cm:Concept: us-gaap:GainLossOnDerivativeInstrumentsHeldForTradingPurposesNet
| Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net |
| us-gaap:GainLossOnDerivativeInstrumentsHeldForTradingPurposesNet |
| Aggregate net gain and losses (whether realized or unrealized) on all derivative instruments held for trading purposes whether or not settled physically. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:GainLossOnDerivativeInstrumentsHeldForTradingPurposesNet |