Investment Securities - Summary of Analysis of Fair Value and Carrying Value of Investment Securities Measured at Amortized Cost (Detail) - CAD ($) $ in Millions		Oct. 31, 2021	Oct. 31, 2020
Financial assets at fair value, investment securities [member]
Disclosure of financial assets [line items]
Cost		$ 18,133	$ 32,129
Financial assets at fair value, investment securities [member] | Canadian federal government issued or guaranteed debt [member]
Disclosure of financial assets [line items]
Cost		12,310	17,955
Financial assets at fair value, investment securities [member] | U.S. treasury and other U.S. agency debt [member]
Disclosure of financial assets [line items]
Cost		4,712	11,048
Financial assets at fair value, investment securities [member] | Other foreign government debt [member]
Disclosure of financial assets [line items]
Cost		970	1,766
Financial assets at fair value, investment securities [member] | Corporate debt [member]
Disclosure of financial assets [line items]
Cost		141	1,360
Financial assets at carrying value, investment securities [member]
Disclosure of financial assets [line items]
Cost	[1]	18,157	31,644
Financial assets at carrying value, investment securities [member] | Canadian federal government issued or guaranteed debt [member]
Disclosure of financial assets [line items]
Cost	[1]	12,372	17,819
Financial assets at carrying value, investment securities [member] | U.S. treasury and other U.S. agency debt [member]
Disclosure of financial assets [line items]
Cost	[1]	4,687	10,726
Financial assets at carrying value, investment securities [member] | Other foreign government debt [member]
Disclosure of financial assets [line items]
Cost	[1]	960	1,744
Financial assets at carrying value, investment securities [member] | Corporate debt [member]
Disclosure of financial assets [line items]
Cost	[1]	$ 138	$ 1,355

[1] Balances are net of allowances, which are not significant.