Equity Securities and Indexed Debt Securities (ZENS) (CenterPoint Energy) - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Unrealized gains (loss) on equity securities	$ 31,000,000	$ (313,000,000)	$ (52,000,000)
Target annual yield on reference shares	2.309%
Investment in equity securities	$ 541,000,000	510,000,000
ZENS-Related Securities
Debt and Equity Securities, FV-NI [Line Items]
Investment in equity securities	538,000,000	$ 507,000,000	$ 820,000,000	$ 871,000,000
ZENS debt, due 2029
Debt and Equity Securities, FV-NI [Line Items]
Principal amount of debt issued	1,000,000,000
Long-term debt, gross	$ 828,000,000
Subordinated note cash exchangeable percentage of fair value	95.00%
Debt instrument interest rate (as a percent)	2.00%
Contingent principal amount	$ 18,000,000
The cash exchange amount from referenced shares per $1,000 face amount of individual notes	618
Face amount of each indexed debt security notes issued by CenterPoint Energy in September 1999	$ 1,000