Revenue Recognition and Allowance for Credit Losses - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts	$ 1,906	$ 1,872	$ 4,500	$ 4,633
Other	(1)	3	25	21
Total	1,905	1,875	4,525	4,654
Lease income	2	2	4	4
Houston Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	1,049	918	1,959	1,721
Other	(5)	(9)	(14)	(20)
Total	1,044	909	1,945	1,701
CERC
Disaggregation of Revenue [Line Items]
Revenue from contracts	682	737	2,167	2,437
Other	(3)	8	24	25
Total	679	745	2,191	2,462
Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	1,207	1,040	2,259	1,998
Other	0	(3)	(3)	(9)
Total	1,207	1,037	2,256	1,989
Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts	698	759	2,239	2,511
Other	(3)	5	26	28
Total	695	764	2,265	2,539
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts	1	73	2	124
Other	2	1	2	2
Total	$ 3	$ 74	$ 4	$ 126