v3.25.4
Debt (Bilateral Letter of Credit Facilities) (Details) - CAD ($)
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Line of Credit Facility [Line Items]    
Minimum term for which collateral in the form of cash and cash equivalents is pledged for 1 month  
Committed Bilateral Letter of Credit Facilites    
Line of Credit Facility [Line Items]    
Outstanding letters of credit $ 321,000,000 $ 329,000,000
Bilateral letter of credit facilities, total available amount 362,000,000 366,000,000
Uncommitted Bilateral Letter of Credit Facilities    
Line of Credit Facility [Line Items]    
Outstanding letters of credit $ 153,000,000 $ 142,000,000