Derivative Financial Instruments (Narrative) (Details) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012 USD ($)	Sep. 30, 2012 Aluminum Futures Contracts [Member] USD ($) lb	Dec. 31, 2011 Aluminum Futures Contracts [Member] USD ($) lb	Sep. 30, 2012 Film Products [Member] EUR (€)
Derivative [Line Items]
Notional Amount		$ 7.2	$ 10.8	€ 16.0
Weight of aluminum that hedged future purchase of aluminum to meet fixed - price forward sales contract obligations, lbs		7,700,000	11,000,000
Amounts of unrealized after-tax gains on derivative instruments	$ 0.2

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration