Note 9 - Investing in Index Futures - Effect of the Futures Contracts, by Risk Exposure Category, on the Statements of Operations (Details) - USD ($)	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Net realized gain (loss) from futures contracts	$ 227,639,802	$ 38,182,150
Net change in unrealized appreciation/depreciation on futures contracts	82,570,068	(1,386,063)
Commodity Contract [Member]
Net realized gain (loss) from futures contracts	227,639,802	38,182,150
Net change in unrealized appreciation/depreciation on futures contracts	$ 82,570,068	$ (1,386,063)

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open agreements to purchase or sell mineral resources, energy, and agricultural products at some future point held at each balance sheet date, that was included in earnings for the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(7)(c)(8))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

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Period Type:	duration