Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 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			(14,569)
Amounts reclassified from accumulated other comprehensive income (loss)			8,091
Total other comprehensive income (loss), net of tax	3,722	(1,299)	(6,478)	3,366
Balance at the end of the period	(277,328)		(277,328)
Pension and other postretirement 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)			9,317
Total other comprehensive income (loss), net of tax			9,317
Balance at the end of the period	(256,725)		(256,725)
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			2,478
Amounts reclassified from accumulated other comprehensive income (loss)			(1,230)
Total other comprehensive income (loss), net of tax			1,248
Balance at the end of the period	(2,955)		(2,955)
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			(17,086)
Total other comprehensive income (loss), net of tax			(17,086)
Balance at the end of the period	(18,588)		(18,588)
Unrealized gain 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			39
Amounts reclassified from accumulated other comprehensive income (loss)			4
Total other comprehensive income (loss), net of tax			43
Balance at the end of the period	$ 940		$ 940