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Financial Instruments (Schedule Of Pretax Effect On Net Income (Loss) And Other Comprehensive Income (Loss) Of Derivative Instruments Classified As Cash Flow Hedges) (Details) - Aluminum Futures Contracts [Member] - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Derivatives, Fair Value [Line Items] |  |  |
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax | $ (2,359) | $ (1,123) | $ 1,501
Cost of Sales [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net | $ (2,736) | $ 1,069 | $ 1,210

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