Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Net sales	$ 393,761	$ 377,698	$ 364,768
Cost of sales	243,185	241,922	233,626
Gross margin	150,576	135,776	131,142
Selling, engineering and administration	99,811	93,407	85,095
Operating earnings	50,765	42,369	46,047
Interest expense, net	921	1,217	1,135
Earnings before income taxes	49,844	41,152	44,912
Provision for income taxes	17,549	15,214	15,234
Net earnings	$ 32,295	$ 25,938	$ 29,678
Earnings per share:
Basic (in dollars per share)	$ 1.12	$ 0.90	$ 1.04
Diluted (in dollars per share)	$ 1.11	$ 0.90	$ 1.03
Shares used in computation of earnings per share:
Basic (in shares)	28,887	28,759	28,613
Impact of dilutive securities (in shares)	163	135	144
Diluted (in shares)	29,050	28,894	28,757