Debt Instrument [Line Items]
Repayments of Debt						$ 300,000,000
High Yield Bonds [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 9,222,940,000		6,644,317,000
High Yield Bonds [Member] | May 2016 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 1,000,000,000
Debt Instrument, Issuance Date				May 1, 2016
High Yield Bonds [Member] | 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Total debt and other obligations		842,090,000		$ 840,322,000
Debt Instrument, Face Amount		$ 850,000,000
Debt Instrument, Maturity Date						Apr. 1, 2022
Debt Instrument, Issuance Date		Apr. 1, 2014				Apr. 1, 2014
Debt Instrument, Interest Rate, Stated Percentage		4.90%	[2]			4.90%
High Yield Bonds [Member] | 4.000% Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 493,833,000		0
Debt Instrument, Face Amount		$ 500,000,000
Debt Instrument, Maturity Date		Mar. 1, 2027
Debt Instrument, Issuance Date		Feb. 1, 2017
Debt Instrument, Interest Rate, Stated Percentage	[2]	4.00%
High Yield Bonds [Member] | 2016 Senior Unsecured Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 1,500,000,000
Debt Instrument, Issuance Date				Feb. 1, 2016
High Yield Bonds [Member] | 3.400% Senior Notes [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 849,859,000		$ 849,698,000
Debt Instrument, Face Amount				$ 250,000,000
Debt Instrument, Issuance Date		Feb. 1, 2016
Debt Instrument, Interest Rate, Stated Percentage		3.40%	[2]	3.40%
High Yield Bonds [Member] | 3.700% Senior Notes [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 742,727,000		$ 741,908,000
Debt Instrument, Face Amount				$ 750,000,000
Debt Instrument, Maturity Date				Jun. 1, 2026
Debt Instrument, Issuance Date		May 1, 2016
Debt Instrument, Interest Rate, Stated Percentage		3.70%	[2]	3.70%
High Yield Bonds [Member] | 4.450% Senior Notes [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 891,145,000		$ 890,118,000
Debt Instrument, Face Amount				$ 900,000,000
Debt Instrument, Maturity Date				Feb. 1, 2026
Debt Instrument, Issuance Date		Feb. 1, 2016
Debt Instrument, Interest Rate, Stated Percentage		4.50%	[2]	4.50%
High Yield Bonds [Member] | 4.750% Senior Unsecured Notes [Member] [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 343,209,000		$ 0
Debt Instrument, Face Amount		$ 350,000,000
Debt Instrument, Maturity Date		May 1, 2047
Debt Instrument, Issuance Date		May 1, 2017
Debt Instrument, Interest Rate, Stated Percentage	[2]	4.80%
High Yield Bonds [Member] | August 2017 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,750,000,000
Debt Instrument, Issuance Date		Aug. 1, 2017
High Yield Bonds [Member] | August 2017 Senior Unsecured 3.200% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 750,000,000
Debt Instrument, Maturity Date		Sep. 1, 2024
Debt Instrument, Interest Rate, Stated Percentage		3.20%
High Yield Bonds [Member] | August 2017 Senior Unsecured 3.650% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,000,000,000
Debt Instrument, Maturity Date		Sep. 1, 2027
Debt Instrument, Interest Rate, Stated Percentage		3.70%
2.250% Senior Notes [Member] | September 2016 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 700,000,000
Debt Instrument, Maturity Date				Sep. 1, 2021
Debt Instrument, Issuance Date				Sep. 1, 2016
Debt Instrument, Interest Rate, Stated Percentage				2.30%
2.381% Secured Notes [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount				$ 500,000,000
2.381% Secured Notes [Member] | September 2016 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				2.40%
Repayments of Debt				$ 500,000,000
Issuance of debt obligation [Member] | 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt		$ 839,000,000
2012 Revolver [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount				0
2012 secured notes tranche B [Member]
Debt Instrument [Line Items]
Total debt and other obligations		$ 1,000,000,000
Maximum [Member] | Variable Rate Revolver 2012 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.00%
Maximum [Member] | Capital Lease Obligations and Other [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		10.00%
Minimum [Member] | Variable Rate Revolver 2012 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.10%
August 2010 Tower Revenue Notes ARD [Domain] | Securitized Debt [Member] | Fixed Rate Securitized Debt August 2010 Tower Revenue Notes 5 [Member]
Debt Instrument [Line Items]
Total debt and other obligations					$ 250,000,000
Collateral Pledged [Member]
Debt Instrument [Line Items]
Debt Instrument, PPE Collaterized Amount		$ 1,100,000,000
Additional Principal Incurred [Member] | 2016 Term Loan A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 500,000,000
Additional Principal Incurred [Member] | Bank Debt [Member] | Senior Unsecured 364-Day Revolving Credit Facility [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				1,000,000,000
February 2016 Senior Note Upsizing [Member] | High Yield Bonds [Member] | 3.400% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 600,000,000
Debt Instrument, Interest Rate, Stated Percentage				3.40%
[1]	As of December 31, 2017, the undrawn availability under the 2016 Revolver was $2.5 billion.
[2]	Represents the weighted-average stated interest rate.
[3]	The 2016 Revolver and senior unsecured term loan A facility ("2016 Term Loan A") bear interest at a rate per annum equal to LIBOR plus a credit spread ranging from 1.125% to 2.000%, based on the Company's senior unsecured debt rating. The Company pays a commitment fee of approximately 0.200% per annum on the undrawn available amount under the 2016 Revolver.

