Trading Activities - Trading Gains and Losses, by Market Sector, on Derivative Instruments (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative [Line Items]
Gain (loss) from trading	$ 6,193,641	$ (27,904,631)	$ (48,100,507)	$ (28,596,942)
Energy [Member]
Derivative [Line Items]
Gain (loss) from trading	6,193,641	(27,407,405)	(48,100,507)	(26,926,017)
Grains [Member]
Derivative [Line Items]
Gain (loss) from trading		156,569		633,102
Indices [Member]
Derivative [Line Items]
Gain (loss) from trading		438,249		(836,720)
Lumber [Member]
Derivative [Line Items]
Gain (loss) from trading		108,627		163,753
Softs [Member]
Derivative [Line Items]
Gain (loss) from trading		$ (1,200,671)		$ (1,631,060)