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Derivative Financial Instruments (Summary Of Location And Fair Value Of Derivative Financial Instruments) (Details) - Aluminum Futures Contracts - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Derivatives, Fair Value [Line Items]    
Net asset (liability), Fair Value $ 884 $ 271
Derivatives Designated As Hedging Instruments [Member] | Accrued Expenses [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Gross Asset 896 308
Liability derivatives: Fair Value $ (12) $ (37)