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