XML 18 R55.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Schedule Of Outstanding Forward Contracts That Were Entered Into Hedge Forecasted Transactions (Detail) | Jun. 30, 2012 mwh | Dec. 31, 2011 mwh
--- | --- | ---
Derivative Instruments, Gain (Loss) [Line Items] |  |
Natural gas (million British thermal units) | 17,780,000 |
Energy Contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Energy contracts (electricity-megawatt hours) | 100,578,295 | 100,578,295
Aluminum Contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Aluminum contracts (kmt) | 1,190 | 1,294

X
- Definition Outstanding Forward Contracts Entered Into As Hedge Forecasted Transactions Measured In British Thermal Units + References No definition available. + Details
Name: | aa_Outstandingforwardcontractsenteredintoashedgeforecastedtransactionsmeasuredinbritishthermalunits
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Outstanding forward contracts entered into as hedge forecasted transactions measured in mega watt hours. + References No definition available. + Details
Name: | aa_OutstandingForwardContractsEnteredIntoAsHedgeForecastedTransactionsMeasuredInMegaWattHours
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Outstanding forward contracts entered into as hedging forecasted transactions measured in kilo metric ton. + References No definition available. + Details
Name: | aa_OutstandingForwardContractsEnteredIntoAsHedgingForecastedTransactionsMeasuredInKiloMetricTon
Namespace Prefix: | aa_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration