Foreign Currency Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Schedule of gains (losses) on foreign currency forward contracts
Net gains (losses) on foreign currency forward contracts	$ (1,984)	$ 1,836	$ (1,232)	$ 1,777
Cost of revenue [Member]
Schedule of gains (losses) on foreign currency forward contracts
Net gains (losses) on foreign currency forward contracts		(122)		(238)
Selling, general and administrative [Member]
Schedule of gains (losses) on foreign currency forward contracts
Net gains (losses) on foreign currency forward contracts	$ (1,984)	$ 1,958	$ (1,232)	$ 2,015