Net Asset Value and Financial Highlights - Schedule of Net Asset Value Per Share (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Asset Value
Net asset value per Share, beginning of period	$ 20.47	$ 21.42
Net realized and change in unrealized gain (loss) on United States Treasury Obligations, Affiliated Investments and Currency Futures Contracts	0.38	0.95
Net investment income (loss)	(0.01)	(0.03)
Net income (loss)	0.37	0.92
Net asset value per Share, end of period	20.84	22.34
Market value per Share, beginning of period	20.46	21.43
Market value per Share, end of period	$ 20.82	$ 22.34
Ratio to average Net Assets
Net investment income (loss)	(0.27%)	(0.55%)
Expenses, after waivers	0.76%	0.78%
Expenses, prior to waivers	0.78%	0.78%
Total Return, at net asset value	1.81%	4.29%
Total Return, at market value	1.76%	4.25%