Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Income Statement [Abstract]
Revenue	$ 169,567	$ 139,039
Cost of revenue	40,198	32,532
Gross margin	129,369	106,507
Research, development, and engineering expenses	31,076	22,770
Selling, general, and administrative expenses	63,697	46,521
Operating income	34,596	37,216
Foreign currency gain (loss)	(134)	(263)
Investment income	3,240	2,012
Other income (expense)	277	270
Income before income tax expense	37,979	39,235
Income tax expense (benefit)	762	(6,236)
Net income	$ 37,217	$ 45,471
Net income per weighted-average common and common-equivalent share:
Basic (in dollars per share)	$ 0.21	$ 0.26
Diluted (in dollars per share)	$ 0.21	$ 0.25
Weighted-average common and common-equivalent shares outstanding:
Basic (in shares)	173,280	172,646
Diluted (in shares)	179,641	178,354
Cash dividends per common share	$ 0.045	$ 0.0375