Contingencies and Commitments	12 Months Ended
Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Contingencies and Commitments	R. Contingencies and Commitments Unless specifically described to the contrary, all matters within Note R are the full responsibility of Alcoa Corporation pursuant to the Separation and Distribution Agreement. Additionally, the Separation and Distribution Agreement provides for cross-indemnities between the Company and Arconic for claims subject to indemnification. Contingencies Litigation. Italy 148—Beginning in 2006, ParentCo and the Italian Energy Authority (Autorità di Regolazione per Energia Reti e Ambiente, formerly l’Autorità per l’Energia Elettrica, il Gas e il Sistema Idrico, the “Energy Authority”) had been in a dispute regarding the calculation of a drawback applied to a portion of the price of power under a special tariff received by Alcoa Trasformazioni S.r.l. (“Trasformazioni,” previously a subsidiary of ParentCo; now a subsidiary of Alcoa Corporation). This dispute arose as a result of a resolution (148/2004) issued in 2004 by the Energy Authority that changed the method for calculating the drawback. Through 2009, Trasformazioni continued to receive the power price drawback for its Portovesme and Fusina smelters in accordance with the original resolution (204/1999), at which time the European Commission declared all such special tariffs to be impermissible “state aid.” Between 2006 and 2014, several judicial hearings occurred related to continuous appeals filed by both ParentCo and the Energy Authority regarding the dispute on the calculation of the drawback; a hearing on the latest appeal was scheduled for May 2018 (see below). Additionally, between 2012 and 2013, Trasformazioni received multiple letters from the agency responsible for making and collecting payments on behalf of the Energy Authority demanding payment for the difference in the drawback calculation between the two resolutions. The latest such demand was for $97 (€76), including interest, and allegedly included consideration of a third resolution (44/2012) issued in 2012 on the calculation of the drawback; Trasformazioni rejected this demand. In the meantime, as a result of the conclusion of the European Commission Matter in January 2016 (see Note R to the Consolidated Financial Statements in Part II Item 8 of Alcoa Corporation’s Annual Report on Form 10-K for the year ended December 31, 2017), ParentCo’s management modified its outlook with respect to a portion of the then-pending legal proceedings related to the drawback dispute. As such, a charge of $37 (€34) was recorded in Restructuring and other charges for the year ended December 31, 2015 to establish a partial reserve for this matter. In December 2017, through an agreement with the Energy Authority, Alcoa Corporation settled this matter for $18 (€15) (paid in January 2018). Accordingly, the Company recorded a reduction of $22 (€19) (the U.S. dollar amount reflects the effects of foreign currency movements since 2015) to its previously established reserve in Restructuring and other charges (see Note D) on the accompanying Statement of Consolidated Operations. In January 2018, subsequent to making the previously referenced payment, Alcoa Corporation and the respective state attorney in Italy filed a joint request with the Regional Administrative Court for Lombardy to have this matter formally dismissed. On October 9, 2018, the court formally dismissed the case and this matter is now closed. Also in December 2017, as part of a separate but related agreement to the above, the Company agreed to transfer ownership of the Portovesme smelter (permanently closed in 2014) to Invitalia, an Italian government agency responsible for managing economic development. Under the provisions of the agreement, the Company will retain the responsibility for environmental-related obligations associated with decommissioning the Portovesme smelter (see below). The agreement further provides that the Company may be relieved of such obligations upon Invitalia exercising an option to receive a cash payment of $23 (€20) from the Company. Additionally, this agreement included a framework for the future settlement of a groundwater remediation project related to the Portovesme site (see Fusina and Portovesme, Italy in Environmental Matters below). In February 2018, the Company completed the transfer of ownership of the Portovesme smelter to Invitalia. The carrying value of the assets related to the Portovesme site were previously written down to zero as a direct result of ParentCo’s decision in 2014 to decommission the facility. In mid-2018, Invitalia sold the Portovesme smelter to SiderAlloys International S.A., a Switzerland company, which intends to restart the facility. In June 2018, Invitalia gave notice to the Company that it was exercising its