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CONTRACTS AND AGREEMENTS (Brokerage Commissions) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions	$ 2,645	$ 4,709	$ 3,219	$ 8,841
Brokerage commissions as a percentage of average daily net assets	0.01%	0.02%	0.01%	0.02%
Rebalancing Investments Transaction [Member]
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions			$ 2,439	$ 7,074
Brokerage commissions as a percentage of average daily net assets	75.77%	80.01%	75.77%	80.01%
Trades Necessitated By Creation And Redemption Activity [Member]
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions			$ 780	$ 1,767
Brokerage commissions as a percentage of average daily net assets	24.23%	19.99%	24.23%	19.99%

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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