Derivative Instruments (Details 1) (Foreign exchange forward contracts [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Effect of derivative instruments in cash flow hedging transactions on income and other comprehensive income
Gains (Losses) on Derivatives Recognized in OCI	$ (478)	$ 395	$ 45	$ 679
Operating expenses [Member]
Effect of derivative instruments in cash flow hedging transactions on income and other comprehensive income
Gains (Losses) Reclassified from OCI into Income	$ (126)	$ 341	$ (165)	$ 613