option under the December 2017 agreement to receive the cash payment thereby releasing the Company from responsibility of all environmental-related obligations associated with a future decommissioning of the Portovesme smelter. The cash payment will be made in three installments, one in each of 2018 (paid $8 (€7) on June 18), 2019, and 2020. Accordingly, Alcoa Corporation recognized a $15 net benefit in Restructuring and other charges (see Note D) on the accompanying Statement of Consolidated Operations, comprised of (i) a $38 reversal of previously accrued asset retirement obligations ($36) and environmental reserves ($2) related to the Company’s former decommissioning plan for the Portovesme smelter, and (ii) a $23 charge to establish a liability for the planned cash payment to Invitalia. Environmental Matters. Alcoa Corporation participates in environmental assessments and cleanups at several locations. These include owned or operating facilities and adjoining properties, previously owned or operating facilities and adjoining properties, and waste sites, including Superfund (Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)) sites. A liability is recorded for environmental remediation when a cleanup program becomes probable and the costs can be reasonably estimated. As assessments and cleanups proceed, the liability is adjusted based on progress made in determining the extent of remedial actions and related costs. The liability can change substantially due to factors such as, among others, the nature and extent of contamination, changes in remedial requirements, and technological changes. Alcoa Corporation’s remediation reserve balance was $280 and $294 at December 31, 2018 and 2017 (of which $44 and $36 was classified as a current liability), respectively, and reflects the most probable costs to remediate identified environmental conditions for which costs can be reasonably estimated. In 2018, the remediation reserve was increased by $16 due to an increase of $9 related to the former Sherwin location (see below), a reversal of $2 (recorded in Restructuring and other charges) related to the Portovesme location (unrelated to the matter below – see Italy 148 in Litigation above), and a net charge of $9 ($7 and $2 were recorded in Cost of goods sold and Restructuring and other charges, respectively) associated with several sites. In 2017, the remediation reserve was increased by $1 due to a charge of $8 related to the planned demolition of the Rockdale smelter (see Note D), a combined reduction of $6 related to the Baie Comeau and Mosjøen locations (see below), a reversal of $4 related to the restart of the Warrick smelter (see Note D), and a net charge of $3 associated with several other sites. In 2016, the remediation reserve was increased by $39 due to a charge of $26 related to the planned demolition of the Suriname refinery and permanent closure of the related bauxite mines (see Note D) and a net charge of $13 associated with several other sites. Of the changes to the remediation reserve in 2017 and 2016, $4 and $26, respectively, was recorded in Restructuring and other charges, while the remainder was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. Payments related to remediation expenses applied against the reserve were $25, $48, and $32 in 2018, 2017, and 2016, respectively. These amounts include expenditures currently mandated, as well as those not required by any regulatory authority or third party. In 2018, the change in the reserve also reflects a decrease of $6 due to the effects of foreign currency translation and an increase of $1 for reclassifications made between this reserve and the Company’s liability for asset retirement obligations. In 2017, the change in the reserve also reflects an increase of $17, including $11 due to the effects of foreign currency translation and $5 for the reclassification of an amount previously included in Asset retirement obligations on Alcoa Corporation’s Consolidated Balance Sheet as of December 31, 2016. In 2016, the change in the reserve also reflects an increase for each of the following: $60 of obligations transferred from ParentCo in connection with the Separation Transaction on November 1, 2016, including Sherwin and East St. Louis described below; $17 for the reclassification of amounts included in other reserves within Other noncurrent liabilities and deferred credits on Alcoa Corporation’s Consolidated Balance Sheet as of December 31, 2015; and $5 due to the effects of foreign currency translation. The Separation and Distribution Agreement includes provisions for the assignment or allocation of environmental liabilities between Alcoa Corporation and Arconic, including certain remediation obligations associated with environmental matters. In general, the respective parties are responsible for the environmental matters