Equity (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at end of period	$ (54,951)	$ (117,004)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	(117,004)	(120,057)	(84,757)
Translation adjustments	14,894	25,858	(10,154)
Amounts reclassified from Accumulated Other Comprehensive Income (Loss)	5,200
Revaluation of derivatives	(282)	538	(287)
Revaluation of derivatives, tax	108	39	173
Defined benefit plan liability adjustment, net of tax	35,938	(38,135)	(35,257)
Defined benefit plan liability adjustment, tax	20,594	14,598	18,380
Amounts reclassified from Accumulated Other Comprehensive Income (Loss)	16,703	14,792	10,398
Amounts reclassified from Accumulated Other Comprehensive Income (Loss), tax	9,570	5,662	5,421
Balance at end of period	(54,951)	(117,004)	(120,057)
Foreign Currency Translation Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	57,310	31,452	41,606
Translation adjustments	14,894	25,858	(10,154)
Amounts reclassified from Accumulated Other Comprehensive Income (Loss)	5,200
Balance at end of period	67,004	57,310	31,452
Revaluation of Derivatives
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	251	(287)
Revaluation of derivatives	(282)	538	(287)
Balance at end of period	(31)	251	(287)
Defined Benefit Plan Liability Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	(174,565)	(151,222)	(126,363)
Defined benefit plan liability adjustment, net of tax	35,938	(38,135)	(35,257)
Amounts reclassified from Accumulated Other Comprehensive Income (Loss)	16,703	14,792	10,398
Balance at end of period	$ (121,924)	$ (174,565)	$ (151,222)