Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Device Payment Plan Agreement Receivables (Detail) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Receivables [Abstract]
Device payment plan agreement receivables, gross	$ 30,805	$ 31,308
Unamortized imputed interest	(976)	(975)
Device payment plan agreement receivables, at amortized cost	29,829	30,333
Allowance	(1,348)	(1,315)
Device payment plan agreement receivables, net	28,481	29,018
Accounts receivable, net	14,902	15,141
Other assets	$ 13,579	$ 13,877