Derivative Instruments - Schedule of Derivative Activity (Details) $ in Millions	Sep. 30, 2024 USD ($) MMBTU	Dec. 31, 2023 USD ($) MMBTU
Derivative Assets Fair Value
Natural gas derivatives	$ 1	$ 0
Derivative Liability [Abstract]
Derivative liability	598	617
CERC
Derivative Assets Fair Value
Natural gas derivatives	1	0
Derivative Liability [Abstract]
Derivative liability	$ 6	$ 11
Natural gas derivatives \| Derivatives not designated as hedging instruments:
Derivative Liability [Abstract]
Derivative gross volume (in MMBtu) \| MMBTU	32,251	27,421
Natural gas derivatives \| Derivatives not designated as hedging instruments: \| CERC
Derivative Liability [Abstract]
Derivative gross volume (in MMBtu) \| MMBTU	27,644	23,504
Current Liabilities: Non-trading derivative liabilities \| Natural gas derivatives \| Derivatives not designated as hedging instruments:
Derivative Assets Fair Value
Derivative Assets Fair Value	$ 0	$ 0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	5	9
Current Liabilities: Non-trading derivative liabilities \| Natural gas derivatives \| Derivatives not designated as hedging instruments: \| CERC
Derivative Assets Fair Value
Derivative Assets Fair Value	0	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	4	8
Current Liabilities: Non-trading derivative liabilities \| Indexed debt securities derivative \| Derivatives not designated as hedging instruments:
Derivative Assets Fair Value
Derivative Assets Fair Value	0	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	591	605
Other Liabilities: Non-trading derivative liabilities \| Natural gas derivatives \| Derivatives not designated as hedging instruments:
Derivative Assets Fair Value
Derivative Assets Fair Value	0	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	2	3
Other Liabilities: Non-trading derivative liabilities \| Natural gas derivatives \| Derivatives not designated as hedging instruments: \| CERC
Derivative Assets Fair Value
Derivative Assets Fair Value	0	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	2	3
Current Assets: Non-trading derivative assets \| Natural gas derivatives \| Derivatives not designated as hedging instruments:
Derivative Assets Fair Value
Derivative Assets Fair Value	1	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	0	0
Current Assets: Non-trading derivative assets \| Natural gas derivatives \| Derivatives not designated as hedging instruments: \| CERC
Derivative Assets Fair Value
Derivative Assets Fair Value	1	0
Derivative Liability [Abstract]
Derivative Liabilities Fair Value	$ 0	$ 0

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