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Summary of Significant Accounting Policies - Other Expense (Income) - Net (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Accounting Policies [Abstract] |  |  |
Interest income | $ 5 | $ 6 | $ 2
Interest on regulatory deferrals | 9 | 9 | 2
Equity-related AFUDC | 9 | 7 | 7
Non-service portion of pension and other postretirement benefit expenses | 2 |  | 3
Earnings (losses) on investments | (7) | (3) | 48
Other income | 4 |  | 1
Total | $ 22 | $ 19 | $ 63

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