Income Taxes	9 Months Ended
Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	K. Income Taxes – The effective tax rate for the third quarter of 2015 and 2014 was 48.5% and 60.3%, respectively. The rate for the 2015 third quarter differs from the U.S. federal statutory rate of 35% primarily due to restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized. The rate for the 2014 third quarter differs from the U.S. federal statutory rate of 35% primarily due to a $56 discrete income tax charge related to a tax rate change in Brazil, restructuring charges related to operations in Italy for which no tax benefit was recognized (see Note D), and an $8 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014), slightly offset by a $9 discrete income tax benefit for the release of a valuation allowance related to operations in Germany due to the initiation of a tax planning strategy. The effective tax rate for the 2015 and 2014 nine-month periods was 41.4% and 76.0%, respectively. The rate for the 2015 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to a loss on the sale of a rolling mill in Russia (see Note E) for which no tax benefit was recognized, a $34 net discrete income tax charge as described below, and restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized. These items were partially offset by foreign income taxed in lower rate jurisdictions. In the first quarter of 2015, AWAC, a joint venture owned 60% by Alcoa and 40% by Alumina Limited (Alcoa consolidates AWAC for financial reporting purposes), recognized an $83 discrete income tax charge (increased to $85 in the 2015 second quarter) for a valuation allowance on certain deferred tax assets, which were related mostly to employee benefits and tax loss carryforwards. Alcoa also had a $50 deferred tax liability (increased to $51 in the 2015 second quarter) related to its 60%-share of these deferred tax assets that was written off as a result of the valuation allowance recognized by AWAC. The rate for the 2014 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to the previously mentioned $56 discrete income tax charge and a $44 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014).

K. Income Taxes – The effective tax rate for the third quarter of 2015 and 2014 was 48.5% and 60.3%, respectively.

The rate for the 2015 third quarter differs from the U.S. federal statutory rate of 35% primarily due to restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized.

The rate for the 2014 third quarter differs from the U.S. federal statutory rate of 35% primarily due to a $56 discrete income tax charge related to a tax rate change in Brazil, restructuring charges related to operations in Italy for which no tax benefit was recognized (see Note D), and an $8 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014), slightly offset by a $9 discrete income tax benefit for the release of a valuation allowance related to operations in Germany due to the initiation of a tax planning strategy.

The effective tax rate for the 2015 and 2014 nine-month periods was 41.4% and 76.0%, respectively.

The rate for the 2015 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to a loss on the sale of a rolling mill in Russia (see Note E) for which no tax benefit was recognized, a $34 net discrete income tax charge as described below, and restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized. These items were partially offset by foreign income taxed in lower rate jurisdictions.

In the first quarter of 2015, AWAC, a joint venture owned 60% by Alcoa and 40% by Alumina Limited (Alcoa consolidates AWAC for financial reporting purposes), recognized an $83 discrete income tax charge (increased to $85 in the 2015 second quarter) for a valuation allowance on certain deferred tax assets, which were related mostly to employee benefits and tax loss carryforwards. Alcoa also had a $50 deferred tax liability (increased to $51 in the 2015 second quarter) related to its 60%-share of these deferred tax assets that was written off as a result of the valuation allowance recognized by AWAC.

The rate for the 2014 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to the previously mentioned $56 discrete income tax charge and a $44 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014).