Note 9 - Income Taxes - Schedule of Reconciliation of Theoretical Tax Expense and Actual Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loss before taxes, as reported in the consolidated statements of operations	$ (16,579)	$ (20,597)	$ (19,022)
Statutory tax rate	34.00%	34.00%	34.00%
Theoretical tax benefits on the above amount at the US statutory tax rate	$ (5,637)	$ (7,003)	$ (6,468)
Income tax at rate other than the U.S. statutory tax rate	68	333	993
Tax advances and non-deductible expenses including equity based compensation expenses	4,298	1,061	1,296
Operating losses and other temporary differences for which valuation allowance was provided	3,001	6,558	4,596
Research and Development Tax Credit	(1,182)
State tax	(536)	(477)	(409)
Impact of rate change	(360)	(82)	49
Change in tax reserve for uncertain tax positions	(1,209)	(320)	(308)
Other individually immaterial income tax items	270	(24)	11
Actual tax expense	$ 1,131	$ 686	$ 376