Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (1,187)us-gaap_NetIncomeLoss	$ 12,437us-gaap_NetIncomeLoss	$ 8,355us-gaap_NetIncomeLoss
Adjustments for changes in:
Foreign exchange translation	(4,703)	1,820	3,193
Unrecognized employee benefit costs (including effects of foreign currency translation)	(21,392)	28,678	(10,520)
Unrealized holding gains on marketable securities	88	431	149
Fair value of cash flow hedges	(323)	(251)	102
Reclassification adjustments for items included in net income:
Amortization of unrecognized employee benefit costs	3,458	5,643	3,962
Realized gains from sale of marketable securities	(111)	(57)	(78)
Realized (gains) losses from settlement of cash flow hedges	95	246	107
Other comprehensive (loss) income	(22,888)	36,510	(3,085)
Comprehensive (loss) income	$ (24,075)us-gaap_ComprehensiveIncomeNetOfTax	$ 48,947us-gaap_ComprehensiveIncomeNetOfTax	$ 5,270us-gaap_ComprehensiveIncomeNetOfTax

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