Regulatory Matters - Schedule of Allowed Equity Return Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Public Utilities, General Disclosures [Line Items]
Allowed equity return not recognized	$ 169		$ 188
Allowed equity return recognized	8	$ 10
Houston Electric
Public Utilities, General Disclosures [Line Items]
Allowed equity return not recognized	90		82
Allowed equity return recognized	7	9
CERC
Public Utilities, General Disclosures [Line Items]
Allowed equity return not recognized	58		$ 54
Allowed equity return recognized	$ 1	$ 1