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Derivative Instruments - Schedule of Derivative Activity (Details) $ in Millions |  |  | 3 Months Ended
--- | --- | --- | ---
Mar. 31, 2024 USD ($) MMBTU | Dec. 31, 2023 USD ($) MMBTU | Mar. 31, 2024 USD ($) | Mar. 31, 2023 USD ($)
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Liability | $ 532 | $ 617 | $ 532 |
Derivative assets | 3 | 0 | 3 |
Derivative, Credit Risk Related Contingent Features [Abstract] |  |  |  |
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position | 9 | 9 | 9 |
Fair value of collateral already posted | 0 | 0 | 0 |
Additional collateral required to be posted if credit risk contingent features triggered | 9 | 9 | 9 |
CERC |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Liability | 10 | 11 | 10 |
Derivative assets | 0 | 0 | 0 |
Derivative, Credit Risk Related Contingent Features [Abstract] |  |  |  |
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position | 8 | 8 | 8 |
Fair value of collateral already posted | 0 | 0 | 0 |
Additional collateral required to be posted if credit risk contingent features triggered | $ 8 | $ 8 | 8 |
Indexed debt securities derivative | Gains (Losses) in Other Income (Expense) |  |  |  |
Income Statement Impact of Derivative Activity [Abstract] |  |  |  |
Gain (loss) on derivative instruments not designated as hedging instruments |  |  | 85 | $ (39)
Energy Related Derivative | Derivatives not designated as hedging instruments: |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative gross volume (in MMBtu) | MMBTU | 20,712 | 27,421 |  |
Energy Related Derivative | Derivatives not designated as hedging instruments: | CERC |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative gross volume (in MMBtu) | MMBTU | 17,753 | 23,504 |  |
Current Assets: Non-trading derivative assets | Interest rate derivatives | Derivatives designated as cash flow hedges: | Cash Flow Hedge |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | $ 3 | $ 0 | 3 |
Derivative Liabilities Fair Value | 0 | 0 | 0 |
Current Liabilities | Indexed debt securities derivative | Derivatives not designated as hedging instruments: |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | 0 | 0 | 0 |
Derivative Liabilities Fair Value | 520 | 605 | 520 |
Current Liabilities | Energy Related Derivative | Derivatives not designated as hedging instruments: |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | 0 | 0 | 0 |
Derivative Liabilities Fair Value | 9 | 9 | 9 |
Current Liabilities | Energy Related Derivative | Derivatives not designated as hedging instruments: | CERC |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | 0 | 0 | 0 |
Derivative Liabilities Fair Value | 8 | 8 | 8 |
Other Liabilities: Non-trading derivative liabilities | Energy Related Derivative | Derivatives not designated as hedging instruments: |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | 0 | 0 | 0 |
Derivative Liabilities Fair Value | 3 | 3 | 3 |
Other Liabilities: Non-trading derivative liabilities | Energy Related Derivative | Derivatives not designated as hedging instruments: | CERC |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] |  |  |  |
Derivative Assets Fair Value | 0 | 0 | 0 |
Derivative Liabilities Fair Value | $ 2 | $ 3 | $ 2 |

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