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Organization and Business (Additional Information) (Detail) | Apr. 10, 2006 USD ($) $ / shares shares | Jun. 30, 2015 $ / shares $ / Unit shares | Dec. 31, 2014 $ / shares | Jun. 30, 2014 $ / shares | Dec. 31, 2013 $ / shares
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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 | $ / Unit |  | 1,000 |  |  |
Limited Partners' Capital Account, Units Authorized | 17,000,000 | 2,127,000,000 |  |  |
Limited Partners' Capital Account, Units Issued | 200,000 |  |  |  |
Net asset value per unit | $ / shares | $ 67.39 | $ 19.93 | $ 20.15 | $ 38.86 | $ 35.23
Value of units issued | $ | $ 13,479,000 |  |  |  |
Creation Baskets [Member] |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |
Number of units per basket |  | 100,000 |  |  |
Redemption Baskets [Member] |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |
Number of units per basket |  | 100,000 |  |  |
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX WTI Crude Oil Futures CL August 2015 contracts, expiring July 21, 2015 [Member] |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |
Number of Contracts |  | 38,345 |  |  |

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