Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (40,669)	$ 7,699	$ (3,624)	$ (1,524)	$ 21,984	$ (38,118)	$ 44,450
Other comprehensive income (loss)
Foreign currency translation adjustment					(2,756)	(1,896)	(229)
Deferred gain on available for sale securities, net of tax					17	442	729
Current period cash flow hedging activity, net of $357 tax benefit in 2015, $838 tax benefit in 2014 and $477 tax expense in 2013					(577)	(1,518)	810
Reclassification of hedging activities into earnings, net of $191 tax benefit in 2015, $489 tax benefit in 2014 and $95 tax benefit in 2013					409	898	152
Current period pension and postretirement plan adjustment, net of $1,222 tax benefit in 2015, $3,292 tax benefit in 2014 and $5,531 tax expense in 2013					(1,204)	(6,483)	8,022
Curtailment gain into earnings, net of $718 tax expense in 2013					0	0	(983)
Reclassification of pension and postretirement adjustments into earnings, net of $420 tax benefit in 2015, $313 tax benefit in 2014 and $740 tax benefit in 2013					856	627	1,101
Total other comprehensive income (loss)					(3,255)	(7,930)	9,602
Comprehensive income (loss)					$ 18,729	$ (46,048)	$ 54,052