cm:Concept: us-gaap:LossContingencyManagementsAssessmentAndProcess
| Loss Contingency, Management's Assessment and Process |
| us-gaap:LossContingencyManagementsAssessmentAndProcess |
| Describes management's process to evaluate the contingency matter and to estimate the impact on the financial statements and ongoing operations, such as added credit risk or loss of customers, including pertinent information to adequately disclose the matter and significant assumptions underlying the estimates. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:LossContingencyManagementsAssessmentAndProcess |