Condensed Consolidated Statements of Earnings (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidated Statements of Earnings (unaudited) [Abstract]
Net sales	$ 83,296	$ 79,014	$ 167,947	$ 155,217
Cost of sales	58,411	56,430	118,830	111,475
Gross margin	24,885	22,584	49,117	43,742
Operating expenses:
Selling expenses	4,046	4,169	8,333	8,256
Research and development expenses	947	947	1,785	1,723
General and administrative expenses	3,276	2,643	6,518	5,263
Operating expenses	8,269	7,759	16,636	15,242
Earnings from operations	16,616	14,825	32,481	28,500
Other expenses (income):
Interest income	(61)	(1)	(113)	(8)
Interest expense	2	3	3	6
Other, net	(7)	(1)	46	(10)
Earnings before income tax expense	16,682	14,824	32,545	28,512
Income tax expense	5,100	4,852	10,075	9,272
Net earnings	$ 11,582	$ 9,972	$ 22,470	$ 19,240
Net earnings per common share - basic (in dollars per share)	$ 0.39	$ 0.34	$ 0.76	$ 0.66
Net earnings per common share - diluted (in dollars per share)	$ 0.38	$ 0.33	$ 0.73	$ 0.64