cm:Level3TextBlock: us-gaap:ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock
| Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block] |
| us-gaap:ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock |
| Tabular disclosure of the amounts related to pension plans and/or other employee benefit plans in accumulated other comprehensive income or loss that have not yet been recognized as components of net periodic benefit cost, such as the net gain (loss), net prior service cost or credit, and net transition asset or obligation. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock |
| NetPeriodicBenefitCostNotyetRecognized |