FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fees Paid and Related Party Transactions [Line Items]
USCF Management Fee									US12NG 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%								0.75%
Estimated directors' fees and expenses									$ 5,704	$ 607,582	$ 1,107,140
Licensing fee incurred									5,674	7,565	8,499
Expense waiver (Note 3)	(26,148)	(13,434)	(12,614)	(16,307)	0	(39,596)	(35,903)	(37,670)	(68,503)	(113,169)	(151,688)
Portion Of Non Interest Expense Directors Fees									0	3,808	7,517
Licensing Agreements | First $1,000,000,000 of combined net assets of the funds
Fees Paid and Related Party Transactions [Line Items]
Fee percentage									0.04%
Licensing Agreements | First $1,000,000,000 of combined net assets of the funds | Maximum
Fees Paid and Related Party Transactions [Line Items]
Combined assets basis for determining fee percentage	1,000,000,000								1,000,000,000
Licensing Agreements | Combined net assets above $1,000,000,000
Fees Paid and Related Party Transactions [Line Items]
Fee percentage									0.02%
Licensing Agreements | Combined net assets above $1,000,000,000 | Minimum
Fees Paid and Related Party Transactions [Line Items]
Combined assets basis for determining fee percentage	1,000,000,000								1,000,000,000
Licensing Agreements | On and after October 20, 2011
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, 2012
Fees Paid and Related Party Transactions [Line Items]
Estimated investor tax reporting cost									75,000	55,000	155,000
Future Period - for the year ending December 31, 2012 | Maximum
Fees Paid and Related Party Transactions [Line Items]
Costs and expenses annual limit for reimbursement									0.15%
Us12ng [Member]
Fees Paid and Related Party Transactions [Line Items]
Portion Of Non Interest Expense Directors Fees									68,503
Us12ng [Member] | Related Public Funds [Member]
Fees Paid and Related Party Transactions [Line Items]
Estimated directors' fees and expenses									$ 540,586