Stockholders' Equity - Summary of Change in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ (24,603)	$ (36,031)	$ (28,089)
Unrealized gain (losses) arising during period	23,172	14,451	(27,918)
Amounts reclassified from accumulated comprehensive loss	204	3,601	15,274
Income tax (expense) benefit	(7,892)	(6,624)	4,702
Net other comprehensive income (loss)	15,484	11,428	(7,942)
Balance	(9,119)	(24,603)	(36,031)
Minimum Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(24,603)	(36,031)	(20,082)
Unrealized gain (losses) arising during period	23,172	14,451	(26,938)
Amounts reclassified from accumulated comprehensive loss	204	3,601	1,841
Income tax (expense) benefit	(7,892)	(6,624)	9,148
Net other comprehensive income (loss)	15,484	11,428	(15,949)
Balance	(9,119)	(24,603)	(36,031)
Natural Gas Swaps [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(146)
Unrealized gain (losses) arising during period			(533)
Amounts reclassified from accumulated comprehensive loss			759
Income tax (expense) benefit			(80)
Net other comprehensive income (loss)			146
Balance
Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			(7,861)
Unrealized gain (losses) arising during period			(447)
Amounts reclassified from accumulated comprehensive loss			12,674
Income tax (expense) benefit			(4,366)
Net other comprehensive income (loss)			7,861
Balance