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Post-Employment Benefits - Summary of Net Remeasurement Gains (Losses) Recognized in OCI (Parenthetical) (Detail) - CAD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Jul. 31, 2025 | Jul. 31, 2025
Pension plan [member] |  |
Disclosure of defined benefit plans [line items] |  |
Transfer of accumulated actuarial losses to retained earnings | $ 5 | $ 5

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- Definition Transfer of accumulated actuarial losses to retained earnings. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table. + References No definition available. + Details
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Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | cm_DefinedBenefitPlansByNameAxis=cm_PensionPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |