v3.20.4
Revenue from Contracts with Customers - Contract Costs (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Apr. 02, 2020
Disaggregation of Revenue [Line Items]      
Deferred incremental costs to obtain contracts $ 1,100,000,000 $ 906,000,000  
Average amortization period, deferred contract costs (in months) 24 months    
Amortization of deferred costs $ 865,000,000 604,000,000  
Contract Liabilities 824,000,000 560,000,000  
Impairment losses recognized on deferred contract cost assets $ 0 $ 0  
Sprint      
Disaggregation of Revenue [Line Items]      
Contract Liabilities     $ 1,700,000,000