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Securities - Summary of Allowance for Credit Losses measured at FVOCI and Amortized Cost (Detail) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Oct. 31, 2025 | Oct. 31, 2024
Disclosure of financial assets [line items] |  |
Balance at beginning of year | $ 4,114 |
Balance at end of year | 4,739 | $ 4,114
Debt securities measured at FVOCI [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 19 |
Balance at end of year | 23 | 19
Debt securities measured at FVOCI and amortized cost [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 36 | 42
Provision for (reversal of) credit losses | 37 | (5)
Foreign exchange and other | 2 | (1)
Balance at end of year | 75 | 36
Debt securities measured at amortized cost [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 17 |
Balance at end of year | 52 | 17
Stage 1 [member] | Debt securities measured at FVOCI [member] | Financial instruments performing [member] | 12-month expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 2 |
Balance at end of year | 3 | 2
Stage 1 [member] | Debt securities measured at FVOCI and amortized cost [member] | Financial instruments performing [member] | 12-month expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 7 | 8
Provision for (reversal of) credit losses | (1) |
Foreign exchange and other |  | (1)
Balance at end of year | 6 | 7
Stage 1 [member] | Debt securities measured at amortized cost [member] | Financial instruments performing [member] | 12-month expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 5 |
Balance at end of year | 3 | 5
Stage 2 [member] | Debt securities measured at FVOCI [member] | Financial instruments performing [member] | Lifetime expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 17 |
Balance at end of year | 20 | 17
Stage 2 [member] | Debt securities measured at FVOCI and amortized cost [member] | Financial instruments performing [member] | Lifetime expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 17 | 20
Provision for (reversal of) credit losses | 2 | (3)
Foreign exchange and other | 1 |
Balance at end of year | 20 | 17
Stage 3 [member] | Financial instruments credit-impaired [member] | Lifetime expected credit losses [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 825 |
Balance at end of year | 989 | 825
Stage 3 [member] | Debt securities measured at FVOCI and amortized cost [member] | Financial instruments credit-impaired [member] | Lifetime expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 12 | 14
Provision for (reversal of) credit losses | 36 | (2)
Foreign exchange and other | 1 |
Balance at end of year | 49 | 12
Stage 3 [member] | Debt securities measured at amortized cost [member] | Financial instruments credit-impaired [member] | Lifetime expected credit losses [member] | Debt securities [member] |  |
Disclosure of financial assets [line items] |  |
Balance at beginning of year | 12 |
Balance at end of year | $ 49 | $ 12

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