Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts	$ 9,327	$ 8,256	$ 7,350
Other	(6)	96	68
Revenues	9,321	8,352	7,418
Lease income	7	7	6
Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	4,095	3,726	3,451
Other	13	37	19
Revenues	4,108	3,763	3,470
Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts	4,969	4,281	3,586
Other	(23)	55	45
Revenues	4,946	4,336	3,631
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts	263	249	313
Other	4	4	4
Revenues	267	253	317
Houston Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	3,417	3,117	2,896
Other	(5)	17	15
Revenues	3,412	3,134	2,911
CERC Corp
Disaggregation of Revenue [Line Items]
Revenue from contracts	4,816	4,148	3,480
Other	(16)	52	51
Revenues	4,800	4,200	3,531
Lease income	$ 3	$ 3	$ 2