Debt and Other Obligations (Sch

Debt and Other Obligations (Scheduled Contractual Maturities) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
2,018	$ 116,045
2,019	167,458
2,020	155,051
2,021	1,824,568
2,022	3,701,737
Thereafter	10,296,901
Total Cash Obligations	16,261,760
Unamortized Discounts	(102,140)
Total Debt and Other Obligations Outstanding	$ 16,159,620

Debt and Other Obligations (Deb

Debt and Other Obligations (Debt Purchases and Repayments) (Details) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

[3]

Sep. 30, 2017

[3]

Jun. 30, 2017

[3]

Mar. 31, 2017

[3]

Dec. 31, 2016

[3]

Sep. 30, 2016

[3]

Jun. 30, 2016

[3]

Mar. 31, 2016

[3]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Debt Instrument [Line Items]

Principal Amount

$ (4,026,390)

$ (1,069,361)

Cash Paid

4,044,834

[1]

1,069,337

[2]

Gains (losses) on retirement of long-term obligations

$ 0

$ 0

$ 0

$ (3,525)

$ 0

$ (10,274)

$ (11,467)

$ (30,550)

$ (3,525)

(52,291)

[4]

(4,157)

[5]

Write-off of deferred financing costs and discounts

33,800

4,200

Fixed Rate Securitized Debt January 2010 Tower Revenue Notes 4 [Domain]

Debt Instrument [Line Items]

Principal Amount

(250,000)

Cash Paid

[2]

250,000

Gains (losses) on retirement of long-term obligations

[5]

(159)

2016 Term Loan A [Member]

Debt Instrument [Line Items]

Principal Amount

0

Cash Paid

0

Gains (losses) on retirement of long-term obligations

[6]

$ (3,525)

Variable Rate 2012 Term Loans Tranche A [Member]

Debt Instrument [Line Items]

Principal Amount

(629,375)

Cash Paid

[1]

629,375

Gains (losses) on retirement of long-term obligations

[4]

(1,498)

August 2010 Tower Revenue Notes [Member]

Debt Instrument [Line Items]

Principal Amount

0

Cash Paid

[1]

0

Gains (losses) on retirement of long-term obligations

[4]

(1,930)

WCP Securitized Notes [Member]

Debt Instrument [Line Items]

Principal Amount

(252,830)

Cash Paid

[2]

252,830

Gains (losses) on retirement of long-term obligations

[5]

2,105

Variable Rate 2012 Term Loans Tranche B [Member]

Debt Instrument [Line Items]

Principal Amount

(2,247,015)

(564,137)

Cash Paid

2,247,015

[1]

564,137

[2]

Gains (losses) on retirement of long-term obligations

(27,122)

[4]

(6,127)

[5]

Fixed Rate Securitized Debt January 2010 Tower Revenue Notes 2 [Member]

Debt Instrument [Line Items]

Principal Amount

(350,000)

Cash Paid

[1]

352,796

Gains (losses) on retirement of long-term obligations

[4]

(3,338)

Fixed Rate Securitized Debt August 2010 Tower Revenue Notes 5 [Member]

Debt Instrument [Line Items]

Principal Amount

(300,000)

Cash Paid

[1]

307,176

Gains (losses) on retirement of long-term obligations

[4]

(8,129)

Fixed Rate High Yield Bonds 7Point125 Percent Senior Notes [Member]

Debt Instrument [Line Items]

Principal Amount

(500,000)

Cash Paid

[1]

508,472

Gains (losses) on retirement of long-term obligations

[4]

$ (10,274)

Other Debt Instruments [Domain]

Debt Instrument [Line Items]

Principal Amount

(2,394)

Cash Paid

[2]

2,370

Gains (losses) on retirement of long-term obligations

[5]

$ 24

[1]

Exclusive of accrued interest.

[2]

Exclusive of accrued interest

[3]

The sum of quarterly information may not agree to year to date information due to rounding.

