cm:Table: us-gaap:CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodTable
| Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table] |
| us-gaap:CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodTable |
| Schedule presenting certain loans acquired in a transfer relating to specific counterparties. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodTable |