Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 05, 2015	Jun. 29, 2014	Jul. 05, 2015	Jun. 29, 2014
Income Statement [Abstract]
Revenue	$ 143,829	$ 92,276	$ 245,202	$ 173,592
Cost of revenue	30,508	18,190	52,852	34,743
Gross margin	113,321	74,086	192,350	138,849
Research, development, and engineering expenses	18,302	12,524	35,288	24,093
Selling, general, and administrative expenses	43,241	35,538	83,174	67,330
Operating income	51,778	26,024	73,888	47,426
Foreign currency gain (loss)	(39)	(74)	620	(184)
Investment income	957	801	1,807	1,588
Other expense	(55)	(75)	(365)	(348)
Income from continuing operations before income tax expense	52,641	26,676	75,950	48,482
Income tax expense on continuing operations	9,125	4,001	12,962	7,991
Income from continuing operations	43,516	22,675	62,988	40,491
Income from discontinued operations, net of tax	198	3,273	1,228	3,963
Net income	$ 43,714	$ 25,948	$ 64,216	$ 44,454
Basic earnings per weighted-average common and common-equivalent share:
Income from continuing operations	$ 0.50	$ 0.26	$ 0.72	$ 0.47
Income from discontinued operations	0.00	0.04	0.02	0.04
Net income	0.50	0.30	0.74	0.51
Diluted earnings per weighted-average common and common-equivalent share:
Income from continuing operations	0.49	0.25	0.71	0.45
Income from discontinued operations	0.00	0.04	0.01	0.05
Net income	$ 0.49	$ 0.29	$ 0.72	$ 0.50
Weighted-average common and common-equivalent shares outstanding:
Basic (in shares)	87,199	86,782	86,977	86,830
Diluted (in shares)	89,185	88,965	88,951	89,112
Cash dividends per common share	$ 0.07	$ 0	$ 0.07	$ 0