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Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Revenues (Details) - USD ($) $ in Millions	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,448	$ 1,330	$ 3,105	$ 2,866
Regulated Electric \| Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,336	1,237	2,630	2,492
Regulated Natural Gas \| Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	110	90	470	363
All Other \| Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	2	3	5	11
Retail
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,141	996	2,427	2,131
Retail \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	472	387	1,068	900
Retail \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	657	596	1,335	1,208
Retail \| Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12	13	24	23
Retail \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,043	931	1,997	1,830
Retail \| Regulated Electric \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	417	350	818	718
Retail \| Regulated Electric \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	615	571	1,159	1,093
Retail \| Regulated Electric \| Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11	10	20	19
Retail \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	96	62	425	290
Retail \| Regulated Natural Gas \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	54	37	249	175
Retail \| Regulated Natural Gas \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	42	25	176	115
Retail \| Regulated Natural Gas \| Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Retail \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	3	5	11
Retail \| All Other \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1	0	1	7
Retail \| All Other \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Retail \| All Other \| Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1	3	4	4
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	74	57	192	132
Wholesale \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	74	57	192	132
Wholesale \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Wholesale \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	66	56	131	119
Transmission \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	66	56	131	119
Transmission \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Transmission \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	128	126	254	268
Interchange \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	123	115	246	240
Interchange \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5	11	8	28
Interchange \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,409	1,235	3,004	2,650
Total revenue from contracts with customers \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,306	1,159	2,566	2,321
Total revenue from contracts with customers \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	101	73	433	318
Total revenue from contracts with customers \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	3	5	11
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	39	95	101	216
Alternative revenue and other \| Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	30	78	64	171
Alternative revenue and other \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	9	17	37	45
Alternative revenue and other \| All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 0	$ 0	$ 0