Condensed Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements Of Income [Abstract]
Net sales	$ 153,293	$ 134,163
Cost of goods sold	(137,220)	(120,734)
Gross margin	16,073	13,429
Other operating income (expense):
Selling expense	(2,086)	(1,815)
General and administrative expense	(5,137)	(3,464)
Defined benefit pension credit	1,899	4,750
Other postretirement benefit credit	1,577	1,300
Total other operating income (expense)	(3,747)	771
Operating income	12,326	14,200
Nonoperating income (expense):
Interest expense	(360)	(275)
Other income (expense), net	(277)	123
Total nonoperating expense	(637)	(152)
Income before income taxes	11,689	14,048
Provision for income taxes	(4,424)	(6,085)
Net income	$ 7,265	$ 7,963
Basic and diluted income per share	$ 0.60	$ 0.66
Basic and diluted weighted average shares outstanding	12,102	12,102