Equity Securities and Indexed Debt Securities (ZENS) (CenterPoint Energy) - Schedule of Securities Classified as Trading (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Carrying Value	$ 452	$ 1,439
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	$ 157	$ 251
Charter Common
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	872,503	872,503
Carrying Value	$ 265	$ 569
WBD Common
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	2,470,685	0
Carrying Value	$ 28	$ 0
Energy Transfer Common Units
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	0	50,999,768
Carrying Value	$ 0	$ 420
Energy Transfer Series G Preferred Units
Debt and Equity Securities, FV-NI [Line Items]
Balance of investment owned (in shares)	0	192,390
Carrying Value	$ 0	$ 196
Other
Debt and Equity Securities, FV-NI [Line Items]
Carrying Value	$ 2	$ 3