Acquisitions and Divestitures	12 Months Ended
Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions and Divestitures	Acquisitions and Divestitures 2018 Divestitures. On April 2, 2018, Arconic completed the sale of its Latin America extrusions business to a subsidiary of Hydro Extruded Solutions AS for $2, following the settlement of post-closing and other adjustments in December 2018. As a result of entering into the agreement to sell the Latin America extrusions business in December 2017, a charge of $41 was recognized in the fourth quarter of 2017 in Restructuring and other charges in the Statement of Consolidated Operations related to the non-cash impairment of the net book value of the business and an additional charge of $2 related to a post-closing adjustment was recognized in the fourth quarter of 2018. The operating results and assets and liabilities of the business were included in the Transportation and Construction Solutions segment. This business generated sales of $25, $115, and $103 in 2018, 2017, and 2016 respectively, and had 612 employees at the time of the divestiture. On July 31, 2018, the Company announced that it had initiated a sale process of its Building and Construction Systems (BCS) business, as part of the Company’s ongoing strategy and portfolio review that commenced in January 2018. BCS is part of the Transportation and Construction Solutions segment and generated third-party sales of approximately $1,140, $1,070, and $1,010 for 2018, 2017, and 2016, respectively. The sale process continues to progress. The Company’s decision regarding whether to sell the business will not be finalized until final binding offers are evaluated at a later stage in the sale process. Until the Company makes that final decision, the BCS business will remain classified as held and in-use in the Consolidated Financial Statements. On October 31, 2018, the Company sold its Texarkana, Texas rolling mill and cast house, which had a combined net book value of $63, to Ta Chen International, Inc. for $302 in cash, subject to post-closing adjustments, plus additional contingent consideration of up to $50. The contingent consideration relates to the achievement of various milestones within 36 months of the transaction closing date associated with operationalizing the rolling mill equipment. The operating results and assets and liabilities of the business were included in the Global Rolled Products segment. The Texarkana rolling mill facility had previously been idle since late 2009. In early 2016, the Company restarted the Texarkana cast house to meet demand for aluminum slab. As part of the agreement, the Company will continue to produce aluminum slab at the facility for a period of 18 months through a lease back of the cast house building and equipment, after which time, Ta Chen will perform toll processing of metal for the Company for a period of six months. The Company will supply Ta Chen with cold-rolled aluminum coil during this 24-month period. The sale of the rolling mill and cast house has been accounted for separately. The gain on the sale of the rolling mill of $154, including the fair value of contingent consideration of $5, was recorded in Restructuring and other charges in the Statement of Consolidated Operations in the fourth quarter of 2018. The Company will reevaluate its estimate of the amount of contingent consideration to which it will be entitled at the end of each reporting period and recognize any changes thereto in the Statement of Consolidated Operations. The Company has continuing involvement related to the lease back of the cast house, and, therefore has deferred the gain associated with the cast house in 2018. As a result, the Company continues to treat the cast house building and equipment that it sold to Ta Chen as owned and therefore reflected these assets in its Consolidated Balance Sheet and has been depreciating them over their remaining useful life. Additionally, the Company recorded the cash proceeds associated with the sale of the cast house assets as a noncurrent liability in its Consolidated Balance Sheet which included a deferred gain of $95. The Company will adopt the new lease accounting standard in the first quarter of 2019, under which the Company's continuing involvement no longer requires deferral of the cast house gain. As such, the deferred gain on the sale of the cast house will be treated as a cumulative effect of an accounting change within retained earnings on January 1, 2019. On December 31, 2018, as part of the Company’s ongoing strategy and portfolio review, Arconic completed the sale of its Eger, Hungary forgings business to Angstrom Automotive Group LLC for $2, which resulted in a loss of $43 recorded in Restructuring and other charges in the Statement of Consolidated Operations. The operating results and assets and liabilities of the business were included in the Engineered Products and Solutions segment. This business generated sales of $32, $38, and $29 in 2018, 2017, and 2016 respectively, and had 180 employees at the time of the divestiture. 2017 Divestitures. In March 2017, Arconic completed the sale of its Fusina, Italy rolling mill to Slim Aluminium. While owned by Arconic, the operating results and assets and liabilities of the Fusina, Italy rolling mill were included in the Global Rolled Products segment. As part of the transaction, Arconic injected $10 of cash into the business and provided a third-party guarantee with a fair value of $5 related to Slim Aluminium’s environmental remediation. The Company recorded a loss on the sale of $60, which was recorded in Restructuring and other charges on the Statement of Consolidated Operations for 2017. The rolling mill generated sales of approximately $54 and $165 for 2017 and 2016, respectively. At the time of the divestiture, the rolling mill had approximately 312 employees. 2016 Divestitures. In April 2016, Arconic completed the sale of the Remmele Medical business to LISI MEDICAL for $102 in cash ($99 net of transaction costs), which was included in Proceeds from the sale of assets and businesses on the accompanying Statement of Consolidated Cash Flows. This business, which was part of the RTI acquisition in 2015, manufactured precision-machined metal products for customers in the minimally invasive surgical device and implantable device markets. Since this transaction occurred within a year of the completion of the RTI acquisition, no gain was recorded on this transaction as the excess of the proceeds over the carrying value of the net assets of this business was reflected as a purchase price adjustment (decrease to goodwill of $44) to the final allocation of the purchase price related to Arconic’s acquisition of RTI. While owned by Arconic, the operating results and assets and liabilities of this business were included in the Engineered Products and Solutions segment. This business generated sales of approximately $20 from January 1, 2016 through the divestiture date, April 29, 2016, and, at the time of the divestiture, had approximately 330 employees. 2014 Acquisitions. In November 2014, Arconic acquired Firth Rixson. The purchase price included an earn-out agreement that required Arconic to make earn-out payments up to an aggregate maximum amount of $150 through December 31, 2020 upon certain conditions. This earn-out was contingent on the Firth Rixson forging business in Savannah, Georgia achieving certain identified financial targets through December 31, 2020. During the fourth quarter of 2016, management determined that payment of the maximum amount was not probable based on the forecasted financial performance of this location. Therefore, the fair value of this liability was reduced by $56 with a corresponding credit to Other income, net on the accompanying Statement of Consolidated Operations. During the fourth quarter of 2017, management determined that payment of the remaining amount of the contingent liability was not probable based on the forecasted financial performance of this location. Therefore, the fair value of this liability was reduced by $81 to zero at December 31, 2017 with a corresponding credit to Other income, net on the accompanying Statement of Consolidated Operations. The fair value of this liability remains at zero at December 31, 2018 based on the forecasted financial performance of this location.

Acquisitions and Divestitures

2018 Divestitures. On April 2, 2018, Arconic completed the sale of its Latin America extrusions business to a subsidiary of Hydro Extruded Solutions AS for $2, following the settlement of post-closing and other adjustments in December 2018. As a result of entering into the agreement to sell the Latin America extrusions business in December 2017, a charge of $41 was recognized in the fourth quarter of 2017 in Restructuring and other charges in the Statement of Consolidated Operations related to the non-cash impairment of the net book value of the business and an additional charge of $2 related to a post-closing adjustment was recognized in the fourth quarter of 2018. The operating results and assets and liabilities of the business were included in the Transportation and Construction Solutions segment. This business generated sales of $25, $115, and $103 in 2018, 2017, and 2016 respectively, and had 612 employees at the time of the divestiture.

On July 31, 2018, the Company announced that it had initiated a sale process of its Building and Construction Systems (BCS) business, as part of the Company’s ongoing strategy and portfolio review that commenced in January 2018. BCS is part of the Transportation and Construction Solutions segment and generated third-party sales of approximately $1,140, $1,070, and $1,010 for 2018, 2017, and 2016, respectively. The sale process continues to progress. The Company’s decision regarding whether to sell the business will not be finalized until final binding offers are evaluated at a later stage in the sale process. Until the Company makes that final decision, the BCS business will remain classified as held and in-use in the Consolidated Financial Statements.

On October 31, 2018, the Company sold its Texarkana, Texas rolling mill and cast house, which had a combined net book value of $63, to Ta Chen International, Inc. for $302 in cash, subject to post-closing adjustments, plus additional contingent consideration of up to $50. The contingent consideration relates to the achievement of various milestones within 36 months of the transaction closing date associated with operationalizing the rolling mill equipment. The operating results and assets and liabilities of the business were included in the Global Rolled Products segment. The Texarkana rolling mill facility had previously been idle since late 2009. In early 2016, the Company restarted the Texarkana cast house to meet demand for aluminum slab. As part of the agreement, the Company will continue to produce aluminum slab at the facility for a period of 18 months through a lease back of the cast house building and equipment, after which time, Ta Chen will perform toll processing of metal for the Company for a period of six months. The Company will supply Ta Chen with cold-rolled aluminum coil during this 24-month period.

