Derivatives And Other Financial Instruments (Fair Values Of Outstanding Derivative Contracts Recorded As Liabilities) (Details) (USD $) In Millions	Jun. 30, 2011		Dec. 31, 2010
Fair value liability derivatives	$ 904		$ 865
Other Current Liabilities [Member] | Derivatives Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value liability derivatives	68		89
Other Current Liabilities [Member] | Derivatives not Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value liability derivatives	52	[1]	52	[1]
Other Current Liabilities [Member] | Derivatives not Designated as Hedging Instruments [Member] | Energy Contract [Member]
Fair value liability derivatives	21	[1]	62	[1]
Other Current Liabilities [Member] | Aluminum Contracts [Member]
Fair value liability derivatives	2		4
Other Current Liabilities [Member] | Energy Contract [Member]
Fair value liability derivatives	11		37
Other Noncurrent Liabilities [Member]
Fair value liability derivatives	13		41
Other Noncurrent Liabilities [Member] | Derivatives Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value liability derivatives	723		647
Other Noncurrent Liabilities [Member] | Derivatives not Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value liability derivatives	32	[1]	33	[1]
Other Noncurrent Liabilities [Member] | Derivatives not Designated as Hedging Instruments [Member] | Embedded Credit Derivative [Member]
Fair value liability derivatives	21	[1]	23	[1]
Derivatives Designated as Hedging Instruments [Member]
Fair value liability derivatives	791		736
Derivatives not Designated as Hedging Instruments [Member]
Fair value liability derivatives	$ 126	[1]	$ 170	[1]

[1] * See the "Other" section within Note P for additional information on Alcoa's purpose for entering into derivatives not designated as hedging instruments and its overall risk management strategies.