Held for Sale and Divestitures (CenterPoint Energy and CERC) - Schedule of Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Total current assets held for sale	$ 2,192	$ 0
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Total current liabilities held for sale	472	0
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	28
Accrued unbilled revenues	14
Natural gas inventory	20
Materials and supplies	8
Property, plant and equipment, net	1,238
Goodwill	403
Regulatory assets	386
Other	95
Total current assets held for sale	2,192
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Short term borrowings	14
Accounts payable	20
Taxes accrued	5
Customer deposits	12
Regulatory liabilities	286
Other	135
Total current liabilities held for sale	472
CERC Corp
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Total current assets held for sale	1,935	0
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Total current liabilities held for sale	472	$ 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	28
Accrued unbilled revenues	14
Natural gas inventory	20
Materials and supplies	8
Property, plant and equipment, net	1,238
Goodwill	146
Regulatory assets	386
Other	95
Total current assets held for sale	1,935
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Short term borrowings	14
Accounts payable	20
Taxes accrued	5
Customer deposits	12
Regulatory liabilities	286
Other	135
Total current liabilities held for sale	$ 472