associated with their operations, and with the properties and other assets assigned to each. Additionally, the Separation and Distribution Agreement lists environmental matters with a shared responsibility between the two companies with an allocation of responsibility and the lead party responsible for management of each matter. For matters assigned to Alcoa Corporation and Arconic under the Separation and Distribution Agreement, the companies have agreed to indemnify each other in whole or in part for environmental liabilities arising from operations prior to the Separation Date. The following description provides details regarding the current status of certain significant reserves related to current or former Alcoa Corporation sites. With the exception of the Fusina, Italy matter, Alcoa Corporation assumed full responsibility of the matters described below. General—The Company is in the process of decommissioning various plants in several countries. As a result, redeveloping these sites for reuse or returning the land to a natural state requires the performance of certain remediation activities. In aggregate, the majority of these activities will be completed at various times in the future with the latest expected to be in 2026, after which ongoing monitoring and other activities will be required. At December 31, 2018 and 2017, the reserve balance associated with these activities was $132 and $150, respectively. Sherwin, TX—In connection with ParentCo’s sale of the Sherwin alumina refinery, which was required to be divested as part of ParentCo’s acquisition of Reynolds Metals Company in 2000, ParentCo agreed to retain responsibility for the remediation of the then-existing environmental conditions, as well as a pro rata share of the final closure of the active bauxite residue waste disposal areas (known as the Copano facility). All ParentCo obligations regarding the Sherwin refinery and Copano facility were transferred from ParentCo to Alcoa Corporation as part of the Separation Transaction on November 1, 2016. Since October 2016, Reynolds Metals Company, a subsidiary of Alcoa Corporation, had been involved in a legal dispute with the owner of Sherwin related to the allocation of responsibility for the environmental obligations at this site. In April 2018, Reynolds Metals Company reached a settlement agreement with the owner of Sherwin, as well as a separate agreement with the Texas Commission on Environmental Quality, that revised the environmental responsibilities and obligations for each related to the Sherwin refinery site and Copano facility. These agreements became effective on May 21, 2018. Accordingly, the Company increased the reserve associated with this matter by $9 to reflect certain incremental obligations under the agreements. At December 31, 2018 and 2017, the reserve balance associated with this matter was $38 and $29, respectively. In management’s judgment, the Company’s reserve as of December 31, 2018 is sufficient to satisfy the provisions of the settlement agreements. Upon changes in facts or circumstances, a change to the reserve may be required. See “Sherwin” in the Other section below for a complete description of this matter. Baie Comeau, Quebec, Canada—Alcoa Corporation has a remediation project related to known polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) contained in sediments of the Anse du Moulin bay, which is near the Company’s Baie Comeau smelter. The project, which was approved by the Quebec Ministry of Sustainable Development, Environment, Wildlife and Parks through a final ministerial decree issued in July 2015, is aimed at dredging and capping of the contaminated sediments. The project work began in April 2017 and was virtually completed in December 2017. At the end of 2017, the Company decreased the reserve for Baie Comeau by $4 to reflect the final cost estimate of the remaining work and the subsequent monitoring program, which is expected to last through 2023. At December 31, 2018 and 2017, the reserve balance associated with this matter was $3 and $5, respectively. Fusina and Portovesme, Italy—The following matters are in regards to an order issued in 2004 to Alcoa Trasformazioni S.r.l. (“Trasformazioni”) (Trasformazioni is now a subsidiary of Alcoa Corporation and owns the Fusina smelter and Portovesme smelter (until February 2017 – see Italy 148 in Litigation above) sites, and Fusina Rolling S.r.l., a new ParentCo subsidiary, now owns the Fusina rolling operations) by the Italian Ministry of Environment and Protection of Land and Sea (the “MOE”) for the development of a clean-up plan related to soil and groundwater contamination in excess of allowable limits under legislative decree and, for only the Fusina site, to institute emergency actions and pay natural resource damages. For the Fusina site, Trasformazioni has a soil