Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 29, 2013		Sep. 30, 2012		Sep. 29, 2013		Sep. 30, 2012
Revenue
Product	$ 83,464		$ 72,437		$ 237,834		$ 222,293
Service	7,324		7,639		20,356		19,818
Total revenue	90,788		80,076		258,190		242,111
Cost of revenue
Product	18,132		15,863		52,506		49,054
Service	3,216		3,643		9,415		10,059
Total cost of revenue	21,348		19,506		61,921		59,113
Gross margin
Product	65,332		56,574		185,328		173,239
Service	4,108		3,996		10,941		9,759
Total gross margin	69,440		60,570		196,269		182,998
Research, development, and engineering expenses	12,184		10,002		35,392		30,663
Selling, general, and administrative expenses	33,877		28,765		99,344		89,441
Operating income	23,379		21,803		61,533		62,894
Foreign currency loss	(442)		(409)		(303)		(1,077)
Investment income	937		823		2,103		3,596
Other expense	(166)		(131)		(306)		(227)
Income before income tax expense	23,708		22,086		63,027		65,186
Income tax expense	2,981		4,281		9,987		13,332
Net income	$ 20,727		$ 17,805		$ 53,130		$ 51,854
Earnings per weighted-average common and common-equivalent share:
Basic	$ 0.24	[1]	$ 0.21	[1]	$ 0.61	[1]	$ 0.61	[1]
Diluted	$ 0.23	[1]	$ 0.20	[1]	$ 0.59	[1]	$ 0.59	[1]
Weighted-average common and common-equivalent shares outstanding:
Basic	87,339	[1]	85,824	[1]	87,578	[1]	85,554	[1]
Diluted	89,359	[1]	87,258	[1]	89,450	[1]	87,220	[1]
Cash dividends per common share	$ 0.000	[1]	$ 0.055	[1]	$ 0.000	[1]	$ 0.160	[1]

[1] Prior period results have been adjusted to reflect the two-for-one stock split effected in the form of a stock dividend which occurred in September 2013.