Income Taxes	3 Months Ended
Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	K. Income Taxes – The effective tax rate was 162.4% and 30.9% for the first quarter of 2019 and 2018, respectively. Alcoa Corporation’s estimated annual effective tax rate for 2019 was 72.2% as of March 31, 2019. This rate differs from the U.S. federal statutory rate of 21% primarily due to foreign income taxed in higher rate jurisdictions, as well as by domestic losses and foreign losses in countries with full valuation reserves resulting in no tax benefit. For the first quarter of 2019, the Provision for income taxes of $150 included two components: (i) the application of the estimated annual tax rate of 72.2% to pre-tax income of $92 ($67), and (ii) an unfavorable tax impact related to the interim period treatment of operational losses in certain jurisdictions for which no tax benefit was recognized ($83). For the first quarter of 2018, the Provision for income taxes of $151 included two components: (i) the application of the estimated annual tax rate of 30.5% to pre-tax income of $491 ($150), and (ii) an unfavorable tax impact related to the interim period treatment of operational losses in certain jurisdictions for which no tax benefit was recognized ($1). The rate for the first quarter of 2018 differs from the U.S. federal statutory rate of 21% primarily due to foreign income taxed in higher rate jurisdictions, as well as by domestic losses and foreign losses in countries with full valuation reserves resulting in no tax benefit.

Income Taxes

3 Months Ended

Mar. 31, 2019

K. Income Taxes – The effective tax rate was 162.4% and 30.9% for the first quarter of 2019 and 2018, respectively. Alcoa Corporation’s estimated annual effective tax rate for 2019 was 72.2% as of March 31, 2019. This rate differs from the U.S. federal statutory rate of 21% primarily due to foreign income taxed in higher rate jurisdictions, as well as by domestic losses and foreign losses in countries with full valuation reserves resulting in no tax benefit.

For the first quarter of 2019, the Provision for income taxes of $150 included two components: (i) the application of the estimated annual tax rate of 72.2% to pre-tax income of $92 ($67), and (ii) an unfavorable tax impact related to the interim period treatment of operational losses in certain jurisdictions for which no tax benefit was recognized ($83).

For the first quarter of 2018, the Provision for income taxes of $151 included two components: (i) the application of the estimated annual tax rate of 30.5% to pre-tax income of $491 ($150), and (ii) an unfavorable tax impact related to the interim period treatment of operational losses in certain jurisdictions for which no tax benefit was recognized ($1). The rate for the first quarter of 2018 differs from the U.S. federal statutory rate of 21% primarily due to foreign income taxed in higher rate jurisdictions, as well as by domestic losses and foreign losses in countries with full valuation reserves resulting in no tax benefit.