v3.26.1
Segment Information (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Net Income (Loss) $ 39 $ 26 $ 104 $ 68
Natural gas 25 24 108 92
Cost of natural sold and transported 9 9 51 42
Operating and maintenance expenses 66 60 131 123
Utilities Operating Expense, Depreciation and Amortization 54 50 108 99
Interest and Debt Expense 21 15 39 31
Income tax expense $ 12 8 32 20
Revenues Including Intersegment Revenues     $ 662  
Number Of Reportable Segments, Disclosed By Definition, Flag true   true  
Related Party Transaction, Electric Domestic Regulated Revenue $ 64 55 $ 132 111
Total revenues        
Segment Reporting [Line Items]        
Net Income (Loss) 39 26 104 68
Regulated Operating Revenue 282 [1] 277 [2] 663 [3] 604 [4]
Electric Fuel and Purchased Power 74 103 183 209
Cost of natural sold and transported 9 9 51 42
Operating and maintenance expenses 66 60 131 123
Utilities Operating Expense, Depreciation and Amortization 54 50 108 99
Segment Reporting, Other Segment Item, Amount 8 6 14 12
Interest and Debt Expense 21 15 39 31
Income tax expense 11 8 32 20
Intersegment Eliminations        
Segment Reporting [Line Items]        
Regulated Operating Revenue     (1)  
Regulated Electric Segment        
Segment Reporting [Line Items]        
Revenues Including Intersegment Revenues     555  
Regulated Electric Segment | Total revenues        
Segment Reporting [Line Items]        
Regulated Operating Revenue, Electric 257 [1] 253 [2] 555 [3] 512 [4]
Net Income (Loss) 41 29 90 58
Electric Fuel and Purchased Power 74 103 183 209
Cost of natural sold and transported 0 0 0 0
Operating and maintenance expenses 58 52 115 106
Utilities Operating Expense, Depreciation and Amortization 47 42 93 84
Segment Reporting, Other Segment Item, Amount 6 5 12 11
Interest and Debt Expense 18 13 34 28
Income tax expense 13 9 28 16
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     107  
Regulated Natural Gas Segment | Total revenues        
Segment Reporting [Line Items]        
Net Income (Loss) (2) (3) 14 10
Natural gas 25 [1] 24 [2] 108 [3] 92 [4]
Electric Fuel and Purchased Power 0 0 0 0
Cost of natural sold and transported 9 9 51 42
Operating and maintenance expenses 8 8 16 17
Utilities Operating Expense, Depreciation and Amortization 7 8 15 15
Segment Reporting, Other Segment Item, Amount 2 1 2 1
Interest and Debt Expense 3 2 5 3
Income tax expense $ (2) $ (1) 4 $ 4
Regulated Natural Gas Segment | Intersegment Eliminations        
Segment Reporting [Line Items]        
Natural gas     $ (1)  
[1] Operating revenues include $64 million of affiliate electric revenue.
[2] Operating revenues include $55 million of affiliate electric revenue.
[3] Operating revenues include $132 million of affiliate electric revenue.
[4] Operating revenues include $111 million of affiliate electric revenue.