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Intangible Assets - Narrative (Details)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
license
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Indefinite-lived Intangible Assets [Line Items]      
Amortization expense for intangible assets $ 26 $ 24 $ 26
Estimated amortization expense      
2021 21    
2022 20    
2023 19    
2024 17    
2025 $ 17    
Auction 103 | UScellular      
Indefinite-lived Intangible Assets [Line Items]      
Licenses won | license 237    
Total winning bid $ 146