cm:Concept: us-gaap:DescriptionOfNatureAndEffectOfAnyAsymmetricalAllocationsToReportableSegments
| Segment Reporting, Asymmetrical Allocations to Segments |
| us-gaap:DescriptionOfNatureAndEffectOfAnyAsymmetricalAllocationsToReportableSegments |
| A description of the nature and effect of any asymmetrical allocations to segments. For example, an entity might allocate depreciation expense to a segment without allocating the related depreciable assets to that segment. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfNatureAndEffectOfAnyAsymmetricalAllocationsToReportableSegments |