v3.25.4
Share-based incentive compensation programs - Narrative (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2025
CAD ($)
Dec. 31, 2024
CAD ($)
Dec. 31, 2023
CAD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation expense charged against income $ 212 $ 116 $ 52
Income tax benefit recognized in income related to compensation expense 51 28 13
Cash payment for compensation expense $ 107 $ 74 $ 68
Restricted Stock Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Percentage of shares that become exercisable in third year 0.50    
Percentage of shares that become exercisable in seventh year 0.50    
Vesting percentage 100.00%    
Award vesting period 3 years    
Percentage restricted stock units vested on fifth anniversary of the grant date 50.00%    
Percentage restricted stock units vested on tenth anniversary of the grant date or retirement 50.00%    
Percentage restricted stock units vested on fifth anniversary of the grant date 50.00%    
Percentage restricted stock units vested on tenth anniversary of the grant date 50.00%    
Before-tax unrecognized compensation expense related to non-vested restricted stock $ 251    
Weighted average vesting period of nonvested restricted stock 4 years 2 months 12 days