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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, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Net asset (liability)	$ (1,254)	$ (487)
Cost of Goods and Services Sold	649,690	558,967	$ 641,140
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
Flexible Packaging Films [Member] [Domain] \| Designated as Hedging Instrument \| Accrued Expenses
Derivatives, Fair Value [Line Items]
Asset derivatives	0	853
Liability derivatives: Aluminum futures contracts	1,255	466
Aluminum Futures Contracts
Derivatives, Fair Value [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	6,215	74	(2,359)
Aluminum Futures Contracts \| Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Net asset (liability)	1,966
Aluminum Futures Contracts \| Prepaid Expenses And Other [Member]
Derivatives, Fair Value [Line Items]
Net asset (liability)		1,538
Aluminum Futures Contracts \| Designated as Hedging Instrument \| Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives	2,085
Liability derivatives: Aluminum futures contracts	(119)
Aluminum Futures Contracts \| Designated as Hedging Instrument \| Accrued Expenses
Derivatives, Fair Value [Line Items]
Asset derivatives		1,560
Liability derivatives: Aluminum futures contracts		(22)
Flexible Packaging Films [Member] \| Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Net asset (liability)	(1,255)	387
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	(2,415)	(4,437)	(856)
Cost of Sales [Member] \| Flexible Packaging Films [Member] [Domain]
Derivatives, Fair Value [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	63	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	5,787	(2,717)	(2,736)
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	$ (337)	$ (6,069)	$ (904)