Revenue Recognition and Allowance for Credit Losses - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts	$ 2,761	$ 2,788
Other	18	(25)
Total	2,779	2,763
Lease income	2	1
Houston Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	803	756
Other	(11)	(10)
Total	792	746
CERC
Disaggregation of Revenue [Line Items]
Revenue from contracts	1,700	1,785
Other	17	(22)
Total	1,717	1,763
Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts	958	898
Other	(6)	(5)
Total	952	893
Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts	1,752	1,845
Other	23	(21)
Total	1,775	1,824
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts	51	45
Other	1	1
Total	$ 52	$ 46