Revenues and Contract Costs - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | segment			2
Revenues from leasing arrangements, captive reinsurance arrangements and interest on equipment financed	$ 715,000,000	$ 779,000,000	$ 2,300,000,000	$ 2,400,000,000
Contract description of timing			Contracts for wireless services are generally either month-to-month and cancellable at any time (typically under a device payment plan) or contain terms ranging from greater than one month to up to two years (typically under a fixed-term plan).
Amortization of deferred contract costs	763,000,000	687,000,000	$ 2,300,000,000	1,900,000,000
Contract assets impairment charge	0	0	0	0
Media Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 1,700,000,000	$ 1,800,000,000	$ 4,700,000,000	$ 5,400,000,000
Wireless postpaid contracts
Disaggregation of Revenue [Line Items]
Percentage of month-to-month contracts of total service contracts	90.00%	87.00%	90.00%	87.00%
Wireline Consumer and Small and Medium Business contracts
Disaggregation of Revenue [Line Items]
Percentage of month-to-month contracts of total service contracts	70.00%	59.00%	70.00%	59.00%
Reseller Arrangements
Disaggregation of Revenue [Line Items]
Contract description of timing			Reseller arrangements generally include a stated contract term, which typically extends longer than two years and, in some cases, include a periodic minimum revenue commitment over the contract term for which revenues will be recognized in future periods.
Consumer
Disaggregation of Revenue [Line Items]
Customer contracts service term			2 years
Business
Disaggregation of Revenue [Line Items]
Contract description of timing			These contracts have varying terms spanning over approximately five years
Maximum | Business
Disaggregation of Revenue [Line Items]
Customer contracts service term			12 months