cm:Concept: us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription
| Share-based Compensation Arrangement by Share-based Payment Award, Description |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription |
| Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription |