cm:Level2TextBlock: us-gaap:InterestExpenseAllocatedToDiscontinuedOperationsPolicy
| Interest Expense Allocated to Discontinued Operations, Policy [Policy Text Block] |
| us-gaap:InterestExpenseAllocatedToDiscontinuedOperationsPolicy |
| Disclosure of accounting policy for allocating interest on borrowings to operations reported as being discontinued. may also include the amount allocated to and reported in discontinued operations. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:InterestExpenseAllocatedToDiscontinuedOperationsPolicy |