Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Net sales	$ 95,662	$ 88,341	$ 179,158	$ 160,149
Cost of sales	60,831	58,495	115,376	105,266
Gross margin	34,831	29,846	63,782	54,883
Selling, engineering and administration	20,610	19,686	41,871	39,998
Operating earnings	14,221	10,160	21,911	14,885
Interest expense, net	311	332	602	580
Earnings before income taxes	13,910	9,828	21,309	14,305
Provision for income taxes	5,096	3,547	7,863	5,117
Net earnings	$ 8,814	$ 6,281	$ 13,446	$ 9,188
Earnings per share: (in dollars per share)
Basic	$ 0.62	$ 0.44	$ 0.94	$ 0.64
Diluted	$ 0.61	$ 0.44	$ 0.94	$ 0.64
Dividends declared per common share	$ 0.18	$ 0.17	$ 0.36	$ 0.34
Shares used in computation of earnings per share: (in shares)
Basic	14,309,509	14,365,536	14,244,135	14,345,143
Impact of dilutive securities	57,844	65,463	73,911	81,806
Diluted	14,367,353	14,430,999	14,318,046	14,426,949