cm:Concept: us-gaap:OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax
| Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments, after Tax |
| us-gaap:OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax |
| Amount, after tax and before adjustments, of gain (loss) from increase (decrease) in value of excluded component of derivative designated and qualifying as hedge. Adjustments include, but are not limited to, reclassifications for sale and settlement, and amounts recognized under systematic and rational method. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax |