SUPPLEMENTAL CONSOLIDATING FINANCIAL INFORMATION - Supplemental Consolidating Statement of Operations Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 173,947	$ 176,792	$ 162,499	$ 161,448	$ 159,027	$ 161,332	$ 132,842	$ 147,236	$ 674,686	$ 600,437	$ 501,713
Costs, expenses and other:
Cost of sales									535,320	466,521	392,787
Depreciation, depletion and amortization									67,231	57,145	45,594
Selling and administrative									50,721	49,908	40,276
Heritage health benefit expenses									13,418	13,388	18,575
Loss (gain) on sales of assets									(74)	528	640
Restructuring charges									5,078	0	0
Other operating income									(22,370)	(15,925)	(6,785)
Total costs, expenses and other									649,324	571,565	491,087
Operating income (loss)	(883)	8,536	11,975	5,734	8,597	15,451	(4,262)	9,086	25,362	28,872	10,626
Other income (expense):
Interest expense									(39,937)	(42,677)	(29,769)
Loss on extinguishment of debt									(64)	(1,986)	(17,030)
Interest income									1,366	1,496	1,444
Other income (loss)									364	723	(2,572)
Total other income (expense)									(38,271)	(42,444)	(47,927)
Income (loss) before income taxes and income of consolidated subsidiaries									(12,909)	(13,572)	(37,301)
Equity in income of subsidiaries									0	0	0
Loss before income taxes									(12,909)	(13,572)	(37,301)
Income tax expense (benefit)									(4,782)	90	(426)
Net income (loss)									(8,127)	(13,662)	(36,875)
Less net loss attributable to noncontrolling interest									(3,430)	(6,436)	(3,775)
Net income (loss) attributable to the Parent company									(4,697)	(7,226)	(33,100)
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									0	0	0
Costs, expenses and other:
Cost of sales									0	0	0
Depreciation, depletion and amortization									354	421	306
Selling and administrative									12,339	13,748	10,616
Heritage health benefit expenses									12,361	12,406	17,754
Loss (gain) on sales of assets									0	13	3
Restructuring charges									0
Other operating income									0	0	0
Total costs, expenses and other									25,054	26,588	28,679
Operating income (loss)									(25,054)	(26,588)	(28,679)
Other income (expense):
Interest expense									(30,417)	(31,301)	(16,365)
Loss on extinguishment of debt									(64)	(1,986)	(7,873)
Interest income									165	253	266
Other income (loss)									1	190	(3,014)
Total other income (expense)									(30,315)	(32,844)	(26,986)
Income (loss) before income taxes and income of consolidated subsidiaries									(55,369)	(59,432)	(55,665)
Equity in income of subsidiaries									42,347	45,762	18,508
Loss before income taxes									(13,022)	(13,670)	(37,157)
Income tax expense (benefit)									(4,895)	(8)	(282)
Net income (loss)									(8,127)	(13,662)	(36,875)
Less net loss attributable to noncontrolling interest									(3,430)	(6,436)	(3,775)
Net income (loss) attributable to the Parent company									(4,697)	(7,226)	(33,100)
Co-Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									87,567	81,285	86,785
Costs, expenses and other:
Cost of sales									63,794	59,299	60,243
Depreciation, depletion and amortization									10,178	10,085	10,175
Selling and administrative									3,609	3,657	4,059
Heritage health benefit expenses									0	0	0
Loss (gain) on sales of assets									0	0	189
Restructuring charges									5,078
Other operating income									0	0	0
Total costs, expenses and other									82,659	73,041	74,666
Operating income (loss)									4,908	8,244	12,119
Other income (expense):
Interest expense									(39)	(39)	(469)
Loss on extinguishment of debt									0	0	(9,073)
Interest income									26	15	14
Other income (loss)									0	0	0
Total other income (expense)									(13)	(24)	(9,528)
Income (loss) before income taxes and income of consolidated subsidiaries									4,895	8,220	2,591
Equity in income of subsidiaries									0	0	0
Loss before income taxes									4,895	8,220	2,591
Income tax expense (benefit)									680	107	(2,498)
