Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 1,185	$ 1,091	$ 960
Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	975	898	788
Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	396	363	322
Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	572	526	460
Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	9	6
Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	202	189	168
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	4	4
Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	16	14	14
Regulated Electric | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	991	910	843
Regulated Electric | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	785	721	675
Regulated Electric | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	293	272	258
Regulated Electric | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	485	441	411
Regulated Electric | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	8	6
Regulated Electric | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	202	189	168
Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	0	0
Regulated Electric | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	11	12	12
Regulated Natural Gas | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	194	180	117
Regulated Natural Gas | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	190	176	113
Regulated Natural Gas | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	103	91	64
Regulated Natural Gas | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	87	85	49
Regulated Natural Gas | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	4	4
Regulated Natural Gas | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	2	2
All Other | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	1
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,201	1,105	974
Total revenues | Regulated Electric
Disaggregation of Revenue [Line Items]
Total revenues	1,002	922	855
Total revenues | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues	198	$ 182	$ 119
Total revenues | All Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 1