Asset Retirement Obligations - Schedule of Carrying Value of Recorded AROs by Major Category (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligations [Line Items]
Spent pot lining disposal	$ 182	$ 187
Closure of bauxite residue areas	190	173
Mine reclamation	189	164
Demolition	28	34
Landfill closure	17	17
Other	4	4
Asset retirement obligation, total	$ 610	$ 579	$ 534

The estimated amount of costs required as of the balance sheet date to comply with regulatory requirements pertaining to the retirement of a waste management facility, which will be paid after one year or beyond the normal operating cycle, if longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

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-Paragraph 8

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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