Summary of Significant Accounting Policies - Summary of the Tiered Valuation Input Levels (Detail) - USD ($)		Mar. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations		$ 200,955,950	[1]	$ 133,489,271	[1]	$ 149,996,759
Commodity Futures Contracts	[2]	15,881,662		(5,416,324)
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Futures Contracts		15,881,662		(5,416,324)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations		$ 200,955,950		$ 133,489,271

[1] $34,994,000 and $24,997,500, respectively is restricted for maintenance margin purposes.

[2] )Unrealized appreciation/(depreciation) is presented above, net by contract