Unaudited Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 12,325	$ 38,104	$ 21,894	$ 85,066
Foreign currency translation adjustment	130	6,450	358	575
Current period cash flow hedging activity, net of $88 tax benefit and $344 tax expense in the three and nine months ended September 30, 2013, respectively, and $2,334 and $2,350 tax expense in the three and nine months ended September 30, 2012, respectively.	(124)	5,209	573	7,483
Reclassification of hedging activities into earnings, net of $24 tax expense and $146 tax benefit in the three and nine months ended September 30, 2013, respectively, and $305 and $2,598 tax expense in the three and nine months ended September 30, 2012, respectively.	(38)	(2,586)	235	(2,808)
Current period pension and postretirement plan adjustment, net of $3,497 tax expense in both the three and nine months ended September 30, 2013, respectively.	3,652	0	3,652	0
Current period curtailment gain into earnings, net of $578 tax expense in both the three and nine months ended September 30, 2013, respectively.	(1,123)	0	(1,123)	0
Reclassification of pension and postretirement adjustments into earnings, net of $109 and $517 tax benefit in the three and nine months ended September 30, 2013, respectively, and $491 and $1,605 tax benefit in the three and nine months ended September 30, 2012, respectively.	254	1,926	1,059	5,823
Comprehensive income	$ 15,076	$ 49,103	$ 26,648	$ 96,139