Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 4,294		$ 4,294		$ 4,294
Goodwill transferred			972		972
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	63		63		63
Accumulated Amortization	(22)		(22)		(19)
Net Balance	41		41		44
Finite-Lived Intangible Assets Amortization Expense Maturity Schedule [Abstract]
Remaining six months of 2022	3		3
2023	6		6
2024	5		5
2025	5		5
2026	5		5
2027	4		4
Electric
Goodwill [Line Items]
Goodwill	936		936		936
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated goodwill impairment charge						$ 185
Natural Gas
Goodwill [Line Items]
Goodwill	2,920		2,920		2,920
Held for sale					398
Corporate and Other
Goodwill [Line Items]
Goodwill	438		438		438
Customer Relationships
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	33		33		33
Accumulated Amortization	(14)		(14)		(12)
Net Balance	19		19		21
Trade Names
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	16		16		16
Accumulated Amortization	(6)		(6)		(5)
Net Balance	10		10		11
Operation and maintenance agreements
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	12		12		12
Accumulated Amortization	(1)		(1)		(1)
Net Balance	11		11		11
Other
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	2		2		2
Accumulated Amortization	(1)		(1)		(1)
Net Balance	1		1		1
Depreciation and amortization expense
Finite-Live Intangible Assets [Abstract]
Amortization expense of intangible assets recorded in Depreciation and amortization	2	$ 2	3	$ 3
CERC
Goodwill [Line Items]
Goodwill	$ 1,583		$ 1,583		1,583
CERC | Natural Gas
Goodwill [Line Items]
Held for sale					$ 144