Supplemental Consolidating Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net sales	$ 776,647	$ 825,847	$ 1,501,978	$ 1,587,837
Cost of sales	638,240	716,307	1,260,851	1,401,559
Selling, general and administrative	41,481	54,955	90,882	109,346
Transaction costs	11,661	2,753	59,640	8,672
Depreciation	12,951	13,089	28,886	26,588
Amortization	2,342	2,342	4,684	4,683
Equity in losses (earnings) of investees	(176)	(332)	(183)	(332)
Operating income (loss)	70,148	36,733	57,218	37,321
Interest Income, Other	638	641	1,302	1,305
Interest Expense	(9,381)	(15,299)	(18,566)	(30,767)
Gains (Losses) on Extinguishment of Debt	0	0	(36,212)	(521)
Other Nonoperating Income (Expense)	(953)	(242)	(1,555)	(4,136)
Interest Expense, Related Party	0		0
Income (loss) before income taxes	60,452	21,833	2,187	3,202
Income tax benefit (expense)	(864)	(3,997)	(7,225)	(9,969)
Net income (loss)	59,588	17,836	(5,038)	(6,767)
Reportable Legal Entities [Member] | Parent Company [Member]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Selling, general and administrative	1,550	7,580	4,557	15,488
Transaction costs	1,459	2,753	39,503	8,672
Depreciation	0	0	0	0
Amortization	0	0	0	0
Equity in losses (earnings) of investees	(45,780)		(49,268)	(37,368)
Operating income (loss)	42,771	27,130	5,208	13,208
Interest Income, Other	0	0	0	0
Interest Expense	(2,319)	(5,295)	(6,301)	(10,587)
Gains (Losses) on Extinguishment of Debt			(17,112)	0
Other Nonoperating Income (Expense)	0	(2)	0	581
Interest Expense, Related Party	20,000		20,392
Income (loss) before income taxes	60,452	21,833	2,187	3,202
Income tax benefit (expense)	(864)	(3,997)	(7,225)	(9,969)
Net income (loss)	59,588	17,836	(5,038)	(6,767)
Reportable Legal Entities [Member] | Subsidiary Issuer [Member]
Net sales	209,558	225,172	409,911	434,216
Cost of sales	223,889	217,303	435,837	419,303
Selling, general and administrative	7,323	4,724	12,626	8,511
Transaction costs	3,913	0	8,009	0
Depreciation	2,712	1,094	8,036	2,370
Amortization	0	0	0	0
Equity in losses (earnings) of investees	(100,420)		(154,388)	(52,165)
Operating income (loss)	72,141	46,651	99,791	56,197
Interest Income, Other	0	0	0	2
Interest Expense	(6,284)	(9,175)	(10,689)	(18,406)
Gains (Losses) on Extinguishment of Debt			(19,100)	(521)
Other Nonoperating Income (Expense)	0	(13)	0	96
Interest Expense, Related Party	(20,077)		(20,734)
Income (loss) before income taxes	45,780	37,463	49,268	37,368
Income tax benefit (expense)	(3,387)	(6,069)	(3,454)	(6,412)
Net income (loss)	42,393	31,394	45,814	30,956
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Net sales	311,234	318,525	606,250	611,798
Cost of sales	264,030	276,824	518,069	539,696
Selling, general and administrative	12,731	21,644	29,967	43,816
Transaction costs	5,833	0	10,453	0
Depreciation	5,578	6,819	11,257	13,018
Amortization	2,336	2,336	4,671	4,671
Equity in losses (earnings) of investees	105		104	4,251
Operating income (loss)	20,621	10,124	31,729	6,346
Interest Income, Other	0	1	0	34
Interest Expense	(673)	(683)	(1,349)	(1,567)
Gains (Losses) on Extinguishment of Debt			0	0
Other Nonoperating Income (Expense)	0	84	0	(367)
Interest Expense, Related Party	204		(61)
Income (loss) before income taxes	20,152	9,526	30,319	4,446
Income tax benefit (expense)	(7,645)	(3,728)	(12,069)	(1,760)
Net income (loss)	12,507	5,798	18,250	2,686
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Net sales	508,988	538,098	981,765	1,040,357
Cost of sales	403,342	478,105	802,568	940,684
Selling, general and administrative	20,128	21,007	43,834	41,531
Transaction costs	456	0	1,675	0
Depreciation	4,661	5,176	9,593	11,200
Amortization	6	6	13	12
Equity in losses (earnings) of investees	(176)		(183)	(332)
Operating income (loss)	80,571	34,136	124,265	47,262
Interest Income, Other	638	640	1,302	1,269
Interest Expense	(105)	(146)	(227)	(207)
Gains (Losses) on Extinguishment of Debt			0	0
Other Nonoperating Income (Expense)	(953)	(334)	(1,555)	(4,856)
Interest Expense, Related Party	12		180
Income (loss) before income taxes	80,163	34,296	123,965	43,468
Income tax benefit (expense)	(2,229)	(2,491)	(2,941)	(3,405)
Net income (loss)	77,934	31,805	121,024	40,063
Consolidation, Eliminations [Member]
Net sales	(253,133)	(255,948)	(495,948)	(498,534)
Cost of sales	(253,021)	(255,925)	(495,623)	(498,124)
Selling, general and administrative	(251)	0	(102)	0
Transaction costs	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
Equity in losses (earnings) of investees	146,095		203,552	85,282
Operating income (loss)	(145,956)	(81,308)	(203,775)	(85,692)
Interest Income, Other	0	0	0	0
Interest Expense	0	0	0	0
Gains (Losses) on Extinguishment of Debt			0	0
Other Nonoperating Income (Expense)	0	23	0	410
Interest Expense, Related Party	(139)		223
Income (loss) before income taxes	(146,095)	(81,285)	(203,552)	(85,282)
Income tax benefit (expense)	13,261	12,288	18,464	11,577
Net income (loss)	$ (132,834)	$ (68,997)	$ (185,088)	$ (73,705)