cm:Level3TextBlock: us-gaap:ScheduleOfOtherNonoperatingExpenseByComponentTextBlock
| Schedule of Other Nonoperating Expense, by Component [Table Text Block] |
| us-gaap:ScheduleOfOtherNonoperatingExpenseByComponentTextBlock |
| Tabular disclosure of the detailed components of other nonoperating expenses. This disclosure may include methodology, assumptions and amounts for : (a) losses on securities (net of profits) and (b) miscellaneous income deductions. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfOtherNonoperatingExpenseByComponentTextBlock |
| OtherExpenseNonoperatingDetailsHierarchy |