Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Income Statement [Abstract]
Net sales	$ 89,690		$ 76,816		$ 247,764		$ 225,106
Cost of sales	63,074		59,667		178,160		173,336
Gross profit	26,616		17,149		69,604		51,770
Selling, general and administrative expenses	9,687		6,747		25,743		19,627
Gain on disposal of assets	0		4		52		17
Income from operations	16,929		10,406		43,913		32,160
Interest expense	(1)		(16)		(2)		(43)
Interest income	61		40		153		55
Other income (expense), net	15		53		252		50
Income before taxes	17,004		10,483		44,316		32,222
Income tax provision	6,482		4,476		14,535		12,351
Net income	$ 10,522		$ 6,007		$ 29,781	[1]	$ 19,871
Earnings per share:
Basic	$ 0.29	[2]	$ 0.16	[2]	$ 0.81	[2]	$ 0.54	[2]
Diluted	$ 0.28	[2]	$ 0.16	[2]	$ 0.80	[2]	$ 0.54	[2]
Cash dividends declared per common share	$ 0	[2]	$ 0	[2]	$ 0.10	[2]	$ 0.08	[2]
Weighted average shares outstanding:
Basic	36,742,262	[2]	36,803,235	[2]	36,752,657	[2]	36,837,686	[2]
Diluted	37,017,561	[2]	37,001,127	[2]	37,041,775	[2]	37,083,695	[2]

[1] Includes cash payment of fractional shares from three-for-two stock split effective July 2, 2013

[2] Reflects three-for-two stock split effective July 2, 2013