Note 15 - Stock-based Compensation - Compensation Related to Stock-based Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total stock-based compensation expense	$ 10,218	$ 8,760	$ 5,157
Tax effect on stock-based compensation expense	668	604	617
Net effect of stock-based compensation expense	9,550	8,156	4,540
Cost of Sales [Member]
Total stock-based compensation expense	3,488	3,369	2,400
Selling and Marketing Expense [Member]
Total stock-based compensation expense	792	452	247
General and Administrative Expense [Member]
Total stock-based compensation expense	$ 5,938	$ 4,939	$ 2,510