Note 8 - Financial Highlights (Details) - Financial Highlights - $ / shares		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Financial Highlights [Abstract]
Net asset value per Share, beginning of period		$ 15.29	[1]	$ 18.77
Net decrease in net assets from operations		(2.12)		(3.48)
Net asset value per Share, end of period	[1]	$ 13.17		$ 15.29
Total return, at net asset value(c)	[2]	(13.87%)		(18.54%)
Ratio to average net assets:
Net investment loss		(0.50%)		(0.50%)
Expenses		0.50%		0.50%
Net investment loss(a)	[3]	$ (0.07)		$ (0.09)
Net realized and unrealized loss(b)	[4]	$ (2.05)		$ (3.39)

[1] Effective January 1, 2014, the Trust qualified as an investment company solely for accounting purposes and not for any other purpose. Disclosure of net asset value per Share is required for investment companies. Please refer to Note 2B.

[2] Based on the change in net asset value of a Share during the period.

[3] Based on average Shares outstanding during the period.

[4] The amounts reported for a Share outstanding may not accord with the change in aggregate gains and losses on investment for the period due to the timing of Trust Share transactions in relation to the fluctuating fair values of the Trust's underlying investment.