XML 42 R49.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Receivables - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended | 12 Months Ended | 3 Months Ended | 1 Months Ended | 3 Months Ended
--- | --- | --- | --- | --- | --- | ---
Mar. 31, 2012 | Jun. 30, 2013 Institution | Jun. 06, 2013 Agreement | Dec. 31, 2012 | Mar. 31, 2012 Minimum [Member] | Mar. 31, 2013 Maximum [Member] | Mar. 31, 2012 Maximum [Member]
Schedule Of Financial Receivables [Line Items] |  |  |  |  |  |  |
Number of arrangement with different financial institution to sell customer receivables |  |  | 3 |  |  |  |
Asset Servicing value |  | $ 0 |  |  |  |  |
Liability servicing value |  | 0 |  |  |  |  |
Funding of customer receivables sold |  |  |  |  | 50 |  | 250
Funding of customer receivables sold after amendment |  |  |  |  |  | 500 |
Deferred purchase price receivable | 254 |  |  |  |  |  |
Additional funding received |  | 5 |  | 205 |  |  |
Purchase price receivable |  | 377 |  |  |  |  |
Number of additional financial institution |  | 2 |  |  |  |  |
Amount of cash draws under arrangement |  | 288 |  |  |  |  |
Amount of cash repayments under arrangement |  | 283 |  |  |  |  |
Accounts receivables |  | 6,650 |  |  |  |  |
Cash collections |  | $ 6,063 |  |  |  |  |

X
- Definition Commitment of additional funding for development of reserves. + References No definition available. + Details
Name: | aa_CommitmentOfAdditionalFundingForDevelopmentOfReserves
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Deferred purchase price customer receivables. + References No definition available. + Details
Name: | aa_DeferredPriceCustomerReceivables
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Funding of customer receivables sold. + References No definition available. + Details
Name: | aa_FundingOfCustomerReceivablesSold
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Funding of customer receivables sold after amendment. + References No definition available. + Details
Name: | aa_FundingOfCustomerReceivablesSoldAfterAmendment
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number Of Arrangements To Sell Customer Receivables + References No definition available. + Details
Name: | aa_NumberOfArrangementsToSellCustomerReceivables
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of financial institutions. + References No definition available. + Details
Name: | aa_NumberOfFinancialInstitutions
Namespace Prefix: | aa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Proceeds from receivable funding. + References No definition available. + Details
Name: | aa_ProceedsFromReceivableFunding
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Repayments for receivable funding. + References No definition available. + Details
Name: | aa_RepaymentsForReceivableFunding
Namespace Prefix: | aa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | aa_ScheduleOfFinancialReceivablesLineItems
Namespace Prefix: | aa_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition For unclassified balance sheet, amounts due from customers or clients for goods or services that have been delivered or sold in the normal course of business. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.9) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_AccountsReceivableGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash inflow associated with the collection of other receivables not otherwise defined in the taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 + Details
Name: | us-gaap_ProceedsFromCollectionOfOtherReceivables
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount due from customers for fees and charges arising from transactions related to the entity's brokerage activities and operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
Name: | us-gaap_ReceivablesFromCustomers
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 + Details
Name: | us-gaap_ServicingAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Aggregate amount of servicing liabilities that are subsequently measured at fair value and servicing liabilities that are subsequently measured using the amortization method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 + Details
Name: | us-gaap_ServicingLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant