XML 38 R73.htm IDEA: XBRL DOCUMENT v2.4.1.9

Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Nov. 14, 2014
Goodwill [Line Items]
Goodwill gross, beginning balance		$ 5,174us-gaap_GoodwillGross	$ 5,198us-gaap_GoodwillGross
Acquisitions		1,898us-gaap_GoodwillAcquiredDuringPeriod
Accumulated impairment losses, beginning balance		(1,759)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss	(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Divestitures		(3)us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit
Goodwill, beginning balance		3,415us-gaap_Goodwill	5,170us-gaap_Goodwill
Impairment	(1,731)us-gaap_GoodwillImpairmentLoss		(1,731)us-gaap_GoodwillImpairmentLoss
Translation		(63)us-gaap_GoodwillTranslationAdjustments	(24)us-gaap_GoodwillTranslationAdjustments
Goodwill gross, ending balance	5,174us-gaap_GoodwillGross	7,006us-gaap_GoodwillGross	5,174us-gaap_GoodwillGross
Accumulated impairment losses, ending balance	(1,759)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss	(1,759)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss	(1,759)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Goodwill, ending balance	3,415us-gaap_Goodwill	5,247us-gaap_Goodwill	3,415us-gaap_Goodwill
Alumina [Member]
Goodwill [Line Items]
Goodwill gross, beginning balance		9us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	10us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Divestitures		(3)us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Goodwill, beginning balance		9us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	10us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Translation		2us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	(1)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Goodwill gross, ending balance	9us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	8us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	9us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Goodwill, ending balance	9us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	8us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember	9us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_AluminaMember
Primary Metals [Member]
Goodwill [Line Items]
Goodwill gross, beginning balance			997us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Goodwill, beginning balance			997us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Impairment	(1,731)us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember		(989)us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Translation			(8)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Goodwill gross, ending balance	989us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	989us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	989us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Accumulated impairment losses, ending balance	(989)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(989)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember	(989)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Goodwill, ending balance	0us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember		0us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_PrimaryMetalsMember
Global Rolled Products [Member]
Goodwill [Line Items]
Goodwill gross, beginning balance		218us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	214us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember
Goodwill, beginning balance		218us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	214us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember
Translation		(8)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	4us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember
Goodwill gross, ending balance	218us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	210us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	218us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember
Goodwill, ending balance	218us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	210us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember	218us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_GlobalRolledProductsMember
Engineered Products and Solutions [Member]
Goodwill [Line Items]
Goodwill gross, beginning balance		2,698us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	2,705us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Acquisitions		1,898us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Accumulated impairment losses, beginning balance		(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Goodwill, beginning balance		2,670us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	2,677us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	1,898us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Translation		(49)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	(7)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Goodwill gross, ending balance	2,698us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	4,547us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	2,698us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Accumulated impairment losses, ending balance	(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	(28)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Goodwill, ending balance	2,670us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	4,519us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	2,670us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember	1,898us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = aa_EngineeredProductsAndSolutionsMember
Corporate [Member]
Goodwill [Line Items]
Goodwill gross, beginning balance		1,260us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	1,272us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Accumulated impairment losses, beginning balance		(742)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Goodwill, beginning balance		518us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	1,272us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Impairment			(742)us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Translation		(8)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	(12)us-gaap_GoodwillTranslationAdjustments / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Goodwill gross, ending balance	1,260us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	1,252us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	1,260us-gaap_GoodwillGross / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Accumulated impairment losses, ending balance	(742)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	(742)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	(742)us-gaap_GoodwillImpairedAccumulatedImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember
Goodwill, ending balance	$ 518us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	$ 510us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember	$ 518us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = us-gaap_CorporateMember

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

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

X

- Definition

Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillTranslationAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

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_GlobalRolledProductsMember
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:

X

- Details

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