SUPPLEMENTAL CONSOLIDATING FINANCIAL INFORMATION - Supplemental Consolidating Statement of Operations Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 337,830	$ 176,792	$ 805,989	$ 500,739
Costs, expenses and other:
Cost of sales	285,524	138,193	670,467	399,142
Depreciation, depletion and amortization	28,175	17,434	68,713	47,257
Selling and administrative	24,434	12,498	68,551	36,354
Heritage health benefit expenses	3,315	4,057	10,246	11,117
Loss on sales of assets	119	(13)	114	(321)
Restructuring charges	3,265	0	11,207	0
Derivative loss	23,691	0	29,621	0
Income from equity affiliates	(1,261)	0	(2,060)	0
Other operating loss (income)	0	(3,913)	151	(19,055)
Total costs, expenses and other	367,262	168,256	857,010	474,494
Operating income (loss)	(29,432)	8,536	(51,021)	26,245
Other income (expense):
Interest expense	(21,251)	(9,909)	(63,835)	(30,145)
Loss on extinguishment of debt	(13)	0	(12,648)	(64)
Interest income	2,468	301	4,351	878
Loss on foreign exchange	(1,742)	0	(5,883)	0
Other income	118	89	697	287
Total other income (expense)	(20,420)	(9,519)	(77,318)	(29,044)
Income (loss) before income taxes and income of consolidated subsidiaries	(49,852)	(983)	(128,339)	(2,799)
Equity in income of subsidiaries	0	0	0	0
Loss before income taxes	(49,852)	(983)	(128,339)	(2,799)
Income tax expense (benefit)	(718)	30	2,979	85
Net loss	(49,134)	(1,013)	(131,318)	(2,884)
Less net loss attributable to noncontrolling interest	0	(3,774)	0	(2,976)
Net income (loss) attributable to the Parent company	(49,134)	2,761	(131,318)	92
Parent/ Issuer
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0	0	0
Costs, expenses and other:
Cost of sales	(1,037)	(371)	(1,508)	(1,141)
Depreciation, depletion and amortization	70	93	225	280
Selling and administrative	5,124	4,191	22,092	12,399
Heritage health benefit expenses	3,099	3,789	9,602	10,322
Loss on sales of assets	0	0	0	0
Restructuring charges	663		1,460
Derivative loss	0		0
Income from equity affiliates	0		0
Other operating loss (income)		0	0	0
Total costs, expenses and other	7,919	7,702	31,871	21,860
Operating income (loss)	(7,919)	(7,702)	(31,871)	(21,860)
Other income (expense):
Interest expense	(18,302)	(7,622)	(55,584)	(22,797)
Loss on extinguishment of debt	0	0	(64)	(64)
Interest income	7,891	29	8,160	105
Loss on foreign exchange	(148)		(5,382)
Other income	5	0	7	0
Total other income (expense)	(10,554)	(7,593)	(52,863)	(22,756)
Income (loss) before income taxes and income of consolidated subsidiaries	(18,473)	(15,295)	(84,734)	(44,616)
Equity in income of subsidiaries	(31,128)	14,281	(47,274)	41,732
Loss before income taxes	(49,601)	(1,014)	(132,008)	(2,884)
Income tax expense (benefit)	(467)	(1)	(690)	0
Net loss	(49,134)	(1,013)	(131,318)	(2,884)
Less net loss attributable to noncontrolling interest	0	(3,774)		(2,976)
Net income (loss) attributable to the Parent company	(49,134)	2,761	(131,318)	92
Co-Issuer
Condensed Financial Statements, Captions [Line Items]
Revenues	21,439	24,911	65,254	67,409
Costs, expenses and other:
Cost of sales	20,799	16,366	58,845	48,221
Depreciation, depletion and amortization	2,503	2,551	7,513	7,632
Selling and administrative	899	907	2,961	2,633
Heritage health benefit expenses	0	0	0	0
Loss on sales of assets	0	0	0	0
Restructuring charges	(39)		459
Derivative loss	23,691		29,621
Income from equity affiliates	0		0
Other operating loss (income)		0	0	0
Total costs, expenses and other	47,853	19,824	99,399	58,486
Operating income (loss)	(26,414)	5,087	(34,145)	8,923
Other income (expense):
Interest expense	(102)	(10)	(220)	(30)
Loss on extinguishment of debt	0	0	0	0
Interest income	1	5	8	20
Loss on foreign exchange	0		0
Other income	0	0	0	0
Total other income (expense)	(101)	(5)	(212)	(10)
Income (loss) before income taxes and income of consolidated subsidiaries	(26,515)	5,082	(34,357)	8,913
Equity in income of subsidiaries	0	0	0	0
Loss before income taxes	(26,515)	5,082	(34,357)	8,913
