v3.25.4
Pensions and other postretirement benefits (Amounts Recognized in the Consolidated Balance Sheet) (Details) - CAD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]    
Noncurrent assets - Pension asset $ 5,362 $ 4,541
Current liabilities (10) (10)
Noncurrent liabilities - Pension and other postretirement benefits (453) (483)
Pensions    
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]    
Noncurrent assets - Pension asset 5,362 4,541
Current liabilities 0 0
Noncurrent liabilities - Pension and other postretirement benefits (329) (350)
Total amount recognized 5,033 4,191
Other postretirement benefits    
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]    
Noncurrent assets - Pension asset 0 0
Current liabilities (10) (10)
Noncurrent liabilities - Pension and other postretirement benefits (124) (133)
Total amount recognized $ (134) $ (143)