Derivatives And Other Financial Instruments (Schedule Of Gains And Losses On Derivative Representing Either Hedge Ineffectiveness Or Hedge Components Excluded From Assessment Of Effectiveness Are Recognized In Current Earnings) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	$ (82)		$ (188)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	(1)	[1]	(40)	[1]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	7	[2]	1	[2]
Amount of loss expected to be recognized into earnings over the next 12 months	4
Amount of gain or (loss) recognized in earnings related to ineffective portion of hedging relationships	9		1
Earnings recognized in relation to amount excluded from the assessment of hedge effectiveness	(2)
Aluminum Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(79)		(189)
Energy Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(5)
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)			1
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	2
Sales [Member] | Aluminum Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)			(38)	[1]
Sales [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)			1	[1]
Cost Of Goods Sold [Member] | Energy Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)			(3)	[1]
Other Income, Net [Member] | Aluminum Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	7	[2]	1	[2]
Other (Income) Expenses, Net [Member] | Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	$ (1)	[1]

[1] Assuming market rates remain constant with the rates at March 31, 2012, a loss of $4 is expected to be recognized in earnings over the next 12 months.

[2] For the first quarter ended March 31, 2012 and 2011, the amount of gain or (loss) recognized in earnings represents $9 and $1, respectively, related to the ineffective portion of the hedging relationships. There was also $(2) recognized in earnings related to the amount excluded from the assessment of hedge effectiveness for the first quarter ended March 31, 2012.