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FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS - Additional Information (Detail) (USD $)
 3 Months Ended
Mar. 31, 2014
Mar. 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, equal to 0.75% per annum of average daily total net assets  
Percentage of average daily net assets 0.75%  
Licensing fee incurred $ 894 $ 1,665
Expense waiver (Note 3) 38,045 14,464
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, 2014 [Member]
    
Fees Paid and Related Party Transactions [Line Items]    
Estimated investor tax reporting cost 100,000  
Future Period - for the year ending December 31, 2014 [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 $ 560,625