CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
REVENUE	$ 247,414	$ 335,629	$ 198,886
COST OF SALES	53,541	54,698	26,288
Gross margin	193,873	280,931	172,598
OPERATING EXPENSES:
Research and development	53,717	49,144	42,744
Selling, general and administrative	46,999	46,808	32,876
Amortization of acquired technology and other intangible assets	21,962	21,983	16,493
Patent costs	7,464	7,010	6,249
Royalty and license expense	6,996	9,739	5,823
Total operating expenses	137,138	134,684	104,185
OPERATING INCOME	56,735	146,247	68,413
Interest income, net	7,659	3,294	2,113
Other expense, net	(83)	(4)	(1,928)
Interest and other expense, net	7,576	3,290	185
INCOME BEFORE INCOME TAXES	64,311	149,537	68,598
INCOME TAX EXPENSE	(5,471)	(45,652)	(20,528)
NET INCOME	$ 58,840	$ 103,885	$ 48,070
NET INCOME PER COMMON SHARE:
BASIC	$ 1.24	$ 2.19	$ 1.02
DILUTED	$ 1.24	$ 2.18	$ 1.02
WEIGHTED AVERAGE SHARES USED IN COMPUTING NET INCOME PER COMMON SHARE:
BASIC	46,849,588	46,725,289	46,408,460
DILUTED	46,896,766	46,805,194	46,535,980
CASH DIVIDEND DECLARED PER COMMON SHARE	$ 0.24	$ 0.12