and groundwater remediation project, which was approved by the MOE through a final ministerial decree issued in August 2014. Additionally, under an administrative agreement reached in February 2014 with the MOE, Trasformazioni is required to make annual payments over a 10-year period for groundwater emergency containment and natural resource damages related to the Fusina site. Trasformazioni began work on the soil remediation project in October 2017 and expects to complete the project by the end of 2019. The MOE assumed the responsibility for the execution of the groundwater remediation/emergency containment in accordance with the February 2014 settlement agreement, as part of a regional effort by the MOE, and project work is slated to begin in 2020. At December 31, 2018 and 2017, the reserve balance associated with all of the foregoing Fusina-related matters (excluding a portion related to the rolling operations – see below) was $5 and $8, respectively. Effective with the Separation Transaction, Arconic retained the portion of Trasformazioni’s obligation related to the Fusina rolling operations. Specifically, under the Separation and Distribution Agreement, Trasformazioni, and with it the Fusina properties, were assigned to Alcoa Corporation. Fusina Rolling S.r.l., entered into a lease agreement for the portion of property that included the rolling operations. Pursuant to the Separation and Distribution Agreement, the liabilities at Fusina described above were allocated between Alcoa Corporation (Trasformazioni) and Arconic (Fusina Rolling S.r.l.). For the Portovesme site, Trasformazioni has a soil remediation project, which was approved by the MOE through a final ministerial decree issued in October 2015. Project work on the soil remediation project commenced in mid-2016 and is expected to be completed by the end of 2019. Additionally, Trasformazioni, along with four other entities that operated in the same industrial park, have submitted a groundwater remediation project, which was preliminarily approved in 2010 by the MOE. Since that time, the parties have performed additional studies and work to be incorporated into the final remedial design. In December 2017, a framework for the future settlement of the groundwater remediation project was included within an agreement to transfer the ownership of the Portovesme smelter to an Italian government agency (see Italy 148 in Litigation above). The MOE has confirmed its acceptance of the proposal set out in the framework; however, the total cost of the groundwater remediation project will not be determined until the final remedial design is completed in mid-2019. The ultimate outcome of this matter may result in a change to the existing reserve for Portovesme. At December 31, 2018 and 2017, the reserve balance associated with all of the foregoing Portovesme-related matters was $12 and $16, respectively. Mosjøen, Norway—Alcoa Corporation has a remediation project related to known PAHs in the sediments located in the harbor and extending out into the fjord, which are near the Company’s Mosjøen smelter. The project, which was approved by the Norwegian Environmental Agency through a final order issued in June 2015, is aimed at dredging and capping of the contaminated sediments. In order to allow for the sediment dredging in the harbor, the project also includes stabilization of the wharf. Project work commenced in early 2016 and the main portion of such work was completed in the second half of 2017. At that time, the Company reexamined its cost estimate for the remaining project work, resulting in a reduction of the reserve associated with this matter by $2. In mid-2018, the remaining project work was completed. At December 31, 2018, there is a small reserve balance for required ongoing reporting and monitoring activities. At December 31, 2017, the reserve balance associated with this matter was $2. East St. Louis, IL—Alcoa Corporation has an ongoing remediation project related to an area used for the disposal of bauxite residue from ParentCo’s former alumina refining operations. The project, which was selected by the U.S. Environmental Protection Agency (EPA) in a Record of Decision issued in July 2012 and approved in a consent decree entered as final in February 2014 by the U.S. Department of Justice, is aimed at implementing a soil cover over the affected area. As a result, ParentCo began the project work in March 2014; the fieldwork on a majority of this project was completed by the end of June 2016. A completion report was approved by the EPA in September 2016 and this matter, for the completed portion of the project, transitioned into a long-term (approximately 30 years) inspection, maintenance, and monitoring program. Fieldwork for the remaining portion of the project is expected to be completed in 2020, at which time it would also