Revenues (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 279	$ 294	$ 870	$ 900
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	263	274	753	767
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	15	20	116	133
All Other | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1	0	1	0
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	231	237	724	733
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87	87	291	295
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	141	148	426	432
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	2	7	6
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	217	219	613	606
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	79	78	229	226
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	136	139	378	374
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2	6	6
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	18	110	127
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8	9	62	69
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5	9	48	58
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Retail | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Retail | All Other | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail | All Other | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail | All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	44	53	133	156
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	43	52	131	153
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1	2	3
Interchange | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	275	290	857	889
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	260	271	744	759
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	19	112	130
Total revenue from contracts with customers | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	4	13	11
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	3	3	9	8
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	1	1	4	3
Alternative revenue and other | All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 0	$ 0	$ 0