Unconsolidated Affiliate (CenterPoint Energy and CERC) - Schedules of Transactions with Enable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CERC Corp
Schedule of Equity Method Investments [Line Items]
Property, plant and equipment from parent	$ 0	$ 23	$ 0
Enable Midstream Partners | CERC Corp
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties		1
Natural Gas Expenses | Enable Midstream Partners
Schedule of Equity Method Investments [Line Items]
Property, plant and equipment from parent	85	86	86
Accounts payable for natural gas purchases from Enable		9
Natural Gas Expenses | Enable Midstream Partners | CERC Corp
Schedule of Equity Method Investments [Line Items]
Property, plant and equipment from parent	$ 85	86	$ 86
Accounts payable for natural gas purchases from Enable		9
Transitional Service | Enable Midstream Partners
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties		$ 1