Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Deferred tax assets, valuation allowance	$ 11	$ 26
Release of valuation allowance	15
Accrued penalties and interest	4
Unrecognized tax benefits that would impact effective tax rate	2
Accrued penalties and interest not included	1
Net uncertain tax liability released	6
Reduction due to lapse of applicable statute of limitations	3
CERC Corp
Business Acquisition [Line Items]
Deferred tax assets, valuation allowance	0	$ 15
Release of valuation allowance	15
State and Local Jurisdiction
Business Acquisition [Line Items]
Operating loss carryforwards	1,300
Deferred tax assets tax credit carryforwards	7
State and Local Jurisdiction | CERC Corp
Business Acquisition [Line Items]
Operating loss carryforwards	972
Deferred tax assets tax credit carryforwards	7
Domestic Tax Authority | CERC Corp
Business Acquisition [Line Items]
Deferred tax assets tax credit carryforwards	$ 2,300