cm:Concept: us-gaap:IncreaseDecreaseInBrokerageReceivables
| Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations |
| us-gaap:IncreaseDecreaseInBrokerageReceivables |
| The increase (decrease) during the reporting period in the total amount due to the entity related to activities and operations with other broker dealers, and clearing organizations, including deposits. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IncreaseDecreaseInBrokerageReceivables |