[4]

Inclusive of $33.8 million related to the write off of deferred financing costs

[5]

Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.

[6]

The losses related to write off of deferred financing costs.

Swaps Foreign Currency Swaps (D

Swaps Foreign Currency Swaps (Details) AUD in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017AUD	Dec. 31, 2015AUD
Derivative [Line Items]
Gains (Losses) on Settled Swaps | $	$ (328)	$ (2,608)	$ 54,475
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments | $			$ 65,200
Foreign Exchange [Member]
Derivative [Line Items]
Derivative, Notional Amount					AUD 1,400,000
May 2015 cash receipt from sale of CCAL [Domain]
Derivative [Line Items]
Derivative, Notional Amount				AUD 1,400,000
Derivative, Inception Date			May 14, 2015
Derivative, Maturity Date			Jun. 12, 2015
Derivative, Currency Sold			US Dollar
Derivative, Currency Bought			Australian Dollar
Derivative, Forward Exchange Rate					0.8072
Installment payment from Buyer [Domain]
Derivative [Line Items]
Derivative, Notional Amount				AUD 155,000	AUD 155,000
Derivative, Inception Date		May 14, 2015
Derivative, Maturity Date		Jan. 4, 2016
Derivative, Currency Sold		US Dollar
Derivative, Currency Bought		Australian Dollar
Derivative, Forward Exchange Rate		0.7984

Fair Value Disclosures (Estimat

Fair Value Disclosures (Estimated Fair Values and Carrying Amounts of Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	$ 314,094	$ 567,599
Cash and cash equivalents, fair value	314,094	567,599
Restricted cash, carrying value	126,065	129,547
Restricted cash, fair value	126,065	129,547
Debt and other obligations, carrying amount	16,159,620	12,171,142
Debt and other obligations, fair value	$ 16,643,725	$ 12,660,013

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation allowance, increase (decrease)	$ (21)	$ 21	$ (3,000)
Federal tax benefits	2,816	$ 227	$ (495)
Stock Compensation Plan [Member]
Operating Loss Carryforwards	237,000
U.S. Federal [Member]
Operating Loss Carryforwards	1,500,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	600,000
Foreign [Member]
Operating Loss Carryforwards	$ 53,200
Maximum [Member] | U.S. Federal [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Maximum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Maximum [Member] | Foreign [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2037
Minimum [Member] | U.S. Federal [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2024
Minimum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2018
Minimum [Member] | Foreign [Member]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2022

Income Taxes (Income (Loss) fro

Income Taxes (Income (Loss) from Continuing Operations before Income Taxes) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Domestic		$ 450,771	$ 349,041	$ 461,293
Foreign	[1]	19,822	24,813	12,536
Income (loss) from continuing operations before income taxes		$ 470,593	$ 373,854	$ 473,829
[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 Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Current Federal										$ (2,816)	$ (227)	$ 495
Current Foreign										(6,050)	(6,820)	(5,675)
Current State										(2,289)	(1,231)	(3,981)
Total current										(11,155)	(8,278)	(9,161)
Deferred Federal										(17,743)	(7,968)	44,716
Deferred Foreign										2,883	(601)	(1,048)
Deferred State										(28)	(34)	16,950
Total deferred										(14,888)	(8,603)	60,618
Benefit (provision) for income taxes		$ (14,753)		$ (2,383)		$ (4,538)		$ (4,369)		(26,043)	(16,881)	51,457
Tax adjustment related to the small cell REIT conversion	[2]									$ 0	$ 0	$ 33,759
[1]	The sum of quarterly information may not agree to year to date information due to rounding.
[2]	During the fourth quarter of 2015, the Company de-recognized the net deferred tax liabilities related to the Company's small cells previously included in one or more TRSs in conjunction with the inclusion of small cells in the REIT in January 2016.

Income Taxes Income Taxes Effec

Income Taxes Income Taxes Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017		Sep. 30, 2017	[3]	Jun. 30, 2017	[3]	Mar. 31, 2017	[3]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount										$ (164,707)	$ (130,849)	$ (165,840)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount										(430)	1,215	(527)
Tax adjustment related to REIT operations										158,812	121,092	(186,649)
Tax adjustment related to the small cell REIT conversion	[1]									0	0	33,759
Losses for which no tax benefit was recognized										(42)	(43)	(414)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount										21	(21)	3,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount										(2,115)	(1,085)	1,210
Foreign Income Tax Expense (Benefit), Continuing Operations										(3,168)	(7,421)	(6,723)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	[2]									(14,628)	0	0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount										214	231	343
Benefit (provision) for income taxes		$ (14,753)	[3]	$ (2,383)		$ (4,538)		$ (4,369)		(26,043)	$ (16,881)	$ 51,457
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	[2]									16,800
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax		$ 2,200								$ 2,200
[1]	During the fourth quarter of 2015, the Company de-recognized the net deferred tax liabilities related to the Company's small cells previously included in one or more TRSs in conjunction with the inclusion of small cells in the REIT in January 2016.
[2]	Pursuant to the Tax Cuts and Jobs Act, which was signed into law in December 2017, the Company was required to write down its net federal deferred tax asset in the amount of $16.8 million as a result of the reduction in the federal corporate tax rate offset by a benefit of $2.2 million related to the refund of the Company's alternative minimum tax credit carryforward.
[3]	The sum of quarterly information may not agree to year to date information due to rounding.

