Investment Securities - Disclosure of Carrying Value of Banks Investment Securities Per Measurement Category (Detail) - CAD ($) $ in Millions	Jul. 31, 2026	Apr. 30, 2026	Oct. 31, 2025
Disclosure of financial assets [line items]
Investment securities	$ 152,681	$ 149,806	$ 149,948
Debt Investments [member] \| Financial assets measured at fair value through other comprehensive income, category [member]
Disclosure of financial assets [line items]
Investment securities	128,066	125,491	123,732
Debt Investments [member] \| Financial assets at amortised cost, category [member]
Disclosure of financial assets [line items]
Investment securities	22,221	21,988	23,722
Debt Investments [member] \| Financial assets at fair value through profit or loss, category [member]
Disclosure of financial assets [line items]
Investment securities	23	2	23
Equity securities [member] \| Investments in equity instruments designated at fair value through other comprehensive income [member]
Disclosure of financial assets [line items]
Investment securities	402	313	398
Equity securities [member] \| Financial assets at fair value through profit or loss, category [member]
Disclosure of financial assets [line items]
Investment securities	$ 1,969	$ 2,012	$ 2,073