cm:Concept: us-gaap:FairValueMeasurementsSensitivityAnalysisDescription
| Unobservable Measurement Input, Uncertainty, Description |
| us-gaap:FairValueMeasurementsSensitivityAnalysisDescription |
| Description of uncertainty of fair value measurement from use of unobservable input, including, but not limited to, inter-relationships among inputs used in fair value measurement. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:FairValueMeasurementsSensitivityAnalysisDescription |