cm:Level3TextBlock: us-gaap:OtherRealEstateRollForwardTableTextBlock
| Other Real Estate, Roll Forward [Table Text Block] |
| us-gaap:OtherRealEstateRollForwardTableTextBlock |
| Tabular disclosure of the change in other real estate on properties owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:OtherRealEstateRollForwardTableTextBlock |