Operating Segments and Concentrations of Credit Risk Operating Segment Results (Details) $ in Millions		3 Months Ended																6 Months Ended			9 Months Ended			12 Months Ended
		Dec. 31, 2019 USD ($)		Sep. 30, 2019 USD ($)		Jun. 30, 2019 USD ($)		Mar. 31, 2019 USD ($)		Dec. 31, 2018 USD ($)		Sep. 30, 2018 USD ($)		Jun. 30, 2018 USD ($)		Mar. 31, 2018 USD ($)		Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)		Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)		Dec. 31, 2019 USD ($)		Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Tower Count		40,000																						40,000
Fiber Miles		80,000																						80,000
Segment Site Rental Revenues				$ 1,287		$ 1,263		$ 1,242		$ 1,231		$ 1,205		$ 1,188		$ 1,171		$ 2,505	$ 2,360		$ 3,793	$ 3,565		$ 5,093		$ 4,796		$ 3,734
Segment services and other				195		184		166		175		156		131		113		350	244		544	399		670		574		521
Net Revenues		$ 1,426	[1]	1,482	[1]	1,447	[1]	1,408	[1]	1,406	[1]	1,361	[1]	1,319	[1]	1,284	[1]	2,855	2,604		4,337	3,964		5,763		5,370		4,255
Segment site rental cost of operations	[2]			369		365		361		353		355		355		347		726	702		1,095	1,057		1,462		1,410		1,144
Segment services and other cost of operations				146		137		124		135	[2]	118	[2]	98	[2]	85	[2]	261	183	[2]	407	301	[2]	524	[2]	434	[2]	399	[2]
Selling, general and administrative				150		155		152		145		145		138		134		307	273		457	418		614		563		426
Stock-based compensation expense								29								23		62	47		91	79		117		103		92
Depreciation, amortization and accretion				388		393		394		389		385		379		374		787	753		1,175	1,138		1,572		1,527		1,241
Interest Expense, Debt				(173)		(169)		(168)		(164)		(160)		(158)		(160)		(337)	(318)		(510)	(478)		683		642		591
Income (Loss) Attributable to Parent, before Tax				247		220		199		206		156		175		104		419	279		667	434		881		641		392
Capital expenditures								(480)								(370)		(998)	(762)		(1,537)	(1,239)		(2,057)		(1,739)		(1,217)
Assets		38,457		38,321		$ 38,124		37,755		32,762		32,621		32,351		32,227		$ 38,124	32,351		38,321	32,621		38,457		32,762
Goodwill		10,078		$ 10,078				$ 10,078		10,078		$ 10,074		$ 10,075		$ 10,075			$ 10,075		$ 10,078	$ 10,074		10,078		10,078		10,021
Amortization of prepaid lease purchase price adjustments																								20		20		20
Towers [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues																								3,389		3,196		2,965
Segment services and other																								653		558		471
Net Revenues																								4,042		3,754		3,436
Segment site rental cost of operations																								864		848		845
Segment services and other cost of operations																								506		415		353
Segment cost of operations																								1,370	[3],[4]	1,263	[5],[6]	1,198	[7],[8]
Segment site rental gross margin																								2,525		2,348		2,120
Segment services and other gross margin																								147		143		118
Selling, general and administrative																								96	[4]	110	[6]	94	[8]
Segment Operating Profit																								2,576		2,381		2,144
Capital expenditures																								543		440		407
Assets		22,357								17,644														22,357		17,644		17,918
Goodwill		5,127								5,127														5,127		5,127		5,127
Fiber [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues																								1,704		1,600		769
Segment services and other																								17		16		50
Net Revenues																								1,721		1,616		819
Segment site rental cost of operations																								559		525		264
Segment services and other cost of operations																								11		11		41
Segment cost of operations																								570	[3],[4]	536	[5],[6]	305	[7],[8]
Segment site rental gross margin																								1,145		1,075		505
Segment services and other gross margin																								6		5		9
Selling, general and administrative																								195	[4]	179	[6]	89	[8]
Segment Operating Profit																								956		901		425
Capital expenditures																								1,473		1,264		782
Assets		15,389								14,512														15,389		14,512		13,669
Goodwill		4,951								4,951														4,951		4,951		4,894
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Selling, general and administrative																								233	[4]	191	[6]	167	[8]
Stock-based compensation expense																								116		108		96
Depreciation, amortization and accretion																								1,572		1,527		1,241
Interest Expense, Debt																								683		642		591
Other Expenses																								47	[9]	173	[10]	82	[11]
Capital expenditures																								41		35		28
Assets		711								606														711		606		619
Goodwill		0								0														0		0		0
Consolidated Entities [Member]
Segment Reporting Information [Line Items]
Segment Site Rental Revenues																								5,093		4,796		3,734
Segment services and other																								670		574		521
Net Revenues																								5,763		5,370		4,255
Segment site rental cost of operations																										1,373
Segment Site Rental Cost of Operations																								1,423				1,109
Segment services and other cost of operations																										426		394
Segment Services and Other Cost of Operations																								517
Segment cost of operations																								1,940	[3],[4]	1,799	[5],[6]	1,503	[7],[8]
Segment site rental gross margin																								3,670		3,423		2,625
Segment services and other gross margin																								153		148		127
Selling, general and administrative																										289	[6]	183	[8]
Segment General and Administrative Expenses	[4]																							291
Segment Operating Profit																								3,532		3,282		2,569
Stock-based compensation expense																								116		108		96
Depreciation, amortization and accretion																								1,572		1,527		1,241
Interest Expense, Debt																								683		642		591
Other Expenses																								47	[9]	173	[10]	82	[11]
Income (Loss) Attributable to Parent, before Tax																								881		641		392
Capital expenditures																								2,057		1,739		1,217
Assets		38,457								32,762														38,457		32,762		32,206
Goodwill		$ 10,078								$ 10,078														10,078		10,078		10,021
Cost of Sales [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense																								26		$ 25		$ 20
Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Stock-based compensation expense																								$ 90

[1] The sum of quarterly information may not agree to year-to-date information due to rounding.

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

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

[4] Segment cost of operations for the year ended December 31, 2019 excludes (1) stock-based compensation expense of $26 million and (2) prepaid lease purchase price adjustments of $20 million. For the year ended December 31, 2019, segment selling, general and administrative expenses exclude stock-based compensation expense of $90 million.

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

[6] 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.

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

[8] 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.

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

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

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