Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 730	$ 564	$ 1,764	$ 1,972
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	741	575	1,876	2,007
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	501	378	1,205	963
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	159	126	356	302
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	325	241	811	631
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17	11	38	30
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	149	109	327	785
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	80	75	226	218
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	2	6	6
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 11	$ 11	$ 112	$ 35