Summary of Operations and Significant Accounting Policies (Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Comprehensive Income Loss [Abstract]
Accumulated other comprehensive loss	$ (35,762)	$ (45,080)	$ (48,000)
Total Comprehensive Income (Loss) summary
Net Income	53,507	80,264	9,848
Translation adjustments	(690)	(1,519)	7,963
Unrealized gain (loss) on defined benefit plan, net of tax	10,008	4,750	(12,346)
Foreign currency gain on forward contracts, net of tax			4,511
Total comprehensive income	62,825	83,495	9,976
Less: NET INCOME attributable to noncontrolling interest	(2,770)	(3,531)	(2,335)
Total comprehensive income attributable to common stockholders	60,055	79,964	7,641
Accumulated Comprehensive Income Translation Adjustmentax	(29,919)	(29,230)
Accumulated Comprehensive Income Defined Benefit Plan	$ (5,843)	$ (15,850)