Financial Instruments, Off-Balance Sheet Risks and Contingencies (Additional Information) (Details) (USD $)
Dec. 31, 2013
Dec. 31, 2012
United States Commodity Index Fund [Member]
   
Carrying Amounts and Fair Values of Financial Instruments or Liabilities [Line Items]    
Cash deposits and investments in Treasuries $ 494,440,076 $ 491,119,704
United States Copper Index Fund [Member]
   
Carrying Amounts and Fair Values of Financial Instruments or Liabilities [Line Items]    
Cash deposits and investments in Treasuries 2,166,695 2,541,590
United States Agriculture Index Fund [Member]
   
Carrying Amounts and Fair Values of Financial Instruments or Liabilities [Line Items]    
Cash deposits and investments in Treasuries 2,328,626 2,679,845
United States Metals Index Fund [Member]
   
Carrying Amounts and Fair Values of Financial Instruments or Liabilities [Line Items]    
Cash deposits and investments in Treasuries $ 2,248,304 $ 2,605,049