Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 29, 2015	Mar. 30, 2014
Net sales:
Products	$ 164,059	$ 169,298
Service	56,757	56,966
Total net sales	220,816	226,264
Cost of sales:
Products	81,501	86,595
Service	34,044	33,345
Total cost of sales	115,545	119,940
Gross profit	105,271	106,324
Operating expenses:
Research and development	23,322	25,646
Selling, general and administrative	45,822	48,462
Restructuring, reorganization, relocation and severance	(121)	1,331
Total operating expenses	69,023	75,439
Operating income	36,248	30,885
Other expense:
Interest income	211	152
Interest expense	(94)	(98)
Other, net	(1,084)	(324)
Total other expense, net	(967)	(270)
Income before income taxes	35,281	30,615
Income tax expense	7,269	5,537
Net income	$ 28,012	$ 25,078
Basic net income per share	$ 0.67	$ 0.59
Diluted net income per share	$ 0.66	$ 0.59
Cash dividends declared per share	$ 0.25	$ 0.12
Shares used in per share calculations:
Basic (in shares)	41,796	42,191
Diluted (in shares)	42,185	42,772