v3.26.1
Pension and other post-retirement benefits (Assumptions and 1% change) (Details) - CAD ($)
Dec. 31, 2025
Dec. 31, 2024
Sensitivity analysis of actuarial assumptions    
Increase in actuarial assumption by 1.00% 1.00%
Decrease in actuarial assumption by 1.00% 1.00%
Percentage of the change in the other assumptions having no significant impact 1.00% 1.00%
Pension Plans [Member]    
Assumptions defined benefit obligation and net pension and other benefit expense    
Discount rate - obligation 4.20% 3.90%
Discount rate - expense 3.90% 3.80%
Rate of compensation increase 2.90% 2.90%
Pension Plans [Member] | Discount rate [Member]    
Sensitivity analysis of actuarial assumptions    
Increase in defined benefit obligation $ (8,905,000)  
Decrease in defined benefit obligation 11,365,000  
Pension Plans [Member] | Rate of compensation increase [Member]    
Sensitivity analysis of actuarial assumptions    
Increase in defined benefit obligation 2,522,000  
Decrease in defined benefit obligation (2,328,000)  
Pension Plans [Member] | Increase of one year in the expected lifetime [Member]    
Sensitivity analysis of actuarial assumptions    
Increase in defined benefit obligation $ 462,000  
Other Benefit Plans [Member]    
Assumptions defined benefit obligation and net pension and other benefit expense    
Discount rate - obligation 4.80% 4.60%
Discount rate - expense 4.60% 4.60%
Health care cost trend rate 5.00% 5.00%
Dental care cost trend rate 4.50% 4.50%
Other Benefit Plans [Member] | Discount rate [Member]    
Sensitivity analysis of actuarial assumptions    
Increase in defined benefit obligation $ (2,432,000)  
Decrease in defined benefit obligation $ 2,902,000