Securities - Schedule of Fair Value of Debt Securities Measured and Equity Securities Designated at FVOCI (Parenthetical) (Detail) - CAD ($) $ in Millions	Jan. 31, 2025	Oct. 31, 2024
Disclosure of financial assets [abstract]
Allowance for credit losses for debt securities measured at FVOCI	$ 20	$ 19

Allowance for credit losses for debt securities measured at fair value through other comprehensive income loss, net.

No definition available.

Name:	cm_AllowanceForCreditLossesForDebtSecuritiesMeasuredAtFairValueThroughOtherComprehensiveIncomeLossNet
Namespace Prefix:	cm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant