v3.20.4
Goodwill, Spectrum License Transactions and Other Intangible Assets - Other Intangible Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]      
Gross Amount $ 6,665 $ 1,527  
Accumulated Amortization (1,367) (1,412)  
Net Amount 5,298 115  
Amortization expense for intangible assets 1,200 82 $ 124
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]      
2021 1,246    
2022 982    
2023 827    
2024 669    
2025 511    
Thereafter 1,063    
Net Amount 5,298 115  
Customer relationships      
Finite-Lived Intangible Assets [Line Items]      
Gross Amount 4,900 1,104  
Accumulated Amortization (865) (1,104)  
Net Amount 4,035 0  
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]      
Net Amount $ 4,035 0  
Customer relationships | Maximum      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets, useful life (in years) 8 years    
Tradenames and patents      
Finite-Lived Intangible Assets [Line Items]      
Gross Amount $ 598 323  
Accumulated Amortization (412) (258)  
Net Amount 186 65  
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]      
Net Amount $ 186 65  
Tradenames and patents | Maximum      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets, useful life (in years) 19 years    
Favorable spectrum leases      
Finite-Lived Intangible Assets [Line Items]      
Gross Amount $ 790 0  
Accumulated Amortization (35) 0  
Net Amount 755 0  
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]      
Net Amount $ 755 0  
Favorable spectrum leases | Maximum      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets, useful life (in years) 27 years    
Other      
Finite-Lived Intangible Assets [Line Items]      
Gross Amount $ 377 100  
Accumulated Amortization (55) (50)  
Net Amount 322 50  
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]      
Net Amount $ 322 $ 50  
Other | Maximum      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets, useful life (in years) 10 years