cm:Concept: us-gaap:AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesStaticPoolLosses
| Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Static Pool Losses |
| us-gaap:AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesStaticPoolLosses |
| The effect of expected static pool losses on the fair value of interests that continue to be held by the transferor. Expected static pool losses can be calculated by summing the actual and projected future credit losses and dividing the sum by the original balance of the pool of assets. |
| cm:Concept |
| Percent (num:percentItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:AssumptionForFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesStaticPoolLosses |