Note P - Share-based Compensation - Share-based Compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total share-based compensation expense	$ 11,804,000	$ 11,120,000	$ 7,795,000
Share-based Payment Arrangement, Option [Member]
Total share-based compensation expense	0	12,000	853,000
Restricted Stock Units (RSUs) [Member]
Total share-based compensation expense	11,804,000	11,108,000	6,942,000
Shares for Convertible Senior Notes [Member]
Total share-based compensation expense	11,804	11,120	7,795
Cost of Sales [Member]
Total share-based compensation expense	772,000	795,000	461,000
Research and Development Expense [Member]
Total share-based compensation expense	2,557,000	2,419,000	1,496,000
Selling and Marketing Expense [Member]
Total share-based compensation expense	1,070,000	925,000	481,000
General and Administrative Expense [Member]
Total share-based compensation expense	$ 7,405,000	$ 6,981,000	$ 5,357,000