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Post-Employment Benefits - Summary of Major Categories of Defined Benefit Plan Assets (Parenthetical) (Detail) - CAD ($) $ in Millions | 12 Months Ended
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Oct. 31, 2025 | Oct. 31, 2024
Disclosure of fair value of plan assets [line items] |  |
Net derivative liability | $ 41,411 | $ 40,654
Canada plan [member] |  |
Disclosure of fair value of plan assets [line items] |  |
Net derivative liability | 29 | 30
Debt securities and deposits issued | 0 | 0
Securities and deposits issued | 0 | 0
Debt securities daily quoted prices in active markets | 372 | 285
Investment funds and other assets daily quoted prices in active markets | $ 40 | $ 33

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