cm:Concept: us-gaap:SharesHeldInEmployeeStockOptionPlanSuspenseShares
| Shares held in Employee Stock Option Plan, Suspense Shares |
| us-gaap:SharesHeldInEmployeeStockOptionPlanSuspenseShares |
| Number of suspense shares held by the Employee Stock Option Plan at balance sheet date. Suspense shares are shares that have not been released, committed to be released or allocated to individual participant accounts. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:SharesHeldInEmployeeStockOptionPlanSuspenseShares |