Device Payment Plan Agreement and Wireless Service Receivables - Balance and Aging of Receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	$ 31,308	$ 29,206
Device payment plan agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	30,333
Unbilled | Financial Asset, Not Past Due | Device payment plan agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	28,916
Billed | Financial Asset, Not Past Due | Device payment plan agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	1,116
Billed | Financial Asset, Past Due | Device payment plan agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Device payment plan agreement receivables, gross	$ 301