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Earnings per Share - Summary of Earnings Per Share (Parenthetical) (Detail) - $ / shares | 12 Months Ended
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Oct. 31, 2025 | Oct. 31, 2024
Earnings per share [abstract] |  |
Outstanding options excluded from calculation of diluted earnings per share | 0 | 2,551,540
Weighted average Exercise price of average outstanding share options excluded from the calculation of diluted earnings per share | $ 0 | $ 70.05

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- Definition Disclosure of instruments with potential future dilutive effect not included in calculation of diluted earnings per share + References No definition available. + Details
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- Definition Weighted average exercise price of average outstanding share options excluded from calculation of diluted earnings per share. + References No definition available. + Details
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Namespace Prefix: | cm_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | ifrs-full_EarningsPerShareAbstract
Namespace Prefix: | ifrs-full_
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Balance Type: | na
Period Type: | duration