CONTRACTS AND AGREEMENTS - Brokerage Commission (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
United States Commodity Index Fund
Contracts and Agreements
Brokerage commissions	$ 31,187	$ 104,902	$ 107,561	$ 410,699
Brokerage commissions as a percentage of average daily net assets	0.10%	0.14%	0.10%	0.14%
United States Commodity Index Fund | Rebalancing Investments Transaction
Contracts and Agreements
Brokerage commissions			$ 100,415	$ 393,159
Brokerage commissions as a percentage of average daily net assets	93.36%	95.73%	93.36%	95.73%
United States Commodity Index Fund | Creation and Redemption Activity
Contracts and Agreements
Brokerage commissions			$ 7,146	$ 17,540
Brokerage commissions as a percentage of average daily net assets	6.64%	4.27%	6.64%	4.27%
United States Copper Index Fund
Contracts and Agreements
Brokerage commissions	$ 1,672	$ 945	$ 4,240	$ 4,792
Brokerage commissions as a percentage of average daily net assets	0.04%	0.06%	0.04%	0.06%
United States Copper Index Fund | Rebalancing Investments Transaction
Contracts and Agreements
Brokerage commissions			$ 2,814	$ 4,189
Brokerage commissions as a percentage of average daily net assets	66.37%	87.42%	66.37%	87.42%
United States Copper Index Fund | Creation and Redemption Activity
Contracts and Agreements
Brokerage commissions			$ 1,426	$ 603
Brokerage commissions as a percentage of average daily net assets	33.63%	12.58%	33.63%	12.58%