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Fair Value Measurements and Trading-Related Revenue - Summary of Trading Revenue (Detail) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Oct. 31, 2025 | Oct. 31, 2024
Trading revenue [abstract] |  |
Interest rates | $ 1,026 | $ 1,003
Foreign exchange | 633 | 579
Equities | 1,131 | 759
Commodities | 365 | 150
Other | 212 | 55
Total trading-related revenue | 3,367 | 2,546
Reported as: |  |
Net interest income | 783 | 169
Non-interest revenue – trading revenues (losses) | 2,584 | 2,377
Total trading-related revenue | $ 3,367 | $ 2,546

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- Definition Revenue expense from interest. + References No definition available. + Details
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- Definition The amount of trading revenue relating to commodity spot and commodity derivative contracts. + References No definition available. + Details
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- Definition The amount of trading revenue relating to Canadian and other government trading securities, corporate debt trading instruments and interest rate derivatives. + References No definition available. + Details
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- Definition The amount of trading revenue relating to trading equities and equity derivatives. + References No definition available. + Details
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- Definition The amount of trading revenue relating to foreign exchange spot and foreign exchange derivative contracts. + References No definition available. + Details
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- Definition The amount of trading revenue relating to managed futures, credit investment management, Harris trading and loan trading and sales. + References No definition available. + Details
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Namespace Prefix: | bmo_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition The amount of trading-related revenues including net interest income arising from interest and dividends related to trading assets and liabilities reported net of interest expense associated with funding and non-interest revenue, excluding underwriting fees and commissions on securities transactions. + References No definition available. + Details
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- Definition The amount of income (expense) relating to trading assets and liabilities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2024-01-01 -Paragraph 85 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_85&doctype=Standard -URIDate 2024-03-27 + Details
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