| Standard label: | Proceeds from Sale of Trust Assets to Pay Expenses |
| Name: | us-gaap:ProceedsFromSaleOfTrustAssetsToPayExpenses |
| Documentation: | Amount of cash inflows from the sale of trust assets to pay trust expenses. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:ProceedsFromSaleOfTrustAssetsToPayExpenses |
| Label | Role | Language |
| Proceeds from Sale of Trust Assets to Pay Expenses | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 230 10 45 16 (c) | http://www.xbrl.org/2009/role/commonPracticeRef | 230 |
| Part Of Roll Up: |
| us-gaap:ProceedsFromOperatingActivities |