XML 79 R58.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Derivatives and Other Financial Instruments - Schedule of Quantitative Information for Level 3 Derivative Contracts (Detail) (USD $) |  |  |  | 3 Months Ended |  | 3 Months Ended |  | 3 Months Ended |  | 3 Months Ended |  | 3 Months Ended |  | 3 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2012 | Mar. 31, 2014 Interrelationship of Future Aluminum and Oil Prices [Member] Aluminum Contracts [Member] Minimum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Interrelationship of Future Aluminum and Oil Prices [Member] Aluminum Contracts [Member] Maximum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] Aluminum Contracts [Member] | Mar. 31, 2014 Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] Aluminum Contracts [Member] Minimum [Member] Discounted Cash Flow [Member] Index | Mar. 31, 2014 Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] Aluminum Contracts [Member] Maximum [Member] Discounted Cash Flow [Member] Index | Mar. 31, 2014 Interrelationship of LME Price to Overall Energy Price [Member] Aluminum Contracts [Member] | Mar. 31, 2014 Interrelationship of LME Price to Overall Energy Price [Member] Aluminum Contracts [Member] Minimum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Interrelationship of LME Price to Overall Energy Price [Member] Aluminum Contracts [Member] Maximum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Price of Electricity Beyond Forward Curve [Member] Energy Contracts [Member] | Mar. 31, 2014 Price of Electricity Beyond Forward Curve [Member] Energy Contracts [Member] Minimum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Price of Electricity Beyond Forward Curve [Member] Energy Contracts [Member] Maximum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Price of Aluminum Beyond Forward Curve [Member] Aluminum Contracts [Member] | Mar. 31, 2014 Price of Aluminum Beyond Forward Curve [Member] Aluminum Contracts [Member] Minimum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Price of Aluminum Beyond Forward Curve [Member] Aluminum Contracts [Member] Maximum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Credit Spread Between Alcoa and Counterparty [Member] Embedded Credit Derivative [Member] | Mar. 31, 2014 Credit Spread Between Alcoa and Counterparty [Member] Embedded Credit Derivative [Member] Minimum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Credit Spread Between Alcoa and Counterparty [Member] Embedded Credit Derivative [Member] Maximum [Member] Discounted Cash Flow [Member] | Mar. 31, 2014 Credit Spread Between Alcoa and Counterparty [Member] Embedded Credit Derivative [Member] Median [Member] Discounted Cash Flow [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative Assets, Fair value | $ 371,000,000 | $ 390,000,000 | $ 596,000,000 |  |  | $ 292,000,000 |  |  | $ 34,000,000 |  |  | $ 11,000,000 |  |  |  |  |  |  |  |  |
Price of aluminum beyond forward curve |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,401 | 2,554 |  |  |  |
Derivative Liabilities, Fair value | 440,000,000 | 479,000,000 |  |  |  |  |  |  |  |  |  |  |  |  | 384,000,000 |  |  | 20,000,000 |  |  |
Expected future aluminum prices |  |  |  | 1,705 | 2,066 |  | 1,724 | 1,958 |  | 1,806 | 2,143 |  |  |  |  |  |  |  |  |  |
Maturity year of future aluminum price |  |  |  | 2014 | 2018 |  | 2014 | 2016 |  | 2014 | 2019 |  |  |  |  | 2023 | 2027 |  |  |  |
Expected future oil prices |  |  |  | 93 | 108 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of credit spread |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.57% | 1.88% | 1.23%
Price of electricity beyond forward curve |  |  |  |  |  |  |  |  |  |  |  |  | $ 82 | $ 154 |  |  |  |  |  |  |
Maturity year of future oil price |  |  |  | 2018 | 2014 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maturity date of electricity beyond forward curve |  |  |  |  |  |  |  |  |  |  |  |  | 2014 | 2036 |  |  |  |  |  |  |
Foreign currency exchange rate |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Foreign currency exchange rate |  |  |  |  |  |  | 0.92 | 0.87 |  |  |  |  |  |  |  |  |  |  |  |  |
Foreign currency exchange rate expected year |  |  |  |  |  |  | 2014 | 2016 |  |  |  |  |  |  |  |  |  |  |  |  |
Consumer price index base year |  |  |  |  |  |  |  | 1982 |  |  |  |  |  |  |  |  |  |  |  |  |
Expected consumer price index |  |  |  |  |  |  | 232 | 246 |  |  |  |  |  |  |  |  |  |  |  |  |
Consumer price index base |  |  |  |  |  |  |  | 100 |  |  |  |  |  |  |  |  |  |  |  |  |
Expected consumer price index, Year |  |  |  |  |  |  | 2014 | 2016 |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Average percentage of credit spread. + References No definition available. + Details
Name: | aa_AveragePercentageOfCreditSpread
Namespace Prefix: | aa_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Base year consumer price index. + References No definition available. + Details
Name: | aa_BaseYearConsumerPriceIndex
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Consumer price index base year. + References No definition available. + Details
Name: | aa_ConsumerPriceIndexBaseYear
Namespace Prefix: | aa_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected consumer price index. + References No definition available. + Details
Name: | aa_ExpectedConsumerPriceIndex
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected date of consumer price index. + References No definition available. + Details
Name: | aa_ExpectedDateOfConsumerPriceIndex
Namespace Prefix: | aa_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected future aluminum prices. + References No definition available. + Details
Name: | aa_ExpectedFutureAluminumPrices
Namespace Prefix: | aa_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected future oil prices. + References No definition available. + Details
Name: | aa_ExpectedFutureOilPrices
Namespace Prefix: | aa_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected price of aluminum through forward curve. + References No definition available. + Details
Name: | aa_ExpectedPriceOfAluminumThroughForwardCurve
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Foreign currency derivatives maturity date. + References No definition available. + Details
Name: | aa_ForeignCurrencyDerivativesMaturityDate
Namespace Prefix: | aa_
Data Type: | us-types:dateStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maturity data of future aluminum price. + References No definition available. + Details
Name: | aa_MaturityDataOfFutureAluminumPrice
Namespace Prefix: | aa_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maturity data of future oil price. + References No definition available. + Details
Name: | aa_MaturityDataOfFutureOilPrice
Namespace Prefix: | aa_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maturity date of electricity beyond forward curve. + References No definition available. + Details
Name: | aa_MaturityDateOfElectricityBeyondForwardCurve
Namespace Prefix: | aa_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Price of electricity through forward curve. + References No definition available. + Details
Name: | aa_PriceOfElectricityThroughForwardCurve
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Foreign exchange rate used to remeasure amounts denominated in a currency other than functional currency into functional currency. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521 + Details
Name: | us-gaap_ForeignCurrencyExchangeRateRemeasurement1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521 + Details
Name: | us-gaap_ForeignCurrencyExchangeRateTranslation1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant