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 9 Months Ended
Jul. 31, 2026
Jul. 31, 2025
Jul. 31, 2026
Jul. 31, 2025
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense $ 6,291 $ 5,869 $ 18,591 $ 17,334
Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense 171 161 517 532
Other post employment benefit expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Total pension and other post-employment benefit expense 30 29 82 89
Defined benefit pension plans [member] | Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Current service costs 50 53 150 157
Past service costs       49
Net interest expense (income) (44) (41) (133) (122)
Administrative expense 5 6 16 17
Defined benefit pension expense 11 18 33 101
Defined contribution pension plans [Member] | Pension Expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Defined contribution pension expense 160 143 484 431
Other post employment benefit [member] | Other post employment benefit expense [Member]        
Disclosure of pension and other post employment plan [Line Items]        
Current service costs 8 9 26 25
Net interest expense (income) 20 18 59 57
Remeasurements of other long-term benefits 2 2 (3) 7
Defined benefit pension expense $ 30 $ 29 $ 82 $ 89