Summary of Significant Accounting Policies (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Recognition Non-cancelable Lease Term	five to 15 years
Capitalized Labor Costs	$ 212	$ 92	$ 86
Useful life of site rental contracts and customer relationships (years)	20 years
Revenue Recognition Non-cancelable Term for Non-wireless Contracts Range, Minimum	three to 20 years
Portion of company site rental costs that are ground lease expenses	50.00%
Ground Lease Agreement Initial Term	five years
Percentage of tax position that is likely of being realized upon ultimate settlement	50.00%
Asset write-down charges	$ 26	17	34
Revenue, Performance Obligation, Description of Payment Terms	45 to 60 days
Revenue, Remaining Performance Obligation, Amount	$ 2,300	2,100
Contract with Customer, Liability, Revenue Recognized	400
Minimum [Member]
Impact of adoption of ASU 2016-02	5,000
Maximum [Member]
Impact of adoption of ASU 2016-02	$ 7,000
Wireless Infrastructure [Member]
Estimated useful life, maximum, in years	20 years
Wireless Infrastructure [Member] \| Minimum [Member]
Estimated useful life, maximum, in years	1 year
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	$ 22	14	$ 27
Other Current Assets [Member]
Straight-Line Site Rental Revenues	92	86
Deferred Revenue [Domain]
Straight-Line Site Rental Revenues	$ 1,400	$ 1,300
Preferred Stock [Member]
Antidilutive securities excluded from computation of earnings per share (in shares)	15

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