cm:Concept: us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedDescription
| Lessee, Operating Lease, Lease Not yet Commenced, Description |
| us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedDescription |
| Description of lessee's operating lease that has not yet commenced. Including, but not limited to, nature of involvement with construction or design of underlying asset for lease. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:LesseeOperatingLeaseLeaseNotYetCommencedDescription |