Note 13 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allocated share-based compensation expense	$ 10,781	$ 10,928	$ 8,558
Cost of Sales [Member]
Allocated share-based compensation expense	2,056	1,543	970
Selling and Marketing Expense [Member]
Allocated share-based compensation expense	2,632	1,942	1,429
Research and Development Expense [Member]
Allocated share-based compensation expense	1,851	1,517	1,091
General and Administrative Expense [Member]
Allocated share-based compensation expense	4,242	5,926	5,068
Stock Options, Restricted Stock, and Other [Member]
Allocated share-based compensation expense	9,591	10,113	7,954
ESPP [Member]
Allocated share-based compensation expense	$ 1,190	$ 815	$ 604