Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Net sales:
Products	$ 170,337	$ 172,644	$ 339,832	$ 341,988
Service	52,141	48,808	103,835	97,019
Total net sales	222,478	221,452	443,667	439,007
Cost of sales:
Products	82,680	85,993	167,863	173,331
Service	32,901	31,030	66,356	63,136
Total cost of sales	115,581	117,023	234,219	236,467
Gross profit	106,897	104,429	209,448	202,540
Operating expenses:
Research and development	25,413	23,306	50,222	46,028
Selling, general and administrative	42,639	42,045	86,163	83,368
Restructuring, reorganization, relocation and severance	395	0	1,090	0
Total operating expenses	68,447	65,351	137,475	129,396
Operating income	38,450	39,078	71,973	73,144
Other expense:
Interest income	137	384	253	955
Interest expense	(669)	(1,003)	(1,485)	(2,087)
Other, net	(920)	(636)	(1,725)	(2,186)
Total other expense, net	(1,452)	(1,255)	(2,957)	(3,318)
Income before income taxes	36,998	37,823	69,016	69,826
Income tax expense	7,005	7,530	12,222	13,866
Net income	$ 29,993	$ 30,293	$ 56,794	$ 55,960
Basic net income per share	$ 0.76	$ 0.80	$ 1.46	$ 1.48
Diluted net income per share	$ 0.72	$ 0.74	$ 1.36	$ 1.37
Cash dividends declared per share	$ 0.12	$ 0.08	$ 0.20	$ 0.08
Shares used in per share calculations:
Basic (in shares)	39,496	37,993	39,012	37,939
Diluted (in shares)	42,281	41,614	42,227	41,579