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Employee Compensation - Pension and Other Employee Future Benefits - Summary of Changes in Number of Key Assumption (Detail) $ in Millions | Oct. 31, 2025 CAD ($)
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Pension Plans [member] | Actuarial assumption of discount rates [member] |  |
Disclosure of defined benefit plans [line items] |  |
Actuarial assumption of discount rates | 4.80% |
Pension Plans [member] | Actuarial assumption of discount rates [member] | Actuarial assumption of discount rates, 1% increase [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | $ (867) |
Pension Plans [member] | Actuarial assumption of discount rates [member] | Actuarial assumption of discount rates, 1% decrease [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | $ 1,073 |
Pension Plans [member] | Actuarial assumption of expected rates of salary increases [member] |  |
Disclosure of defined benefit plans [line items] |  |
Actuarial assumption of discount rates | 2.10% |
Pension Plans [member] | Actuarial assumption of expected rates of salary increases [member] | Actuarial assumption of expected rate of compensation, 0.25% increase [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | $ 36 |
Pension Plans [member] | Actuarial assumption of expected rates of salary increases [member] | Actuarial assumption of expected rate of compensation, 0.25% decrease [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | (35) |
Pension Plans [member] | Actuarial assumption of mortality rates [member] | Actuarial assumption of mortality, 1 year shorter life expectancy [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | (165) |
Pension Plans [member] | Actuarial assumption of mortality rates [member] | Actuarial assumption of mortality, 1 year longer life expectancy [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | $ 161 |
Other employee future benefit plans [member] | Actuarial assumption of discount rates [member] |  |
Disclosure of defined benefit plans [line items] |  |
Actuarial assumption of discount rates | 4.70% |
Other employee future benefit plans [member] | Actuarial assumption of discount rates [member] | Actuarial assumption of discount rates, 1% increase [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | $ (70) |
Other employee future benefit plans [member] | Actuarial assumption of discount rates [member] | Actuarial assumption of discount rates, 1% decrease [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | 83 |
Other employee future benefit plans [member] | Actuarial assumption of mortality rates [member] | Actuarial assumption of mortality, 1 year shorter life expectancy [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | (19) |
Other employee future benefit plans [member] | Actuarial assumption of mortality rates [member] | Actuarial assumption of mortality, 1 year longer life expectancy [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | $ 19 |
Other employee future benefit plans [member] | Actuarial assumption of health care cost trend rates [member] |  |
Disclosure of defined benefit plans [line items] |  |
Actuarial assumption of discount rates | 4.70% | [1]
Other employee future benefit plans [member] | Actuarial assumption of health care cost trend rates [member] | Actuarial assumption of medical cost trend rate, 1% increase [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible increase in actuarial assumption | $ 30 |
Other employee future benefit plans [member] | Actuarial assumption of health care cost trend rates [member] | Actuarial assumption of medical cost trend rate, 1% decrease [member] |  |
Disclosure of defined benefit plans [line items] |  |
Increase (decrease) in benefit obligation due to reasonably possible decrease in actuarial assumption | $ (28) |
[1] | Trending to 4.0% in 2041 and remaining at that level thereafter.

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- Definition The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [domain]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2024-01-01 -Paragraph 144 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_144&doctype=Standard -URIDate 2024-03-27 + Details
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- Definition The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [domain]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2024-01-01 -Paragraph 145 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_145_a&doctype=Standard -URIDate 2024-03-27 + Details
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