Equity (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive loss, net of tax, at the end of the period	$ (120,057)	$ (84,757)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive loss, net of tax, at the beginning of the period	(84,757)	(100,090)	(140,591)
Translation adjustments	(10,154)	17,465	23,793
Revaluation of derivatives	(287)	2,363	13,354
Revaluation of derivatives, tax	173	1,486	7,843
Defined benefit plan liability adjustment, net of tax	(24,859)	(4,495)	3,354
Defined benefit plan liability adjustment, tax	12,959	2,639	1,970
Accumulated other comprehensive loss, net of tax, at the end of the period	(120,057)	(84,757)	(100,090)
Foreign Currency Translation Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive loss, net of tax, at the beginning of the period	41,606	24,141	348
Translation adjustments	(10,154)	17,465	23,793
Accumulated other comprehensive loss, net of tax, at the end of the period	31,452	41,606	24,141
Revaluation of Derivatives
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive loss, net of tax, at the beginning of the period		(2,363)	(15,717)
Revaluation of derivatives	(287)	2,363	13,354
Accumulated other comprehensive loss, net of tax, at the end of the period	(287)		(2,363)
Defined Benefit Plan Liability Adjustment
Increase (Decrease) In Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive loss, net of tax, at the beginning of the period	(126,363)	(121,868)	(125,222)
Defined benefit plan liability adjustment, net of tax	(24,859)	(4,495)	3,354
Accumulated other comprehensive loss, net of tax, at the end of the period	$ (151,222)	$ (126,363)	$ (121,868)