Foreign Currencies, Foreign Currency Translation and Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Functional Currencies Foreign Currency Translation And Comprehensive Income Loss [Abstract]
Foreign exchange transaction gains/(losses)	$ 1,000,000	$ 0	$ 2,000,000	$ (1,000,000)
Total Comprehensive Income (Loss)
Net income	10,707,000	22,069,000	49,694,000	55,299,000
Translation adjustment	(6,852,000)	7,361,000	(621,000)	(3,552,000)
Unrealized gain/(loss) on defined benefit plan, net of tax	(3,783,000)	1,802,000	1,347,000	(4,068,000)
Comprehensive income	72,000	31,232,000	50,420,000	47,679,000
Less: Comprehensive income attributable to noncontrolling interest	750,000	907,000	2,072,000	2,532,000
Total comprehensive income (loss) attributable to common stockholders	$ (678,000)	$ 30,325,000	$ 48,348,000	$ 45,147,000