Note 11 - Income Taxes (Details) - Deferred Tax Assets and Liabilities - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Research tax credits	$ 8,869	$ 10,393
Deferred compensation	5,038	2,326
Other expenses not currently deductible	3,519	2,535
Stock-based compensation	1,912	4,068
Net operating losses		298
Depreciation and amortization	(52)	181
Total deferred tax assets	19,286	19,801
Valuation allowance	(18,614)	(19,051)
Net deferred tax assets	$ 672	$ 750