cm:Table: us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleTable
| Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Table] |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleTable |
| Disclosure of information about the accretable yield of certain loans acquired in transfer accounted for as debt securities. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleTable |