FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS - (Additional Information) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fees Paid and Related Party Transactions [Line Items]
USCF Management Fee			UNL is contractually obligated to pay USCF a fee, which is paid monthly, equal to 0.75%per annum of average daily total net assets.
Estimated directors fees and expenses	$ 715	$ 1,340	$ 2,493	$ 4,651
Licensing fee incurred	570	610	1,891	2,214
Expense waiver (Note 3)	$ 23,085	$ 39,383	$ 64,848	$ 118,128
Licensing Agreements [Member] | On and after October 20, 2011 [Member]
Fees Paid and Related Party Transactions [Line Items]
Fee percentage			0.015%
Assets basis for determining fee percentage			on all net assets
Future Period - for the year ending December 31, 2015 [Member]
Fees Paid and Related Party Transactions [Line Items]
Estimated investor tax reporting cost			$ 86,000
Future Period - for the year ending December 31, 2015 [Member] | Maximum [Member]
Fees Paid and Related Party Transactions [Line Items]
Costs and expenses annual limit for reimbursement			0.15%
UNL [Member]
Fees Paid and Related Party Transactions [Line Items]
Estimated directors fees and expenses			$ 3,000
UNL [Member] | Related Public Funds [Member]
Fees Paid and Related Party Transactions [Line Items]
Estimated directors fees and expenses			$ 569,300