Consolidated Statements of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Earnings [Abstract]
Net sales	$ 291,867	$ 255,071	$ 219,438
Cost of sales	205,866	177,034	152,480
Gross margin	86,001	78,037	66,958
Operating expenses:
Selling expenses	16,284	15,608	14,350
Research and development expenses	2,890	3,190	3,298
General and administrative expenses	10,602	9,469	8,651
Total operating expenses	29,776	28,267	26,299
Earnings from operations	56,225	49,770	40,659
Other expenses (income):
Interest income	(184)	(289)	(107)
Interest expense	84	90	209
Other, net	(413)	(162)	(45)
Earnings before income tax expense	56,738	50,131	40,602
Income tax expense	17,973	16,854	13,817
Net earnings	$ 38,765	$ 33,277	$ 26,785
Net earnings per common share - basic (in dollars per share)	$ 1.36	$ 1.19	$ 0.98
Net diluted earnings per common share - diluted (in dollars per share)	$ 1.28	$ 1.12	$ 0.93