Stock-Based Compensation - UScellular, Performance Stock Units (Details) - Common Shares - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Shares issued and granted under stock compensation plans
Award vesting period	3 years
Performance Share Units | UScellular Long-Term Incentive Plans
Stock based compensation, Nonvested shares rollforward, number of shares
Nonvested stock units, beginning of period - Number of shares (in shares)	1,248,000
Granted number of shares (in shares)	643,000
Vested number of shares (in shares)	(300,000)
Forfeited number of shares (in shares)	(134,000)
Nonvested stock units, end of period - Number of shares (in shares)	1,457,000	1,248,000
Stock based compensation, Nonvested shares weighted average grant date fair value
Nonvested stock units - beginning of period weighted average grant date fair value (USD per share)	$ 32.51
Granted weighted average grant date fair value (USD per share)	21.26	$ 31.35	$ 37.67
Vested weighted average grant date fair value (USD per share)	28.41
Forfeited weighted average grant date fair value (USD per share)	26.53
Nonvested stock units - end of period weighted average grant date fair value (USD per share)	$ 27.37	$ 32.51
Shares issued and granted under stock compensation plans
Fair value of vested stock units	$ 7	$ 6	$ 22
Award vesting period	3 years
Performance Share Units | UScellular Long-Term Incentive Plans | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	100.00%
Performance Share Units | UScellular Long-Term Incentive Plans | 2021 and 2022 grants
Shares issued and granted under stock compensation plans
Performance period	3 years
Performance Share Units | UScellular Long-Term Incentive Plans | 2023 grants
Shares issued and granted under stock compensation plans
Performance period	1 year
Performance Share Units | UScellular Long-Term Incentive Plans | UScellular | 2021 grants
Shares issued and granted under stock compensation plans
Incremental expense of plan modification	$ 3
Performance Share Units | UScellular Long-Term Incentive Plans | UScellular | 2022 grants
Shares issued and granted under stock compensation plans
Incremental expense of plan modification	$ 1
Performance Share Units | UScellular Long-Term Incentive Plans | Minimum | 2021 and 2022 grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	75.00%
Performance Share Units | UScellular Long-Term Incentive Plans | Minimum | 2023 grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	0.00%
Performance Share Units | UScellular Long-Term Incentive Plans | Maximum | 2021 and 2022 grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	200.00%
Performance Share Units | UScellular Long-Term Incentive Plans | Maximum | 2023 grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	150.00%
Performance Share Units | UScellular Long-Term Incentive Plans | Maximum | Discretionary | 2021 and 2022 grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share awards target	100.00%