XML 18 R142.htm IDEA: XBRL DOCUMENT v2.4.1.9

Pension and Other Postretirement Benefits - Schedule of Fair Value of Pension Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	$ 11,833us-gaap_DefinedBenefitPlanFairValueOfPlanAssets	$ 10,421us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	3,969us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	3,852us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Equity Securities [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,463us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	2,588us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Equity Securities [Member] | Hedge Funds, Equity Long (Short) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	963us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_HedgeFundsEquityLongShortMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	744us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_HedgeFundsEquityLongShortMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Equity Securities [Member] | Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	543us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_PrivateEquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	520us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_PrivateEquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	5,311us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	4,271us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Fixed Income Securities [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	4,898us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	3,802us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Fixed Income Securities [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	413us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	469us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,553us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	2,298us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Other Investments [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	516us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	375us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Other Investments [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	629us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	636us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Other Investments [Member] | Discretionary and Systematic Macro Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,408us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_DiscretionaryAndSystematicMacroHedgeFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	1,287us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_InvestmentTypeAxis = aa_DiscretionaryAndSystematicMacroHedgeFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	4,446us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	3,602us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,156us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	1,084us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 1 [Member] | Equity Securities [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,156us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	1,084us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 1 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,998us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	2,251us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Level 1 [Member] | Fixed Income Securities [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,998us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	2,251us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Level 1 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	292us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	267us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 1 [Member] | Other Investments [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	140us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	143us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 1 [Member] | Other Investments [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	152us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	124us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	3,462us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member	3,398us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,131us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	1,360us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 2 [Member] | Equity Securities [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,131us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	1,360us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 2 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,313us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	2,020us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Level 2 [Member] | Fixed Income Securities [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,900us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	1,551us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = aa_IntermediateAndLongDurationGovernmentCreditMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Level 2 [Member] | Fixed Income Securities [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	413us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember	469us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_FixedIncomeSecuritiesMember
Level 2 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	18us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	18us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 2 [Member] | Other Investments [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	18us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	18us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	3,925us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	3,421us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Level 3 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,682us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	1,408us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 3 [Member] | Equity Securities [Member] | Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	176us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	144us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_EquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 3 [Member] | Equity Securities [Member] | Hedge Funds, Equity Long (Short) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	963us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_HedgeFundsEquityLongShortMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	744us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_HedgeFundsEquityLongShortMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 3 [Member] | Equity Securities [Member] | Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	543us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_PrivateEquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember	520us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_PrivateEquityFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Level 3 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	2,243us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	2,013us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 3 [Member] | Other Investments [Member] | Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	376us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	232us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = aa_OtherFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 3 [Member] | Other Investments [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	459us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	494us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = us-gaap_RealEstateFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember
Level 3 [Member] | Other Investments [Member] | Discretionary and Systematic Macro Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	$ 1,408us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = aa_DiscretionaryAndSystematicMacroHedgeFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember	$ 1,287us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_InvestmentTypeAxis = aa_DiscretionaryAndSystematicMacroHedgeFundsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherInvestmentsMember

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

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