Income Taxes	6 Months Ended
Jun. 30, 2014
Income Tax Disclosure [Abstract]
Income Taxes	L. Income Taxes – The effective tax rate for the second quarter of 2014 and 2013 was 37.7% (provision on income) and 16.5% (provision on a loss), respectively. The rate for the 2014 second quarter differs from the U.S. federal statutory rate of 35% primarily due to the U.S. tax impact of deemed distributions from otherwise lower tax rate foreign jurisdictions and operational income of certain foreign subsidiaries taxed in lower rate jurisdictions, mostly offset by a $20 favorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (partial reversal of the 2014 first quarter impact). The rate for the 2013 second quarter differs (by (51.5) percentage points) from the U.S. federal statutory rate of 35% primarily due to a $103 nondeductible charge for a legal matter, restructuring charges related to operations in Canada (benefit at a lower tax rate) and Italy (no tax benefit) (see Note D), and a $10 discrete income tax charge related to prior year taxes in Spain and Australia. The effective tax rate for the 2014 and 2013 six-month periods was 1.5% (provision on a loss) and 79.4% (provision on income), respectively. The rate for the 2014 six-month period differs (by (36.5) percentage points) from the U.S. federal statutory rate of 35% primarily due to a $36 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact is expected to reverse by the end of 2014). The rate for the 2013 six-month period differs from the U.S. federal statutory rate of 35% primarily due to the previously mentioned $103 nondeductible charge, restructuring charges in Canada and Italy, and $10 discrete income tax charge, somewhat offset by a $19 discrete income tax benefit related to new U.S. tax legislation. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law and reinstated various expired or expiring temporary business tax provisions through 2013. Two specific temporary business tax provisions that expired in 2011 and impacted Alcoa are the look-through rule for payments between related controlled foreign corporations and the research and experimentation credit. The expiration of these two provisions resulted in Alcoa recognizing a higher income tax provision of $19 in 2012. As tax law changes are accounted for in the period of enactment, Alcoa recognized the previously mentioned discrete income tax benefit in the 2013 first quarter related to the 2012 tax year to reflect the extension of these provisions. In December 2011, one of Alcoa’s subsidiaries in Brazil applied for a tax holiday related to its expanded mining and refining operations. During 2013, the application was amended and re-filed. The deadline for the Brazilian government to deny the application was July 11, 2014. Since Alcoa did not receive notice that its application was denied, the tax holiday took effect automatically on July 12, 2014. As a result, the tax rate for this subsidiary will decrease significantly (from 34% to 15%), resulting in future cash tax savings over the 10-year holiday period (retroactively effective as of January 1, 2013). Additionally, a portion of the subsidiary’s net deferred tax asset that reverses within the holiday period will be remeasured at the new lower tax rate in the 2014 third quarter. This remeasurement will result in a decrease to this subsidiary’s net deferred tax asset and a noncash charge to earnings of approximately $60.

L. Income Taxes – The effective tax rate for the second quarter of 2014 and 2013 was 37.7% (provision on income) and 16.5% (provision on a loss), respectively.

The rate for the 2014 second quarter differs from the U.S. federal statutory rate of 35% primarily due to the U.S. tax impact of deemed distributions from otherwise lower tax rate foreign jurisdictions and operational income of certain foreign subsidiaries taxed in lower rate jurisdictions, mostly offset by a $20 favorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (partial reversal of the 2014 first quarter impact).

The rate for the 2013 second quarter differs (by (51.5) percentage points) from the U.S. federal statutory rate of 35% primarily due to a $103 nondeductible charge for a legal matter, restructuring charges related to operations in Canada (benefit at a lower tax rate) and Italy (no tax benefit) (see Note D), and a $10 discrete income tax charge related to prior year taxes in Spain and Australia.

The effective tax rate for the 2014 and 2013 six-month periods was 1.5% (provision on a loss) and 79.4% (provision on income), respectively.

The rate for the 2014 six-month period differs (by (36.5) percentage points) from the U.S. federal statutory rate of 35% primarily due to a $36 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact is expected to reverse by the end of 2014).

The rate for the 2013 six-month period differs from the U.S. federal statutory rate of 35% primarily due to the previously mentioned $103 nondeductible charge, restructuring charges in Canada and Italy, and $10 discrete income tax charge, somewhat offset by a $19 discrete income tax benefit related to new U.S. tax legislation.

On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law and reinstated various expired or expiring temporary business tax provisions through 2013. Two specific temporary business tax provisions that expired in 2011 and impacted Alcoa are the look-through rule for payments between related controlled foreign corporations and the research and experimentation credit. The expiration of these two provisions resulted in Alcoa recognizing a higher income tax provision of $19 in 2012. As tax law changes are accounted for in the period of enactment, Alcoa recognized the previously mentioned discrete income tax benefit in the 2013 first quarter related to the 2012 tax year to reflect the extension of these provisions.

In December 2011, one of Alcoa’s subsidiaries in Brazil applied for a tax holiday related to its expanded mining and refining operations. During 2013, the application was amended and re-filed. The deadline for the Brazilian government to deny the application was July 11, 2014. Since Alcoa did not receive notice that its application was denied, the tax holiday took effect automatically on July 12, 2014. As a result, the tax rate for this subsidiary will decrease significantly (from 34% to 15%), resulting in future cash tax savings over the 10-year holiday period (retroactively effective as of January 1, 2013). Additionally, a portion of the subsidiary’s net deferred tax asset that reverses within the holiday period will be remeasured at the new lower tax rate in the 2014 third quarter. This remeasurement will result in a decrease to this subsidiary’s net deferred tax asset and a noncash charge to earnings of approximately $60.