Fees Paid By Each Trust Series And Related Party Transactions (Additional Information) (Details) (USD $)
 12 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended 3 Months Ended 12 Months Ended 0 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2013
Directors and Officers Liability Insurance [Member]
Dec. 31, 2012
Directors and Officers Liability Insurance [Member]
Dec. 31, 2013
United States Commodity Index Fund [Member]
Dec. 31, 2012
United States Commodity Index Fund [Member]
Dec. 31, 2011
United States Commodity Index Fund [Member]
Dec. 31, 2013
United States Commodity Index Fund [Member]
Directors and Officers Liability Insurance [Member]
Dec. 31, 2012
United States Commodity Index Fund [Member]
Directors and Officers Liability Insurance [Member]
Dec. 31, 2013
United States Copper Index Fund [Member]
Sep. 30, 2013
United States Copper Index Fund [Member]
Jun. 30, 2013
United States Copper Index Fund [Member]
Mar. 31, 2013
United States Copper Index Fund [Member]
Dec. 31, 2012
United States Copper Index Fund [Member]
Sep. 30, 2012
United States Copper Index Fund [Member]
Jun. 30, 2012
United States Copper Index Fund [Member]
Mar. 31, 2012
United States Copper Index Fund [Member]
Dec. 31, 2013
United States Copper Index Fund [Member]
Dec. 31, 2012
United States Copper Index Fund [Member]
Dec. 31, 2011
United States Copper Index Fund [Member]
Dec. 31, 2013
United States Copper Index Fund [Member]
Directors and Officers Liability Insurance [Member]
Dec. 31, 2012
United States Copper Index Fund [Member]
Directors and Officers Liability Insurance [Member]
May 29, 2012
United States Copper Index Fund [Member]
Maximum [Member]
Dec. 31, 2013
United States Agriculture Index Fund [Member]
Sep. 30, 2013
United States Agriculture Index Fund [Member]
Jun. 30, 2013
United States Agriculture Index Fund [Member]
Mar. 31, 2013
United States Agriculture Index Fund [Member]
Dec. 31, 2012
United States Agriculture Index Fund [Member]
Sep. 30, 2012
United States Agriculture Index Fund [Member]
Jun. 30, 2012
United States Agriculture Index Fund [Member]
Mar. 31, 2012
United States Agriculture Index Fund [Member]
Dec. 31, 2013
United States Agriculture Index Fund [Member]
Dec. 31, 2012
United States Agriculture Index Fund [Member]
Dec. 31, 2011
United States Agriculture Index Fund [Member]
Dec. 31, 2013
United States Agriculture Index Fund [Member]
Directors and Officers Liability Insurance [Member]
Dec. 31, 2012
United States Agriculture Index Fund [Member]
Directors and Officers Liability Insurance [Member]
May 29, 2012
United States Agriculture Index Fund [Member]
Maximum [Member]
Dec. 31, 2013
United States Metals Index Fund [Member]
Sep. 30, 2013
United States Metals Index Fund [Member]
Jun. 30, 2013
United States Metals Index Fund [Member]
Mar. 31, 2013
United States Metals Index Fund [Member]
Dec. 31, 2012
United States Metals Index Fund [Member]
Sep. 30, 2012
United States Metals Index Fund [Member]
Jun. 30, 2012
United States Metals Index Fund [Member]
Mar. 31, 2012
United States Metals Index Fund [Member]
Dec. 31, 2013
United States Metals Index Fund [Member]
Dec. 31, 2012
United States Metals Index Fund [Member]
Dec. 31, 2011
United States Metals Index Fund [Member]
Dec. 31, 2013
United States Metals Index Fund [Member]
Directors and Officers Liability Insurance [Member]
Dec. 31, 2012
United States Metals Index Fund [Member]
Directors and Officers Liability Insurance [Member]
May 30, 2012
United States Metals Index Fund [Member]
Maximum [Member]
Fees Paid and Related Party Transactions [Line Items]                                                                                                        
Percentage of average daily net assets paid           0.95%         0.65%               0.65%           0.80%               0.80%           0.70%               0.70%          
USCF Management Fee USCI, CPER, USAG and USMI is contractually obligated to pay USCF a fee, which is paid monthly, equal to 0.95%per annum of average daily total net assets.                                                                                                      
Percentage of waiver management fee           0.00% 0.00% 0.01%                     3.56% 3.78% 3.95% [1],[2]     0.95%                 3.42% [1] 3.63% [1],[3] 0.00% [1]     0.95%                 3.26% [1] 3.88% [1],[4] 0.00% [1]     0.95%
Trustee annual fee $ 3,000                                                                                                      
Noninterest Expense Directors Fees 63,886 44,987 19,335 555,465 540,586 62,997 44,348 19,303 104,184 68,533                 283 [5] 265 [5] 32 [5] 488 415                   295 [6] 220 [6] 0 [6] 471 220                   311 [7] 154 [7] 0 [7] 493 154  
Estimated investor tax reporting cost           400,000                         50,000                           75,000                           75,000          
Costs and expenses annual limit for reimbursement           0.15%                         0.15%                           0.15%                           0.15%          
Expense waiver $ 245,726 $ 232,531 $ 49,360     $ 0 $ 0 $ 36,907     $ (14,618) $ (19,181) $ (24,095) $ (23,895) $ (31,459) $ (23,656) $ (20,257) $ (20,992) $ 81,789 [5] $ 96,364 [5] $ 12,453 [5]       $ (4,637) $ (17,041) $ (30,231) $ (29,863) $ (30,132) $ (26,019) $ (20,700) $ 0 $ 81,772 [6] $ 76,851 [6] $ 0 [6]       $ (4,987) $ (17,110) $ (30,264) $ (29,804) $ (30,139) $ (25,996) $ (3,181) $ 0 $ 82,165 [7] $ 59,316 [7] $ 0 [7]      
[1] Annualized.
[2] The commencement of operations of CPER was November 15, 2011.
[3] The commencement of operations of USAG was April 13, 2012.
[4] The commencement of operations of USMI was June 19, 2012.
[5] The commencement of operations of the United States Copper Index Fund was November 15, 2011.
[6] The commencement of operations of the United States Agriculture Index Fund was April 13, 2012.
[7] The commencement of operations of the United States Metals Index Fund was June 19, 2012.