Equity (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023
Cumulative preferred stock, outstanding (in shares)	0	800,000	800,000
Preferred stock, value outstanding	$ 0	$ 790	$ 790
Total income allocated to preferred shareholders	50	49	95
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(31)	(64)
Prior service cost	1	(1)
Actuarial losses	1	8
Settlement	0	67
Reclassification of deferred loss from cash flow hedges realized in net income	0	1
Tax benefit (expense)	1	(2)
Net current period other comprehensive income (loss)	(4)	33	26
Ending balance	(35)	(31)	(64)
Net deferred gain from cash flow hedges	1	0	0
Other Pension, Postretirement and Supplemental Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Remeasurement of pension and other postretirement plans	(8)	(40)
CERC Corp
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	16	10
Prior service cost	(2)	(1)
Actuarial losses	2	1
Settlement	0	0
Reclassification of deferred loss from cash flow hedges realized in net income	0	0
Tax benefit (expense)	0	(4)
Net current period other comprehensive income (loss)	0	6	0
Ending balance	16	16	$ 10
Net deferred gain from cash flow hedges	0	0
CERC Corp | Other Pension, Postretirement and Supplemental Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Remeasurement of pension and other postretirement plans	$ 0	$ 10
Common Stock
Common stock, dividends declared per share (in dollars per share)	$ 0.7800	$ 0.7200	$ 0.6600
Common Stock dividends paid per share (in dollars per share)	0.7700	0.7000	0.6500
Series A Preferred Stock
Preferred stock, dividends declared (in dollars per share)	30.6250	61.2500	61.2500
Preferred stock dividends paid per share (in dollars per share)	61.2500	$ 61.2500	$ 61.2500
Preferred stock liquidation preference (in dollar per share)	$ 1,000			$ 1,000
Cumulative preferred stock, outstanding (in shares)	0	800,000	800,000
Preferred stock, value outstanding	$ 0	$ 790	$ 790
Income allocated to preferred shareholders	$ 50	$ 49	$ 49
Series B Preferred Stock
Preferred stock, dividends declared (in dollars per share)	$ 0	$ 0	$ 35.0000
Preferred stock dividends paid per share (in dollars per share)	$ 0	$ 0	$ 52.5000
Income allocated to preferred shareholders	$ 0	$ 0	$ 46
Total income allocated to preferred shareholders	$ 50	$ 49	$ 95
Series C Preferred Stock
Preferred stock, dividends declared (in dollars per share)	$ 0	$ 0	$ 0
Preferred stock dividends paid per share (in dollars per share)	$ 0	$ 0	$ 0.1600