Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 169,097	$ 199,047	$ 336,332	$ 372,531
Cost of revenue	50,320	50,967	91,520	97,251
Gross margin	118,777	148,080	244,812	275,280
Research, development, and engineering expenses	30,397	28,079	66,343	58,321
Selling, general, and administrative expenses	60,153	68,245	129,291	135,056
Restructuring charges (Note 16)	14,798	0	14,798	0
Intangible asset impairment charges (Note 8)	19,571	0	19,571	0
Operating income (loss)	(6,142)	51,756	14,809	81,903
Foreign currency gain (loss)	336	140	(2,667)	(108)
Investment income	3,291	5,223	8,520	10,128
Other income (expense)	203	(144)	20	783
Income (loss) before income tax expense (benefit)	(2,312)	56,975	20,682	92,706
Income tax expense (benefit)	(1,170)	8,226	1,347	10,853
Net Income	$ (1,142)	$ 48,749	$ 19,335	$ 81,853
Net income (loss) per weighted-average common and common-equivalent share:
Basic (usd per share)	$ (0.01)	$ 0.28	$ 0.11	$ 0.48
Diluted (usd per share)	$ (0.01)	$ 0.28	$ 0.11	$ 0.47
Weighted-average common and common-equivalent shares outstanding:
Basic (shares)	172,283	171,318	172,345	171,209
Diluted (shares)	172,283	175,448	175,499	175,528
Cash dividends per common share (usd per share)	$ 0.055	$ 0.050	$ 0.110	$ 0.100