Income Taxes (Components of Def

Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property and equipment	$ 4,940	$ 3,945
Deferred site rental receivable	6,907	6,192
Deferred Tax Liabilities, Gross	11,847	10,137
Deferred Tax Assets, Goodwill and Intangible Assets	4,460	22,377
Net operating loss carryforwards	20,800	21,143
Deferred ground lease payable	2,060	1,646
Accrued liabilities	5,161	5,511
Receivable allowance	317	383
Other	1,431	1,726
Valuation allowance, asset	(1,172)	(6,627)
Total deferred income tax assets, net	33,057	46,159
Deferred Tax Assets, Net	21,210	36,022
Domestic Tax Authority [Member]
Valuation allowance, asset	0	(21)
Deferred Tax Assets, Net	25,260	42,927
State and Local Jurisdiction [Member]
Valuation allowance, asset	0	0
Deferred Tax Assets, Net	1,142	1,170
Foreign Tax Authority [Member]
Valuation allowance, asset	$ (1,172)	$ (6,606)

Income Taxes (Jurisdictional Co

Income Taxes (Jurisdictional Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes (Jurisdictional components of deferred taxes)
Gross, asset	$ 22,382	$ 42,649
Valuation allowance, asset	(1,172)	(6,627)
Net deferred income tax assets (liabilities)	21,210	36,022
Deferred Tax Liabilities, Net		36,022
U.S. Federal [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	1,500,000
Gross, asset	25,260	42,948
Valuation allowance, asset	0	(21)
Net deferred income tax assets (liabilities)	25,260	42,927
State and Local Jurisdiction [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	600,000
Gross, asset	1,142	1,170
Valuation allowance, asset	0	0
Net deferred income tax assets (liabilities)	1,142	1,170
Foreign [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	53,200
Gross, asset	(4,020)	(1,469)
Valuation allowance, asset	(1,172)	(6,606)
Deferred Tax Liabilities, Net	(5,192)	$ (8,075)
Stock Compensation Plan [Member]
Income Taxes (Jurisdictional components of deferred taxes)
Operating Loss Carryforwards	$ 237,000

Income Taxes Income Taxes (Unre

Income Taxes Income Taxes (Unrecognized Tax Benefits) (Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 3,080	$ 6,770
Additions based on current year tax positions	0	116
Reductions as a result of the lapse of statute limitations	(3,080)	(3,806)
Balance at end of year	$ 0	$ 3,080

Stockholders' Equity (Details)

