Receivables and Related Allowance for Credit Losses - Schedule of Equipment Installment Plan Receivables (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) class segment	Dec. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Portfolio segments | segment	2
Customer classes | class	2
EIP receivables, gross	$ 7,089	$ 8,480
Unamortized imputed discount	(453)	(483)
EIP receivables, net of unamortized imputed discount	6,636	7,997
Allowance for credit losses	(287)	(328)
EIP receivables, net of allowance for credit losses and imputed discount	6,349	7,669
Equipment installment plan receivables, net of allowance for credit losses and imputed discount
Accounts, Notes, Loans and Financing Receivable [Line Items]
EIP receivables, net of allowance for credit losses and imputed discount	4,470	5,123
Equipment installment plan receivables due after one year, net of allowance for credit losses and imputed discount
Accounts, Notes, Loans and Financing Receivable [Line Items]
EIP receivables, net of allowance for credit losses and imputed discount	$ 1,879	$ 2,546
EIP Receivables Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted average effective imputed interest rate	9.90%	8.00%