Derivatives And Other Financial Instruments (Schedule Of Fair Value Gains And Losses On Derivatives Contracts Recorded In Earnings) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	$ 39	$ (32)	$ (71)
Sales [Member] | Aluminum Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	(13)	5	(9)
Other (Income) Expenses, Net [Member] | Aluminum Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	13	(18)	(38)
Other (Income) Expenses, Net [Member] | Embedded Credit Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	(5)	(2)
Other (Income) Expenses, Net [Member] | Energy Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	47	(23)	(30)
Other (Income) Expenses, Net [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	$ (3)	$ 6	$ 6