Financial Derivative Instruments - Impact of Cash Flow Hedges (Details) - Cash flow hedging - Foreign currency derivatives - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Gains (losses) for designated hedge contracts
(Gain) loss recognized in AOCI on derivatives	$ 1,262	$ (3,881)	$ 3,131	$ (3,904)
(Gain) loss reclassified from AOCI into income	$ 418	$ (1,095)	$ (7,020)	$ (4,431)