Foreign Currency Derivative Instruments (Details 1) (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 foreign currency gains and losses on underlying assets and liabilities
Net gains and losses on foreign currency forward contracts were partially offset on assets and liabilities	$ 1,976	$ (1,950)	$ 1,124	$ (1,966)
Cost of revenue [Member]
Schedule of foreign currency gains and losses on underlying assets and liabilities
Net gains and losses on foreign currency forward contracts were partially offset on assets and liabilities	(17)	138	(1)	223
Selling, general and administrative [Member]
Schedule of foreign currency gains and losses on underlying assets and liabilities
Net gains and losses on foreign currency forward contracts were partially offset on assets and liabilities	$ 1,993	$ (2,088)	$ 1,125	$ (2,189)