transition into a long-term inspection, maintenance, and monitoring program. This obligation was transferred from ParentCo to Alcoa Corporation as part of the Separation Transaction on November 1, 2016. At December 31, 2018 and 2017, the reserve balance associated with this matter was $3 and $4, respectively. Tax. Spain—In July 2013, following a corporate income tax audit covering the 2006 through 2009 tax years, an assessment was received as a result of Spain’s tax authorities disallowing certain interest deductions claimed by a former Spanish consolidated tax group previously owned by ParentCo. The following month, ParentCo filed an appeal of this assessment in Spain’s Central Tax Administrative Court. In conjunction with this appeal, as required under Spanish tax law, ParentCo provided financial assurance in this matter in the form of both a bank guarantee (Arconic) and a lien secured with the San Ciprian smelter (Alcoa Corporation) to Spain’s tax authorities. In January 2015, Spain’s Central Tax Administrative Court denied ParentCo’s appeal of this assessment. Two months later, ParentCo filed an appeal of the assessment in Spain’s National Court (the “National Court”). The amount of this assessment, including interest, was $152 (€131) as of June 30, 2018. On July 6, 2018, the National Court denied ParentCo’s appeal of the assessment; however, the decision includes a requirement that Spain’s tax authorities issue a new assessment, which considers available net operating losses of the former Spanish consolidated tax group from prior tax years that can be utilized during the assessed tax years. Spain’s tax authorities will not issue a new assessment until this matter is resolved; however, based on estimated calculations completed by Arconic and Alcoa Corporation (collectively, the “Companies”), the amount of the new assessment, including applicable interest, is expected to be in the range of $25 to $61 (€21 to €53) after consideration of available net operating losses and tax credits. Under the Tax Matters Agreement related to the Separation Transaction, Arconic and Alcoa Corporation are responsible for 51% and 49%, respectively, of the assessed amount in the event of an unfavorable outcome. On July 12, 2018, the Companies sent a letter to the National Court seeking clarification on one part of the decision. A response was received from the National Court on October 1, 2018, resulting in no change to its July 6, 2018 decision. On November 8, 2018, the Companies filed a petition for appeal to Spain’s Supreme Court, to which Spain’s tax authorities have filed their opposition. Notwithstanding the petition for appeal, based on a review of the bases on which the National Court decided this matter, Alcoa Corporation management no longer believes that the Companies are more likely than not (greater than 50%) to prevail in this matter. Accordingly, Alcoa Corporation recorded a charge of $30 (€26) in Provision for income taxes on the accompanying Statement of Consolidated Operations to establish a liability for its 49% share of the estimated loss in this matter, representing management’s best estimate at this time. As indicated above, at a future point in time, the Companies will receive an updated assessment from Spain’s tax authorities, which may result in a change to management’s estimate following further analysis. Separately, in January 2017, the National Court issued a decision in favor of the former Spanish consolidated tax group related to a similar assessment for the 2003 through 2005 tax years, effectively making that assessment null and void. Additionally, in August 2017, in lieu of receiving a formal assessment, the Companies reached a settlement with Spain’s tax authorities for the 2010 through 2013 tax years that had been under audit for a similar matter. Alcoa Corporation’s share of this settlement was not material to the Company’s Consolidated Financial Statements. The ultimate outcomes related to the 2003 through 2005 and the 2010 through 2013 tax years are not indicative of the potential ultimate outcome of the assessment for the 2006 through 2009 tax years due to procedural differences. Also, it is possible that the Companies may receive similar assessments for tax years subsequent to 2013; however, management does not expect any such assessment, if received, to be material to Alcoa Corporation’s Consolidated Financial Statements. Brazil (AWAB)—In March 2013, AWAB was notified by the Brazilian Federal Revenue Office (RFB) that approximately $110 (R$220) of value added tax credits previously claimed are being disallowed and a penalty of 50% assessed. Of this amount, AWAB received $41 (R$82) in cash in May 2012. The value-added tax credits were claimed by AWAB for both fixed assets and export sales related to the Juruti bauxite mine and São Luís refinery expansion. The RFB