CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
Net income	$ 41,204	$ 27,989	$ 65,669
Other comprehensive income, before tax
Foreign currency translation adjustments	5,224	(5,624)	(10,616)
Unrealized gain/(loss) on derivatives
Unrealized derivative gains/(losses) arising during period	(2,062)	(6,306)	2,486
Less: Reclassification adjustments for gains/(losses) included in net income	(2,210)	(2,269)	2,782
Unrealized gain/(loss) on derivatives	148	(4,037)	(296)
Defined benefit pension plan
Net gain/(loss) arising during period	(1,313)	861	329
Defined benefit pension plan	(1,313)	861	329
Total other comprehensive income (loss), before tax	4,059	(8,800)	(10,583)
Income tax (expense) benefit related to items in other comprehensive income	237	1,502	(117)
Total other comprehensive income (loss), net of tax	4,296	(7,298)	(10,700)
Comprehensive income, net of tax	$ 45,500	$ 20,691	$ 54,969