cm:Level3TextBlock: us-gaap:ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock
| Schedule of Business Acquisitions, by Acquisition [Table Text Block] |
| us-gaap:ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock |
| Tabular disclosure of a material business combination completed during the period, including background, timing, and recognized assets and liabilities. This table does not include leveraged buyouts. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock |
| BusinessAcquisitionsByAcquisition |