Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Assets
Total assets	$ 1,986,970	$ 3,653,141
Total assets	1,986,970	3,653,141
Liabilities
Total liabilities	1,762,602	1,428,659
Total liabilities	1,762,602	1,428,659
Futures Contracts [Member]
Assets
Total assets	1,503,294	2,377,628
Total assets	1,503,294	2,377,628
Liabilities
Total liabilities	1,005,209	639,577
Total liabilities	1,005,209	639,577
Forward Contracts [Member]
Assets
Total assets	483,676	1,275,513
Total assets	483,676	1,275,513
Liabilities
Total liabilities	757,393	789,082
Total liabilities	757,393	789,082
Level 1 [Member]
Assets
Total assets	1,503,294	2,377,628
Total assets	1,503,294	2,377,628
Liabilities
Total liabilities	1,005,209	639,577
Total liabilities	1,005,209	639,577
Level 1 [Member] | Futures Contracts [Member]
Assets
Total assets	1,503,294	2,377,628
Total assets	1,503,294	2,377,628
Liabilities
Total liabilities	1,005,209	639,577
Total liabilities	1,005,209	639,577
Level 2 [Member]
Assets
Total assets	483,676	1,275,513
Total assets	483,676	1,275,513
Liabilities
Total liabilities	757,393	789,082
Total liabilities	757,393	789,082
Level 2 [Member] | Forward Contracts [Member]
Assets
Total assets	483,676	1,275,513
Total assets	483,676	1,275,513
Liabilities
Total liabilities	757,393	789,082
Total liabilities	$ 757,393	$ 789,082