cm:Level3TextBlock: us-gaap:ScheduleOfExpectedBenefitPaymentsTableTextBlock
| Schedule of Expected Benefit Payments [Table Text Block] |
| us-gaap:ScheduleOfExpectedBenefitPaymentsTableTextBlock |
| Tabular disclosure of benefits expected to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfExpectedBenefitPaymentsTableTextBlock |
| ExpectedBenefitPayments |