Summary of Significant Accounting Policies - Summary of the Tiered Valuation Input Levels (Detail) - USD ($)	Dec. 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	$ 846,158,812	$ 1,077,913,905	$ 1,006,974,568
Money Market Mutual Fund	3,786,312
Total Investments, at value (cost $849,976,394 and $1,077,885,299, respectively)	849,945,124	1,077,913,905
Currency Futures Contracts	1,988,810	9,076,613
Total Investments	851,933,934	1,086,990,518
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Mutual Fund	3,786,312
Total Investments, at value (cost $849,976,394 and $1,077,885,299, respectively)	3,786,312
Currency Futures Contracts	1,988,810	9,076,613
Total Investments	5,775,122	9,076,613
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	846,158,812	1,077,913,905
Total Investments, at value (cost $849,976,394 and $1,077,885,299, respectively)	846,158,812
Total Investments	$ 846,158,812	$ 1,077,913,905