cm:Concept: us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedOptionToTerminate
| Lessee, Operating Lease, Lease Not yet Commenced, Option to Terminate |
| us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedOptionToTerminate |
| Description of terms and conditions of option to terminate lessee's operating lease that has not yet commenced. Includes, but is not limited to, information about option recognized as part of right-of-use asset and lease liability. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedOptionToTerminate |