Long-Term Debt	9 Months Ended
Sep. 30, 2016
Debt Disclosure [Abstract]
Long-Term Debt	I. Long-Term Debt – In September 2016, Alcoa Nederland Holding B.V, a wholly owned subsidiary of Alcoa Corporation, which was a wholly owned subsidiary of Arconic, completed an offering of $750 aggregate principal amount of 6.75% senior notes due 2024 and $500 aggregate principal amount of 7.00% senior notes due 2026 (together “the Notes”), in preparation for the Separation Transaction which became effective before the opening of the NYSE on November 1, 2016. Concurrent with the closing, Arconic was required to place into escrow $1,309, which represented the net proceeds from the offering of the Notes of $1,228, along with additional cash on hand of $81 which represented the necessary cash to fund the redemption of the Notes, pay all regularly scheduled interest on the Notes through a specified date as defined in the Notes, and a premium on the principal of the Notes if the Separation Transaction was not completed by a certain time as defined in the Notes. The cash held in escrow is included in Restricted cash in the Consolidated Balance Sheet at September 30, 2016. The net proceeds from the Notes of $1,228 are not reflected on the accompanying Statement of Consolidated Cash Flows for the nine months ended September 30, 2016 as they represent a noncash financing activity. The release of the escrowed funds will be subject to conditions set forth in the escrow agreements. Alcoa Corporation intends to use the proceeds from the offering to make a payment to Arconic to fund the transfer of certain assets from Arconic to Alcoa Corporation relating to the Separation Transaction and for general corporate purposes. The notes are guaranteed on a senior unsecured basis by Alcoa Corporation. In September 2016, Arconic entered into an amendment to its Five-Year Revolving Credit Agreement (as amended). The amendment was entered into to permit the Separation Transaction and to amend certain terms of the Credit Agreement including the replacement of the existing financial covenant with a leverage ratio and reduction of total commitments available from $4,000 to $3,000. The existing financial covenant, currently based upon Consolidated Net Worth (as defined in the Credit Agreement) will be replaced. Arconic will be required to maintain a ratio of Indebtedness (as defined in the Credit Agreement), to Consolidated EBITDA (as defined in the Credit Agreement) of 5.50 to 1.00 for the period of the four fiscal quarters most recently ended, declining to 3.50 to 1.00 on December 31, 2019 and thereafter. The amendment became effective on the separation date of November 1, 2016.

I. Long-Term Debt – In September 2016, Alcoa Nederland Holding B.V, a wholly owned subsidiary of Alcoa Corporation, which was a wholly owned subsidiary of Arconic, completed an offering of $750 aggregate principal amount of 6.75% senior notes due 2024 and $500 aggregate principal amount of 7.00% senior notes due 2026 (together “the Notes”), in preparation for the Separation Transaction which became effective before the opening of the NYSE on November 1, 2016. Concurrent with the closing, Arconic was required to place into escrow $1,309, which represented the net proceeds from the offering of the Notes of $1,228, along with additional cash on hand of $81 which represented the necessary cash to fund the redemption of the Notes, pay all regularly scheduled interest on the Notes through a specified date as defined in the Notes, and a premium on the principal of the Notes if the Separation Transaction was not completed by a certain time as defined in the Notes. The cash held in escrow is included in Restricted cash in the Consolidated Balance Sheet at September 30, 2016. The net proceeds from the Notes of $1,228 are not reflected on the accompanying Statement of Consolidated Cash Flows for the nine months ended September 30, 2016 as they represent a noncash financing activity.

The release of the escrowed funds will be subject to conditions set forth in the escrow agreements. Alcoa Corporation intends to use the proceeds from the offering to make a payment to Arconic to fund the transfer of certain assets from Arconic to Alcoa Corporation relating to the Separation Transaction and for general corporate purposes. The notes are guaranteed on a senior unsecured basis by Alcoa Corporation.

In September 2016, Arconic entered into an amendment to its Five-Year Revolving Credit Agreement (as amended). The amendment was entered into to permit the Separation Transaction and to amend certain terms of the Credit Agreement including the replacement of the existing financial covenant with a leverage ratio and reduction of total commitments available from $4,000 to $3,000. The existing financial covenant, currently based upon Consolidated Net Worth (as defined in the Credit Agreement) will be replaced. Arconic will be required to maintain a ratio of Indebtedness (as defined in the Credit Agreement), to Consolidated EBITDA (as defined in the Credit Agreement) of 5.50 to 1.00 for the period of the four fiscal quarters most recently ended, declining to 3.50 to 1.00 on December 31, 2019 and thereafter. The amendment became effective on the separation date of November 1, 2016.