has disallowed credits they allege belong to the consortium in which AWAB owns an interest and should not have been claimed by AWAB. Credits have also been disallowed as a result of challenges to apportionment methods used, questions about the use of the credits, and an alleged lack of documented proof. AWAB presented defense of its claim to the RFB on April 8, 2013. If AWAB is successful in this administrative process, the RFB would have no further recourse. If unsuccessful in this process, AWAB has the option to litigate at a judicial level. Separately from AWAB’s administrative appeal, in June 2015, new tax law was enacted repealing the provisions in the tax code that were the basis for the RFB assessing a 50% penalty in this matter. As such, the estimated range of reasonably possible loss is $0 to $27 (R$103), whereby the maximum end of the range represents the portion of the disallowed credits applicable to the export sales and excludes the 50% penalty. Additionally, the estimated range of disallowed credits related to AWAB’s fixed assets is $0 to $30 (R$117), which would increase the net carrying value of AWAB’s fixed assets if ultimately disallowed. It is management’s opinion that the allegations have no basis; however, at this time, the Company is unable to reasonably predict an outcome for this matter. Brazil (Alumínio)—Between 2000 and 2002, Alumínio sold approximately 2,000 metric tons of metal per month from its Poços de Caldas facility, located in the State of Minas Gerais (the “State”), Brazil, to Alfio, a customer also located in the State. Sales in the State were exempted from value-added tax (VAT) requirements. Alfio subsequently sold metal to customers outside of the State, but did not pay the required VAT on those transactions. In July 2002, Alumínio received an assessment from State auditors on the theory that Alumínio should be jointly and severally liable with Alfio for the unpaid VAT. In June 2003, the administrative tribunal found Alumínio liable, and Alumínio filed a judicial case in the State in February 2004 contesting the finding. In May 2005, the Court of First Instance found Alumínio solely liable, and a panel of a State appeals court confirmed this finding in April 2006. Alumínio filed a special appeal to the Superior Tribunal of Justice (STJ) in Brasilia (the federal capital of Brazil) later in 2006. In 2011, the STJ (through one of its judges) reversed the judgment of the lower courts, finding that Alumínio should neither be solely nor jointly and severally liable with Alfio for the VAT, which ruling was then appealed by the State. In August 2012, the STJ agreed to have the case reheard before a five-judge panel. On February 21, 2017, the lead judge of the STJ issued a ruling confirming that Alumínio should be held liable in this matter. On March 16, 2017, Alumínio filed an appeal to have its case reheard before the five-judge panel as originally agreed to by the STJ in August 2012. Separately, in June 2017, the State opened a tax amnesty program. At the end of August 2017, Alumínio elected to submit this matter for consideration into the amnesty program, which the State approved. As a result, under the terms of the amnesty program, this matter was settled for $8 (R$25). In 2017, a charge for the settlement amount was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. Prior to submitting this matter for consideration into the amnesty program, the assessment, including penalties and interest, totaled $46 (R$145). This matter is now closed. Other. Reynolds—On January 11, 2016, Sherwin Alumina Company, LLC (“Sherwin”), the current owner of a refinery previously owned by ParentCo (see below), and one of its affiliate entities, filed bankruptcy petitions in Corpus Christi, Texas for reorganization under Chapter 11 of the U.S. Bankruptcy Code. Sherwin informed the bankruptcy court that it intends to cease operations because it is not able to continue its bauxite supply agreement. On November 23, 2016, the bankruptcy court approved Sherwin’s plans for cessation of its operations. On February 16, 2017, Sherwin filed a bankruptcy Chapter 11 Plan (the “Plan”) and, on February 17, 2017, the court approved that Plan. In 2000, ParentCo acquired Reynolds Metals Company (“Reynolds,” a subsidiary of Alcoa Corporation), which included an alumina refinery in Gregory, Texas. As a condition of the Reynolds acquisition, ParentCo was required to divest this alumina refinery. In accordance with the terms of the divestiture in 2000, ParentCo agreed to retain responsibility for certain environmental obligations (see Sherwin, TX in Environmental Matters above) and assigned to the buyer an Energy Services Agreement (“ESA”) with Gregory Power Partners (“Gregory Power”) for purchase of steam and electricity by the refinery. Through the bankruptcy proceedings, the owner of