Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 04, 2015	Sep. 28, 2014	Oct. 04, 2015	Sep. 28, 2014
Income Statement [Abstract]
Revenue	$ 107,587	$ 154,356	$ 352,789	$ 327,948
Cost of revenue	26,319	37,712	79,171	72,455
Gross margin	81,268	116,644	273,618	255,493
Research, development, and engineering expenses	16,977	17,532	52,265	41,625
Selling, general, and administrative expenses	35,806	43,773	118,980	111,103
Operating income	28,485	55,339	102,373	102,765
Foreign currency gain (loss)	(40)	794	580	610
Investment income	841	776	2,648	2,364
Other income (expense)	(23)	202	(388)	(146)
Income from continuing operations before income tax expense	29,263	57,111	105,213	105,593
Income tax expense on continuing operations	3,441	9,430	16,403	17,422
Income from continuing operations, net of tax	25,822	47,681	88,810	88,171
Pretax income from discontinued operations	0	2,719	1,228	6,683
Gain on sale of discontinued business, net of tax	78,290	0	78,290	0
Discontinued operations, net of tax	78,290	2,719	79,518	6,683
Net Income	$ 104,112	$ 50,400	$ 168,328	$ 94,854
Basic earnings per weighted-average common and common-equivalent share:
Income from continuing operations	$ 0.30	$ 0.55	$ 1.02	$ 1.01
Income from discontinued operations	0.91	0.03	0.92	0.08
Net income	1.21	0.58	1.94	1.09
Diluted earnings per weighted-average common and common-equivalent share:
Income from continuing operations	0.29	0.53	1.00	0.99
Income from discontinued operations	0.90	0.04	0.90	0.07
Net income	$ 1.19	$ 0.57	$ 1.90	$ 1.06
Weighted-average common and common-equivalent shares outstanding:
Basic	86,303	86,963	86,756	86,875
Diluted	87,776	89,167	88,559	89,145
Cash dividends per common share	$ 0.07	$ 0	$ 0.14	$ 0