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Employee Compensation - Pension and Other Employee Future Benefits - Additional Information (Detail) - CAD ($)
$ in Millions
 12 Months Ended
Oct. 31, 2025
Oct. 31, 2024
Disclosure of defined benefit plans [line items]    
Estimated Benefit payments $ 605  
Increase Decrease In Defined Benefit Plan Assets Recognized In Other Comprehensive Income 47  
Other comprehensive loss write down of surplus assets 62  
Recognized As Reduction In Employee Compensation Expense [Member]    
Disclosure of defined benefit plans [line items]    
Defined benefit plans impact of plan amendments expenses 19  
Pension Plans [member]    
Disclosure of defined benefit plans [line items]    
Defined benefit plans impact of plan amendments expenses 19  
Pension Plans [member] | Scenario, Forecast [Member]    
Disclosure of defined benefit plans [line items]    
Estimated Benefit payments 41  
Other employee future benefit plans [member]    
Disclosure of defined benefit plans [line items]    
Defined benefit plans impact of plan amendments expenses   $ 84
Other comprehensive loss write down of surplus assets 0  
Other employee future benefit plans [member] | Employee Compensation Expense [Member]    
Disclosure of defined benefit plans [line items]    
Defined benefit plan amendments gain loss 84  
Other employee future benefit plans [member] | Scenario, Forecast [Member]    
Disclosure of defined benefit plans [line items]    
Estimated Benefit payments $ 23