Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,819	$ (2,048)
Other comprehensive income:
Foreign currency translation adjustments	4,058	4,258
Retirement plans related adjustments	61	276
Unrealized gain on cash flow hedges	422	231
Other comprehensive income before tax	4,541	4,765
Income tax expense	35	419
Other comprehensive income, net of tax	4,506	4,346
Total comprehensive income	$ 6,325	$ 2,298