| Standard label: | Memberships in Exchanges Owned |
| Name: | us-gaap:MembershipsInExchangesOwned |
| Documentation: | Amount of capitalized cost for obtaining membership with right to do business on trading exchange. |
| 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:MembershipsInExchangesOwned |
| Label | Role | Language |
| Memberships in Exchanges Owned | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 940 340 25 1 (b) | http://www.xbrl.org/2009/role/commonPracticeRef | 940 |