Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Houston Electric
Related Party Transaction [Line Items]
Cash dividends paid to parent	$ 51	$ 37
Cash dividend paid to parent related to the sale of the Arkansas and Oklahoma Natural Gas businesses	0	0
Contribution from parent	650	637
Non-cash capital contribution from parent in payment for property, plant and equipment below	0	38
Cash paid to parent for property, plant and equipment below	0	52
Property, plant and equipment from parent	0	90
Houston Electric | Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	(3)	(6)
Houston Electric | CenterPoint Energy | Operation and maintenance expense
Related Party Transaction [Line Items]
Corporate service charges	35	39
CERC
Related Party Transaction [Line Items]
Cash dividends paid to parent	204	38
Cash dividend paid to parent related to the sale of the Arkansas and Oklahoma Natural Gas businesses	0	720
Contribution from parent	0	0
Non-cash capital contribution from parent in payment for property, plant and equipment below	0	54
Cash paid to parent for property, plant and equipment below	0	48
Property, plant and equipment from parent	0	102
CERC | Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	3	6
CERC | CenterPoint Energy | Operation and maintenance expense
Related Party Transaction [Line Items]
Corporate service charges	$ 50	$ 58
Investments | Houston Electric
Related Party Transaction [Line Items]
Money pool weighted average interest rate (as a percent)	5.27%		4.75%
Investments | CERC
Related Party Transaction [Line Items]
Money pool weighted average interest rate (as a percent)	5.27%		4.75%
Accounts and notes receivable (payable) - affiliate companies | Houston Electric
Related Party Transaction [Line Items]
Money pool investments (borrowings)	$ 313		$ (642)
Accounts and notes receivable (payable) - affiliate companies | CERC
Related Party Transaction [Line Items]
Money pool investments (borrowings)	$ 30		$ 0