Accumulated Other Comprehensive Loss (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	$ (51,113)	$ (104,632)	$ (42,686)	$ (114,054)
Other comprehensive income (loss) before reclassifications, net of tax	7,672	(2,702)	2,001	6,720
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(637)	(382)	(3,393)	(382)
Total other comprehensive income (loss)	7,035	(3,084)	(1,392)	6,338
Ending balance	(44,078)	(107,716)	(44,078)	(107,716)
Gains (losses) on derivatives designated as hedging instruments | Interest rate derivative
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	471	766	1,096	0
Other comprehensive income (loss) before reclassifications, net of tax	39	(220)	(844)	409
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	121	135	379	272
Total other comprehensive income (loss)	160	(85)	(465)	681
Ending balance	631	681	631	681
Gains (losses) on derivatives designated as hedging instruments | Foreign currency derivatives
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	95	6,690	8,277	0
Other comprehensive income (loss) before reclassifications, net of tax	7,714	(2,482)	2,784	6,311
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(793)	(1,898)	(4,045)	(4,001)
Total other comprehensive income (loss)	6,921	(4,380)	(1,261)	2,310
Ending balance	7,016	2,310	7,016	2,310
Defined Benefit Pension Items
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	(51,714)	(112,088)	(52,059)	(114,054)
Other comprehensive income (loss) before reclassifications, net of tax	0	0	105	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	44	1,381	284	3,347
Total other comprehensive income (loss)	44	1,381	389	3,347
Ending balance	(51,670)	(110,707)	(51,670)	(110,707)
Short-term investments
Rollforward of Accumulated other comprehensive income (loss)
Beginning balance	35		0
Other comprehensive income (loss) before reclassifications, net of tax	(81)		(44)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(9)		(11)
Total other comprehensive income (loss)	(90)		(55)
Ending balance	$ (55)		$ (55)