Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 5,846	$ 1,224	$ 2,610
Other comprehensive income (loss):
Foreign currency translation adjustments	9,660	(4,811)	(4,598)
Retirement plans related adjustments	7,720	(899)	(5,945)
Unrealized (loss) gain on cash flow hedges	(456)	138	0
Other comprehensive income (loss) before tax	16,924	(5,572)	(10,543)
Income tax expense (benefit)	494	371	(631)
Other comprehensive income (loss), net of tax	16,430	(5,943)	(9,912)
Total comprehensive income (loss)	$ 22,276	$ (4,719)	$ (7,302)