CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 255,215	$ 37,630	$ 193,857
Other comprehensive income (loss)
Gains (losses) and reclassification adjustments for derivatives, net of tax	4,738	4,780	(20,254)
Pension and other postretirement adjustments, net of tax	21,788	(7,159)	(8,398)
Cumulative translation adjustment	13,572	14,445	(14,108)
Comprehensive income	$ 295,313	$ 49,696	$ 151,097