Derivatives And Other Financial Instruments (Fair Values Of Outstanding Derivative Contracts Recorded As Assets) (Details) (USD $) In Millions	Jun. 30, 2011		Dec. 31, 2010
Fair value asset derivatives	$ 108		$ 147
Prepaid Expenses and Other Current Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value asset derivatives	31		48
Prepaid Expenses and Other Current Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Foreign Exchange Contracts [Member]
Fair value asset derivatives	2		2
Prepaid Expenses and Other Current Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts [Member]
Fair value asset derivatives	15		19
Prepaid Expenses and Other Current Assets [Member] | Derivatives not Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value asset derivatives	2	[1]	3	[1]
Prepaid Expenses and Other Current Assets [Member] | Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Contracts [Member]
Fair value asset derivatives	6		13
Prepaid Expenses and Other Current Assets [Member] | Aluminum Contracts [Member]
Fair value asset derivatives			4
Other Noncurrent Assets [Member]
Fair value asset derivatives	6		19
Other Noncurrent Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Aluminum Contracts [Member]
Fair value asset derivatives	10		22
Other Noncurrent Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Energy Contract [Member]
Fair value asset derivatives	27		9
Other Noncurrent Assets [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts [Member]
Fair value asset derivatives	25		62
Other Noncurrent Assets [Member] | Derivatives not Designated as Hedging Instruments [Member] | Foreign Exchange Contracts [Member]
Fair value asset derivatives	2	[1]	1	[1]
Other Noncurrent Assets [Member] | Derivatives not Designated as Hedging Instruments [Member] | Interest Rate Contracts [Member]
Fair value asset derivatives			2
Derivatives Designated as Hedging Instruments [Member]
Fair value asset derivatives	110		162
Derivatives not Designated as Hedging Instruments [Member]
Fair value asset derivatives	$ 4	[1]	$ 4	[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.