Foreign Currency Derivative Instruments (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of foreign currency gains and losses on underlying assets and liabilities
Net gains (loss) on foreign currency forward contracts were partially offset on assets and liabilities	$ 254	$ 2,721	$ (2,558)	$ 2,505