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CONTRACTS AND AGREEMENTS (Brokerage Commissions) (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 22,207 | $ 19,025 | $ 4,643
Brokerage commissions as a percentage of average daily net assets | 0.02% | 0.03% | 0.01%
Rebalancing Investments Transaction [Member] |  |  |
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 17,872 | $ 11,997 | $ 3,665
Brokerage commissions as a percentage of average daily net assets | 80.48% | 63.06% | 78.94%
Trades Necessitated By Creation And Redemption Activity [Member] |  |  |
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 4,335 | $ 7,028 | $ 978
Brokerage commissions as a percentage of average daily net assets | 19.52% | 36.94% | 21.06%

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