Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Assets
Total assets	$ 137,302	$ 21,567,614
Liabilities
Total liabilities	108,245	15,690,280
Futures Contracts [Member]
Assets
Total assets		9,793,492
Liabilities
Total liabilities		4,789,432
Forward Contracts [Member]
Assets
Total assets	137,302	11,774,122
Liabilities
Total liabilities	108,245	10,900,848
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member]
Assets
Total assets		9,793,492
Liabilities
Total liabilities		4,789,432
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] | Futures Contracts [Member]
Assets
Total assets		9,793,492
Liabilities
Total liabilities		4,789,432
Significant Other Observable Inputs (Level 2) [Member]
Assets
Total assets	137,302	11,774,122
Liabilities
Total liabilities	108,245	10,900,848
Significant Other Observable Inputs (Level 2) [Member] | Forward Contracts [Member]
Assets
Total assets	137,302	11,774,122
Liabilities
Total liabilities	$ 108,245	$ 10,900,848