Stock-Based Incentive Compensation Plans and Employee Benefit Plans - Change in Control Agreements and Other Employee Matters (Details) $ in Millions		12 Months Ended
	Jul. 21, 2021 USD ($)	Dec. 31, 2021 salary_severance_benefits
Concentration Risk [Line Items]
Maximum number of times annual salary included in severance benefits | salary_severance_benefits		3
Board of Directors Chairman
Concentration Risk [Line Items]
Lump sum cash payment for separation | $	$ 28
Workforce Subject to Collective Bargaining Arrangements Expiring in May 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		15.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in May 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		2.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in April 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		5.00%
Workforce Subject to Collective Bargaining Arrangements Expiring December 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		3.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in December 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		3.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in June 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		5.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in July 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Workforce Subject to Collective Bargaining Arrangements Expiring June 2022, Additional | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		3.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in September 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Workforce Subject to Collective Bargaining Arrangements Expiring in October 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		1.00%
Workforce Subject to Collective Bargaining Arrangements | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		37.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		54.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in April 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring December 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in December 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in June 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in July 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring June 2022, Additional | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in September 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements Expiring in October 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
Houston Electric | Workforce Subject to Collective Bargaining Arrangements | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		54.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in May 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		3.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in April 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		12.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring December 2023 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in December 2025 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		7.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in June 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		14.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in July 2022 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		1.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring June 2022, Additional | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in September 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements Expiring in October 2021 | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		0.00%
CERC Corp | Workforce Subject to Collective Bargaining Arrangements | Employees Subject To Collective Bargaining Agreements | Labor Force Concentration Risk
Concentration Risk [Line Items]
Concentration risk (as a percent)		37.00%