Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 48,061us-gaap_NetIncomeLoss	$ 18,288us-gaap_NetIncomeLoss	$ 28,129us-gaap_NetIncomeLoss
Other comprehensive (loss) income:
Adjustment to pension liability	(17,053)	16,001	(6,176)
Income tax (benefit) expense	(6,650)	6,240	(2,408)
Other comprehensive (loss) income	(10,403)	9,761	(3,768)
Comprehensive income	$ 37,658us-gaap_ComprehensiveIncomeNetOfTax	$ 28,049us-gaap_ComprehensiveIncomeNetOfTax	$ 24,361us-gaap_ComprehensiveIncomeNetOfTax

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount before tax, after reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity.

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