Income Taxes (Deferred Tax Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets
Accrued employee benefits and compensation	$ 9,168	$ 9,350
Postretirement benefit obligations	7,866	2,860
Tax loss and credit carryforwards	16,533	15,041
Reserves and accruals	7,092	6,908
Depreciation and amortization	17,862	21,496
Other	2,550us-gaap_DeferredTaxAssetsOther	3,772us-gaap_DeferredTaxAssetsOther
Total deferred tax assets	61,071us-gaap_DeferredTaxAssetsGross	59,427us-gaap_DeferredTaxAssetsGross
Less deferred tax asset valuation allowance	(7,691)	(7,302)
Total deferred tax assets, net of valuation allowance	53,380us-gaap_DeferredTaxAssetsNet	52,125us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities
Investment in joint ventures, net	0	0
Depreciation and amortization	14,303	15,839
Other	344us-gaap_DeferredTaxLiabilitiesOther	238us-gaap_DeferredTaxLiabilitiesOther
Total deferred tax liabilities	14,647us-gaap_DeferredIncomeTaxLiabilities	16,077us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax asset	$ 38,733us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 36,048us-gaap_DeferredTaxAssetsLiabilitiesNet

Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from employee compensation.

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Amount of deferred tax liability attributable to taxable temporary differences from investments in unconsolidated subsidiaries and investments in other affiliates which are not controlled nor consolidated.

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