Equity Securities and Indexed Debt Securities (ZENS) (CenterPoint Energy) - Schedule of Securities Classified as Trading (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Carrying Value	$ 548	$ 510
AT&T Common
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	10,212,945	10,212,945
Carrying Value	$ 197	$ 188
Charter Common
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	872,503	872,503
Carrying Value	$ 312	$ 296
WBD Common
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	2,470,685	2,470,685
Carrying Value	$ 37	$ 23
Other
Debt and Equity Securities, FV-NI [Line Items]
Carrying Value	$ 2	$ 3