Note 11 - Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expenses (benefit) at statutory rate	$ (21,832)	$ (32,562)	$ 3,895
State income taxes	594	(585)	222
Research and development credits	(13,283)	(12,983)	(8,566)
Change in valuation allowance	13,757	40,028	9,768
Impact of foreign operations	5,925	(1,951)	(13,570)
Unrecognized tax benefits	5,340	3,596	3,151
Stock-based compensation	(381)	(10,248)	(9,925)
Prior year return to provision adjustment	1,422	1,105	(524)
Effect of U. S. tax law change		(4,602)
Impairment of intangibles		(2,328)
Other	247	(646)	492
Total	$ (8,211)	$ (21,176)	$ (15,057)