Selected Quarterly Information (Unaudited) - Schedule of Quarterly Financial Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Income
Interest Income	$ 503,822	$ 547,064	$ 525,897	$ 559,049	$ 458,540	$ 627,072	$ 692,867	$ 797,805	$ 2,135,832	$ 2,576,284	$ 4,050,279
Total Income	503,822	547,064	525,897	559,049	458,540	627,072	692,867	797,805	2,135,832	2,576,284	4,050,279
Expenses
Sponsor's fee	(167,184)	(169,120)	(168,750)	(175,456)	(179,966)	(174,819)	(175,173)	(183,859)	(680,510)	(713,817)	(836,139)
Total Expenses	(167,184)	(169,120)	(168,750)	(175,456)	(179,966)	(174,819)	(175,173)	(183,859)	(680,510)	(713,817)	(836,139)
Net Income	$ 336,638	$ 377,944	$ 357,147	$ 383,593	$ 278,574	$ 452,253	$ 517,694	$ 613,946	$ 1,455,322	$ 1,862,467	$ 3,214,140
Basic and Diluted Earnings per Share	$ 0.16	$ 0.17	$ 0.16	$ 0.16	$ 0.12	$ 0.19	$ 0.22	$ 0.24	$ 0.65	$ 0.77	$ 1.20
Weighted-average Shares Outstanding	2,095,652	2,205,435	2,269,663	2,343,478	2,351,087	2,345,109	2,388,333	2,551,087	2,228,219	2,409,016	2,667,397
Cash Dividends per Share	$ 0.18	$ 0.17	$ 0.17	$ 0.15	$ 0.15	$ 0.20	$ 0.23	$ 0.24	$ 0.66	$ 0.81	$ 1.25
Other Comprehensive (Loss)/Income:
Currency translation adjustment	$ (9,535)	$ 19,228	$ (5,941)	$ 8,075	$ 18	$ 11,377	$ 13,754	$ (5,633)	$ 11,827	$ 19,516	$ (98,982)
Total Comprehensive Income	$ 327,103	$ 397,172	$ 351,206	$ 391,668	$ 278,592	$ 463,630	$ 531,448	$ 608,313	$ 1,467,149	$ 1,881,983	$ 3,115,158

Aggregate dividends paid during the period for each share of common stock outstanding.

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