Background and Summary of Significant Accounting Policies - Correction of Immaterial Errors (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2021
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounts receivable, less allowance of $34 and $36	$ 261	$ 347
Assets	16,337	18,956
Accounts payable	362	231
Retained earnings	706	3,517
Affiliated Entity
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Advances to affiliates	$ 0	569
Correction of Error from Understatement of Revenues and Network Expenses Prior to 2021
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounts receivable, less allowance of $34 and $36		38
Assets		31
Liabilities		18
Retained earnings			$ 13
Correction of Error from Understatement of Revenues and Network Expenses Prior to 2021 | Affiliated Entity
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Advances to affiliates		$ (7)