Consolidated Statements of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Statements of Earnings [Abstract]
Net sales	$ 337,173	$ 310,393	$ 291,867
Cost of sales	239,752	220,854	205,866
Gross margin	97,421	89,539	86,001
Operating expenses:
Selling expenses	15,920	15,934	16,284
Research and development expenses	3,622	3,422	2,890
General and administrative expenses	12,277	10,406	10,602
Total operating expenses	31,819	29,762	29,776
Earnings from operations	65,602	59,777	56,225
Other expenses (income):
Interest income	(277)	(10)	(184)
Interest expense	24	10	84
Other, net	37	(67)	(413)
Earnings before income tax expense	65,818	59,844	56,738
Income tax expense	20,944	19,839	17,973
Net earnings	$ 44,874	$ 40,005	$ 38,765
Basic net earnings per common share (in dollars per share)	$ 1.51	$ 1.38	$ 1.36
Diluted net earnings per common share (in dollars per share)	$ 1.45	$ 1.32	$ 1.28