cm:Concept: us-gaap:DescriptionOfLocationOfForeignCurrencyCashFlowHedgeDerivativesOnBalanceSheet
| Description of Location of Foreign Currency Cash Flow Hedge Derivatives on Balance Sheet |
| us-gaap:DescriptionOfLocationOfForeignCurrencyCashFlowHedgeDerivativesOnBalanceSheet |
| Description of where the foreign currency derivatives designated as cash flow hedges are reported in the balance sheet. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfLocationOfForeignCurrencyCashFlowHedgeDerivativesOnBalanceSheet |