Divestitures (CenterPoint Energy and CERC) - Schedule of Pre-tax Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	$ 244	$ 181	$ 974	$ 510
CERC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	28	57	866	334
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	0	10	9	62
Arkansas and Oklahoma Natural Gas Businesses | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | CERC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from Continuing Operations Before Income Taxes	$ 0	$ 10	$ 9	$ 62