XML 131 R144.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Derivatives And Other Financial Instruments (Schedule Of Reconciliation Of Activity For Derivative Contracts On A Net Basis) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010
Level 3 [Member] |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |
Balance at end of year | $ 618 |  | $ 779 |
Financial Instruments [Member] |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |
Balance at beginning of year | 779 |  | 831 |
Sales-(decrease) | (63) |  | (38) |
Cost of goods sold-(increase) | (15) |  | (20) |
Other (income) expenses, net-(increase) decrease | (43) |  | 25 |
Other comprehensive (loss) income-(increase) | (35) |  | (19) |
Purchases, sales, issuances, and settlements | (5) | [1] |  |
Balance at end of year | 618 |  | 779 |
Sales |  |  |  |
Cost of goods sold |  |  |  |
Other (income) expenses, net-(increase) decrease | (5) |  | 22 |
Pension And Other Postretirement Benefit Plans' Assets [Member] |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |
Balance at beginning of year | 1,499 |  | 920 |
Other comprehensive (loss) income-(increase) | 100 |  | 130 |
Transfers into and (or) out of Level 3 |  | [2] |  | [2]
Balance at end of year | $ 2,760 |  | $ 1,499 |
[1] | In 2011, there was an issuance of a Level 3 financial instrument related to a natural gas supply contract (see below). There were no purchases, sales, or settlements of Level 3 financial instruments in 2011 and 2010.
[2] | In 2011 and 2010, there were no transfers of financial instruments into or out of Level 3

X
- Definition Fair value assets measured on recurring basis gain loss included in cost of goods sold. + References No definition available. + Details
Name: | aa_FairValueAssetsMeasuredOnRecurringBasisGainLossIncludedInCostOfGoodsSold
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair Value Assets Measured On Recurring Basis Gain Loss Included In Other Expenses + References No definition available. + Details
Name: | aa_FairValueAssetsMeasuredOnRecurringBasisGainLossIncludedInOtherExpenses
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value assets measured on recurring basis gain loss included in sales. + References No definition available. + Details
Name: | aa_FairValueAssetsMeasuredOnRecurringBasisGainLossIncludedInSales
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Cost Of Goods Sold + References No definition available. + Details
Name: | aa_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetCostOfGoodsSold
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Other Expenses + References No definition available. + Details
Name: | aa_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOtherExpenses
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales Increase Decrease + References No definition available. + Details
Name: | aa_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSalesIncreaseDecrease
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(3) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant