cm:Table: us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelTable
| Certain Loans Acquired in Transfer Accounted for as Debt Securities, Not Accounted for Using Income Recognition Model [Table] |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelTable |
| Disclosure of information about certain loans acquired in transfer accounted for as debt securities for which the income recognition model is not applied. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelTable |