Loans, Impaired Loans and Allowance for Credit Losses - Additional Information (Detail) - CAD ($) $ in Millions	3 Months Ended
	Apr. 30, 2022	Jan. 31, 2022	Oct. 31, 2021
Base case scenario [member]
Disclosure of detailed information about financial instruments [line items]
ACL (Stage 1 and Stage 2)	$ 3,771	$ 3,960	$ 4,076
Base case scenario [member] | Previously stated [member]
Disclosure of detailed information about financial instruments [line items]
ACL (Stage 1 and Stage 2)	3,698	3,900	3,998
Pessimistic scenario [member]
Disclosure of detailed information about financial instruments [line items]
ACL (Stage 1 and Stage 2)	679	675	866
Probability Weighted Scenarios [Member]
Disclosure of detailed information about financial instruments [line items]
ACL (Stage 1 and Stage 2)	$ 391	$ 381	$ 407