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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%.

X

- Definition

The amount of expense during the period for floor brokerage fees paid to other broker-dealers to execute trades on their behalf, stock exchange fees, order flow fees, and clearance fees.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Percentage of Average Daily Net Assets

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