Operating Segments Operating Segments Table (Details) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2018 USD ($)		Sep. 30, 2017 USD ($)		Sep. 30, 2018 USD ($)		Sep. 30, 2017 USD ($)		Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Tower Count		40,000				40,000
Segment site rental revenues		$ 1,184		$ 893		$ 3,507		$ 2,619
Network services and other revenue		191		170		497		499
Revenues		$ 1,375		1,063		$ 4,004		3,118
Fiber Miles		65,000				65,000
Segment site rental cost of operations	[1]	$ 355		281		$ 1,057		815
Network services and other costs	[1]	119		107		304		310
Segment selling, general and administrative expenses		145		100		418		300
Stock-based compensation expense						79		67
Depreciation, Amortization and Accretion, Net		385		296		1,138		880
Interest expense and amortization of deferred financing costs		160		154		478		430
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		169		118		471		358
Capital expenditures						1,241		852
Total Assets		32,644				32,644				$ 32,229
Amortization of prepaid lease purchase price adjustments		5				15
Segment cost of operations share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		7		6		19		12
Towers [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		782		725		2,318		2,159
Network services and other revenue		189		153		489		461
Revenues		971		878		2,807		2,620
Segment site rental cost of operations		215		212		641		632
Network services and other costs		115		91		292		277
Segment cost of operations	[1]	330	[2]	303	[2]	933	[3]	909	[3]
Segment site rental gross margin		567		513		1,677		1,527
Segment network services gross margin		74		62		197		184
Segment selling, general and administrative expenses		28	[2]	22	[2]	81	[3]	69	[3]
Segment Operating Profit		613		553		1,793		1,642
Capital expenditures		123		109		318		317
Total Assets		17,694		18,099		17,694		18,099
Small Cells [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		402		168		1,189		460
Network services and other revenue		2		17		8		38
Revenues		404		185		1,197		498
Segment site rental cost of operations		131		60		388		158
Network services and other costs		1		14		6		31
Segment cost of operations	[1]	132	[2]	74	[2]	394	[3]	189	[3]
Segment site rental gross margin		271		108		801		302
Segment network services gross margin		1		3		2		7
Segment selling, general and administrative expenses		45	[2]	18	[2]	131	[3]	55	[3]
Segment Operating Profit		227		93		672		254
Capital expenditures		348		172		900		514
Total Assets		14,326		5,927		14,326		5,927
Consolidated Total [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		1,184		893		3,507		2,619
Network services and other revenue		191		170		497		499
Revenues		1,375		1,063		4,004		3,118
Segment site rental cost of operations		346		272		1,029		790
Network services and other costs		116		105		298		308
Segment cost of operations	[1]	462	[2]	377	[2]	1,327	[3]	1,098	[3]
Segment site rental gross margin		838		621		2,478		1,829
Segment network services gross margin		75		65		199		191
Segment selling, general and administrative expenses		73	[2]	40	[2]	212	[3]	124	[3]
Segment Operating Profit		840		646		2,465		1,896
Stock-based compensation expense		32		25		84		67
Depreciation, Amortization and Accretion, Net		385		296		1,138		880
Interest expense and amortization of deferred financing costs		160		154		478		430
Other expenses to reconcile to income (loss) from continuing operations before income taxes		47		12		153		40
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		169		118		471		358
Capital expenditures		478		289		1,241		852
Total Assets		32,644		31,012		32,644		31,012
Other [Member]
Segment Reporting Information [Line Items]
Segment selling, general and administrative expenses		47	[2]	41	[2]	141	[3]	121	[3]
Segment Operating Profit
Stock-based compensation expense		32		25		84		67
Depreciation, Amortization and Accretion, Net		385		296		1,138		880
Interest expense and amortization of deferred financing costs		160		154		478		430
Other expenses to reconcile to income (loss) from continuing operations before income taxes	[4]	47		12		153		40
Capital expenditures		7		8		23		21
Total Assets		624		6,986		624		6,986
Segment G&A share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		$ 25		$ 19		$ 65		$ 55

[1] Exclusive of depreciation, amortization and accretion shown separately.

[2] Segment cost of operations excludes (1) stock-based compensation expense of $7 million and $6 million for the three months ended September 30, 2018 and 2017, respectively, and (2) prepaid lease purchase price adjustments of $5 million for both of the three months ended September 30, 2018 and 2017. Selling, general and administrative expenses exclude stock-based compensation expense of $25 million and $19 million for the three months ended September 30, 2018 and 2017, respectively.

[3] Segment cost of operations excludes (1) stock-based compensation expense of $19 million and $12 million for the nine months ended September 30, 2018 and 2017, respectively, and (2) prepaid lease purchase price adjustments of $15 million for both of the nine months ended September 30, 2018 and 2017. Selling, general and administrative expenses exclude stock-based compensation expense of $65 million and $55 million for the nine months ended September 30, 2018 and 2017, respectively.

[4] See condensed consolidated statement of operations for further information.