Annual report pursuant to Section 13 and 15(d)

Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details)

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Derivative Instruments And Hedging Strategies (Recognized Gains (Losses) On Derivative Instruments Not Designated As Hedging Instruments) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
Derivative [Line Items]  
Derivative gains (losses), net $ 19,727
Exchange Option Liability  
Derivative [Line Items]  
Derivative gains (losses), net 19,436
Forward currency exchange, option and future contracts  
Derivative [Line Items]  
Derivative gains (losses), net $ 291