Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	$ (162,258)
Other comprehensive income (loss) before reclassifications	3,467
Amounts reclassified from accumulated other comprehensive income (loss)	3,895
Total other comprehensive income (loss)	7,362	(10,200)
Balance at the end of the period	(154,896)
Pension and other postretirement plans
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(165,150)
Amounts reclassified from accumulated other comprehensive income (loss)	3,519
Total other comprehensive income (loss)	3,519
Balance at the end of the period	(161,631)
Unrealized gain/(loss) on hedges
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(1,679)
Other comprehensive income (loss) before reclassifications	1,303
Amounts reclassified from accumulated other comprehensive income (loss)	376
Total other comprehensive income (loss)	1,679
Foreign currency translation adjustment
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	4,571
Other comprehensive income (loss) before reclassifications	2,164
Total other comprehensive income (loss)	2,164
Balance at the end of the period	$ 6,735