Summary of Significant Accounting Policies - Summary of the Tiered Valuation Input Levels (Detail) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	$ 700,927,362	$ 1,077,913,905	$ 1,006,974,568
Money Market Mutual Fund	39,228,727
Currency Futures Contracts	317,845	9,076,613
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Mutual Fund	39,228,727
Currency Futures Contracts	317,845	9,076,613
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	$ 700,927,362	$ 1,077,913,905