Derivative Financial Instruments (Summary Of Location And Fair Value Of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Flexible Packaging Films [Member] [Domain] \| Accrued Expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ (330)	$ (558)
Aluminum Futures Contracts
Derivatives, Fair Value [Line Items]
Net asset (liability), Fair Value	(62)	562
Derivatives Designated As Hedging Instruments [Member] \| Flexible Packaging Films [Member] [Domain] \| Accrued Expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Liability derivatives: Fair Value	330	558
Derivatives Designated As Hedging Instruments [Member] \| Aluminum Futures Contracts \| Accrued Expenses [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	491	578
Liability derivatives: Fair Value	$ (553)	$ (16)

Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant