Proposed Separation Transaction	9 Months Ended
Sep. 30, 2019
Restructuring and Related Activities [Abstract]
Proposed Separation Transaction	Proposed Separation Transaction On February 8, 2019, Arconic announced, as part of its strategy and portfolio review, a separation of its portfolio into two independent, publicly-traded companies. The EP&F businesses will remain in the existing company (Remain Co.) which will be renamed Howmet Aerospace Inc. at separation. The GRP businesses will comprise Spin Co. and will be named Arconic Corporation at separation. The Company will also consider the sale of businesses that do not best fit into EP&F and GRP. The Company is targeting to complete the separation in the second quarter of 2020. The separation transaction is subject to a number of conditions, including, but not limited to, final approval by Arconic’s Board of Directors, receipt of a favorable opinion of legal counsel with respect to the tax-free nature of the transaction for U.S. federal income tax purposes, completion of financing, and the effectiveness of a Form 10 registration statement to be filed with the U.S. Securities and Exchange Commission. The Company expects the Form 10 filing to be available in the fourth quarter of 2019. Arconic may, at any time and for any reason until the proposed transaction is complete, abandon the separation plan or modify or change its terms. In the third quarter and nine months ended September 30, 2019, Arconic recognized $25 and $44, respectively, in Selling, general administrative, and other expenses on the accompanying Statement of Consolidated Operations for costs related to the proposed separation transaction.

On February 8, 2019, Arconic announced, as part of its strategy and portfolio review, a separation of its portfolio into two independent, publicly-traded companies. The EP&F businesses will remain in the existing company (Remain Co.) which will be renamed Howmet Aerospace Inc. at separation. The GRP businesses will comprise Spin Co. and will be named Arconic Corporation at separation. The Company will also consider the sale of businesses that do not best fit into EP&F and GRP. The Company is targeting to complete the separation in the second quarter of 2020. The separation transaction is subject to a number of conditions, including, but not limited to, final approval by Arconic’s Board of Directors, receipt of a favorable opinion of legal counsel with respect to the tax-free nature of the transaction for U.S. federal income tax purposes, completion of financing, and the effectiveness of a Form 10 registration statement to be filed with the U.S. Securities and Exchange Commission. The Company expects the Form 10 filing to be available in the fourth quarter of 2019. Arconic may, at any time and for any reason until the proposed transaction is complete, abandon the separation plan or modify or change its terms. In the third quarter and nine months ended September 30, 2019, Arconic recognized $25 and $44, respectively, in Selling, general administrative, and other expenses on the accompanying Statement of Consolidated Operations for costs related to the proposed separation transaction.