Divestitures (CenterPoint Energy and CERC) - Schedule of Pre-tax Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	$ 730	$ 329
Arkansas and Oklahoma Natural Gas Businesses | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	9	52
CERC Corp
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	748	193
CERC Corp | Arkansas and Oklahoma Natural Gas Businesses | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	$ 9	$ 52