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ORGANIZATION AND BUSINESS (Additional Information) (Details) | 1 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Nov. 30, 2009 | Nov. 18, 2009 USD ($) $ / shares shares | Dec. 31, 2017 $ / shares $ / Baskets $ / Units | Dec. 31, 2016 $ / shares | Dec. 31, 2015 $ / shares | Dec. 31, 2014 $ / shares | Dec. 31, 2013 $ / shares
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ / Units |  |  | 350 |  |  |  |
Number of initially registered units on Form S-1 with the U.S. Securities and Exchange Commission | 30,000,000 |  |  |  |  |  |
Net asset value per share | $ / shares |  | $ 50.00 | $ 9.26 | $ 11.75 | $ 9.72 | $ 13.69 | $ 13.69
Number of units issued | shares |  | 200,000 |  |  |  |  |
Value of unit issued | $ |  | $ 10,000,000 |  |  |  |  |
Commenced investment operations date | Nov. 18, 2009 |  |  |  |  |  |
Number of registered units |  |  | 30,000,000 |  |  |  |
Creation Baskets [Member] |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Number of units per basket |  |  | 50,000 |  |  |  |
Redemption Baskets [Member] |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Number of units per basket |  |  | 50,000 |  |  |  |

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