v3.25.4
POST-EMPLOYMENT BENEFITS - Benefit Plan Costs (Details) - Domestic defined benefit plans - CAD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of net defined benefit liability (asset) [line items]    
Current service cost $ 74 $ 86
Past service cost 13 0
Net interest income (10) (8)
Net pension expense 77 78
Administrative expense 3 3
Total pension cost recognized in net income 80 81
Plan assets    
Disclosure of net defined benefit liability (asset) [line items]    
Net interest income (117) (110)
Administrative expense 3 3
Accrued benefit obligation    
Disclosure of net defined benefit liability (asset) [line items]    
Current service cost 74 86
Past service cost 13 0
Net interest income $ 107 $ 102