Subsequent Events	3 Months Ended
Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	N. Subsequent Events Management evaluated all activity of Arconic and concluded that no subsequent events have occurred that would require recognition in the Consolidated Financial Statements or disclosure in the Notes to the Consolidated Financial Statements, with the exception of the events disclosed below. On April 17, 2017, the Company announced that, effective April 13, 2017, Klaus Kleinfeld, by mutual agreement with the Arconic Board of Directors (the “Board”), had stepped down as Chairman and Chief Executive Officer of Arconic and resigned as a Board member. The Board appointed David P. Hess, a current member of the Board, as Interim Chief Executive Officer of the Company, and Patricia F. Russo, who was then serving as Lead Director of the Company, as Interim Chair of the Board, effective April 13, 2017. The Board has formed a search committee to oversee the selection and appointment of a permanent Chief Executive Officer. On April 5, 2017, Arconic announced three separate cash tender offers by Citigroup Global Markets Inc. and Credit Suisse Securities (USA) LLC (together, the “Investment Entities”) for the purchase of the Company’s 6.500% Senior Notes due 2018, 6.750% Senior Notes due 2018, and 5.720% Senior Notes due 2019, up to a maximum purchase amount of $1,000 aggregate principal amount of notes, subject to certain conditions. On April 19, 2017, Arconic announced that the Investment Entities had purchased notes totaling $795 in aggregate principal amount. On April 24, 2017, the Company purchased $295 in aggregate principal amount of its senior notes from the Investment Entities for cash of $320. On April 25, 2017, the Company agreed to acquire $500 in aggregate principal amount of the 2018 Notes held by the Investment Entities for consideration, at the Company’s election, consisting of (i) cash, (ii) shares of common stock of Alcoa Corporation owned by the Company or (iii) a combination thereof. On April 26, 2017, the Company elected to acquire such notes (i) in exchange for 12,958,767 Alcoa Corporation shares (the “Debt Exchange”) at $35.91 per share and (ii) for $77 in cash (the “Cash Purchase”). The Debt Exchange is expected to close on May 4, 2017, and the Cash Purchase is expected to close on May 5, 2017, each subject to customary closing conditions. The Investment Entities intend to negotiate to sell to the Company for cash any additional notes tendered to, and purchased by, the Investment Entities pursuant to the tender offers, which are expected to expire on May 2, 2017. In the second quarter, the Company anticipates recording a pre-tax gain of approximately $167 on the exchange of common stock of Alcoa Corporation and interest expense associated primarily with the early tender of its senior notes of approximately $50 to $60. Arconic Inc. and certain officers and directors are named as defendants in a lawsuit filed on April 18, 2017 in Pennsylvania state court, the Philadelphia County Court of Common Pleas, by plaintiff shareholder Arthur Ehrlich on behalf of himself and other similarly situated shareholders alleging breach of fiduciary duty related to Arconic’s April 12, 2017 filing of a Form 8-K in which the company disclosed that it had given notice of a “potential change in control” under the terms of a rabbi trust agreement. Plaintiffs allege that this statement constitutes an improper attempt to coerce shareholders into voting for incumbent directors. We believe that this lawsuit is without merit and intend to defend it vigorously. Arconic Inc. and certain officers and directors are named as defendants in a lawsuit filed on April 19, 2017 in the United States District Court for the Southern District of New York by plaintiff City of Atlanta Firefighters Pension Fund alleging violations of the Exchange Act related to Arconic’s April 12, 2017 filing of a Form 8-K in which the company disclosed that it had given notice of a “potential change in control” under the terms of a rabbi trust agreement. Plaintiff alleges that this statement constitutes an improper attempt to coerce shareholders into voting for incumbent directors. We believe that this lawsuit is without merit and intend to defend it vigorously.

N. Subsequent Events

Management evaluated all activity of Arconic and concluded that no subsequent events have occurred that would require recognition in the Consolidated Financial Statements or disclosure in the Notes to the Consolidated Financial Statements, with the exception of the events disclosed below.

On April 17, 2017, the Company announced that, effective April 13, 2017, Klaus Kleinfeld, by mutual agreement with the Arconic Board of Directors (the “Board”), had stepped down as Chairman and Chief Executive Officer of Arconic and resigned as a Board member. The Board appointed David P. Hess, a current member of the Board, as Interim Chief Executive Officer of the Company, and Patricia F. Russo, who was then serving as Lead Director of the Company, as Interim Chair of the Board, effective April 13, 2017. The Board has formed a search committee to oversee the selection and appointment of a permanent Chief Executive Officer.

On April 5, 2017, Arconic announced three separate cash tender offers by Citigroup Global Markets Inc. and Credit Suisse Securities (USA) LLC (together, the “Investment Entities”) for the purchase of the Company’s 6.500% Senior Notes due 2018, 6.750% Senior Notes due 2018, and 5.720% Senior Notes due 2019, up to a maximum purchase amount of $1,000 aggregate principal amount of notes, subject to certain conditions.

On April 19, 2017, Arconic announced that the Investment Entities had purchased notes totaling $795 in aggregate principal amount. On April 24, 2017, the Company purchased $295 in aggregate principal amount of its senior notes from the Investment Entities for cash of $320.

On April 25, 2017, the Company agreed to acquire $500 in aggregate principal amount of the 2018 Notes held by the Investment Entities for consideration, at the Company’s election, consisting of (i) cash, (ii) shares of common stock of Alcoa Corporation owned by the Company or (iii) a combination thereof. On April 26, 2017, the Company elected to acquire such notes (i) in exchange for 12,958,767 Alcoa Corporation shares (the “Debt Exchange”) at $35.91 per share and (ii) for $77 in cash (the “Cash Purchase”). The Debt Exchange is expected to close on May 4, 2017, and the Cash Purchase is expected to close on May 5, 2017, each subject to customary closing conditions. The Investment Entities intend to negotiate to sell to the Company for cash any additional notes tendered to, and purchased by, the Investment Entities pursuant to the tender offers, which are expected to expire on May 2, 2017.

In the second quarter, the Company anticipates recording a pre-tax gain of approximately $167 on the exchange of common stock of Alcoa Corporation and interest expense associated primarily with the early tender of its senior notes of approximately $50 to $60.

Arconic Inc. and certain officers and directors are named as defendants in a lawsuit filed on April 18, 2017 in Pennsylvania state court, the Philadelphia County Court of Common Pleas, by plaintiff shareholder Arthur Ehrlich on behalf of himself and other similarly situated shareholders alleging breach of fiduciary duty related to Arconic’s April 12, 2017 filing of a Form 8-K in which the company disclosed that it had given notice of a “potential change in control” under the terms of a rabbi trust agreement. Plaintiffs allege that this statement constitutes an improper attempt to coerce shareholders into voting for incumbent directors. We believe that this lawsuit is without merit and intend to defend it vigorously.

Arconic Inc. and certain officers and directors are named as defendants in a lawsuit filed on April 19, 2017 in the United States District Court for the Southern District of New York by plaintiff City of Atlanta Firefighters Pension Fund alleging violations of the Exchange Act related to Arconic’s April 12, 2017 filing of a Form 8-K in which the company disclosed that it had given notice of a “potential change in control” under the terms of a rabbi trust agreement. Plaintiff alleges that this statement constitutes an improper attempt to coerce shareholders into voting for incumbent directors. We believe that this lawsuit is without merit and intend to defend it vigorously.