cm:Concept: us-gaap:GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet
| Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net |
| us-gaap:GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet |
| Aggregate impact of foreign currency derivatives on earnings for the period. Includes impact of foreign currency cash flow hedge ineffectiveness and the ineffectiveness of fair value hedging derivatives and full change in fair value of the foreign currency derivatives not designated as hedging instruments. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet |