Held for Sale, Divestitures and Mergers (CenterPoint Energy and CERC) - Discontinued Operations Narrative (Details)						3 Months Ended		12 Months Ended
	Dec. 02, 2021 USD ($)	Feb. 16, 2021 USD ($)	Jun. 01, 2020 USD ($)	Apr. 09, 2020 USD ($)	Feb. 03, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Preferred unit exchange ratio	0.0265
Proceeds from divestitures (Note 4)								$ 22,000,000	$ 1,215,000,000	$ 0
Goodwill impairment						$ 0	$ 0	0	185,000,000	$ 0
OGE
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payment upon termination of partnership		$ 30,000,000
CERC Corp
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestitures (Note 4)								22,000,000	365,000,000
Enable Midstream Partners
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash received	$ 5,000,000
Infrastructure Services Disposal Group
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price of outstanding equity interests					$ 850,000,000
Proceeds from divestitures (Note 4)				$ 850,000,000
Receivable from sale of disposal group											$ 4,000,000
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy				$ 129,000,000
Current tax expense (benefit) of cash taxes payable upon sale									158,000,000
Goodwill impairment									82,000,000
Cost to sell									14,000,000
Pre-tax gain on sale									6,000,000
Maximum contractual exposure under Securities Purchase Agreement								21,000,000
Energy Services Disposal Group
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price of outstanding equity interests								$ 400,000,000
Proceeds from divestitures (Note 4)			$ 286,000,000
Receivable from sale of disposal group												$ 79,000,000
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy			4,000,000
Goodwill impairment									62,000,000
Cost to sell									6,000,000
Current tax expense of cash taxes payable upon sale									4,000,000
Loss from reclassification to held for sale									31,000,000
Energy Services Disposal Group | CERC Corp
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net deferred tax liabilities on sale recognized as deferred income tax benefit by CenterPoint Energy			$ 4,000,000
Goodwill impairment									62,000,000
Pre-tax gain on sale									(3,000,000)
Current tax expense of cash taxes payable upon sale									$ 4,000,000