Revenue Recognition - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,953	$ 1,906	$ 4,909	$ 4,500
Other	(8)	(1)	(43)	25
Total	1,944	1,905	4,864	4,525
Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)		(2)
Houston Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,014	1,049	1,906	1,959
Other	(6)	(5)	(14)	(14)
Total	1,008	1,044	1,892	1,945
CERC
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	736	682	2,555	2,167
Other	(5)	(3)	(36)	24
Total	731	679	2,519	2,191
Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,195	1,207	2,267	2,259
Other	(4)	0	(10)	(3)
Total	1,191	1,207	2,257	2,256
Electric \| Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	756	698	2,639	2,239
Other	(5)	(3)	(35)	26
Total	750	695	2,602	2,265
Natural Gas \| Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)		(2)
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	1	3	2
Other	1	2	2	2
Total	3	$ 3	5	$ 4
Corporate and Other \| Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0		$ 0