Accumulated Other Comprehensive Loss (Schedule of Items Reclassified to Statement of Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Effect on net income due to items reclassified from Accumulated Other Comprehensive Income	$ (11,511)	$ (47,041)
Pension and Postretirement Liability Adjustments [Member] | Amortization of Prior Service Cost/(Credit) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Expense/(income)	(908)
Pension and Postretirement Liability Adjustments [Member] | Amortization of Transition Obligation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Expense/(income)	17
Pension and Postretirement Liability Adjustments [Member] | Amortization of Net Actuarial Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Expense/(income)	1,664
Pension and Postretirement Liability Adjustments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Expense/(income)	773
Income tax effect	(270)
Effect on net income due to items reclassified from Accumulated Other Comprehensive Income	$ 503