Derivatives And Other Financial Instruments (Schedule Of Reconciliation Of Activity For Derivative Contracts) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Ending balance	$ 704
Aluminum Contracts [Member] | Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	10
Sales - (decrease)	(3)
Other income, net - (increase)	(1)
Other comprehensive income - decrease (increase)	2
Purchases, sales, issuances, and settlements		[1]
Transfers into and (or) out of Level 3		[1]
Ending balance	8
Aluminum Contracts [Member] | Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	602
Sales - (decrease)	(10)
Other comprehensive income - decrease (increase)	82
Purchases, sales, issuances, and settlements		[1]
Transfers into and (or) out of Level 3		[1]
Ending balance	674
Embedded Credit Derivative [Member] | Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	28
Purchases, sales, issuances, and settlements		[1]
Transfers into and (or) out of Level 3		[1]
Ending balance	28
Other income, net - (increase)	(1)
Energy Contracts [Member] | Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	2
Other comprehensive income - decrease (increase)	(2)
Purchases, sales, issuances, and settlements		[1]
Transfers into and (or) out of Level 3		[1]
Energy Contracts [Member] | Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other comprehensive income - decrease (increase)	10
Purchases, sales, issuances, and settlements		[1]
Transfers into and (or) out of Level 3		[1]
Ending balance	$ 10

[1] There were no purchases, sales, issuances or settlements of Level 3 financial instruments. Additionally, there were no transfers of financial instruments into or out of Level 3.