Annual report pursuant to Section 13 and 15(d)

Financial Instruments and Risk Management (Gross Notional Amount of Outstanding Derivatives) (Details)

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Financial Instruments and Risk Management (Gross Notional Amount of Outstanding Derivatives) (Details) - Foreign Exchange Forward [Member] - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Notional Amount $ 417,707 $ 471,822
Not Designated as Hedging Instrument [Member]    
Derivatives, Fair Value [Line Items]    
Derivative, Notional Amount $ 326,280 $ 214,086