cm:Concept: us-gaap:DescriptionOfEffectOnPreviouslyReportedSegmentInformationForChangeInCompositionOfReportableSegments
| Description of Effect on Previously Reported Segment Information for Change in Composition of Reportable Segments |
| us-gaap:DescriptionOfEffectOnPreviouslyReportedSegmentInformationForChangeInCompositionOfReportableSegments |
| Disclosure about a restatement of previous periods' segment information resulting from a change in the composition of the entity's reportable segments. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfEffectOnPreviouslyReportedSegmentInformationForChangeInCompositionOfReportableSegments |