Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net sales:
Products	$ 685,651	$ 722,666	$ 709,438
Service	244,481	233,614	218,016
Total net sales	930,132	956,280	927,454
Cost of sales:
Products	336,071	369,043	352,630
Service	139,470	139,082	136,039
Total cost of sales	475,541	508,125	488,669
Gross profit	454,591	448,155	438,785
Operating expenses:
Research and development	95,569	102,613	101,947
Selling, general and administrative	181,563	196,777	179,560
Impairment of goodwill and long-lived assets	26,596	905	0
Restructuring and reorganization	(563)	18,459	1,090
Total operating expenses	303,165	318,754	282,597
Operating income	151,426	129,401	156,188
Other expense:
Interest income	1,078	897	428
Interest expense	(694)	(600)	(1,890)
Other, net	(4,018)	(2,768)	(3,124)
Total other expense, net	(3,634)	(2,471)	(4,586)
Income before income taxes	147,792	126,930	151,602
Income tax expense	23,783	21,866	24,929
Net income	$ 124,009	$ 105,064	$ 126,673
Basic net income per share	$ 2.99	$ 2.50	$ 3.13
Diluted net income per share	2.96	2.47	3.01
Cash dividends declared per share	$ 1.15	$ 0.87	$ 0.44
Shares used in per share calculations:
Basic (in shares)	41,419	41,969	40,446
Diluted (in shares)	41,839	42,528	42,395