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CONTRACTS AND AGREEMENTS (Brokerage Commissions) (Details) - USD ($) | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 574 |  | $ 4,132
Brokerage commissions as a percentage of average daily net assets | 0.00% | [1] | 0.01%
Rebalancing Investments Transaction [Member] |  |  |
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 34 |  | $ 3,515
Brokerage commissions as a percentage of average daily net assets | 5.92% |  | 85.07%
Trades Necessitated By Creation And Redemption Activity [Member] |  |  |
Long Duration Contracts Assumptions By Product And Guarantee [Line Items] |  |  |
Brokerage commissions | $ 540 |  | $ 617
Brokerage commissions as a percentage of average daily net assets | 94.08% |  | 14.93%
[1] | Represents less than 0.005%.

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