cm:Concept: us-gaap:TroubledDebtRestructuringDebtorSubsequentPeriodsContingentPaymentsConditions
| Troubled Debt Restructuring, Debtor, Subsequent Periods, Contingent Payments, Conditions |
| us-gaap:TroubledDebtRestructuringDebtorSubsequentPeriodsContingentPaymentsConditions |
| For a debtor, a description of the circumstance, events, or conditions that would cause payments to occur or the creditor to forgive the contingent portion of recorded debt. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:TroubledDebtRestructuringDebtorSubsequentPeriodsContingentPaymentsConditions |