Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Tax Contingency [Line Items]
Effective income tax rate (as a percent)	19.00%	27.00%	25.00%	26.00%
Net uncertain tax liability	$ 29		$ 29
Houston Electric
Income Tax Contingency [Line Items]
Effective income tax rate (as a percent)	22.00%	21.00%	22.00%	21.00%
CERC
Income Tax Contingency [Line Items]
Effective income tax rate (as a percent)	25.00%	170.00%	22.00%	25.00%