Note 8 - Employee Benefit Plans - Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Stock-based compensation expenses	[1]	$ 3,369	$ 3,368
Cost of Sales [Member]
Stock-based compensation expenses		652	909
Research and Development Expense [Member]
Stock-based compensation expenses		1,588	1,455
Selling, General and Administrative Expenses [Member]
Stock-based compensation expenses		$ 1,129	$ 1,004

[1] The stock-based compensation expense during the three months ended March 31, 2020 includes immaterial expense or credit adjustments related to cash-settled SARs granted to certain employees. The Company accounted for these awards as liability awards and the amount was included in accrued compensation and related benefits. All remaining outstanding SARs were fully exercised in the third quarter of 2020.