Hedging Instruments (Derivatives Designated In Cash Flow Hedging Relationships) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Foreign Currency Fair Value Hedge Derivative [Line Items]
Cost of revenue	$ 262,250	$ 248,313	$ 506,709	$ 482,870
Cash flow hedging | Derivatives and non-derivatives designated as hedging instruments | Foreign currency exchange contracts | Costs of revenue
Foreign Currency Fair Value Hedge Derivative [Line Items]
Amount of (loss) gain reclassified from accumulated other comprehensive income into income	$ 2,509	$ (833)	$ 3,920	$ (2,668)