Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net sales	$ 358,632	$ 356,322	$ 321,140
Cost of sales	249,951	248,059	231,348
Gross profit	108,681	108,263	89,792
Selling, general and administrative expenses	37,438	40,562	33,989
Gain on disposal of assets	(59)	(305)	(22)
Income from operations	71,302	68,006	55,825
Interest income, net	161	276	221
Other (expense) income, net	(124)	(36)	248
Income before taxes	71,339	68,246	56,294
Income tax provision	25,611	24,088	18,747
Net income	$ 45,728	$ 44,158	$ 37,547
Earnings per share:
Basic (usd per share)	$ 0.85	$ 0.81	$ 0.68
Diluted (usd per share)	0.84	0.80	0.68
Cash dividends declared per common share	$ 0.22	$ 0.18	$ 0.13
Weighted average shares outstanding:
Basic	54,045,841	54,809,319	55,119,150
Diluted	54,481,484	55,369,016	55,587,381