Stockholders' Equity (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares		Sep. 30, 2017USD ($)$ / shares		Jun. 30, 2017USD ($)$ / shares		Mar. 31, 2017USD ($)$ / shares		Dec. 31, 2017USD ($)shares$ / shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Vesting Period									3 years
Preferred Stock, Liquidation Preference, Value	$ 1,650,000								$ 1,650,000	$ 0
Dividends, Common Stock, Cash	$ 428,800,000	[1]	$ 389,600,000	[1]	$ 350,300,000	[1]	$ 343,300,000	[1]	$ 1,512,034,000	1,244,423,000
Proceeds from Issuance of Common Stock										$ 1,325,865,000
Conversion factor, Preferred Stock | shares										1.188
6.875% Mandatory Convertible Preferred Stock, Par or Stated Value Per Share | $ / shares	$ 0.01								$ 0.01
Purchases of common stock, value									$ 23,300,000	$ 24,900,000	$ 29,700,000
At the Market Stock Offering Program, aggregate value of common stock	$ 500,000,000								$ 500,000,000
Life to Date Shares Sold Under ATM | shares	3,800,000								3,800,000
Life to Date Net Proceeds Under ATM	$ 323,800,000								$ 323,800,000
Life to Date Fees Under ATM	3,300,000								3,300,000
Availability Under ATM	$ 150,000,000								150,000,000
Common Stock, Dividends, Per Share, Cash Paid | $ / shares	$ 1.05		$ 0.950		$ 0.950		$ 0.950
Preferred Stock, Dividends, Per Share, Cash Paid | $ / shares	$ 17.1875		$ 18.142
Dividends, Preferred Stock, Cash	$ 28,400,000		$ 29,900,000								43,988,000
Net proceeds from issuance of preferred stock									$ 1,607,759,000	0	$ 0
Minimum [Member]
Conversion factor, Preferred Stock | shares									8.6806
Maximum [Member]
Conversion factor, Preferred Stock | shares									10.4167
Preferred Stock [Member]
Dividends Payable, Date Declared	Dec. 15, 2017		Sep. 21, 2017
Dividends Payable, Date of Record	Jan. 15, 2018		Oct. 15, 2017
Dividends Payable, Date to be Paid	Feb. 1, 2018		Nov. 1, 2017
Common Stock [Member]
Dividends Payable, Date Declared	Oct. 15, 2017		Aug. 3, 2017		May 18, 2017		Feb. 17, 2017
Dividends Payable, Date of Record	Dec. 15, 2017		Sep. 15, 2017		Jun. 16, 2017		Mar. 17, 2017
Dividends Payable, Date to be Paid	Dec. 29, 2017		Sep. 29, 2017		Jun. 30, 2017		Mar. 31, 2017
November 2016 Equity Offering [Member]
Proceeds from Issuance of Common Stock										$ 1,000,000,000
Preferred Stock [Member]
Preferred Stock, Liquidation Preference, Value	$ 1,000								$ 1,000
Preferred Stock, Redemption Date									Aug. 1, 2020
Preferred Stock, Dividend Rate, Percentage									6.875%
Preferred Stock [Member] | July 2017 Equity Offering [Member]
Stock Issued During Period, Shares, New Issues | shares									1,650,000
Sale of Stock, Transaction Date									Jul. 26, 2017
Preferred Stock, Dividend Rate, Percentage									6.875%
Preferred Stock, Per Share Sales Price | $ / shares									$ 1,000
Net proceeds from issuance of preferred stock									$ 1,600,000,000
Common Stock [Member]
Stock Issued During Period, Shares, New Issues | shares									45,142,300	15,178,064
Proceeds from Issuance of Common Stock										$ 152,000
Purchases of common stock, shares | shares									(259,331)	(289,531)	(336,526)
Common Stock [Member] | May 2017 Equity Offering [Member]
Stock Issued During Period, Shares, New Issues | shares									4,750,000
Proceeds from Issuance of Common Stock									$ 442,000,000
Sale of Stock, Transaction Date									May 1, 2017
Common Stock [Member] | July 2017 Equity Offering [Member]
Stock Issued During Period, Shares, New Issues | shares									40,150,000
Proceeds from Issuance of Common Stock									$ 3,800,000,000
Sale of Stock, Transaction Date									Jul. 26, 2017
Common Stock [Member] | November 2016 Equity Offering [Member]
Stock Issued During Period, Shares, New Issues | shares										11,400,000
Preferred Stock [Member] | Preferred Stock [Member]
Conversion of Stock, Shares Converted | shares										9,800,000
Preferred Stock [Member] | Common Stock [Member]
Conversion of Stock, Shares Issued | shares										11,600,000
[1]	Inclusive of dividends accrued for holders of unvested RSUs, which will be paid when and if the RSUs vest

Stockholders' Equity Tax Treatm

Stockholders' Equity Tax Treatment of Dividends Paid (Details) - $ / shares	3 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid	$ 17.1875	$ 18.142
Common Stock, Dividends, Per Share, Cash Paid	$ 1.05	$ 0.950	$ 0.950	$ 0.950
Preferred Stock [Member]
Class of Stock [Line Items]
Payment Date	Feb. 1, 2018	Nov. 1, 2017
Common Stock [Member]
Class of Stock [Line Items]
Payment Date	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017
Common Stock [Member]
Class of Stock [Line Items]
Non-Taxable Distribution	$ 0	$ 0	$ 0	$ 0
Ordinary Taxable Dividend Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid		18.142
Common Stock, Dividends, Per Share, Cash Paid	1.050	0.950	0.950	0.950
Qualified Taxable Dividend Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid		6.629
Common Stock, Dividends, Per Share, Cash Paid	0.384	0.347	0.347	0.347
Long-Term Capital Gain Distribution Per Share [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid		0
Common Stock, Dividends, Per Share, Cash Paid	$ 0	$ 0	$ 0	$ 0

Stock-based Compensation (Narra

Stock-based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)	11.2
Vesting Period	3 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)	3
Shares granted, number of shares	1.3	1.3
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)	$ 73.52	$ 68.53	$ 69.96
Weighted-average requisite service period (years)	2 years 6 months
Restricted stock or unit expense	$ 88.7	$ 76.3	$ 57.1
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, number of shares	0.6
Time Vesting Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, number of shares	0.7
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized	$ 72.9
Period for recognition	1 year

