Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	$ (270,850)
Other comprehensive income (loss) before reclassifications	(14,239)
Amounts reclassified from accumulated other comprehensive income (loss)	4,039
Net current-period other comprehensive income (loss)	(10,200)
Total other comprehensive income (loss), net of tax	(10,200)	4,665
Balance at the end of the period	(281,050)
Pension and other post-retirement plans
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(266,042)
Amounts reclassified from accumulated other comprehensive income (loss)	4,659
Net current-period other comprehensive income (loss)	4,659
Total other comprehensive income (loss), net of tax	4,659
Balance at the end of the period	(261,383)
Unrealized gain/(loss) on hedges
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(4,203)
Other comprehensive income (loss) before reclassifications	1,338
Amounts reclassified from accumulated other comprehensive income (loss)	(616)
Net current-period other comprehensive income (loss)	722
Total other comprehensive income (loss), net of tax	722
Balance at the end of the period	(3,481)
Foreign currency translation adjustment
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(1,502)
Other comprehensive income (loss) before reclassifications	(15,625)
Net current-period other comprehensive income (loss)	(15,625)
Total other comprehensive income (loss), net of tax	(15,625)
Balance at the end of the period	(17,127)
Unrealized gain/(loss) on investments
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	897
Other comprehensive income (loss) before reclassifications	48
Amounts reclassified from accumulated other comprehensive income (loss)	(4)
Net current-period other comprehensive income (loss)	44
Total other comprehensive income (loss), net of tax	44
Balance at the end of the period	$ 941