Note 8 - Financial Highlights (Details) - Financial Highlights - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Financial Highlights [Abstract]
Net asset value per Share, beginning of period		$ 21.18	$ 33.82	$ 21.36	[1]	$ 32.17
Total return(c)(d)	[2],[3]	(19.59%)	(12.66%)	(20.27%)		(8.18%)
Ratio to average net assets:
Net investment loss(e)	[4]	(0.82%)	(0.77%)	(0.81%)		(0.77%)
Expenses(e)	[4]	0.84%	0.80%	0.83%		0.82%
Net investment loss(a)	[5]	$ (0.04)	$ (0.06)	$ (0.12)		$ (0.19)
Net realized and unrealized loss(b)	[6]	(4.11)	(4.22)	(4.21)		(2.44)
Net decrease in net assets from operations		(4.15)	(4.28)	(4.33)		(2.63)
Net asset value per Share, end of period		$ 17.03	$ 29.54	$ 17.03		$ 29.54

[1] Previously reported as "Statements of Financial Condition." Please refer to Note 2A.

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

[3] Percentage is not annualized.

[4] Percentage is annualized.

[5] Based on average Shares outstanding during each period.

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