cm:Concept: us-gaap:RetailLandSalesEstimatedCostOfMajorImprovementsArea
| Retail Land Sales, Estimated Cost of Major Improvements, Area |
| us-gaap:RetailLandSalesEstimatedCostOfMajorImprovementsArea |
| Description of each major area from which sales are being made and in which significant expenditures for improvements are planned for each of the five years following the balance sheet date. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:RetailLandSalesEstimatedCostOfMajorImprovementsArea |