Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ (8,612)	$ (9,327)	$ (8,256)
Other	87	(6)	96
Total	8,696	9,321	8,352
Lease income	8	7	7
Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)
Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(4,275)	(4,095)	(3,726)
Other	15	13	37
Total	4,290	4,108	3,763
Electric | Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(4,210)	(4,969)	(4,281)
Other	69	(23)	55
Total	4,276	4,946	4,336
Natural Gas | Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(127)	(263)	(249)
Other	3	4	4
Total	130	267	253
Corporate and Other | Consolidation, Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0
Houston Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3,684)	(3,417)	(3,117)
Other	(7)	(5)	17
Total	3,677	3,412	3,134
CERC Corp
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(4,083)	(4,816)	(4,148)
Other	66	(16)	52
Total	4,149	4,800	4,200
Lease income	$ 4	$ 3	$ 3