Additional Financial Information - Related Party Transactions (Details) - Affiliates - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
|
| Accounts Payable and Accrued Liabilities [Line Items] | |||
| Fees incurred for use of the T-Mobile brand | $ 80 | $ 80 | $ 80 |
| International long distance agreement | 20 | 25 | 37 |
| Reimbursement of certain administrative expenses | $ 4 | $ 4 | $ 5 |