Foreign Currency Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of gains (losses) on foreign currency forward contracts
Net gains (loss) on foreign currency forward contracts	$ 1,636	$ (405)	$ 2,399	$ (339)