Derivatives - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments,Gain (Loss) [Line Items]
Net gain (loss) on foreign currency exchange contracts	$ (1,331)	$ 234
Not Designated as Hedging Instrument | Foreign Currency Exchange Contracts | Other Income (Expense), Net
Derivative Instruments,Gain (Loss) [Line Items]
Net gain (loss) on foreign currency exchange contracts	$ (1,300)	$ 200