Equity (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at end of period	$ (117,004)	$ (120,057)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	(120,057)	(84,757)	(100,090)
Translation adjustments	25,858	(10,154)	17,465
Revaluation of derivatives	538	(287)	2,363
Revaluation of derivatives, tax	39	173	1,486
Defined benefit plan liability adjustment, net of tax	(23,343)	(24,859)	(4,495)
Defined benefit plan liability adjustment, tax	8,936	12,959	2,639
Balance at end of period	(117,004)	(120,057)	(84,757)
Foreign Currency Translation Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	31,452	41,606	24,141
Translation adjustments	25,858	(10,154)	17,465
Balance at end of period	57,310	31,452	41,606
Revaluation of Derivatives
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	(287)		(2,363)
Revaluation of derivatives	538	(287)	2,363
Balance at end of period	251	(287)
Defined Benefit Plan Liability Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period	(151,222)	(126,363)	(121,868)
Defined benefit plan liability adjustment, net of tax	(23,343)	(24,859)	(4,495)
Balance at end of period	$ (174,565)	$ (151,222)	$ (126,363)