Net income (loss)									4,215	8,113	5,089
Less net loss attributable to noncontrolling interest									0	0	0
Net income (loss) attributable to the Parent company									4,215	8,113	5,089
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									214,481	184,506	58,544
Costs, expenses and other:
Cost of sales									174,204	134,683	49,439
Depreciation, depletion and amortization									27,452	19,571	7,936
Selling and administrative									11,092	9,993	4,566
Heritage health benefit expenses									0	0	0
Loss (gain) on sales of assets									115	251	59
Restructuring charges									0
Other operating income									(22,367)	(17,452)	(7,258)
Total costs, expenses and other									190,496	147,046	54,742
Operating income (loss)									23,985	37,460	3,802
Other income (expense):
Interest expense									(295)	(378)	(657)
Loss on extinguishment of debt									0	0	(84)
Interest income									522	294	206
Other income (loss)									328	395	170
Total other income (expense)									555	311	(365)
Income (loss) before income taxes and income of consolidated subsidiaries									24,540	37,771	3,437
Equity in income of subsidiaries									0	0	0
Loss before income taxes									24,540	37,771	3,437
Income tax expense (benefit)									8,461	0	(26)
Net income (loss)									16,079	37,771	3,463
Less net loss attributable to noncontrolling interest									0	0	0
Net income (loss) attributable to the Parent company									16,079	37,771	3,463
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									414,085	366,105	411,908
Costs, expenses and other:
Cost of sales									338,769	303,998	338,629
Depreciation, depletion and amortization									29,247	27,068	27,177
Selling and administrative									23,681	24,037	21,508
Heritage health benefit expenses									1,057	982	821
Loss (gain) on sales of assets									(189)	264	389
Restructuring charges									0
Other operating income									(3)	0	0
Total costs, expenses and other									392,562	356,349	388,524
Operating income (loss)									21,523	9,756	23,384
Other income (expense):
Interest expense									(9,221)	(11,039)	(12,370)
Loss on extinguishment of debt									0	0	0
Interest income									688	1,014	1,050
Other income (loss)									35	138	272
Total other income (expense)									(8,498)	(9,887)	(11,048)
Income (loss) before income taxes and income of consolidated subsidiaries									13,025	(131)	12,336
Equity in income of subsidiaries									0	0	0
Loss before income taxes									13,025	(131)	12,336
Income tax expense (benefit)									(47)	4,410	7,263
Net income (loss)									13,072	(4,541)	5,073
Less net loss attributable to noncontrolling interest									0	0	0
Net income (loss) attributable to the Parent company									13,072	(4,541)	5,073
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									(41,447)	(31,459)	(55,524)
Costs, expenses and other:
Cost of sales									(41,447)	(31,459)	(55,524)
Depreciation, depletion and amortization									0	0	0
Selling and administrative									0	(1,527)	(473)
Heritage health benefit expenses									0	0	0
Loss (gain) on sales of assets									0	0	0
Restructuring charges									0
Other operating income									0	1,527	473
Total costs, expenses and other									(41,447)	(31,459)	(55,524)
Operating income (loss)									0	0	0
Other income (expense):
Interest expense									35	80	92
Loss on extinguishment of debt									0	0	0
Interest income									(35)	(80)	(92)
Other income (loss)									0	0	0
Total other income (expense)									0	0	0
Income (loss) before income taxes and income of consolidated subsidiaries									0	0	0
Equity in income of subsidiaries									(42,347)	(45,762)	(18,508)
Loss before income taxes									(42,347)	(45,762)	(18,508)
Income tax expense (benefit)									(8,981)	(4,419)	(4,883)
Net income (loss)									(33,366)	(41,343)	(13,625)
Less net loss attributable to noncontrolling interest									0	0	0
Net income (loss) attributable to the Parent company									$ (33,366)	$ (41,343)	$ (13,625)