Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 30,960	$ (39,800)	$ (33,400)
Other comprehensive income
Defined pension and postretirement pension plans	1,670	250	1,810
Foreign currency translation	6,050	(12,620)	(12,370)
Derivative instruments	(650)	(730)	(2,650)
Other Comprehensive Income (Loss)	7,070	(13,100)	(13,210)
Total comprehensive income (loss)	$ 38,030	$ (52,900)	$ (46,610)