Note 9 - Income Taxes (Details) - Effective Income Tax Rate Reconciliation (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Effective Income Tax Rate Reconciliation [Abstract]      
Provision (benefit) at statutory rate $ (7,096) $ (3,886) $ (2,456)
State income taxes 1,651 303 200
Research and development credits (7,384) (5,850) (1,345)
Change in valuation allowance 5,271 6,781 15,247
Foreign earnings, taxed at different rates 6,381 2,888 1,649
Unrecognized tax benefits 1,713 1,708 1,487
Stock-based compensation 166 142 336
Tax exempt income (83) (157) (197)
Prior year return to provision adjustment 292 (257) (1,264)
Cortina acquisition transaction cost 444    
Other 383 80 16
$ 1,738 $ 1,752 $ 13,673