FAIR VALUE OF FINANCIAL INSTRUMENTS (Effect of Derivative Instruments on Statements of Operations of Usci, Cper, Usag and Usmi) (Details) - USD ($)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
United States Commodity Index Fund [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	$ (3,351,005)	$ 4,628,257
Change in Unrealized Gain (Loss) on Derivatives Recognized in Income	18,150,103	(2,082,239)
United States Commodity Index Fund [Member] \| Commodity Contracts [Member] \| Futures [Member] \| Realized gain (loss) on closed positions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(3,351,005)	4,628,257
United States Commodity Index Fund [Member] \| Commodity Contracts [Member] \| Futures [Member] \| Change in unrealized gain (loss) on open positions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Derivatives Recognized in Income	18,150,103	(2,082,239)
United States Copper Index Fund [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(263,113)	362,412
Change in Unrealized Gain (Loss) on Derivatives Recognized in Income	1,436,100	(1,589,363)
United States Copper Index Fund [Member] \| Commodity Contracts [Member] \| Futures [Member] \| Realized gain (loss) on closed positions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gain (Loss) on Derivatives Recognized in Income	(263,113)	362,412
United States Copper Index Fund [Member] \| Commodity Contracts [Member] \| Futures [Member] \| Change in unrealized gain (loss) on open positions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Derivatives Recognized in Income	$ 1,436,100	$ (1,589,363)

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The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open derivatives, commodity, or energy contracts, held at each balance sheet date, that was included in earnings for the period.

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