Comprehensive Income (Reclassification Out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2014		Dec. 31, 2013	Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 51,766			$ 43,861		$ 164,943		$ 70,704
Tax impact	(9,773)			(8,461)		(45,996)		(22,981)
Net income	41,993		67,755	35,400		118,947		47,723
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	(11)	[1],[2]		(2)	[1],[2]	(33)	[1],[2]	(6)	[1],[2]
Actuarial gains/(losses)	(4,398)	[1],[2]		(10,798)	[1],[2]	(14,036)	[1],[2]	(30,942)	[1],[2]
Income before income taxes	(4,409)	[1],[2]		(51,109)	[1],[2]	(14,069)	[1],[2]	(71,257)	[1],[2]
Tax impact	1,675	[1],[2]		19,421	[1],[2]	5,346	[1],[2]	27,078	[1],[2]
Net income	(2,734)	[1]		(31,688)	[1]	(8,723)	[1]	(44,179)	[1]
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	890	[1],[2]		1,526	[1],[2]	2,670	[1],[2]	4,576	[1],[2]
Actuarial gains/(losses)	(449)	[1],[2]		(1,695)	[1],[2]	(1,893)	[1],[2]	(6,151)	[1],[2]
Income before income taxes	441	[1],[2]		(169)	[1],[2]	777	[1],[2]	(1,575)	[1],[2]
Tax impact	(168)	[1],[2]		64	[1],[2]	(295)	[1],[2]	598	[1],[2]
Net income	$ 273	[1]		$ (105)	[1]	$ 482	[1]	$ (977)	[1]

[1] Amounts in parentheses indicate losses.

[2] These accumulated other comprehensive loss components are included in the computation of net periodic pension and OPEB costs (see Note 15 - Retirement Plans for additional details).