Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2016	Oct. 04, 2015	Oct. 02, 2016	Oct. 04, 2015
Income Statement [Abstract]
Revenue	$ 147,952	$ 107,587	$ 391,431	$ 352,789
Cost of revenue	32,749	26,319	88,930	79,171
Gross margin	115,203	81,268	302,501	273,618
Research, development, and engineering expenses	18,603	16,977	58,829	52,265
Selling, general, and administrative expenses	42,072	35,806	123,125	118,980
Operating income	54,528	28,485	120,547	102,373
Foreign currency gain (loss)	(607)	(40)	(377)	580
Investment income	2,047	841	4,631	2,648
Other income (expense)	374	(23)	803	(388)
Income from continuing operations before income tax expense	56,342	29,263	125,604	105,213
Income tax expense on continuing operations	2,667	3,441	14,030	16,403
Net income from continuing operations	53,675	25,822	111,574	88,810
Net income from discontinued operations	0	78,290	(255)	79,518
Net Income	$ 53,675	$ 104,112	$ 111,319	$ 168,328
Basic earnings per weighted-average common and common-equivalent share:
Net income from continuing operations	$ 0.63	$ 0.30	$ 1.31	$ 1.02
Net income (loss) from discontinued operations	0.00	0.91	0.00	0.92
Net income	0.63	1.21	1.31	1.94
Diluted earnings per weighted-average common and common-equivalent share:
Net income from continuing operations	0.61	0.29	1.29	1.00
Net income (loss) from discontinued operations	0.00	0.90	(0.01)	0.90
Net income	$ 0.61	$ 1.19	$ 1.28	$ 1.90
Weighted-average common and common-equivalent shares outstanding:
Basic	85,460	86,303	85,167	86,756
Diluted	87,346	87,776	86,805	88,559
Cash dividends per common share	$ 0.075	$ 0.07	$ 0.22	$ 0.14