Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenues	$ 2,779	$ 2,763
Net income	325	531
Total Assets	37,752		$ 38,546
Continuing Operations
Segment Reporting Information [Line Items]
Total Assets	37,752		38,546
Houston Electric
Segment Reporting Information [Line Items]
Revenues	792	746
Net income	108	61
Total Assets	16,069		15,339
Houston Electric | Affiliates of NRG
Segment Reporting Information [Line Items]
Revenues	227	225
Houston Electric | Affiliates of Vistra Energy Corp.
Segment Reporting Information [Line Items]
Revenues	114	105
Electric | Affiliates of NRG
Segment Reporting Information [Line Items]
Revenues	227	225
Electric | Affiliates of Vistra Energy Corp.
Segment Reporting Information [Line Items]
Revenues	114	105
Natural Gas
Segment Reporting Information [Line Items]
Revenues	1,775	1,824
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	52	46
Corporate and Other | Pension and Other Postretirement Plans Costs
Segment Reporting Information [Line Items]
Regulatory assets	391		405
Operating Segments | Electric
Segment Reporting Information [Line Items]
Revenues	952	893
Net income	123	82
Total Assets	19,858		19,024
Operating Segments | Natural Gas
Segment Reporting Information [Line Items]
Revenues	1,775	1,824
Net income	234	398
Total Assets	16,407		18,043
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	52	46
Net income	(32)	$ 51
Total Assets	$ 1,487		$ 1,479