cm:Concept: us-gaap:BusinessCombinationAssetsArisingFromContingenciesAmountRecognizedOtherThanAtFairValue
| Business Combination, Assets Arising from Contingencies, Amount Recognized, Other than at Fair Value |
| us-gaap:BusinessCombinationAssetsArisingFromContingenciesAmountRecognizedOtherThanAtFairValue |
| The amount, measured at other than acquisition-date fair value, of all the assets acquired that arise from contingencies and were recognized by the entity, if the acquisition-date fair value cannot be determined and other criteria (as defined) related to the contingencies have been met. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:BusinessCombinationAssetsArisingFromContingenciesAmountRecognizedOtherThanAtFairValue |