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Goodwill and Other Intangibles (CenterPoint Energy 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	Dec. 31, 2020
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 4,294
Disposals			134
Goodwill, ending balance	$ 4,160		4,160
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	2		2		$ 63
Accumulated Amortization	(1)		(1)		(25)
Net Balance	1		1		38
Depreciation and amortization expense
Finite-Live Intangible Assets [Abstract]
Amortization expense of intangible assets recorded in Depreciation and amortization	0	$ 1	3	$ 4
Customer relationships
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	0		0		33
Accumulated Amortization	0		0		(16)
Net Balance	0		0		17
Trade names
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	0		0		16
Accumulated Amortization	0		0		(6)
Net Balance	0		0		10
Operation and maintenance agreements
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	0		0		12
Accumulated Amortization	0		0		(2)
Net Balance	0		0		10
Other
Finite-Live Intangible Assets [Abstract]
Gross Carrying Amount	2		2		2
Accumulated Amortization	(1)		(1)		(1)
Net Balance	1		1		$ 1
CERC
Goodwill [Roll Forward]
Goodwill, beginning balance			1,583
Goodwill, ending balance	1,583		1,583
Electric
Goodwill [Roll Forward]
Goodwill, beginning balance			936
Disposals			0
Goodwill, ending balance	936		936
Goodwill, Impaired, Accumulated Impairment Loss [Abstract]
Accumulated goodwill impairment charge						$ 185
Natural Gas
Goodwill [Roll Forward]
Goodwill, beginning balance			2,920
Disposals			0
Goodwill, ending balance	2,920		2,920
Corporate and Other
Goodwill [Roll Forward]
Goodwill, beginning balance			438
Disposals			134
Goodwill, ending balance	$ 304		$ 304