Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ (93,368)	$ 10,073	$ 66,333
Other comprehensive income (loss):
Pension and other post-retirement benefit adjustments, net of tax	7,514	(1,395)	33,201
Change in fair value of derivative instruments, net of tax	866	1,345	(1,235)
Foreign currency translation adjustments, net of tax	11,645	(4,915)	(13,751)
Other comprehensive income (loss), net of tax	20,025	(4,965)	18,215
Comprehensive income (loss)	$ (73,343)	$ 5,108	$ 84,548