| Standard label: | Cash and Securities Segregated under Securities Exchange Commission Regulation |
| Name: | us-gaap:CashAndSecuritiesSegregatedUnderSecuritiesExchangeCommissionRegulation |
| Documentation: | Cash and securities deposited in a special reserve account for the exclusive benefit of customers. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:CashAndSecuritiesSegregatedUnderSecuritiesExchangeCommissionRegulation |
| Label | Role | Language |
| Cash and Securities Segregated under Securities Exchange Commission Regulation | http://www.xbrl.org/2003/role/label | en-US |
| Cash and Securities Segregated under Securities Exchange Commission Regulation, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |