Financial Highlights (Per Unit Performance Data and Other Supplemental Financial Data) (Details) (USD $)
 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended
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]
Aug. 10, 2010
United States Commodity 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]
Nov. 15, 2011
United States Copper 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]
Apr. 13, 2012
United States Agriculture 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]
Jun. 19, 2012
United States Metals Index Fund [Member]
Increase Decrease In Partners Capital RollForward [Abstract]                                
Net asset value, beginning of year $ 58.45 $ 58.47 $ 64.37 $ 50.00 $ 25.43 $ 24.47 [1] $ 25.00 [1] $ 25.00 [2] $ 25.56 [3] $ 25.00 [3] $ 0 $ 25.00 [4] $ 26.47 [5] $ 25.00 [5] $ 0 $ 25.00 [6]
Total income (loss) $ (1.75) $ 0.67 $ (5.16)   $ (2.31) $ 1.21 $ (0.49) [1]   $ (2.52) $ 0.77 [3] $ 0   $ (4.29) $ 1.59 [5] $ 0  
Total expenses $ (0.64) $ (0.69) $ (0.74)   $ (0.20) $ (0.25) $ (0.04) [1]   $ (0.25) $ (0.21) [3] $ 0   $ (0.21) $ (0.12) [5] $ 0  
Net increase (decrease) in net asset value $ (2.39) $ (0.02) $ (5.90)   $ (2.51) $ 0.96 $ (0.53) [1]   $ (2.77) $ 0.56 [3] $ 0   $ (4.50) $ 1.47 [5] $ 0  
Net asset value, end of year $ 56.06 $ 58.45 $ 58.47 $ 50.00 $ 22.92 $ 25.43 $ 24.47 [1] $ 25.00 [2] $ 22.79 $ 25.56 [3] $ 25.00 [3] $ 25.00 [4] $ 21.97 $ 26.47 [5] $ 25.00 [5] $ 25.00 [6]
Total Return (4.09%) (0.03%) (9.17%)   (9.87%) 3.92% (2.12%) [1]   (10.84%) 2.24% [3] 0.00%   (17.00%) 5.88% [5] 0.00%  
Ratios to Average Net Assets                                
Total income (loss) (3.25%) (0.74%) (15.97%)   (10.06%) 5.35% (2.01%) [1]   (10.53%) 7.33% [3] 0.00%   (15.12%) 6.92% [5] 0.00%  
Management fees 0.95% 0.95% 0.95%   0.65% [7] 0.78% [7] 0.95% [1],[7],[8]   0.80% [7],[8] 0.83% [3],[7],[8] 0.00% [8]   0.70% [8],[9] 0.70% [5],[8],[9] 0.00% [8]  
Total expenses excluding management fees 0.19% 0.20% 0.21%   3.77% 3.98% 4.17% [1],[8]   3.68% [8] 3.91% [3],[8] 0.00% [8]   3.46% [8] 4.09% [5],[8] 0.00% [8]  
Expenses waived 0.00% 0.00% (0.01%)   (3.56%) (3.78%) (3.95%) [1],[8]   (3.42%) [8] (3.63%) [3],[8] 0.00% [8]   (3.26%) [8] (3.88%) [5],[8] 0.00% [8]  
Net expenses excluding management fees 0.19% 0.20% 0.20%   0.21% 0.20% 0.22% [1],[8]   0.25% [8] 0.28% [3],[8] 0.00% [8]   0.20% [8] 0.21% [5],[8] 0.00% [8]  
Net income (loss) (4.39%) (1.89%) (17.12%)   (10.92%) 4.37% (2.16%) [1],[8]   (11.58%) 6.53% [3] 0.00%   (16.02%) 6.43% [5] 0.00%  
[1] The commencement of operations of CPER was November 15, 2011.
[2] The commencement of operations of the United States Copper Index Fund was November 15, 2011.
[3] The commencement of operations of USAG was April 13, 2012.
[4] The commencement of operations of the United States Agriculture Index Fund was April 13, 2012.
[5] The commencement of operations of USMI was June 19, 2012.
[6] The commencement of operations of the United States Metals Index Fund was June 19, 2012.
[7] Effective as of May 29, 2012 (and continuing at least through May 1, 2014), USCF voluntarily agreed to waive the management fee paid by CPER from 0.95% to 0.65% per annum of average daily total net assets.
[8] Annualized.
[9] Effective as of May 30, 2012 (and continuing at least through May 1, 2014), USCF voluntarily agreed to waive the management fee paid by USMI from 0.95% to 0.70% per annum of average daily total net assets.