Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Income Statement [Abstract]
Net sales	$ 321,140		$ 303,114		$ 266,220
Cost of sales	231,348		232,615		219,939
Gross profit	89,792		70,499		46,281
Selling, general and administrative expenses	33,989		26,261		22,310
(Gain) loss on disposal of assets	(22)		4		1,802
Income from operations	55,825		44,234		22,169
Interest income (expense), net	221		42		(179)
Other income (expense), net	248		41		(477)
Income before taxes	56,294		44,317		21,513
Income tax provision	18,747		16,868		7,527
Net income	$ 37,547		$ 27,449		$ 13,986
Earnings per share:
Basic (usd per share)	$ 1.02	[1]	$ 0.75	[1]	$ 0.38	[1]
Diluted (usd per share)	$ 1.01	[1]	$ 0.74	[1]	$ 0.37	[1]
Cash dividends declared per common share	$ 0.20	[1]	$ 0.24	[1],[2]	$ 0.16	[1]
Weighted average shares outstanding:
Basic	36,746,100	[1]	36,825,170	[1]	37,034,778	[1]
Diluted	37,058,254	[1]	37,048,826	[1]	37,321,719	[1]

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

[2] Includes special dividend of $0.08 per common share paid on December 24, 2012.