Divestitures (CenterPoint Energy and CERC) - Divestitures Narrative (Details) mi in Thousands, $ in Millions			3 Months Ended		9 Months Ended		12 Months Ended
	May 21, 2023 USD ($)	Apr. 29, 2021 USD ($) mi	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	May 31, 2022 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale			$ 0	$ 0	$ (12)	$ 303
Miles of pipeline (in miles) | mi		17
Transition services agreement charges			0	10	1	29
Transition services agreement, accounts receivable			0		0		$ 1
CERC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestitures, net of cash divested					0	2,075
Gain (loss) on sale			$ 0	$ 0	0	$ 557
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Energy Systems Group
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity purchase agreement, purchase price	$ 157
Proceeds from divestitures, net of cash divested	$ 154
Gain (loss) on sale					(12)
Transaction costs					3
Current tax expense of divestiture					$ 33
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Arkansas and Oklahoma Natural Gas Businesses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestitures, net of cash divested		$ 2,150
Gain (loss) on sale							303
Transaction costs							59
Recovery of costs		$ 425
Receivables, net								$ 15
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Arkansas and Oklahoma Natural Gas Businesses | CERC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale							557
Transaction costs							$ 59
Receivables, net								$ 15