Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 487	$ 563	$ 986	$ 1,034
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	496	658	1,004	1,135
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	362	377	742	704
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	91	100	192	197
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	257	264	524	486
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	13	26	21
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	51	109	96	178
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	72	74	146	146
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	3	2	6
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 9	$ 95	$ 18	$ 101