Comprehensive Income (Reclassification Out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2013		Dec. 31, 2012	Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 43,861			$ 107,365		$ 70,704		$ 190,265
Tax impact	(8,461)			(35,739)		(22,981)		(66,150)
Net income	35,400		29,199	71,626		47,723		124,115
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	(2)	[1],[2]		50	[1],[2]	(6)	[1],[2]	150	[1],[2]
Actuarial gains/(losses)	(10,798)	[1],[2]		(6,845)	[1],[2]	(30,942)	[1],[2]	(22,418)	[1],[2]
Pension settlement costs	(40,309)	[1],[2]				(40,309)	[1],[2]
Income before income taxes	(51,109)	[1],[2]		(6,795)	[1],[2]	(71,257)	[1],[2]	(22,268)	[1],[2]
Tax impact	19,421	[1],[2]		2,582	[1],[2]	27,078	[1],[2]	8,462	[1],[2]
Net income	(31,688)	[1],[2]		(4,213)	[1],[2]	(44,179)	[1],[2]	(13,806)	[1],[2]
Reclassification out of Accumulated Other Comprehensive Income [Member] | Postretirement Costs [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	1,526	[1],[2]		2,545	[1],[2]	4,576	[1],[2]	7,551	[1],[2]
Actuarial gains/(losses)	(1,695)	[1],[2]		(1,831)	[1],[2]	(6,151)	[1],[2]	(5,653)	[1],[2]
Income before income taxes	(169)	[1],[2]		714	[1],[2]	(1,575)	[1],[2]	1,898	[1],[2]
Tax impact	64	[1],[2]		(271)	[1],[2]	598	[1],[2]	(721)	[1],[2]
Net income	$ (105)	[1],[2]		$ 443	[1],[2]	$ (977)	[1],[2]	$ 1,177	[1],[2]

[1] Amounts in parentheses indicate losses.

[2] These accumulated other comprehensive loss components are included in the computation of net periodic pension and postretirement benefit cost (see Note 16 - Retirement Plans for additional details).