v3.20.2
Sale Of Equipment Installment Receivable (Equipment Installment and AT&T Revolving Programs) (Narrative) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2020
Mar. 31, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Accounts Payable And Accrued Liabilities, Current $ 41,881     $ 41,881   $ 45,956
Guarantee Obligations [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Accounts Payable And Accrued Liabilities, Current 213     213   148
Guarantee Obligation 315     315   384
Finance Receivables [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Supplemental Deferred Purchase Price 232   $ 261 585 $ 570  
Other Assets [Member] | Deferred Purchase Price [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Other Assets 2,319     2,319   2,336
Other Current Assets [Member] | Deferred Purchase Price [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Other Assets 1,591     1,591   1,569
Revolving [Member]            
Accounts, Notes, Loans and Financing Receivable [Line Items]            
Agreement Amount With Purchaser To Transfer Financial Assets Accounted For As Sales   $ 5,300       $ 4,300
Receivables pledged as collateral $ 3,745     $ 3,745