Regulatory Matters (Details) - USD ($) $ in Millions			3 Months Ended
	Jan. 23, 2020	Apr. 05, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Amount of allowed equity return not recognized in the period			$ 162
Amount Of Allowed Equity Return Recognized In Period			6	$ 11
Rate case expense			2,120		$ 2,117
Houston Electric [Member]
Amount of allowed equity return not recognized in the period			162
Amount Of Allowed Equity Return Recognized In Period			6	$ 11
Rate case expense			891		915
CERC Corp [Member]
Rate case expense			$ 192		191
CenterPoint Energy Houston Electric 2019 Rate Case [Member]
Requested revenue increase		$ 194
Houston electric stipulation and settlement agreement [Member]
Requested revenue increase	$ 13
Return on Equity	9.40%
Debt Capital Structure	57.50%
Equity Capital Structure	42.50%
Unprotected excess deferred income tax	$ 105
Rate case expense [Member] | Houston electric stipulation and settlement agreement [Member]
Rate case expense					$ 12