Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Income Statement [Abstract]
Revenue	$ 211,264	$ 178,080	$ 380,831	$ 317,119
Cost of revenue	54,169	42,164	94,367	74,696
Gross margin	157,095	135,916	286,464	242,423
Research, development, and engineering expenses	26,888	23,377	57,964	46,147
Selling, general, and administrative expenses	66,752	52,518	130,449	99,039
Operating income	63,455	60,021	98,051	97,237
Foreign currency gain (loss)	(195)	(184)	(329)	(447)
Investment income	3,559	2,138	6,799	4,150
Other income (expense)	(246)	(169)	31	101
Income before income tax expense	66,573	61,806	104,552	101,041
Income tax expense (benefit)	10,377	5,311	11,139	(925)
Net Income	$ 56,196	$ 56,495	$ 93,413	$ 101,966
Net income per weighted-average common and common-equivalent share:
Basic	$ 0.33	$ 0.33	$ 0.54	$ 0.59
Diluted	$ 0.32	$ 0.32	$ 0.52	$ 0.57
Weighted-average common and common-equivalent shares outstanding:
Basic	172,370	173,278	172,825	172,960
Diluted	177,149	179,228	178,418	178,904
Cash dividends per common share	$ 0.045	$ 0.0425	$ 0.09	$ 0.080