Condensed Consolidated Statements of Earnings (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Consolidated Statements of Earnings (unaudited) [Abstract]
Net sales	$ 135,141	$ 144,862
Cost of sales	92,317	101,732
Gross margin	42,824	43,130
Operating expenses:
Selling expenses	13,087	11,786
Research and development expenses	1,942	1,448
General and administrative expenses	7,827	4,858
Total operating expenses	22,856	18,092
Earnings from operations	19,968	25,038
Other expenses (income):
Interest income	(3)	(2)
Interest expense	1,843	1,881
Other, net	147	74
Earnings before income tax expense	17,981	23,085
Income tax expense	6,095	7,913
Net earnings	$ 11,886	$ 15,172
Net earnings per common share - basic (in dollars per share)	$ 0.38	$ 0.49
Net earnings per common share - diluted (in dollars per share)	$ 0.37	$ 0.48