cm:Concept: us-gaap:DerivativeCreditRiskRelatedContingentFeaturesTriggeringCircumstances
| Derivative, Credit Risk Related Contingent Features, Triggering Circumstances |
| us-gaap:DerivativeCreditRiskRelatedContingentFeaturesTriggeringCircumstances |
| Description of the circumstances in which credit-risk-related contingent features could be triggered in derivative instruments that are in a net liability position at the end of the reporting period. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativeCreditRiskRelatedContingentFeaturesTriggeringCircumstances |