Income tax expense (benefit)	0	0	0	0
Net loss	(26,515)	5,082	(34,357)	8,913
Less net loss attributable to noncontrolling interest	0	0		0
Net income (loss) attributable to the Parent company	(26,515)	5,082	(34,357)	8,913
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenues	316,391	149,079	740,742	423,266
Costs, expenses and other:
Cost of sales	265,762	115,587	613,075	339,004
Depreciation, depletion and amortization	25,602	14,791	60,975	39,345
Selling and administrative	18,834	7,867	44,694	22,547
Heritage health benefit expenses	0	0	0	0
Loss on sales of assets	119	(13)	114	(321)
Restructuring charges	2,641		9,288
Derivative loss	0		0
Income from equity affiliates	(1,261)		(2,060)
Other operating loss (income)		(3,913)	150	(19,054)
Total costs, expenses and other	311,697	134,319	726,236	381,521
Operating income (loss)	4,694	14,760	14,506	41,745
Other income (expense):
Interest expense	(10,614)	(2,281)	(15,813)	(7,329)
Loss on extinguishment of debt	(13)	0	(12,584)	0
Interest income	2,343	267	3,941	760
Loss on foreign exchange	(1,594)		(501)
Other income	113	89	691	289
Total other income (expense)	(9,765)	(1,925)	(24,266)	(6,280)
Income (loss) before income taxes and income of consolidated subsidiaries	(5,071)	12,835	(9,760)	35,465
Equity in income of subsidiaries	0	0	0	0
Loss before income taxes	(5,071)	12,835	(9,760)	35,465
Income tax expense (benefit)	3,362	1,742	2,244	6,200
Net loss	(8,433)	11,093	(12,004)	29,265
Less net loss attributable to noncontrolling interest	0	0		0
Net income (loss) attributable to the Parent company	(8,433)	11,093	(12,004)	29,265
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenues	0	17,149	(7)	38,037
Costs, expenses and other:
Cost of sales	0	20,958	55	41,031
Depreciation, depletion and amortization	0	0	0	0
Selling and administrative	(423)	(467)	(1,196)	(1,225)
Heritage health benefit expenses	216	268	644	795
Loss on sales of assets	0	0	0	0
Restructuring charges	0		0
Derivative loss	0		0
Income from equity affiliates	0		0
Other operating loss (income)		0	1	(1)
Total costs, expenses and other	(207)	20,759	(496)	40,600
Operating income (loss)	207	(3,610)	489	(2,563)
Other income (expense):
Interest expense	0	(2)	0	(12)
Loss on extinguishment of debt	0	0	0	0
Interest income	0	6	24	16
Loss on foreign exchange	0		0
Other income	0	0	(1)	(2)
Total other income (expense)	0	4	23	2
Income (loss) before income taxes and income of consolidated subsidiaries	207	(3,606)	512	(2,561)
Equity in income of subsidiaries	0	0	0	0
Loss before income taxes	207	(3,606)	512	(2,561)
Income tax expense (benefit)	1	1	0	0
Net loss	206	(3,607)	512	(2,561)
Less net loss attributable to noncontrolling interest	0	0		0
Net income (loss) attributable to the Parent company	206	(3,607)	512	(2,561)
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Revenues	0	(14,347)	0	(27,973)
Costs, expenses and other:
Cost of sales	0	(14,347)	0	(27,973)
Depreciation, depletion and amortization	0	(1)	0	0
Selling and administrative	0	0	0	0
Heritage health benefit expenses	0	0	0	0
Loss on sales of assets	0	0	0	0
Restructuring charges	0		0
Derivative loss	0		0
Income from equity affiliates	0		0
Other operating loss (income)		0	0	0
Total costs, expenses and other	0	(14,348)	0	(27,973)
Operating income (loss)	0	1	0	0
Other income (expense):
Interest expense	7,767	6	7,782	23
Loss on extinguishment of debt	0	0	0	0
Interest income	(7,767)	(6)	(7,782)	(23)
Loss on foreign exchange	0		0
Other income	0	0	0	0
Total other income (expense)	0	0	0	0
Income (loss) before income taxes and income of consolidated subsidiaries	0	1	0	0
Equity in income of subsidiaries	31,128	(14,281)	47,274	(41,732)
Loss before income taxes	31,128	(14,280)	47,274	(41,732)
Income tax expense (benefit)	(3,614)	(1,712)	1,425	(6,115)
Net loss	34,742	(12,568)	45,849	(35,617)
Less net loss attributable to noncontrolling interest	0	0		0
Net income (loss) attributable to the Parent company	$ 34,742	$ (12,568)	$ 45,849	$ (35,617)