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Non-Derivative Fair Value Measurements (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity investments in unconsolidated subsidiaries |  | $ 239 |  | $ 246 |
Miscellaneous investments |  | 165 |  | 156 |
Debt Securities, Available-for-sale, Unrealized Gain |  | 1,700 |  | 1,400 |
Debt Securities, Available-for-sale, Unrealized Loss |  | 44 |  | 49 |
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] |  |  |  |  |
Due in one year or less |  | 9 |  |  |
Due in 1 to 5 years |  | 341 |  |  |
Due in 5 to 10 years |  | 271 |  |  |
Due after 10 years |  | 287 |  |  |
Total |  | 908 |  |  |
Debt Securities, Available-for-sale, Unrealized Gain |  | 1,700 |  | 1,400 |
Debt Securities, Available-for-sale, Unrealized Loss |  | 44 |  | 49 |
Fair Value Measured on a Recurring Basis | Cost |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Decommissioning Fund Investments |  | 2,208 | [1] | 2,130 | [2]
Fair Value Measured on a Recurring Basis | Cost | Cash equivalents |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Cash equivalents |  | 68 | [1] | 39 | [2]
Fair Value Measured on a Recurring Basis | Cost | Commingled funds |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment | [2] |  |  | 703 |
Investments, Fair Value Disclosure | [1] | 696 |  |  |
Fair Value Measured on a Recurring Basis | Cost | Debt securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Debt securities |  | 903 | [1] | 866 | [2]
Fair Value Measured on a Recurring Basis | Cost | Equity securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity Securities, FV-NI |  | 541 | [1] | 522 | [2]
Fair Value Measured on a Recurring Basis | Fair Value |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment |  | 1,041 | [1] | 1,025 | [2]
Decommissioning Fund Investments |  | 3,869 | [1] | 3,494 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Cash equivalents |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Cash equivalents |  | 68 | [1] | 39 | [2]
Alternative investment |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Commingled funds |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment |  | 1,041 | [1] | 1,025 | [2]
Investments, Fair Value Disclosure |  | 1,041 |  |  |
Fair Value Measured on a Recurring Basis | Fair Value | Debt securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Debt securities |  | 908 | [1] | 846 | [2]
Alternative investment |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Equity securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity Securities, FV-NI |  | 1,852 | [1] | 1,584 | [2]
Alternative investment |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 1 |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Decommissioning Fund Investments |  | 1,918 | [1] | 1,622 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Cash equivalents |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Cash equivalents |  | 68 | [1] | 39 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Commingled funds |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment | [2] |  |  | 0 |
Investments, Fair Value Disclosure | [1] | 0 |  |  |
Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Debt securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Debt securities |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Equity securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity Securities, FV-NI |  | 1,850 | [1] | 1,583 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 2 |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Decommissioning Fund Investments |  | 900 | [1] | 833 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Cash equivalents |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Cash equivalents |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Commingled funds |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment | [2] |  |  | 0 |
Investments, Fair Value Disclosure | [1] | 0 |  |  |
Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Debt securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Debt securities |  | 898 | [1] | 832 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Equity securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity Securities, FV-NI |  | 2 | [1] | 1 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 3 |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Decommissioning Fund Investments |  | 10 | [1] | 14 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Cash equivalents |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Cash equivalents |  | 0 | [1] | 0 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Commingled funds |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Alternative investment | [2] |  |  | 0 |
Investments, Fair Value Disclosure | [1] | 0 |  |  |
Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Debt securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Debt securities |  | 10 | [1] | 14 | [2]
Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Equity securities |  |  |  |  |
Nuclear decommissinoning fund [Abstract] |  |  |  |  |
Equity Securities, FV-NI |  | $ 0 | [1] | $ 0 | [2]
[1] | Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $239 million of equity method investments and $165 million of rabbi trust assets and other miscellaneous investments.
[2] | Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $246 million of equity method investments and $156 million of rabbi trust assets and other miscellaneous investments.

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