Consolidated Condensed Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Net sales	$ 92,963	$ 87,130	$ 253,112	$ 245,337
Cost of sales	59,860	52,800	165,126	151,942
Gross margin	33,103	34,330	87,986	93,395
Selling, engineering and administration	19,230	20,219	59,228	57,741
Operating earnings	13,873	14,111	28,758	35,654
Interest expense (income), net	264	286	844	729
Earnings before income taxes	13,609	13,825	27,914	34,925
Provision for income taxes	4,560	4,968	9,677	12,377
Net earnings	$ 9,049	$ 8,857	$ 18,237	$ 22,548
Earnings per share:
Basic	$ 0.63	$ 0.63	$ 1.27	$ 1.57
Diluted	$ 0.63	$ 0.62	$ 1.26	$ 1.56
Dividends declared – Common stock	$ 0.18	$ 0.17	$ 0.52	$ 0.49
Shares used in computation of earnings per share:
Basic	14,371,718	14,128,055	14,353,700	14,393,644
Impact of dilutive securities	75,017	57,851	79,543	65,140
Diluted	14,446,735	14,185,906	14,433,243	14,458,784