Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Houston Electric
Related Party Transaction [Line Items]
Cash dividends paid to parent	$ 79	$ 74	$ 239	$ 141
Cash dividend paid to parent related to the sale of the Arkansas and Oklahoma Natural Gas businesses	0	0	0	0
Contribution from parent	235	0	885	1,143
Net assets acquired in the Restructuring	0	0	0	0
Non-cash capital contribution from parent in payment for property, plant and equipment below	0	0	0	38
Cash paid to parent for property, plant and equipment below	0	0	0	65
Property, plant and equipment from parent	0	0	0	103
Houston Electric | Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	(1)	3	(7)	(12)
Houston Electric | Operation and maintenance expense | CenterPoint Energy
Related Party Transaction [Line Items]
Corporate service charges	$ 40	38	$ 115	114
Houston Electric | Investments
Related Party Transaction [Line Items]
Weighted average interest rate	5.56%		5.56%		4.75%
CERC
Related Party Transaction [Line Items]
Cash dividends paid to parent	$ 36	13	$ 347	124
Cash dividend paid to parent related to the sale of the Arkansas and Oklahoma Natural Gas businesses	0	0	0	720
Contribution from parent	0	0	500	125
Net assets acquired in the Restructuring	0	0	0	2,345
Non-cash capital contribution from parent in payment for property, plant and equipment below	0	0	0	54
Cash paid to parent for property, plant and equipment below	0	0	0	61
Property, plant and equipment from parent	0	0	0	115
CERC | Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	1	(3)	7	12
CERC | Operation and maintenance expense | CenterPoint Energy
Related Party Transaction [Line Items]
Corporate service charges	$ 56	$ 54	$ 162	$ 163
CERC | Investments
Related Party Transaction [Line Items]
Weighted average interest rate	5.56%		5.56%		4.75%
Accounts and notes receivable (payable) - affiliate companies | Houston Electric
Related Party Transaction [Line Items]
Money pool investments (borrowings)	$ 400		$ 400		$ (642)
Accounts and notes receivable (payable) - affiliate companies | CERC
Related Party Transaction [Line Items]
Money pool investments (borrowings)	$ 86		$ 86		$ 0