Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (38,118)	$ 44,450	$ 108,698
Other comprehensive income (loss)
Foreign currency translation adjustment	(1,896)	(229)	145
Deferred gain on available for sale securities	442	729	265
Current period cash flow hedging activity, net of $838 tax benefit in 2014, $477 tax expense in 2013 and $2,471 tax expense in 2012	(1,518)	810	7,658
Reclassification of hedging activities into earnings, net of $489 tax benefit in 2014, $95 tax benefit in 2013 and $2,630 tax expense in 2012	898	152	(2,757)
Current period pension and postretirement plan adjustment, net of $3,292 tax benefit in 2014, $5,531 tax expense in 2013 and $1,553 tax benefit in 2012	(6,483)	8,022	(1,716)
Curtailment gain into earnings, net of $718 tax expense in 2013	0	(983)	0
Reclassification of pension and postretirement adjustments into earnings, net of $313 tax benefit in 2014, $740 tax benefit in 2013 and $2,056 tax benefit in 2012	627	1,101	5,885
Total other comprehensive income (loss)	(7,930)	9,602	9,480
Comprehensive income (loss)	$ (46,048)	$ 54,052	$ 118,178