CONDENSED CONSOLIDATED STATEMENTS OF INCOME - UNAUDITED - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 244,108	$ 251,414	$ 730,046	$ 742,063
Cost of revenue (exclusive of depreciation, shown separately below)	131,073	132,054	400,432	393,251
Other operating expenses:
Research and development	30,425	32,551	90,025	95,787
Selling, general and administrative	47,032	46,694	136,415	137,984
Depreciation	5,817	5,365	17,016	15,919
Restructuring and reorganization charges	814	1,330	4,277	3,271
Total operating expenses	215,161	217,994	648,165	646,212
Operating income	28,947	33,420	81,881	95,851
Other income (expense):
Interest expense	(3,641)	(4,390)	(11,894)	(13,448)
Amortization of original issue discount	(751)	(709)	(2,221)	(2,099)
Interest and investment income, net	254	392	1,086	1,328
Other, net	(2,067)	108	(3,184)	(123)
Total other	(6,205)	(4,599)	(16,213)	(14,342)
Income before income taxes	22,742	28,821	65,668	81,509
Income tax provision	(9,176)	(7,262)	(20,222)	(21,320)
Net income	$ 13,566	$ 21,559	$ 45,446	$ 60,189
Weighted-average shares outstanding:
Basic	32,115	32,016	32,070	32,079
Diluted	32,273	32,518	32,296	32,472
Earnings per common share:
Basic	$ 0.42	$ 0.67	$ 1.42	$ 1.88
Diluted	$ 0.42	$ 0.66	$ 1.41	$ 1.85