Note 9 - Investing in Index Futures - Effect of the Futures Contracts, by Risk Exposure Category, on the Statements of Financial Condition (Details) - USD ($)	Sep. 30, 2026	Dec. 31, 2025
Receivable for variation margin on open futures contracts	$ 10,586,199	$ 0
Payable for variation margin on open futures contracts	0	11,332,892
Commodity Contract [Member]
Receivable for variation margin on open futures contracts	10,586,199	0
Payable for variation margin on open futures contracts	$ 0	$ 11,332,892

Amount payable to other broker-dealer and clearing organization, including, but not limited to, security failed-to-receive, deposit received for security loaned, open transaction, and floor-brokerage payable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 15c3-1
-Number 240
-Section 15c3-1
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 940
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481833/940-20-45-3

Name:	srt_PayablesToBrokerDealersAndClearingOrganizations
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant