Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 515	$ 419
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	521	428
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	413	312
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	114	86
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	288	217
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	9
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	25	36
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	76	71
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	6	9
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1	$ 0