Debt - Repurchase Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Equipment installment plan receivables	$ 1,151	$ 1,211
Repurchase Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	200
Amount repaid during the period	60
Amounts borrowed and outstanding	0
Amount available for use	200
Repurchase Agreement | Other current liabilities
Debt Instrument [Line Items]
Amounts borrowed and outstanding		$ 60
Repurchase Agreement | Assets pledged
Debt Instrument [Line Items]
Equipment installment plan receivables	$ 669
Lender's cost of funds | Repurchase Agreement
Debt Instrument [Line Items]
Contractual spread	1.35%