v3.26.1
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT - Carrying value and fair value of long-term debt and derivative financial instruments (Details) - CAD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Carrying value    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Long-term debt $ (6,824.3) $ (7,619.7)
Carrying value | Forward contract    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) (1.5) 6.9
Carrying value | Interest rate swaps    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) (7.2) (7.2)
Carrying value | Cross-currency swaps    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) 33.0 141.5
Fair value    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Long-term debt (6,849.3) (7,540.0)
Fair value | Cash flow hedges    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) 24.3 141.2
Fair value | Forward contract    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) (1.5) 6.9
Fair value | Interest rate swaps    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) (7.2) (7.2)
Fair value | Cross-currency swaps    
FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT    
Derivative financial asset (liability) $ 33.0 $ 141.5