v3.26.1
Miscellaneous financial information - Narrative (Details) - CAD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2026
Employee Severance      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges $ (50) $ 330 $ (50)