Derivative Financial Instruments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2013 Aluminum Futures Contracts [Member] USD ($) lb	Dec. 31, 2012 Aluminum Futures Contracts [Member] USD ($) lb	Mar. 31, 2013 Film Products [Member] EUR (€)	Dec. 31, 2012 Film Products [Member] EUR (€)	Mar. 31, 2013 Derivatives Not Designated as Hedging Instruments Aluminum Futures Contracts [Member] USD ($)	Dec. 31, 2012 Derivatives Not Designated as Hedging Instruments Aluminum Futures Contracts [Member] USD ($)
Derivative [Line Items]
Notional Amount		$ 6,200,000	$ 6,200,000	€ 9,900,000	€ 9,900,000
Weight of aluminum that hedged future purchase of aluminum to meet fixed - price forward sales contract obligations, lbs		6,800,000	6,700,000
Offsetting asset position for derivatives						0	0
Offsetting liability position for derivatives						0	0
Amounts of unrealized after-tax losses on derivative instruments	$ 200,000