cm:Concept: us-gaap:DescriptionOfTypesOfForeignCurrencyCashFlowHedgingInstrumentsUsed
| Description of Types of Foreign Currency Cash Flow Hedging Instruments Used |
| us-gaap:DescriptionOfTypesOfForeignCurrencyCashFlowHedgingInstrumentsUsed |
| Description of the types of foreign currency derivative instruments designated as hedging instruments in cash flow hedges. For example, forwards, options, and so forth. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfTypesOfForeignCurrencyCashFlowHedgingInstrumentsUsed |