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Financial Instruments (Summary Of Location And Fair Value Of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Derivatives, Fair Value [Line Items] |  |  |
Net asset (liability) | $ (2,188) | $ (2,720) |
Flexible Packaging Films [Member] [Domain] | Accrued Expenses |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Asset derivatives | (852) |  |
Net asset (liability) |  | (1,053) |
Flexible Packaging Films [Member] [Domain] | Designated as Hedging Instrument | Prepaid Expenses And Other [Member] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Asset derivatives | 83 | 37 |
Flexible Packaging Films [Member] [Domain] | Designated as Hedging Instrument | Accrued Expenses |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Liability derivatives: Aluminum futures contracts | 935 | 1,090 |
Aluminum Futures Contracts |  |  |
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
Aluminum Futures Contracts | Accrued Expenses |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Net asset (liability) | (1,253) | (1,630) |
Aluminum Futures Contracts | Designated as Hedging Instrument | Accrued Expenses |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Asset derivatives | 6 | 20 |
Liability derivatives: Aluminum futures contracts | (1,259) | (1,650) |
Selling, General and Administrative Expenses [Member] | Flexible Packaging Films [Member] [Domain] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax | (856) | (2,105) | (561)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net |  |  | (43)
Cost of Sales [Member] | Flexible Packaging Films [Member] [Domain] |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax | 0 | 0 | 0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net | 62 | 62 | 62
Cost of Sales [Member] | Aluminum Futures Contracts |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net | (2,736) | 1,069 | 1,210
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Currency Forward Contracts |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cost of Goods and Services Sold | (62) | (62) | (62)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Aluminum Futures Contracts |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cost of Goods and Services Sold | 2,736 | (1,069) | $ (1,210)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Selling, General and Administrative Expenses [Member] | Foreign Currency Forward Contracts |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cost of Goods and Services Sold | $ (904) | $ (1,796) |

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