v3.20.4
Sales of Certain Receivables - Sales of Receivables and Continuing Involvement (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]      
Other current assets $ 2,496 $ 1,972  
Other long-term assets 2,779 1,891  
Accounts payable and accrued liabilities 10,196 6,746  
Other current liabilities 810 1,673  
Other long-term liabilities 5,412 954  
Of which:      
Losses from sales of receivables 36 130 $ 157
Factoring and EIP Securitization Arrangement | Variable Interest Entity, Primary Beneficiary      
Of which:      
Maximum exposure to loss, Factoring VIE 1,200    
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 2,528 2,584  
Other current assets 766 694  
Carrying amounts of deferred purchase price assets 884 781  
Other long-term assets 120 89  
Accounts payable and accrued liabilities 0 25  
Other current liabilities 357 342  
Other long-term liabilities 4 18  
Net cash proceeds since inception 1,715 1,944  
Of which:      
Change in net cash proceeds during the year-to-date period (229) 65  
Net cash proceeds funded by reinvested collections 1,944 1,879  
Losses from sales of receivables 36 130 $ 157
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 764 692  
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 $ 120 $ 89