Stock-based Compensation (Summa

Stock-based Compensation (Summary of Restricted Stock Awards Activity) (Details) - Restricted Stock Units (RSUs) [Member] - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1,300	1,300
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	1,359
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	747
Shares outstanding at the beginning of the year, number of shares	2,677
Shares outstanding at the end of year, number of shares	2,968	2,677
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	(321)

Stock-based Compensation (Sum73

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation [Abstract]
Risk-free rate	1.50%	0.90%	1.00%
Expected volatility	18.00%	19.00%	19.00%
Expected dividend rate	4.40%	4.24%	4.00%

Stock-based Compensation (Sum74

Stock-based Compensation (Summary of Restricted Stock Awards Vested) (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares vested	747	828	946
Fair value on vesting date	$ 67,241	$ 71,325	$ 83,244
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	2,968	2,677
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	1,359
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	747
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	321

Stock-based Compensation (Stock

Stock-based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 96,435	$ 96,538	$ 67,148
Site Rental Cost of Operations [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	14,942	14,371	8,969
Network Services and Other Costs of Operations [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,961	7,717	5,370
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 76,532	$ 74,450	$ 52,809

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Subject to or Available for Operating Lease [Line Items]
Weighted average remaining term of tenant leases	6 years
Maximum Current Term	20 years
Tenant Leases 2017	$ 3,401,845
Tenant Leases 2018	3,277,019
Tenant Leases 2019	3,160,514
Tenant Leases 2020	3,028,825
Tenant Leases 2021	2,805,519
Tenant Leases thereafter	5,628,294
Total tenant leases	$ 21,302,016
Percentage of wireless infrastructure that has non-cancelable operating leases	76.00%
Operating Leases, Owned Land Under Tower, Expiration Term	20 years
Operating Leases, Leased Land Under Tower, Expiration Term	10 years
Operating leases 2017	$ 635,321
Operating leases 2018	632,775
Operating leases 2019	622,587
Operating leases 2020	617,951
Operating leases 2021	609,796
Operating leases thereafter	7,941,187
Total operating leases	11,059,617
Rental expense from operating leases	710,200	$ 677,900	$ 657,100
Contingent rental payments	$ 100,100	$ 96,900	$ 91,800
Greater than 10 Years, Inclusive of Renewals at the Company's Option [Member]
Property Subject to or Available for Operating Lease [Line Items]
Percentage of site rental gross margin that is derived from towers where the lease for the land has a final expiration date	90.00%
Greater than 20 Years, Inclusive of Renewals at the Company's Option [Member]
Property Subject to or Available for Operating Lease [Line Items]
Percentage of site rental gross margin that is derived from towers where the lease for the land has a final expiration date	75.00%

Operating Segments and Concen77

Operating Segments and Concentrations of Credit Risk (Major Customers) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allocated Share-based Compensation Expense	$ 96,435	$ 96,538	$ 67,148
Concentration Risk, Percentage	86.00%	88.00%	89.00%
AT&T [Member]
Concentration Risk, Percentage	25.00%	27.00%	27.00%
Sprint [Member]
Concentration Risk, Percentage	17.00%	16.00%	19.00%
Verizon Wireless [Member]
Concentration Risk, Percentage	22.00%	22.00%	21.00%
T-Mobile [Member]
Concentration Risk, Percentage	22.00%	23.00%	22.00%
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 76,500	$ 74,500	$ 52,800
Cost of Sales [Member]
Allocated Share-based Compensation Expense	$ 19,900	$ 22,100	$ 14,300

