Unaudited Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (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]
Tax expense on current period cash flow hedging activity	$ (88)	$ 2,334	$ 344	$ 2,350
Tax expense (benefit) on reclassification of hedging activities into earnings	24	305	(146)	2,598
Tax expense on current pension and postretirement plan adjustment	3,497	0	3,497	0
Tax expense on current period curtailment gain	578	0	578	0
Tax benefit on reclassification of pension and postretirement into earnings	$ (109)	$ (491)	$ (517)	$ (1,605)