Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 670	$ 730	$ 1,656	$ 1,764
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	677	741	1,681	1,876
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	501	501	1,243	1,205
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164	159	356	356
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	319	325	843	811
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18	17	44	38
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	88	149	184	327
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81	80	227	226
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers			2	6
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 7	$ 11	$ 25	$ 112