Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 267	$ 260	$ 577	$ 591
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	246	236	502	490
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	21	24	75	101
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	206	214	455	493
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	78	81	185	204
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	127	131	267	285
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	2	3	4
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	186	192	383	396
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	68	143	150
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	119	122	237	242
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	2	3	4
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	20	22	72	97
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12	13	42	54
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8	9	30	43
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	59	41	115	89
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	58	41	113	88
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	0	2	1
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	265	255	570	582
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	244	233	496	484
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21	22	74	98
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	2	5	7	9
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	2	3	6	6
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 2	$ 1	$ 3