cm:Concept: us-gaap:DescriptionOfAccountingMethodForForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments
| Description of Accounting Method for Foreign Currency Derivative Instruments Not Designated as Hedging Instruments |
| us-gaap:DescriptionOfAccountingMethodForForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments |
| General discussion of the accounting for foreign currency derivatives designated as hedging instruments in fair value hedges. Includes discussion of where derivatives and the gain (loss) on derivatives are reported in the financial statements. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfAccountingMethodForForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments |