Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Foreign currency exchange forwards	Jun. 30, 2012 Foreign currency exchange forwards	Jun. 30, 2013 Foreign currency exchange forwards	Jun. 30, 2012 Foreign currency exchange forwards	Jun. 30, 2013 Not Designated as Hedges	Dec. 31, 2012 Not Designated as Hedges	Jun. 30, 2013 Not Designated as Hedges Foreign currency exchange forwards	Dec. 31, 2012 Not Designated as Hedges Foreign currency exchange forwards
Derivative financial instruments
Notional amount of derivative instruments									$ 3,300	$ 9,590	$ 3,300	$ 9,590
Fair value of derivative instruments									32	244	32	244
Amount of Realized and Unrealized Net Gain and Changes in the Fair value of Forward Contracts					(71)	(158)	157	(78)
Weighted average notional amount of derivatives outstanding	$ 1,360	$ 2,560	$ 1,994	$ 2,501