Note 12 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allocated share-based compensation expense	$ 14,673	$ 10,781	$ 10,928
Cost of Sales [Member]
Allocated share-based compensation expense	2,451	2,056	1,543
Selling and Marketing Expense [Member]
Allocated share-based compensation expense	3,121	2,632	1,942
Research and Development Expense [Member]
Allocated share-based compensation expense	2,440	1,851	1,517
General and Administrative Expense [Member]
Allocated share-based compensation expense	6,661	4,242	5,926
Stock Options, Restricted Stock, and Other [Member]
Allocated share-based compensation expense	13,327	9,591	10,113
ESPP [Member]
Allocated share-based compensation expense	$ 1,346	$ 1,190	$ 815