Comprehensive Income (Reclassification Out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 162,720		$ 228,952		$ 245,951
Tax impact	(47,242)		(75,638)		(88,343)
Net income	115,478		153,314		157,608
Pension Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	(8)		199
Actuarial gains/(losses)	36,930		29,890
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	(8)	[1]	199	[1]	199	[1]
Actuarial gains/(losses)	(36,930)	[1]	(29,890)	[1]	(15,364)	[1]
Pension settlement costs	(44,163)	[1]
Income before income taxes	(81,101)	[1]	(29,691)	[1]	(15,165)	[1]
Tax impact	30,818	[1]	11,282	[1]	5,763	[1]
Net income	(50,283)	[1]	(18,409)	[1]	(9,402)	[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	6,101	[1]	10,068	[1]	10,198	[1]
Actuarial gains/(losses)	(7,846)	[1]	(7,537)	[1]	(4,424)	[1]
Income before income taxes	(1,745)	[1]	2,531	[1]	5,774	[1]
Tax impact	663	[1]	(962)	[1]	(2,194)	[1]
Net income	$ (1,082)	[1]	$ 1,569	[1]	$ 3,580	[1]

[1] Amounts in parentheses indicate losses.