CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUE:
Total revenue	$ 428,867	$ 405,177	$ 247,414
COST OF SALES	85,478	75,374	53,541
Gross margin	343,389	329,803	193,873
OPERATING EXPENSES:
Research and development	83,894	71,276	53,717
Selling, general and administrative	61,346	59,613	46,999
Amortization of acquired technology and other intangible assets	21,969	21,962	21,962
Patent costs	7,529	6,833	7,464
Royalty and license expense	11,125	11,776	6,996
Total operating expenses	185,863	171,460	137,138
OPERATING INCOME	157,526	158,343	56,735
Interest income, net	5,139	10,795	7,659
Other income (expense), net	864	767	(83)
Interest and other income, net	6,003	11,562	7,576
INCOME BEFORE INCOME TAXES	163,529	169,905	64,311
INCOME TAX EXPENSE	(30,157)	(31,601)	(5,471)
NET INCOME	$ 133,372	$ 138,304	$ 58,840
NET INCOME PER COMMON SHARE:
BASIC	$ 2.80	$ 2.92	$ 1.24
DILUTED	$ 2.80	$ 2.92	$ 1.24
WEIGHTED AVERAGE SHARES USED IN COMPUTING NET INCOME PER COMMON SHARE:
BASIC	47,198,982	46,959,775	46,849,588
DILUTED	47,236,994	46,995,462	46,896,766
CASH DIVIDEND DECLARED PER COMMON SHARE	$ 0.60	$ 0.40	$ 0.24
Material sales
REVENUE:
Total revenue	$ 229,749	$ 243,413	$ 153,204
Royalty and license fees
REVENUE:
Total revenue	185,054	150,022	80,644
Contract research services
REVENUE:
Total revenue	$ 14,064	$ 11,742	$ 13,566