Trading Activities - Gross Fair Values of Derivative Instruments of Futures and Forward Contracts Traded (Detail) - Futures Contracts [Member]	Dec. 31, 2018 USD ($)
Derivative [Line Items]
Total unrealized appreciation on open futures contracts	$ 15,181
Total unrealized depreciation on open futures contracts	(25,826)
Net unrealized depreciation on open futures contracts	(10,645)
Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open futures contracts	15,181
Total unrealized depreciation on open futures contracts	$ (25,826)

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This element represents the excess of the cost (face amount, notional amount) of an investment (security, contract) over its fair value which deficiency has not been recognized in earnings of the entity.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=50485924&loc=SL6090603-123010

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This element represents the net excess or deficiency of the fair value of an investment (security, contract) over or under its cost (face amount, notional amount), respectively, which excess value or deficiency has not been recognized in earnings of the entity.

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