Note 7 - Stock-based Compensation - Stock-based Compensation Plan Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share based compensation expense	$ 60,607	$ 52,617	$ 44,989
Tax benefit related to stock-based compensation	4,383	5,054
Cost of Sales [Member]
Share based compensation expense	1,888	1,654	1,575
Research and Development Expense [Member]
Share based compensation expense	15,990	14,816	14,041
Selling, General and Administrative Expenses [Member]
Share based compensation expense	$ 42,729	$ 36,147	$ 29,373

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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