Wireless Licenses, Goodwill and Other Intangible Assets - Composition of Other Intangible Assets, Net (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 28,485	$ 27,477
Accumulated Amortization	(16,808)	(18,064)
Net Amount	11,677	9,413
Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Amount	4,201	4,021
Accumulated Amortization	(1,126)	(1,961)
Net Amount	$ 3,075	2,060
Customer lists | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	5 years
Customer lists | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	13 years
Non-Network Internal-Use Software
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 21,310	21,685
Accumulated Amortization	(14,897)	(15,104)
Net Amount	$ 6,413	6,581
Non-Network Internal-Use Software | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	5 years
Non-Network Internal-Use Software | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	7 years
Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 2,974	1,771
Accumulated Amortization	(785)	(999)
Net Amount	$ 2,189	$ 772
Other | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	4 years
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life for finite-lived intangible assets, years	25 years