Operating Segments and Concen78

Operating Segments and Concentrations of Credit Risk Operating Segment Results (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Tower Count	40,000
Segment Site Rental Revenues	$ 3,669,191	$ 3,233,307	$ 3,018,413
Segment Network Services and Other Revenues	686,414	687,918	645,438
Segment Revenues	4,355,605	3,921,225	3,663,851
Segment Site Rental Cost of Operations	1,108,854	987,668	934,370
Segment Network Services and Other Cost of Operations	414,825	409,454	352,187
Segment Cost of Operations	1,523,679	1,397,122	1,286,557
Segment site rental gross margin	2,560,337	2,245,639	2,084,043
Segment network services gross margin	271,589	278,464	293,251
Segment General and Administrative Expenses	350,165	296,580	258,111
Segment Operating Profit	2,481,761	2,227,523	2,119,183
Allocated Share-based Compensation Expense	96,435	96,538	67,148
Amortization of prepaid lease purchase price adjustments	20,100	21,300	20,500
Depreciation, Amortization and Accretion, Net	1,242,408	1,108,551	1,036,178
Interest expense and amortization of deferred financing costs	590,682	515,032	527,128
Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes	81,643	133,548	14,900
Income (Loss) from Continuing Operations Before Income Taxes	470,593	373,854	473,829
Capital Expenditures	1,228,071	873,883	908,892
Assets	32,229,570	22,675,092	21,936,966
Goodwill	$ 10,021,468	5,757,676	5,513,551
Fiber Miles	60,000
Towers [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues	$ 2,899,554	2,830,708	2,734,045
Segment Network Services and Other Revenues	636,532	603,689	591,655
Segment Revenues	3,536,086	3,434,397	3,325,700
Segment Site Rental Cost of Operations	844,795	840,209	827,175
Segment Network Services and Other Cost of Operations	374,134	344,595	309,025
Segment Cost of Operations	1,218,929	1,184,804	1,136,200
Segment site rental gross margin	2,054,759	1,990,499	1,906,870
Segment network services gross margin	262,398	259,094	282,630
Segment General and Administrative Expenses	93,662	92,903	91,899
Segment Operating Profit	2,223,495	2,156,690	2,097,601
Capital Expenditures	418,476	429,526	564,753
Assets	17,940,893	18,394,572	17,974,847
Goodwill	5,127,259	5,114,639	4,863,847
Small Cells [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues	769,637	402,599	284,368
Segment Network Services and Other Revenues	49,882	84,229	53,783
Segment Revenues	819,519	486,828	338,151
Segment Site Rental Cost of Operations	264,059	147,459	107,195
Segment Network Services and Other Cost of Operations	40,691	64,859	43,162
Segment Cost of Operations	304,750	212,318	150,357
Segment site rental gross margin	505,578	255,140	177,173
Segment network services gross margin	9,191	19,370	10,621
Segment General and Administrative Expenses	89,048	60,676	38,379
Segment Operating Profit	425,721	213,834	149,415
Capital Expenditures	782,409	409,710	314,882
Assets	13,669,636	3,440,600	3,511,956
Goodwill	4,894,209	643,037	649,704
Other [Member]
Segment Reporting Information [Line Items]
Segment General and Administrative Expenses	167,455	143,001	127,833
Segment Operating Profit	(167,455)	(143,001)	(127,833)
Allocated Share-based Compensation Expense	96,435	96,538	67,148
Depreciation, Amortization and Accretion, Net	1,242,408	1,108,551	1,036,178
Interest expense and amortization of deferred financing costs	590,682	515,032	527,128
Other income (expenses) to reconcile to income (loss) from continuing operations before income taxes	81,643	133,548	14,900
Capital Expenditures	27,186	34,647	29,257
Assets	619,041	839,920	450,163
Goodwill	0	0	0
Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Allocated Share-based Compensation Expense	76,500	74,500	52,800
Cost of Sales [Member]
Segment Reporting Information [Line Items]
Allocated Share-based Compensation Expense	$ 19,900	$ 22,100	$ 14,300

Supplemental Cash Flow Inform79

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Line Items]
Interest paid	$ 546,543	$ 470,655	$ 489,970
Income taxes paid (refund)	16,427	13,821	28,771
Increase (Decrease) in accounts payable for purchases of property and equipment	2,279	17,922	(7,042)
Purchase of property and equipment under capital leases and installment purchases	31,999	52,322	60,270
Installment payment receivable for sale of subsidiary	0	0	117,384
Preferred Stock Dividends Accrued but not Paid	$ 28,359	$ 0	$ 10,997

Quarterly Financial Informati80

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Net revenues	$ 1,238,090		$ 1,063,238		$ 1,038,335		$ 1,015,942		$ 1,032,416		$ 992,016		$ 962,409		$ 934,384		$ 4,355,605	$ 3,921,225		$ 3,663,851
Operating income (loss)	268,429		260,567		258,500		256,549		262,038		244,254		231,185		211,739		1,044,045	949,216		946,180
Benefit (provision) for income taxes	(14,753)		(2,383)		(4,538)		(4,369)										(26,043)	(16,881)		51,457
Gains (losses) on retirement of long-term obligations	0		0		0		(3,525)		0		(10,274)		(11,467)		(30,550)		(3,525)	(52,291)	[2]	(4,157)	[3]
Net income (loss) attributable to CCIC stockholders	$ 98,104		$ 115,194		$ 112,114		$ 119,138		$ 124,709		$ 98,366		$ 86,058		$ 47,840		$ 444,550	$ 356,973		$ 1,520,992
Net income (loss) attributable to CCIC common stockholders, per common share:
Basic (in dollars per share)	$ 0.17		$ 0.22		$ 0.31		$ 0.33		$ 0.35		$ 0.26		$ 0.22		$ 0.11		$ 1.01	$ 0.95		$ 4.44
Diluted (in dollars per share)	$ 0.17		$ 0.21		$ 0.31		$ 0.33		$ 0.35		$ 0.26		$ 0.22		$ 0.11		$ 1.01	$ 0.95		$ 4.42
[1]	The sum of quarterly information may not agree to year to date information due to rounding.
[2]	Inclusive of $33.8 million related to the write off of deferred financing costs
[3]	Inclusive of $4.2 million related to the write off of deferred financing costs, premiums and discounts.

