Financial Highlights - Schedule of Net Asset Value Per Share (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Asset Value
Net asset value per Share, beginning of period	$ 26.03	$ 23.62	$ 25.48	$ 24.00
Net realized and change in unrealized gain (loss) on United States Treasury Obligations, Affiliated Investments and Currency Futures Contracts	(0.18)	1.31	0.27	0.90
Net investment income (loss)	0.11	0.04	0.21	0.07
Net income (loss)	(0.07)	1.35	0.48	0.97
Net asset value per Share, end of period	25.96	24.97	25.96	24.97
Market value per Share, beginning of period	26.03	23.60	25.47	24.04
Market value per Share, end of period	$ 25.98	$ 24.96	$ 25.98	$ 24.96
Ratio to average Net Assets
Net investment income (loss)	1.66%	0.68%	1.64%	0.58%
Expenses, after waivers	0.75%	0.76%	0.75%	0.76%
Expenses, prior to waivers	0.77%	0.78%	0.77%	0.77%
Total Return, at net asset value	(0.27%)	5.72%	1.88%	4.04%
Total Return, at market value	(0.19%)	5.76%	2.00%	3.83%