Condensed Consolidated Statements of Earnings (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Condensed Consolidated Statements of Earnings (unaudited) [Abstract]
Net sales	$ 140,128	$ 160,490	$ 419,763	$ 378,715
Cost of sales	96,954	116,003	291,592	278,678
Gross margin	43,174	44,487	128,171	100,037
Operating expenses:
Selling expenses	11,807	11,458	34,960	24,199
Research and development expenses	1,510	1,445	4,450	3,337
General and administrative expenses	6,935	6,300	17,027	17,353
Operating expenses	20,252	19,203	56,437	44,889
Earnings from operations	22,922	25,284	71,734	55,148
Other expenses (income):
Interest income	(3)	(3)	(7)	(62)
Interest expense	1,617	2,052	5,092	3,368
Other, net	119	26	209	(30)
Earnings before income tax expense	21,189	23,209	66,440	51,872
Income tax expense	7,213	8,031	22,377	18,068
Net earnings	$ 13,976	$ 15,178	$ 44,063	$ 33,804
Net earnings per common share - basic (in dollars per share)	$ 0.45	$ 0.50	$ 1.42	$ 1.12
Net earnings per common share - diluted (in dollars per share)	$ 0.44	$ 0.49	$ 1.40	$ 1.09