cm:Concept: us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum
| Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum |
| Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock. |
| cm:Concept |
| Percent (num:percentItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum |