cm:Concept: us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights
| Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights |
| Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights |