v3.21.2
Sales of Certain Receivables - Sales of Receivables and Continuing Involvement (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]          
Other current assets $ 1,642   $ 1,642   $ 2,496
Other long-term assets 12,266   12,266   2,779
Other current liabilities 877   877   810
Other long-term liabilities 5,229   5,229   5,412
Of which:          
Gain (loss) on sale of receivables 12 $ (30) 30 $ (55)  
Factoring and EIP Securitization Arrangement | Variable Interest Entity, Primary Beneficiary          
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]          
Derecognized net service receivables and EIP receivables 2,491   2,491   2,528
Other current assets 638   638   766
Carrying amounts of deferred purchase price assets 770   770   884
Other long-term assets 133   133   120
Other current liabilities 313   313   357
Other long-term liabilities 4   4   4
Net cash proceeds since inception     1,755   1,715
Of which:          
Change in net cash proceeds during the year-to-date period     40   (229)
Net cash proceeds funded by reinvested collections     1,715   1,944
Gain (loss) on sale of receivables 12 $ (30) 30 $ (55)  
Factoring and EIP Securitization Arrangement | Other current assets - of which, deferred purchase price | Variable Interest Entity, Primary Beneficiary          
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]          
Carrying amounts of deferred purchase price assets 637   637   764
Factoring and EIP Securitization Arrangement | Other long-term assets - of which, deferred purchase price | Variable Interest Entity, Primary Beneficiary          
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]          
Carrying amounts of deferred purchase price assets $ 133   $ 133   $ 120