cm:Concept: us-gaap:DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
| Deferred Compensation Arrangement with Individual, Common Stock Reserved for Future Issuance |
| us-gaap:DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance |
| Number of common shares reserved for future issuance related to deferred compensation arrangements with individuals. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance |