Additional Valuation Information - Summary of the Tiered Valuation Input Levels (Detail) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	$ 18,984,562	$ 23,853,157
Money Market Mutual Fund	1,591,026
Total Investments, at value (cost $20,575,247and $23,852,335, respectively)	20,575,588	23,853,157
Commodity Futures Contracts	(1,798,035)	(1,599,451)
Total Investments	18,777,553	22,253,706
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Mutual Fund	1,591,026
Total Investments, at value (cost $20,575,247and $23,852,335, respectively)	1,591,026
Commodity Futures Contracts	(1,798,035)	(1,599,451)
Total Investments	(207,009)	(1,599,451)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	18,984,562	23,853,157
Total Investments, at value (cost $20,575,247and $23,852,335, respectively)	18,984,562
Total Investments	$ 18,984,562	$ 23,853,157