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CONTRACTS AND AGREEMENTS (Brokerage Commissions) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions	$ 4,643	$ 4,869	$ 13,484	$ 17,285
Brokerage commissions as a percentage of average daily net assets	0.02%	0.02%	0.02%	0.02%
Rebalancing Investments Transaction [Member]
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions			$ 10,815	$ 13,033
Brokerage commissions as a percentage of average daily net assets	80.21%	75.40%	80.21%	75.40%
Trades Necessitated By Creation And Redemption Activity [Member]
Long Duration Contracts Assumptions By Product And Guarantee [Line Items]
Brokerage commissions			$ 2,669	$ 4,252
Brokerage commissions as a percentage of average daily net assets	19.79%	24.60%	19.79%	24.60%

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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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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