v3.26.1
Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
0    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity [1] $ 150  
Commercial Paper    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity 150 $ 150
Amount outstanding at period end 0 0
Average amount outstanding 0 3
Maximum amount outstanding 0 $ 50
Weighted average interest rate, computed on a daily basis   4.57%
Money Pool    
Short-term Debt [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity 150 $ 150
Amount outstanding at period end 0 8
Average amount outstanding 20 2
Maximum amount outstanding $ 58 $ 42
Weighted average interest rate, computed on a daily basis 3.69% 4.25%
Weighted average interest rate at period end   3.88%
[1] Expires in December 2029.