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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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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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