cm:Concept: us-gaap:NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1
| Noncash or Part Noncash Acquisition, Other Liabilities Assumed |
| us-gaap:NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1 |
| Amount of liabilities, classified as other, assumed in acquiring a business or in consideration for an asset received in a noncash or part noncash acquisition. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:NoncashOrPartNoncashAcquisitionOtherLiabilitiesAssumed1 |