SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Additional Information) (Details)	3 Months Ended
	Mar. 31, 2019 $ / Basket shares	Mar. 31, 2018 $ / Basket	Nov. 15, 2011 $ / Basket	Nov. 10, 2010 $ / Basket	Aug. 10, 2010 $ / Basket
Significant Accounting Policies [Line Items]
Cash equivalents maturity period	6 years
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ / Basket					1,000
United States Commodity Index Fund [Member]
Significant Accounting Policies [Line Items]
Weighted average shares outstanding | shares	5
United States Copper Index Fund [Member]
Significant Accounting Policies [Line Items]
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ / Basket		1,000	1,000	1,000
Weighted average shares outstanding | shares	40
Redemption Baskets [Member] | United States Commodity Index Fund [Member]
Significant Accounting Policies [Line Items]
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ / Basket	350
Creation Baskets [Member] | Effective as of May 1, 2012 [Member] | United States Commodity Index Fund [Member]
Significant Accounting Policies [Line Items]
Weighted average shares outstanding | shares	50,000