XML 160 R107.htm IDEA: XBRL DOCUMENT v2.4.1.9

Segment and Geographic Area Information - Schedule of Operating Results of Alcoa's Reportable Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Total sales	$ 6,377us-gaap_SalesRevenueGoodsNet	$ 6,239us-gaap_SalesRevenueGoodsNet	$ 5,836us-gaap_SalesRevenueGoodsNet	$ 5,454us-gaap_SalesRevenueGoodsNet	$ 5,585us-gaap_SalesRevenueGoodsNet	$ 5,765us-gaap_SalesRevenueGoodsNet	$ 5,849us-gaap_SalesRevenueGoodsNet	$ 5,833us-gaap_SalesRevenueGoodsNet	$ 23,906us-gaap_SalesRevenueGoodsNet	$ 23,032us-gaap_SalesRevenueGoodsNet	$ 23,700us-gaap_SalesRevenueGoodsNet
Equity income (loss)									(90)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments	(68)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments	(28)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments
Depreciation, depletion, and amortization									1,289aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses	1,337aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses	1,374aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses
Income taxes									854aa_SegmentReportingInformationIncomeTaxExpensesBenefits	448aa_SegmentReportingInformationIncomeTaxExpensesBenefits	535aa_SegmentReportingInformationIncomeTaxExpensesBenefits
ATOI									2,043aa_SegmentReportingInformationProfitsLosses	1,217aa_SegmentReportingInformationProfitsLosses	1,357aa_SegmentReportingInformationProfitsLosses
Capital expenditures									1,126aa_SegmentReportingInformationCapitalExpenditures	1,105aa_SegmentReportingInformationCapitalExpenditures
Equity investments	1,785aa_SegmentReportingInformationEquityMethodInvestments				1,775aa_SegmentReportingInformationEquityMethodInvestments				1,785aa_SegmentReportingInformationEquityMethodInvestments	1,775aa_SegmentReportingInformationEquityMethodInvestments
Goodwill	4,737aa_SegmentReportingInformationReportedGoodwill				2,897aa_SegmentReportingInformationReportedGoodwill				4,737aa_SegmentReportingInformationReportedGoodwill	2,897aa_SegmentReportingInformationReportedGoodwill
Total assets	31,232aa_SegmentReportingInformationReportedAssets				29,247aa_SegmentReportingInformationReportedAssets				31,232aa_SegmentReportingInformationReportedAssets	29,247aa_SegmentReportingInformationReportedAssets
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales									28,723us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember	27,795us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember	28,777us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales									5,057aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	5,034aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	5,350aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember
Total sales									(5,057)us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	(5,034)us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	(5,350)us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember
Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales									23,666aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember	22,761aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember	23,427aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember
Alumina [Member]
Segment Reporting Information [Line Items]
Equity income (loss)									(29)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	(4)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	5aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Depreciation, depletion, and amortization									387aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	426aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	455aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Income taxes									153aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	66aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	(27)aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
ATOI									370aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	259aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	90aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Capital expenditures									246aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	322aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Equity investments	669aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				628aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				669aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	628aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Goodwill	8aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				9aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				8aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	9aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Total assets	7,350aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				8,248aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember				7,350aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	8,248aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Alumina [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales									5,450us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	5,561us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	5,402us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Alumina [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales									1,941aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	2,235aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	2,310aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Alumina [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales									3,509aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	3,326aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	3,092aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Primary Metals [Member]
Segment Reporting Information [Line Items]
Equity income (loss)									(34)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(51)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(27)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Depreciation, depletion, and amortization									494aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	526aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	532aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Income taxes									203aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(74)aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	106aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
ATOI									594aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(20)aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	309aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Capital expenditures									176aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	224aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Equity investments	890aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember				947aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember				890aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	947aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Total assets	9,308aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember				10,341aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember				9,308aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	10,341aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Primary Metals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales									9,731us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	9,217us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	10,309us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Primary Metals [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales									2,931aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	2,621aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	2,877aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Primary Metals [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales									6,800aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	6,596aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	7,432aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Global Rolled Products [Member]
Segment Reporting Information [Line Items]
Equity income (loss)									(27)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	(13)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	(6)aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Depreciation, depletion, and amortization									235aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	226aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	229aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Income taxes									124aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	108aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	159aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
ATOI									312aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	252aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	346aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Capital expenditures									389aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	335aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Equity investments	226aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				200aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				226aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	200aa_SegmentReportingInformationEquityMethodInvestments / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Goodwill	210aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				218aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				210aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	218aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Total assets	4,908aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				4,647aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember				4,908aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	4,647aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Global Rolled Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales									7,536us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	7,284us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	7,541us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Global Rolled Products [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales									185aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	178aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	163aa_SegmentReportingInformationIntersegmentRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Global Rolled Products [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales									7,351aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	7,106aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember	7,378aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_FlatRolledProductsMember
Engineered Products and Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, and amortization									173aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	159aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	158aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Income taxes									374aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	348aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	297aa_SegmentReportingInformationIncomeTaxExpensesBenefits / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
ATOI									767aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	726aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	612aa_SegmentReportingInformationProfitsLosses / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Capital expenditures									315aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	224aa_SegmentReportingInformationCapitalExpenditures / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Goodwill	4,519aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember				2,670aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember				4,519aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	2,670aa_SegmentReportingInformationReportedGoodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Total assets	9,666aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember				6,011aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember				9,666aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	6,011aa_SegmentReportingInformationReportedAssets / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Engineered Products and Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales									6,006us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	5,733us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	5,525us-gaap_SalesRevenueGoodsNet / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Engineered Products and Solutions [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales									$ 6,006aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	$ 5,733aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	$ 5,525aa_SegmentReportingInformationRevenuesFromExternalCustomers / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = aa_ThirdPartySalesMember / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember

X

- Definition

Segment Reporting Information Capital Expenditures

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationCapitalExpenditures
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Segment reporting information depreciation depletion and amortization expense total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationDepreciationDepletionAndAmortizationExpenses
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Equity in net income of equity method investees of segment total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationEquityInNetIncomeOfEquityMethodInvesteesOfSegments
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Segment Reporting Information Equity Method Investments

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationEquityMethodInvestments
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Segment reporting information income tax expense benefit total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationIncomeTaxExpensesBenefits
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Segment reporting information intersegment revenue total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationIntersegmentRevenues
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Segment reporting information profit loss total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationProfitsLosses
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Segment reporting information's assets.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationReportedAssets
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Segment reporting information's goodwill.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationReportedGoodwill
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Segment reporting information revenue from external customers total.

+ References

No definition available.

+ Details

Name:	aa_SegmentReportingInformationRevenuesFromExternalCustomers
Namespace Prefix:	aa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(a))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

Name:	us-gaap_SalesRevenueGoodsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=aa_ThirdPartySalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aa_AluminaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aa_EngineeredProductsAndSolutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aa_FlatRolledProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=aa_PrimaryMetalsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: