cm:Level3TextBlock: us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock
| Schedule of Maturities of Long-term Debt [Table Text Block] |
| us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock |
| Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock |
| LongTermDebtMaturities |