Regulatory Matters (Details) - USD ($) $ in Millions			3 Months Ended		9 Months Ended
	Jan. 23, 2020	Apr. 05, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Apr. 13, 2020	Dec. 31, 2019
Amount of allowed equity return not recognized in the period					$ 144
Amount Of Allowed Equity Return Recognized In Period			$ 10	$ 14	24	$ 38
Rate case expense			2,150		2,150			$ 2,117
Houston Electric [Member]
Amount of allowed equity return not recognized in the period					144
Amount Of Allowed Equity Return Recognized In Period			10	$ 14	24	$ 38
Rate case expense			873		873			915
CERC Corp [Member]
Rate case expense			206		206			191
Incremental Uncollectible Receivables, Regulatory Asset			14		14
Natural Gas Distribution [Member]
Incremental Uncollectible Receivables, Regulatory Asset			16		16
CenterPoint Energy Houston Electric 2019 Rate Case [Member]
Requested revenue increase		$ 194
Houston electric stipulation and settlement agreement [Member]
Return on Equity	9.40%
Debt Capital Structure	57.50%
Equity Capital Structure	42.50%
Unprotected excess deferred income tax	$ 105
Houston electric stipulation and settlement agreement [Member] | Houston Electric [Member]
Requested revenue increase	$ 13
Rate case expense [Member] | Houston electric stipulation and settlement agreement [Member]
Rate case expense								$ 12
Public Utility Commission of Texas [Member]
COVID-19 ERP Regulatory Liability			10		10
ERCOT Loan, COVID-19 ERP							$ 5
ERCOT Loan, COVID-19 ERP, Outstanding			5		5
Public Utility Commission of Texas [Member] | Houston Electric [Member]
COVID-19 ERP Regulatory Liability			10		10
ERCOT Loan, COVID-19 ERP							$ 5
ERCOT Loan, COVID-19 ERP, Outstanding			$ 5		$ 5