Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Receivables (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 23,742	$ 26,162
Allowance for credit losses	1,070	0
Accounts receivable, net of allowance	22,672	$ 25,429
Device payment plan agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	12,017
Allowance for credit losses	584
Accounts receivable, net of allowance	11,433
Wireless service
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	5,089
Allowance for credit losses	234
Accounts receivable, net of allowance	4,855
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	6,636
Allowance for credit losses	252
Accounts receivable, net of allowance	$ 6,384