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Derivatives And Other Financial Instruments (Schedule Of Outstanding Forward Contracts That Were Entered Into To Hedge Forward Transactions) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010
Foreign Exchange Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Foreign exchange contracts |  | 20
Energy Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Energy contracts (electricity - megawatt hours) | 100,578,295 | 100,578,295
Aluminum Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Aluminum contracts (kmt) | 1,294 | 1,285

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- Definition Outstanding Forward Contracts Entered Into As Hedge Forecasted Transactions, Foreign Exchange Contracts + References No definition available. + Details
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- Definition OutstandingForwardContractsEnteredIntoAsHedgeForecastedTransactionsMeasuredInMegawattHours + References No definition available. + Details
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- Definition Outstanding Forward Contracts Entered Into As Hedging Forecasted Transactions Measured In Kmt + References No definition available. + Details
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Namespace Prefix: | aa_
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Balance Type: | na
Period Type: | duration

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- Details
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