Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 563	$ 488	$ 1,034	$ 1,408
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	658	498	1,135	1,432
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	377	296	704	584
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	100	85	197	176
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	264	201	486	389
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	10	21	19
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	109	118	178	676
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	74	72	146	143
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	2	6	5
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 95	$ 10	$ 101	$ 24