The sale of the rolling mill and cast house has been accounted for separately. The gain on the sale of the rolling mill of $154, including the fair value of contingent consideration of $5, was recorded in Restructuring and other charges in the Statement of Consolidated Operations in the fourth quarter of 2018. The Company will reevaluate its estimate of the amount of contingent consideration to which it will be entitled at the end of each reporting period and recognize any changes thereto in the Statement of Consolidated Operations. The Company has continuing involvement related to the lease back of the cast house, and, therefore has deferred the gain associated with the cast house in 2018. As a result, the Company continues to treat the cast house building and equipment that it sold to Ta Chen as owned and therefore reflected these assets in its Consolidated Balance Sheet and has been depreciating them over their remaining useful life. Additionally, the Company recorded the cash proceeds associated with the sale of the cast house assets as a noncurrent liability in its Consolidated Balance Sheet which included a deferred gain of $95. The Company will adopt the new lease accounting standard in the first quarter of 2019, under which the Company's continuing involvement no longer requires deferral of the cast house gain. As such, the deferred gain on the sale of the cast house will be treated as a cumulative effect of an accounting change within retained earnings on January 1, 2019.

On December 31, 2018, as part of the Company’s ongoing strategy and portfolio review, Arconic completed the sale of its Eger, Hungary forgings business to Angstrom Automotive Group LLC for $2, which resulted in a loss of $43 recorded in Restructuring and other charges in the Statement of Consolidated Operations. The operating results and assets and liabilities of the business were included in the Engineered Products and Solutions segment. This business generated sales of $32, $38, and $29 in 2018, 2017, and 2016 respectively, and had 180 employees at the time of the divestiture.

2017 Divestitures. In March 2017, Arconic completed the sale of its Fusina, Italy rolling mill to Slim Aluminium. While owned by Arconic, the operating results and assets and liabilities of the Fusina, Italy rolling mill were included in the Global Rolled Products segment. As part of the transaction, Arconic injected $10 of cash into the business and provided a third-party guarantee with a fair value of $5 related to Slim Aluminium’s environmental remediation. The Company recorded a loss on the sale of $60, which was recorded in Restructuring and other charges on the Statement of Consolidated Operations for 2017. The rolling mill generated sales of approximately $54 and $165 for 2017 and 2016, respectively. At the time of the divestiture, the rolling mill had approximately 312 employees.

2016 Divestitures. In April 2016, Arconic completed the sale of the Remmele Medical business to LISI MEDICAL for $102 in cash ($99 net of transaction costs), which was included in Proceeds from the sale of assets and businesses on the accompanying Statement of Consolidated Cash Flows. This business, which was part of the RTI acquisition in 2015, manufactured precision-machined metal products for customers in the minimally invasive surgical device and implantable device markets. Since this transaction occurred within a year of the completion of the RTI acquisition, no gain was recorded on this transaction as the excess of the proceeds over the carrying value of the net assets of this business was reflected as a purchase price adjustment (decrease to goodwill of $44) to the final allocation of the purchase price related to Arconic’s acquisition of RTI. While owned by Arconic, the operating results and assets and liabilities of this business were included in the Engineered Products and Solutions segment. This business generated sales of approximately $20 from January 1, 2016 through the divestiture date, April 29, 2016, and, at the time of the divestiture, had approximately 330 employees.

2014 Acquisitions. In November 2014, Arconic acquired Firth Rixson. The purchase price included an earn-out agreement that required Arconic to make earn-out payments up to an aggregate maximum amount of $150 through December 31, 2020 upon certain conditions. This earn-out was contingent on the Firth Rixson forging business in Savannah, Georgia achieving certain identified financial targets through December 31, 2020. During the fourth quarter of 2016, management determined that payment of the maximum amount was not probable based on the forecasted financial performance of this location. Therefore, the fair value of this liability was reduced by $56 with a corresponding credit to Other income, net on the accompanying Statement of Consolidated Operations. During the fourth quarter of 2017, management determined that payment of the remaining amount of the contingent liability was not probable based on the forecasted financial performance of this location. Therefore, the fair value of this liability was reduced by $81 to zero at December 31, 2017 with a corresponding credit to Other income, net on the accompanying Statement of Consolidated Operations. The fair value of this liability remains at zero at December 31, 2018 based on the forecasted financial performance of this location.