Investment Securities - Summary of Analysis of Fair Value and Carrying Value of Investment Securities Measured at Amortized Cost (Detail) - CAD ($) $ in Millions		Oct. 31, 2025	Oct. 31, 2024
Financial assets at fair value, investment securities [member]
Disclosure of financial assets [line items]
Cost		$ 23,239	$ 28,422
Financial assets at fair value, investment securities [member] | Canadian federal government issued or guaranteed debt [member]
Disclosure of financial assets [line items]
Cost		5,553	8,722
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		15,178	17,440
Financial assets at fair value, investment securities [member] | Other foreign government debt [member]
Disclosure of financial assets [line items]
Cost		2,285	2,044
Financial assets at fair value, investment securities [member] | Corporate debt [member]
Disclosure of financial assets [line items]
Cost		223	216
Financial assets at carrying value, investment securities [member]
Disclosure of financial assets [line items]
Cost	[1]	23,722	29,412
Financial assets at carrying value, investment securities [member] | Canadian federal government issued or guaranteed debt [member]
Disclosure of financial assets [line items]
Cost	[1]	5,467	8,721
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]	15,758	18,440
Financial assets at carrying value, investment securities [member] | Other foreign government debt [member]
Disclosure of financial assets [line items]
Cost	[1]	2,281	2,041
Financial assets at carrying value, investment securities [member] | Corporate debt [member]
Disclosure of financial assets [line items]
Cost	[1]	$ 216	$ 210

[1] Balances are net of allowances, which are $1 (2024 – $1).