v3.26.1
Borrowings and Other Financing Instruments - Letters of Credit (Details) - USD ($)
Jun. 30, 2026
Dec. 31, 2025
Line of Credit Facility [Line Items]    
Short-term debt $ 45,000,000 $ 220,000,000
Letter of Credit    
Line of Credit Facility [Line Items]    
Short-term debt 0 0
Letter of Credit | Continuing Letter of Credit Agreement    
Line of Credit Facility [Line Items]    
Short-term debt 0  
Line of Credit Facility, Maximum Borrowing Capacity 150,000,000  
Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Direct advances on the credit facility outstanding 0 $ 0
Line of Credit Facility, Maximum Borrowing Capacity [1] $ 600,000,000  
[1] Expires in December 2029