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2012
Subsequent Event [Line Items]
Debt Instrument, Issuance Date						Oct. 1, 2012
Debt Instrument, Face Amount						$ 1,650
Debt Instrument, Interest Rate, Stated Percentage						5.30%
Debt Instrument Maturity Date Range						Jan. 1, 2023
Common Stock, Dividends, Per Share, Cash Paid	$ 1.05	$ 0.950	$ 0.950	$ 0.950
Dividend Declared [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared					Feb. 21, 2018
Dividends Payable, Date to be Paid					Mar. 30, 2018
Dividends Payable, Date of Record					Mar. 16, 2018
Paid subsequent to year end [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$ 1.050
Debt [Member] | January 2018 Senior Note [Member] | High Yield Bonds [Member]
Subsequent Event [Line Items]
Debt Instrument, Issuance Date					Jan. 16, 2018
Debt Instrument, Face Amount	$ 1,750				$ 1,750
Debt [Member] | 3.150% Senior Notes [Member] | High Yield Bonds [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount	$ 750				$ 750
Debt Instrument, Interest Rate, Stated Percentage	3.20%				3.20%
Debt Instrument Maturity Date Range					Jul. 1, 2023
Debt [Member] | 3.800% Senior Notes [Member] | High Yield Bonds [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount	$ 1,000				$ 1,000
Debt Instrument, Interest Rate, Stated Percentage	3.80%				3.80%
Debt Instrument Maturity Date Range					Feb. 1, 2028

Schedule II - Valuation and Q82

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		$ 11,314		$ 9,574	$ 10,037
Charged to operations		4,360		4,873	2,958
Credited to operations		(4,591)		(3,133)	(3,421)
Effect of exchange rate changes or Other adjustments		0		0	0
Valuation allowance and reserves, other adjustments		2,663	[1]	0	0
Balance at end of year		13,746		11,314	9,574
Deferred Tax Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		6,627		1,994	21,038
Charged to operations		59		586	164
Credited to operations		0		0	0
Valuation Allowances and Reserves, Additions for Recoveries		5,514		2,236	3,000
Effect of exchange rate changes or Other adjustments		0		0	0
Valuation allowance and reserves, other adjustments	[2]	0		6,283	(16,208)
Balance at end of year		$ 1,172		$ 6,627	$ 1,994
[1]	the 2017 Acquisitions.
[2]	Inclusive of (1) the effects of acquisitions and (2) the inclusion of small cells in the REIT in January 2016.

Schedule III - Schedule of Re83

Schedule III - Schedule of Real Estate and Depreciation (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2017USD ($)tower	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate, Number of Units | tower		40,153
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 4,580,581
Gross Amount of Accumulated Depreciation Carried		(7,303,230)	$ (6,446,448)	$ (5,648,598)
Depreciation		(889,983)	(810,549)
Amount of Accumulated Depreciation Sold or Disposed		26,391	24,190
Other Deductions to Accumulated Depreciation		6,810	(11,491)
Real Estate Period Deductions to Accumulated Depreciation		33,201	12,699
Gross Amount of Property Carried		20,109,562	16,120,896	$ 15,110,835
Other Acquisitions	[2],[3]	2,787,829	130,139
Wireless Infrastructure Construction and Improvements		1,062,589	709,538
Purchase of land interests		80,647	74,579
Sustaining Capital Expenditures		56,480	55,417
Other Additions	[4]	46,537	95,049
Total Additions		4,034,082	1,064,722
Cost of Real Estate Sold or Disposed		$ (45,416)	$ (54,661)
[1]	Certain of the Company's debt is secured by (1) a pledge of the equity interests in each applicable issuer and (2) a security interest in the applicable issuers' leases with tenants to lease tower space (space licenses).
[2]	Includes acquisitions of communications infrastructure.
[3]	Inclusive of changes between the final purchase price allocation and the preliminary purchase price allocations.
[4]	The Company has omitted this information, as it would be impracticable to compile such information on a tower-by-tower basis.