Basis of Presentation	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	A. Basis of Presentation The interim Consolidated Financial Statements of Arconic Inc. and its subsidiaries (“Arconic” or the “Company”) are unaudited. These Consolidated Financial Statements include all adjustments, consisting only of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The results reported in these Consolidated Financial Statements are not necessarily indicative of the results that may be expected for the entire year. The 2016 year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). This Form 10-Q report should be read in conjunction with Arconic’s Annual Report on Form 10-K for the year ended December 31, 2016, which includes all disclosures required by GAAP. Certain amounts in previously issued financial statements were reclassified to conform to the current period presentation. The separation of Alcoa Inc. into two standalone, publicly-traded companies, Arconic Inc. (the new name for Alcoa Inc.) and Alcoa Corporation, became effective on November 1, 2016 (the “Separation Transaction”). The financial results of Alcoa Corporation for all periods prior to the Separation Transaction have been retrospectively reflected in the Statement of Consolidated Operations as discontinued operations and, as such, have been excluded from continuing operations and segment results for the third quarter and nine months ended September 30, 2016. The cash flows, equity and comprehensive income related to Alcoa Corporation have not been segregated and are included in the accompanying Statement of Consolidated Cash Flows, Statement of Changes in Consolidated Equity and Statement of Consolidated Comprehensive Income, respectively, for the third quarter and nine months ended September 30, 2016. Pursuant to the authorization provided at a special meeting of Arconic common shareholders held on October 5, 2016, shareholders approved a 1-for-3 reverse stock split of Arconic’s outstanding and authorized shares of common stock (the “Reverse Stock Split”). As a result of the Reverse Stock Split, every three shares of issued and outstanding common stock were combined into one issued and outstanding share of common stock, without any change in the par value per share. The Reverse Stock Split reduced the number of shares of common stock outstanding from approximately 1.3 billion shares to approximately 0.4 billion shares. The Company’s common stock began trading on a reverse stock split-adjusted basis on the New York Stock Exchange on October 6, 2016.

A. Basis of Presentation

The interim Consolidated Financial Statements of Arconic Inc. and its subsidiaries (“Arconic” or the “Company”) are unaudited. These Consolidated Financial Statements include all adjustments, consisting only of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The results reported in these Consolidated Financial Statements are not necessarily indicative of the results that may be expected for the entire year. The 2016 year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). This Form 10-Q report should be read in conjunction with Arconic’s Annual Report on Form 10-K for the year ended December 31, 2016, which includes all disclosures required by GAAP. Certain amounts in previously issued financial statements were reclassified to conform to the current period presentation.

The separation of Alcoa Inc. into two standalone, publicly-traded companies, Arconic Inc. (the new name for Alcoa Inc.) and Alcoa Corporation, became effective on November 1, 2016 (the “Separation Transaction”). The financial results of Alcoa Corporation for all periods prior to the Separation Transaction have been retrospectively reflected in the Statement of Consolidated Operations as discontinued operations and, as such, have been excluded from continuing operations and segment results for the third quarter and nine months ended September 30, 2016. The cash flows, equity and comprehensive income related to Alcoa Corporation have not been segregated and are included in the accompanying Statement of Consolidated Cash Flows, Statement of Changes in Consolidated Equity and Statement of Consolidated Comprehensive Income, respectively, for the third quarter and nine months ended September 30, 2016.

Pursuant to the authorization provided at a special meeting of Arconic common shareholders held on October 5, 2016, shareholders approved a 1-for-3 reverse stock split of Arconic’s outstanding and authorized shares of common stock (the “Reverse Stock Split”). As a result of the Reverse Stock Split, every three shares of issued and outstanding common stock were combined into one issued and outstanding share of common stock, without any change in the par value per share. The Reverse Stock Split reduced the number of shares of common stock outstanding from approximately 1.3 billion shares to approximately 0.4 billion shares. The Company’s common stock began trading on a reverse stock split-adjusted basis on the New York Stock Exchange on October 6, 2016.