Segment Information (Reconciliation Of Total Segment ATOI To Consolidated Net Income (Loss)) (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Total segment ATOI	$ 635	$ 381	$ 1,190	$ 687
Interest expense	(163)	(119)	(274)	(237)
Noncontrolling interests	(55)	(34)	(113)	(56)
Discontinued operations	(4)	(1)	(5)	(8)
Consolidated net income (loss) attributable to Alcoa	322	136	630	(65)
Unallocated Amounts [Member]
Impact of LIFO	(27)	(3)	(51)	(17)
Interest expense	(106)	(77)	(178)	(154)
Noncontrolling interests	(55)	(34)	(113)	(56)
Corporate expense	(76)	(59)	(143)	(126)
Restructuring and other charges	(22)	(21)	(28)	(143)
Discontinued operations	(4)	(1)	(5)	(8)
Other	$ (23)	$ (50)	$ (42)	$ (248)

This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items before deduction or consideration of the amount which may be allocable to noncontrolling interests, if any. Includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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+ Details

- Definition

The cost of borrowed funds accounted for as interest that was charged against earnings during the period.

+ References+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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+ Details

- Definition

The portion of net Income or Loss attributable to the noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent.

+ References

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+ Details