XML 50 R66.htm IDEA: XBRL DOCUMENT
v2.3.0.15

Derivatives And Other Financial Instruments (Outstanding Forward Contracts That Were Entered Into Hedge Forcasted Transactions) (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2011 | Dec. 31, 2010
Aluminum contracts (kmt) | 1,237 | 1,285
Energy Contract [Member] |  |
Electricity (megawatt hours) | 100,578,295 | 100,578,295
Foreign exchange contracts | $ 5 | $ 20

X
- Definition Outstanding Forward Contracts Entered Into As Hedge Forecasted Transactions, Foreign Exchange Contracts + Details
Name: | aa_OutstandingForwardContractsEnteredIntoAsHedgeForecastedTransactionsForeignExchangeContracts
Namespace Prefix: | aa
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition OutstandingForwardContractsEnteredIntoAsHedgeForecastedTransactionsMeasuredInMegawattHours + Details
Name: | aa_Outstandingforwardcontractsenteredintoashedgeforecastedtransactionsmeasuredinmegawatthours
Namespace Prefix: | aa
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Outstanding Forward Contracts Entered Into As Hedging Forecasted Transactions Measured In Kmt + Details
Name: | aa_Outstandingforwardcontractsenteredintoashedgingforecastedtransactionsmeasuredinkmt
Namespace Prefix: | aa
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration