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Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	$ 1		$ 1		$ 12
Derivative Liabilities Fair Value	630		630		578
Not Designated as Hedging Instrument \| CERC
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	1		1		9
Derivative Liabilities Fair Value	0		0		0
Energy Related Derivative \| Current Assets: Non-trading derivative assets \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	1		1		9
Derivative Liabilities Fair Value	0		0		0
Energy Related Derivative \| Current Assets: Non-trading derivative assets \| Not Designated as Hedging Instrument \| CERC
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	1		1		7
Derivative Liabilities Fair Value	0		0		0
Energy Related Derivative \| Other Assets: Non-trading derivative assets \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0		0		2
Derivative Liabilities Fair Value	0		0		0
Energy Related Derivative \| Other Assets: Non-trading derivative assets \| Not Designated as Hedging Instrument \| CERC
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0		0		2
Derivative Liabilities Fair Value	0		0		0
Interest rate derivatives \| Current Assets: Non-trading derivative assets \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0		0		1
Derivative Liabilities Fair Value	0		0		0
Interest rate derivatives \| Economic hedge
Derivatives, Fair Value [Line Items]
Economic hedge	0		0		84
Indexed debt securities derivative \| Gains (Losses) in Other Income (Expense)
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments	(47)	$ 210	(52)	$ 381
Indexed debt securities derivative \| Current Liabilities \| Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	0		0		0
Derivative Liabilities Fair Value	$ 630		$ 630		$ 578