Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Consolidated Statements of Income [Abstract]
Net sales	$ 152,747	$ 155,955	$ 306,040	$ 290,118
Cost of goods sold	(136,177)	(139,735)	(273,397)	(260,469)
Gross margin	16,570	16,220	32,643	29,649
Other operating income (expense):
Selling expense	(2,206)	(1,983)	(4,292)	(3,798)
General and administrative expense	(5,586)	(4,260)	(10,723)	(7,724)
Defined benefit pension credit	1,898	4,750	3,797	9,500
Other postretirement benefit credit	1,577	1,299	3,154	2,599
Total other operating income (expense)	(4,317)	(194)	(8,064)	577
Operating income	12,253	16,026	24,579	30,226
Nonoperating income (expense):
Interest expense	(333)	(328)	(693)	(603)
Other income (expense), net	(70)	425	(347)	548
Total nonoperating income (expense)	(403)	97	(1,040)	(55)
Income before income taxes	11,850	16,123	23,539	30,171
Provision for income taxes	(4,529)	(6,404)	(8,953)	(12,489)
Net income	$ 7,321	$ 9,719	$ 14,586	$ 17,682
Basic and diluted income per share	$ 0.60	$ 0.80	$ 1.21	$ 1.46
Basic and diluted weighted average shares outstanding	12,102	12,102	12,102	12,102