FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS - (Additional Information) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fees Paid and Related Party Transactions [Line Items]
USCF Management Fee	UNL is contractually obligated to pay USCF a fee, which is paid monthly, that is equal to 0.75% per annum of average daily total net assets
Estimated directors fees and expenses	$ 3,140	$ 6,009	$ 7,620
Assets basis for determining fee percentage	on all net assets
Licensing fee incurred	$ 2,377	2,879	5,001
Expense waiver (Note 3)	$ 89,122	128,906	100,580
Licensing Agreements [Member]
Fees Paid and Related Party Transactions [Line Items]
Fee percentage	0.015%
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	86,000	125,000
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] | Related Public Funds [Member]
Fees Paid and Related Party Transactions [Line Items]
Estimated directors fees and expenses	$ 569,303	$ 567,863	$ 555,465