Condensed Consolidated Statements of Earnings (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Consolidated Statements of Earnings (unaudited) [Abstract]
Net sales	$ 132,230	$ 83,296	$ 218,225	$ 167,947
Cost of sales	99,895	58,411	162,675	118,830
Gross margin	32,335	24,885	55,550	49,117
Operating expenses:
Selling expenses	8,552	4,046	12,741	8,333
Research and development expenses	1,119	947	1,892	1,785
General and administrative expenses	6,155	3,276	11,053	6,518
Operating expenses	15,826	8,269	25,686	16,636
Earnings from operations	16,509	16,616	29,864	32,481
Other expenses (income):
Interest income	(13)	(61)	(59)	(113)
Interest expense	1,315	2	1,316	3
Other, net	(84)	(7)	(56)	46
Earnings before income tax expense	15,291	16,682	28,663	32,545
Income tax expense	5,559	5,100	10,037	10,075
Net earnings	$ 9,732	$ 11,582	$ 18,626	$ 22,470
Net earnings per common share - basic (in dollars per share)	$ 0.32	$ 0.39	$ 0.62	$ 0.76
Net earnings per common share - diluted (in dollars per share)	$ 0.31	$ 0.38	$ 0.60	$ 0.73