| Standard label: | Open Option Contracts Written, Number of Shares |
| Name: | us-gaap:OpenOptionContractsWrittenNumberOfShares |
| Documentation: | The number of shares for the open option contracts written on the investment. |
| Object type: | cm:Concept |
| Data type: | Decimal (xbrli:decimalItemType) |
| Period type: | As Of (instant) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:OpenOptionContractsWrittenNumberOfShares |
| Label | Role | Language |
| Open Option Contracts Written, Number of Shares | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 946 320 S99 3 (SX 210.12-12B.3,Column B) | http://fasb.org/us-gaap/role/ref/legacyRef | 946 |