Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Receivables (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 24,852	$ 26,162
Allowance for credit losses	1,055	0
Accounts receivable, net of allowance	23,797	$ 25,429
Device Payment Plan Agreement Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	12,824
Allowance for credit losses	606
Accounts receivable, net of allowance	12,218
Wireless Service Plan Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	5,244
Allowance for credit losses	228
Accounts receivable, net of allowance	5,016
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	6,784
Allowance for credit losses	221
Accounts receivable, net of allowance	$ 6,563