Operating Segments Operating Segments Table (Details) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2019 USD ($)		Jun. 30, 2018 USD ($)		Jun. 30, 2019 USD ($)		Jun. 30, 2018 USD ($)		Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Tower Count		40,000				40,000
Fiber Miles		75,000				75,000
Amortization of prepaid lease purchase price adjustments		$ 5				$ 10
Segment site rental revenues		1,238		$ 1,169		2,457		$ 2,323
Services and other revenue		240		161		447		307
Segment Revenues		1,478		1,330		2,904		2,630
Segment site rental cost of operations	[1]	365		355		726		702
Services and other costs	[1]	138		99		263		185
Segment selling, general and administrative expenses		155		138		307		273
Stock-based compensation expense						62		47
Depreciation, Amortization and Accretion, Net		393		379		787		753
Interest expense and amortization of deferred financing costs		169		158		337		318
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		250		185		466		303
Capital expenditures						998		763
Total Assets		38,147				38,147				$ 32,785
Segment cost of operations share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		8		6		14		13
Towers [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		816		771		1,621		1,536
Services and other revenue		237		158		440		300
Segment Revenues		1,053		929		2,061		1,836
Segment site rental cost of operations		218		216		429		427
Services and other costs		134		94		254		176
Segment cost of operations	[3]	352	[2]	310	[2]	683	[4]	603	[4]
Segment site rental gross margin		598		555		1,192		1,109
Segment network services gross margin		103		64		186		124
Segment selling, general and administrative expenses		24	[2]	27	[2]	50	[4]	53	[4]
Segment Operating Profit		677		592		1,328		1,180
Capital expenditures		136		98		257		195
Total Assets		22,149		17,780		22,149		17,780
Fiber [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		422		398		836		787
Services and other revenue		3		3		7		7
Segment Revenues		425		401		843		794
Segment site rental cost of operations		136		130		277		256
Services and other costs		2		3		5		5
Segment cost of operations	[3]	138	[2]	133	[2]	282	[4]	261	[4]
Segment site rental gross margin		286		268		559		531
Segment network services gross margin		1		0		2		2
Segment selling, general and administrative expenses		51	[2]	44	[2]	98	[4]	87	[4]
Segment Operating Profit		236		224		463		446
Capital expenditures		371		289		726		552
Total Assets		15,215		14,100		15,215		14,100
Consolidated Total [Member]
Segment Reporting Information [Line Items]
Segment site rental revenues		1,238		1,169		2,457		2,323
Services and other revenue		240		161		447		307
Segment Revenues		1,478		1,330		2,904		2,630
Segment site rental cost of operations		354		346		706		683
Services and other costs		136		97		259		181
Segment cost of operations	[3]	490	[2]	443	[2]	965	[4]	864	[4]
Segment site rental gross margin		884		823		1,751		1,640
Segment network services gross margin		104		64		188		126
Segment selling, general and administrative expenses		75	[2]	71	[2]	148	[4]	140	[4]
Segment Operating Profit		913		816		1,791		1,626
Stock-based compensation expense		32		26		61		52
Depreciation, Amortization and Accretion, Net		393		379		787		753
Interest expense and amortization of deferred financing costs		169		158		337		318
Other expenses to reconcile to income (loss) from continuing operations before income taxes	[5]	13		21		28		106
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		250		185		466		303
Capital expenditures		518		393		998		763
Total Assets		38,147		32,374		38,147		32,374
Other [Member]
Segment Reporting Information [Line Items]
Segment selling, general and administrative expenses		56		47		112		94
Segment Operating Profit
Stock-based compensation expense		32		26		61		52
Depreciation, Amortization and Accretion, Net		393		379		787		753
Interest expense and amortization of deferred financing costs		169		158		337		318
Other expenses to reconcile to income (loss) from continuing operations before income taxes	[5]	13		21		28		106
Capital expenditures		11		6		15		16
Total Assets		783		494		783		494
Segment G&A share-based compensation [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense		$ 24		$ 20		$ 47		$ 39

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

[2] Segment cost of operations for the three months ended June 30, 2019 and 2018 excludes (1) stock-based compensation expense of $8 million and $6 million, respectively, and (2) prepaid lease purchase price adjustments of $5 million, for both periods. For the three months ended June 30, 2019 and 2018 segment selling, general and administrative expenses exclude stock-based compensation expense of $24 million and $20 million, respectively.

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

[4] Segment cost of operations for the six months ended June 30, 2019 and 2018 excludes (1) stock-based compensation expense of $14 million and $13 million, respectively, and (2) prepaid lease purchase price adjustments of $10 million, for both periods. For the six months ended June 30, 2019 and 2018 segment selling, general and administrative expenses exclude stock-based compensation expense of $47 million and $39 million, respectively.

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