v3.26.3
Segment Information (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting [Line Items]        
Net Income (Loss) $ 53 $ 43 $ 157 $ 111
Natural gas 19 18 127 110
Cost of natural sold and transported 7 6 58 48
Operating and maintenance expenses 74 58 205 181
Utilities Operating Expense, Depreciation and Amortization 56 51 164 150
Interest and Debt Expense 22 19 61 50
Income tax expense $ 16 12 48 32
Revenues Including Intersegment Revenues     $ 1,011  
Number Of Reportable Segments, Disclosed By Definition, Flag true   true  
Electric, affiliates $ 72 59 $ 204 170
Total revenues        
Segment Reporting [Line Items]        
Net Income (Loss) 51 40 155 108
Regulated Operating Revenue 349 [1] 309 [2] 1,012 [3] 913 [4]
Electric Fuel and Purchased Power 119 118 302 327
Cost of natural sold and transported 7 6 58 48
Operating and maintenance expenses 73 58 204 181
Utilities Operating Expense, Depreciation and Amortization 56 51 164 150
Segment Reporting, Other Segment Item, Amount 5 6 19 18
Interest and Debt Expense 22 19 61 50
Income tax expense 16 11 48 31
Intersegment Eliminations        
Segment Reporting [Line Items]        
Regulated Operating Revenue     (1)  
Regulated Electric Segment        
Segment Reporting [Line Items]        
Revenues Including Intersegment Revenues     885  
Regulated Electric Segment | Total revenues        
Segment Reporting [Line Items]        
Regulated Operating Revenue, Electric 330 [1] 291 [2] 885 [3] 803 [4]
Net Income (Loss) 56 44 146 102
Electric Fuel and Purchased Power 119 118 302 327
Cost of natural sold and transported 0 0 0 0
Operating and maintenance expenses 65 52 180 158
Utilities Operating Expense, Depreciation and Amortization 47 43 140 127
Segment Reporting, Other Segment Item, Amount 5 5 17 16
Interest and Debt Expense 20 16 54 44
Income tax expense 18 13 46 29
Regulated Electric Segment | Intersegment Eliminations        
Segment Reporting [Line Items]        
Regulated Operating Revenue, Electric     0  
Regulated Natural Gas Segment        
Segment Reporting [Line Items]        
Revenues Including Intersegment Revenues     126  
Regulated Natural Gas Segment | Total revenues        
Segment Reporting [Line Items]        
Net Income (Loss) (5) (4) 9 6
Natural gas 19 [1] 18 [2] 127 [3] 110 [4]
Electric Fuel and Purchased Power 0 0 0 0
Cost of natural sold and transported 7 6 58 48
Operating and maintenance expenses 8 6 24 23
Utilities Operating Expense, Depreciation and Amortization 9 8 24 23
Segment Reporting, Other Segment Item, Amount 0 1 2 2
Interest and Debt Expense 2 3 7 6
Income tax expense (2) (2) 2 2
Regulated Natural Gas Segment | Intersegment Eliminations        
Segment Reporting [Line Items]        
Natural gas     (1)  
All Other        
Segment Reporting [Line Items]        
Net Income (Loss) $ 2 $ 3 $ 2 $ 3
[1] Operating revenues include $72 million of affiliate electric revenue.
[2] Operating revenues include $59 million of affiliate electric revenue.
[3] Operating revenues include $204 million of affiliate electric revenue.
[4] Operating revenues include $170 million of affiliate electric revenue.