Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
6.7% Senior Notes | UScellular
Financial Instruments
Interest rate	6.70%
Book Value | Retail
Financial Instruments
Long-term debt	$ 1,500	$ 1,500
Book Value | Institutional
Financial Instruments
Long-term debt	536	535
Book Value | Other
Financial Instruments
Long-term debt	1,486	944
Fair Value | Level 2 | Retail
Financial Instruments
Long-term debt	1,156	1,594
Fair Value | Level 2 | Institutional
Financial Instruments
Long-term debt	425	659
Fair Value | Level 2 | Other
Financial Instruments
Long-term debt	$ 1,486	$ 944
Interest rate | Institutional and Other | Minimum
Financial Instruments
Fair value assumption, interest rate	2.22%	1.31%
Interest rate | Institutional and Other | Maximum
Financial Instruments
Fair value assumption, interest rate	7.75%	4.40%