Supplemental Consolidating Financial Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net sales	$ 738,551	$ 723,062		$ 2,326,388	$ 2,309,485
Cost of sales	663,536	645,170		2,065,095	2,017,667
Selling, general and administrative	53,658	60,966		162,544	177,227
Depreciation	12,323	13,435		38,911	40,517
Amortization	2,342	2,342		7,025	7,025
Equity in earnings of investees	(105)	0		(437)	(72)
Restructuring and relocation costs	0	(4)		460	254
Operating income	(1,438)	1,153		35,883	66,867
Interest income	600	690		1,905	2,197
Interest expense	(15,564)	(15,356)		(46,331)	(44,698)
Loss on debt extinguishment	0	0		(521)	(6,275)
Other income (expense), net	(1,036)	(501)		(5,172)	1,622
Income before income taxes	(17,438)	(14,014)		(14,236)	19,713
Income tax benefit (expense)	(518)	(3,800)	3,000	(10,487)	(4,050)
Net income (loss)	(17,956)	(17,814)		(24,723)	15,663
Reportable Legal Entities [Member] | Parent Company [Member]
Net sales	0	0		0	0
Cost of sales	0	0		0	0
Selling, general and administrative	9,788	12,446		24,816	31,851
Depreciation	0	0		0	0
Amortization	0	0		0	0
Equity in earnings of investees	(6,134)	3,448		(43,502)	(67,760)
Restructuring and relocation costs		(15)		460	(15)
Operating income	(11,889)	(8,983)		1,319	35,924
Interest income	0	0		0	0
Interest expense	(5,549)	(5,031)		(16,136)	(16,405)
Loss on debt extinguishment				0	(843)
Other income (expense), net	0	0		581	1,037
Income before income taxes	(17,438)	(14,014)		(14,236)	19,713
Income tax benefit (expense)	(518)	(3,800)		(10,487)	(4,050)
Net income (loss)	(17,956)	(17,814)		(24,723)	15,663
Reportable Legal Entities [Member] | Subsidiary Issuer [Member]
Net sales	217,299	200,307		651,515	587,278
Cost of sales	205,854	190,790		625,157	557,444
Selling, general and administrative	4,193	1,955		12,704	10,696
Depreciation	1,219	1,140		3,589	3,599
Amortization	0	0		0	0
Equity in earnings of investees	(9,576)	6,878		(61,741)	(85,792)
Restructuring and relocation costs		111		0	264
Operating income	15,609	13,189		71,806	101,067
Interest income	0	1		2	12
Interest expense	(9,162)	(9,743)		(27,568)	(27,563)
Loss on debt extinguishment				(521)	(5,432)
Other income (expense), net	(313)	1		(217)	(324)
Income before income taxes	6,134	3,448		43,502	67,760
Income tax benefit (expense)	792	(3,249)		(5,620)	(2,643)
Net income (loss)	6,926	199		37,882	65,117
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Net sales	299,667	302,625		911,465	939,662
Cost of sales	265,903	271,950		805,599	835,099
Selling, general and administrative	20,378	23,775		64,194	67,203
Depreciation	6,212	6,741		19,230	20,397
Amortization	2,335	2,336		7,006	7,007
Equity in earnings of investees	289	16		4,540	(43)
Restructuring and relocation costs		(100)		0	8
Operating income	4,550	(2,061)		10,896	9,991
Interest income	(1)	26		33	128
Interest expense	(724)	(576)		(2,291)	(701)
Loss on debt extinguishment				0	0
Other income (expense), net	602	85		235	250
Income before income taxes	4,427	(2,526)		8,873	9,668
Income tax benefit (expense)	(1,752)	1,289		(3,512)	(3,547)
Net income (loss)	2,675	(1,237)		5,361	6,121
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Net sales	463,861	447,080		1,504,218	1,470,619
Cost of sales	434,059	409,395		1,374,743	1,313,194
Selling, general and administrative	19,299	22,790		60,830	67,477
Depreciation	4,892	5,554		16,092	16,521
Amortization	7	6		19	18
Equity in earnings of investees	(105)	0		(437)	(72)
Restructuring and relocation costs		0		0	(3)
Operating income	5,709	9,335		52,971	73,484
Interest income	601	663		1,870	2,057
Interest expense	(129)	(6)		(336)	(29)
Loss on debt extinguishment				0	0
Other income (expense), net	(1,321)	(572)		(6,177)	655
Income before income taxes	4,860	9,420		48,328	76,167
Income tax benefit (expense)	(634)	(391)		(4,039)	267
Net income (loss)	4,226	9,029		44,289	76,434
Consolidation, Eliminations [Member]
Net sales	(242,276)	(226,950)		(740,810)	(688,074)
Cost of sales	(242,280)	(226,965)		(740,404)	(688,070)
Selling, general and administrative	0	0		0	0
Depreciation	0	0		0	0
Amortization	0	0		0	0
Equity in earnings of investees	15,421	(10,342)		100,703	153,595
Restructuring and relocation costs		0		0	0
Operating income	(15,417)	(10,327)		(101,109)	(153,599)
Interest income	0	0		0	0
Interest expense	0	0		0	0
Loss on debt extinguishment				0	0
Other income (expense), net	(4)	(15)		406	4
Income before income taxes	(15,421)	(10,342)		(100,703)	(153,595)
Income tax benefit (expense)	1,594	2,351		13,171	5,923
Net income (loss)	$ (13,827)	$ (7,991)		$ (87,532)	$ (147,672)