Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Net sales	$ 825,847	$ 812,171	$ 1,587,837	$ 1,586,423
Cost of sales	716,307	693,346	1,401,559	1,372,497
Selling, general and administrative	57,708	62,484	117,558	116,261
Depreciation	13,089	13,455	26,588	27,082
Amortization	2,342	2,341	4,683	4,683
Equity in earnings of investees	(332)	(72)	(332)	(72)
Restructuring and relocation costs	0	41	460	258
Operating income	36,733	40,576	37,321	65,714
Interest income	641	775	1,305	1,507
Interest expense	(15,299)	(14,778)	(30,767)	(29,342)
Loss on debt extinguishment	0	0	(521)	(6,275)
Other income (expense), net	(242)	1,568	(4,136)	2,123
Income before income taxes	21,833	28,141	3,202	33,727
Income tax benefit (expense)	(3,997)	2,959	(9,969)	(250)
Net income (loss)	$ 17,836	$ 31,100	$ (6,767)	$ 33,477
Earnings (loss) per common share - basic (in dollars per share)	$ 0.38	$ 0.67	$ (0.14)	$ 0.72
Earnings (loss) per common share - diluted (in dollars per share)	$ 0.37	$ 0.66	$ (0.14)	$ 0.71