Operating Segments and Concentrations of Credit Risk Operating Segment Results (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Tower Count	40,000
Fiber Miles	65,000
Segment Site Rental Revenues	$ 4,716		$ 3,669		$ 3,233
Segment Services and Other Revenues	707		687		688
Segment Revenues	5,423		4,356		3,921
Segment Site Rental Cost of Operations	1,373		1,109		987
Segment Services and Other Cost of Operations	429		415		410
Segment Cost of Operations	1,802	[1],[2]	1,524	[3],[4]	1,397	[5],[6]
Segment site rental gross margin	3,343		2,560		2,246
Segment services and other gross margin	278		272		278
Segment General and Administrative Expenses	289	[2]	183	[4]	153	[6]
Segment Operating Profit	3,332		2,649		2,371
Allocated Share-based Compensation Expense	108		96		97
Depreciation, amortization and accretion	1,528		1,242		1,109
Interest expense and amortization of deferred financing costs	642		591		515
Other income (expenses) to reconcile to income (loss) before income taxes	173	[7]	82	[8]	133	[9]
Income (Loss) Before Income Taxes	690		471		374
Capital expenditures	1,741		1,228		874
Assets	32,785		32,229		22,675
Goodwill	10,078		10,021		5,758
Amortization of prepaid lease purchase price adjustments	20		20		22
Towers [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues	3,116		2,900		2,831
Segment Services and Other Revenues	691		637		604
Segment Revenues	3,807		3,537		3,435
Segment Site Rental Cost of Operations	848		845		840
Segment Services and Other Cost of Operations	418		374		345
Segment Cost of Operations	1,266	[1],[2]	1,219	[3],[4]	1,185	[5],[6]
Segment site rental gross margin	2,268		2,055		1,991
Segment services and other gross margin	273		263		259
Segment General and Administrative Expenses	110	[2]	94	[4]	93	[6]
Segment Operating Profit	2,431		2,224		2,157
Capital expenditures	442		418		430
Assets	17,667		17,941		18,395
Goodwill	5,127		5,127		5,115
Fiber [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues	1,600		769		402
Segment Services and Other Revenues	16		50		84
Segment Revenues	1,616		819		486
Segment Site Rental Cost of Operations	525		264		147
Segment Services and Other Cost of Operations	11		41		65
Segment Cost of Operations	536	[1],[2]	305	[3],[4]	212	[5],[6]
Segment site rental gross margin	1,075		505		255
Segment services and other gross margin	5		9		19
Segment General and Administrative Expenses	179	[2]	89	[4]	60	[6]
Segment Operating Profit	901		425		214
Capital expenditures	1,264		782		409
Assets	14,512		13,669		3,441
Goodwill	4,951		4,894		643
Other [Member]
Segment Reporting Information [Line Items]
Segment General and Administrative Expenses	191	[2]	167	[4]	143	[6]
Segment Operating Profit
Allocated Share-based Compensation Expense	108		96		97
Depreciation, amortization and accretion	1,528		1,242		1,109
Interest expense and amortization of deferred financing costs	642		591		515
Other income (expenses) to reconcile to income (loss) before income taxes	173	[7]	82	[8]	133	[9]
Capital expenditures	35		28		35
Assets	606		619		839
Goodwill	0		0		0
Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Allocated Share-based Compensation Expense	83		76		75
Cost of Sales [Member]
Segment Reporting Information [Line Items]
Allocated Share-based Compensation Expense	$ 25		$ 20		$ 22

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

[2] Segment cost of operations for the year ended December 31, 2018 excludes (1) stock-based compensation expense of $25 million and (2) prepaid lease purchase price adjustments of $20 million For the year ended December 31, 2018, Segment selling, general and administrative expenses exclude stock-based compensation expense of $83 million.

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

[4] Segment cost of operations for the year ended December 31, 2017 excludes (1) stock-based compensation expense of $20 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2017. Segment selling, general and administrative expenses exclude stock-based compensation expense of $76 million.

[5] Exclusive of depreciation, amortization and accretion shown separately

[6] Segment cost of operations for the year ended December 31, 2016 excludes (1) stock-based compensation expense of $22 million and (2) prepaid lease purchase price adjustments of $22 million. For the year ended December 31, 2016, Segment selling, general and administrative expenses exclude stock-based compensation expense of $75 million for the year ended .

[7] See consolidated statement of operations for further information.

[8] See consolidated statement of operations for further information.

[9] See consolidated statement of operations for further information.