cm:Level3TextBlock: us-gaap:ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock
| Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] |
| us-gaap:ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock |
| Tabular disclosure of the net gain (loss) and net prior service cost or credit recognized in other comprehensive income (loss) for the period for pension plans and/or other employee benefit plans, and reclassification adjustments of other comprehensive income (loss) for the period, as those amounts, including amortization of the net transition asset or obligation, are recognized as components of net periodic benefit cost. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock |
| AmountsRecognizedInOtherComprehensiveIncomeLoss |