Fair Value Measurements - Derivative Instrument Fair Value Based on Hierarchy (Detail)	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 9,088,612
Derivative liabilities	7,799,575
Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	6,579,887
Derivative liabilities	4,822,376
Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,203,511
Derivative liabilities	2,567,628
Option [Member] | Contracts Purchased [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	305,214
Option [Member] | Contracts Sold [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	409,571
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	6,885,101
Derivative liabilities	5,231,947
Level 1 [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	6,579,887
Derivative liabilities	4,822,376
Level 1 [Member] | Option [Member] | Contracts Purchased [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	305,214
Level 1 [Member] | Option [Member] | Contracts Sold [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	409,571
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,203,511
Derivative liabilities	2,567,628
Level 2 [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,203,511
Derivative liabilities	$ 2,567,628