Held for Sale, Divestitures and Mergers (CenterPoint Energy and CERC) - Schedule of Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Total current assets held for sale	$ 2,338	$ 0
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Total current liabilities held for sale	562	0
Non-current assets held for sale	0	782
Arkansas and Oklahoma Natural Gas Businesses | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Receivables, net	46
Accrued unbilled revenues	48
Natural gas inventory	46
Materials and supplies	9
Property, plant and equipment, net	1,314
Goodwill	398
Investment in unconsolidated affiliate	0
Regulatory assets	471
Other	6
Total current assets held for sale	2,338
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Short term borrowings	36
Accounts payable	40
Taxes accrued	7
Customer deposits	12
Regulatory liabilities	365
Other	102
Total current liabilities held for sale	562
CERC Corp
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Total current assets held for sale	2,084	0
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Total current liabilities held for sale	562	$ 0
CERC Corp | Arkansas and Oklahoma Natural Gas Businesses | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Receivables, net	46
Accrued unbilled revenues	48
Natural gas inventory	46
Materials and supplies	9
Property, plant and equipment, net	1,314
Goodwill	144
Investment in unconsolidated affiliate	0
Regulatory assets	471
Other	6
Total current assets held for sale	2,084
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Short term borrowings	36
Accounts payable	40
Taxes accrued	7
Customer deposits	12
Regulatory liabilities	365
Other	102
Total current liabilities held for sale	$ 562