v3.26.1
Employee benefits - Pension and other post-employment benefits - Summary of Composition of Pension and Other Post-employment Benefit Expense (Detail) - CAD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Apr. 30, 2026
Apr. 30, 2025
Apr. 30, 2026
Apr. 30, 2025
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense $ 6,011 $ 5,478 $ 12,300 $ 11,465
Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense 152 196 346 371
Other post employment benefit expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense 26 31 52 60
Defined benefit pension plans [member] | Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Current service costs 50 52 100 104
Past service costs   49   49
Net interest expense (income) (45) (41) (89) (81)
Administrative expense 6 5 11 11
Defined benefit pension expense 11 65 22 83
Defined contribution pension plans [Member] | Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Defined contribution pension expense 141 131 324 288
Other post employment benefit [member] | Other post employment benefit expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Current service costs 9 8 18 16
Net interest expense (income) 19 20 39 39
Remeasurements of other long-term benefits (2) 3 (5) 5
Defined benefit pension expense $ 26 $ 31 $ 52 $ 60