cm:Concept: us-gaap:PreferredStockConversionBasis
| Preferred Stock, Conversion Basis |
| us-gaap:PreferredStockConversionBasis |
| Describe the conversion features of preferred stock if preferred stock is convertible. That is, shares of preferred stock into which another convertible security was converted, or shares of preferred stock into which another class of preferred stock was converted. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:PreferredStockConversionBasis |