Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net Income (loss)	$ 806	$ (34,638)	$ 6,510
Foreign currency adjustment	2,481	(758)	(1,875)
Change in pension loss, net of taxes of $308, $71, and $327, in 2017, 2016 and 2015, respectively	606	(1,365)	2,828
Other comprehensive income (loss)	3,087	(2,123)	953
Comprehensive income (loss)	$ 3,893	$ (36,761)	$ 7,463