cm:Concept: us-gaap:RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1
| SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Life Used for Depreciation |
| us-gaap:RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1 |
| Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. |
| cm:Concept |
| xbrli:durationItemType |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:RealEstateAndAccumulatedDepreciationLifeUsedForDepreciation1 |