Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments And Risk Management (Effect And Classification Of Derivative Instruments) (Details)

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Financial Instruments And Risk Management (Effect And Classification Of Derivative Instruments) (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Derivative Instruments Designated As Cash Flow Hedges [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (loss) recognized in other comprehensive income or loss $ (5,232) $ (1,438)
Cost Of Sales [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (loss) reclassified from accumulated other comprehensive income or loss to income or loss for the effective portion (2,206) 54
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net 1,925 794
Sales [Member] | Derivative Instruments Designated As Cash Flow Hedges [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (loss) reclassified from accumulated other comprehensive income or loss to income or loss for the effective portion 5 144
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net 6 3
Other Non-operating Income (Expense) [Member] | Derivative Instruments Not Designated As Cash Flow Hedges [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (loss) recognized in income or loss $ (602) $ (1,688)