cm:Concept: us-gaap:PropertySubjectToOrAvailableForOperatingLeaseAccumulatedDepreciation
| Property Subject to or Available for Operating Lease, Accumulated Depreciation |
| us-gaap:PropertySubjectToOrAvailableForOperatingLeaseAccumulatedDepreciation |
| The amount of accumulated depreciation, by major property class, recorded on property subject to or available for lease as of the balance sheet date. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:PropertySubjectToOrAvailableForOperatingLeaseAccumulatedDepreciation |