Trading Activities - Schedule of Trading Gains and Losses by Market Sector, on Derivative Instruments (Detail)	12 Months Ended
Dec. 31, 2018 USD ($)
Derivative [Line Items]
Total trading results	$ 399,468
Currencies [Member]
Derivative [Line Items]
Total trading results	332,447
Energy [Member]
Derivative [Line Items]
Total trading results	1,882
Indices [Member]
Derivative [Line Items]
Total trading results	68,307
Interest Rates U.S. [Member]
Derivative [Line Items]
Total trading results	17,489
Interest Rates Non-U.S. [Member]
Derivative [Line Items]
Total trading results	(14,624)
Metals [Member]
Derivative [Line Items]
Total trading results	$ (6,033)

Aggregate net gain and losses (whether realized or unrealized) on all derivative instruments held for trading purposes whether or not settled physically.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4F
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624186-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41322-113958

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration