CONDENSED CONSOLIDATED STATEMENTS OF INCOME - UNAUDITED - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 240,321	$ 245,856	$ 485,938	$ 490,649
Cost of revenue (exclusive of depreciation, shown separately below)	138,153	132,234	269,359	261,197
Other operating expenses:
Research and development	29,263	30,645	59,600	63,236
Selling, general and administrative	44,999	45,372	89,383	91,290
Depreciation	5,634	5,441	11,199	10,554
Restructuring and reorganization charges	2,497	1,826	3,463	1,941
Total operating expenses	220,546	215,518	433,004	428,218
Operating income	19,775	30,338	52,934	62,431
Other income (expense):
Interest expense	(4,040)	(4,498)	(8,253)	(9,058)
Amortization of original issue discount	(740)	(700)	(1,470)	(1,390)
Interest and investment income, net	303	417	832	936
Other, net	(1,048)	1,280	(1,117)	(231)
Total other	(5,525)	(3,501)	(10,008)	(9,743)
Income before income taxes	14,250	26,837	42,926	52,688
Income tax provision	(3,884)	(7,458)	(11,046)	(14,058)
Net income	$ 10,366	$ 19,379	$ 31,880	$ 38,630
Weighted-average shares outstanding:
Basic	32,100	32,093	32,047	32,111
Diluted	32,258	32,458	32,308	32,448
Earnings per common share:
Basic	$ 0.32	$ 0.60	$ 0.99	$ 1.20
Diluted	$ 0.32	$ 0.60	$ 0.99	$ 1.19