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Employee Compensation - Pension and Other Employee Future Benefits - Summary Of Asset Allocation Ranges, Weighted-Average Actual Asset Allocations And Fair Values Of Plan Assets (Detail) - CAD ($) $ in Millions | 12 Months Ended
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Oct. 31, 2025 | Oct. 31, 2024
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
% of total | 100.00% | 100.00%
Plan assets, at fair value | $ 9,456 | $ 9,156
Level 1 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | 1,245 | 1,156
Level 2 and 3 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | $ 8,211 | $ 8,000
Equities [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
% of total | 21.00% | 22.00%
Plan assets, at fair value | $ 2,008 | $ 1,912
Equities [Member] | Level 1 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | 1,139 | 1,060
Equities [Member] | Level 2 and 3 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | $ 869 | $ 852
Fixed Income Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
% of total | 49.00% | 49.00%
Plan assets, at fair value | $ 4,657 | $ 4,563
Fixed Income Investments [Member] | Level 1 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | 106 | 96
Fixed Income Investments [Member] | Level 2 and 3 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | $ 4,551 | $ 4,467
Private Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
% of total | 30.00% | 29.00%
Plan assets, at fair value | $ 2,791 | $ 2,681
Private Investments [Member] | Level 2 and 3 of fair value hierarchy [member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Plan assets, at fair value | $ 2,791 | $ 2,681
Bottom of range [member] | Equities [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 15.00% | 15.00%
Bottom of range [member] | Fixed Income Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 40.00% | 40.00%
Bottom of range [member] | Private Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 10.00% | 10.00%
Top of range [member] | Equities [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 40.00% | 40.00%
Top of range [member] | Fixed Income Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 55.00% | 55.00%
Top of range [member] | Private Investments [Member] |  |
Disclosure Of Detailed Information About Allocation Of Plan Assets And Weighted Average Actual Asset Allocations And Fair Value Of Plan Assets [Line Items] |  |
Target range | 35.00% | 35.00%

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