Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Device Payment Plan Receivables, Net (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	$ 21,303	$ 17,959
Unamortized imputed interest	(358)	(453)
Device payment plan agreement receivables, at amortized cost	20,945	17,506
Allowance	(759)	(940)
Device payment plan agreement receivables, net	20,186	16,566
Account receivable, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, net	12,783	11,601
Other assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, net	$ 7,403	$ 4,965