Sherwin exercised its right under the U.S. Bankruptcy Code to reject the agreement from 2000 containing the previously mentioned retained responsibility, which had the effect of terminating all rights and responsibilities of the parties to the agreement. As a result of Sherwin’s initial bankruptcy filing, separate legal actions were initiated against Reynolds by Gregory Power and Sherwin as described below. Gregory Power: On January 26, 2016, Gregory Power delivered notice to Reynolds that Sherwin’s bankruptcy filing constitutes a breach of the ESA; on January 29, 2016, Reynolds responded that the filing does not constitute a breach. On September 16, 2016, Gregory Power filed a complaint in the bankruptcy case against Reynolds alleging breach of the ESA. In response to this complaint, on November 10, 2016, Reynolds filed both a motion to dismiss, including a jury demand, and a motion to withdraw the reference to the bankruptcy court based on the jury demand. On July 18, 2017, the district court ordered that any trial would be held to a jury in district court, but that the bankruptcy court would retain jurisdiction on all pre-trial matters. Since that time, Gregory Power filed an amended complaint to include Allied Alumina LLC (“Allied”), the successor to the original purchaser of the refinery from Reynolds. In September 2018, Reynolds and Allied filed their respective answers to the amended complaint, and Allied filed a cross complaint against Reynolds, which was answered by Reynolds on October 15, 2018. The court has yet to rule on several pending pretrial matters. At this time, Alcoa Corporation is unable to reasonably predict the ultimate outcome of this matter. Sherwin: On October 4, 2016, the Texas Commission on Environmental Quality (TCEQ) filed suit against Sherwin in the bankruptcy proceeding seeking to hold Sherwin responsible for remediation of alleged environmental conditions at the Sherwin refinery site and related bauxite residue waste disposal areas (known as the Copano facility). On October 11, 2016, Sherwin filed a similar suit against Reynolds in the case. As provided in the Plan, Sherwin, including certain affiliated companies, and Reynolds had been negotiating an allocation among them as to the ownership of and responsibility for certain areas of the refinery and the Copano facility. In March 2018, Reynolds and Sherwin reached a settlement agreement that assigns to Reynolds all environmental liabilities associated with the Copano facility and assigns to Sherwin all environmental liabilities associated with the Sherwin refinery site. Additionally, Reynolds and the TCEQ reached an agreement that defines the operating and environmental steps required for the Copano facility, which Reynolds intends to operate for the purpose of managing materials other than bauxite residue waste, including third-party dredge material. The effectiveness and enforceability of each of these two agreements are pre-conditioned on the other being accepted by the bankruptcy court. A public notice and comment period on these agreements expired on April 26, 2018 without material affect to the documents. On June 5, 2018, the bankruptcy court accepted and entered the agreements into the judicial record as submitted (May 21, 2018 serves as the “effective date” for both agreements). On June 5, 2018, the transaction between Sherwin and Reynolds was completed. Under the agreement with Sherwin, in exchange for assuming full responsibility for the environmental-related liabilities (see below related to the Company’s existing reserve) associated with the Copano facility, Reynolds assumed ownership of the land that comprises the Copano facility, as well as land that serves as a buffer around the Copano facility and other related assets. A third-party appraisal estimated the fair value of the land and other assets to be $16. Under the agreement with TCEQ, a portion of the Copano facility must be closed within 10 years and the remaining portion must be closed within 30 years, both timeframes began on the effective date. Also, Reynolds is required to install upgrades to certain dust control systems and repair certain structures and drainage systems at the Copano facility, and prepare and submit to TCEQ a preliminary groundwater assessment report (submitted on November 5, 2018) and a drinking water survey report (waived due to no evidence of a contaminant release) related to the Copano facility within 180 days of the effective date. Accordingly, the Company recognized $16 in properties, plants, and equipment, $9 in environmental remediation liabilities, and $7 in other related liabilities. Additionally, the Company paid $12 into a trust managed by the state of Texas as financial assurance of the Company’s performance in completing the required obligations. This amount will be returned to the Company upon satisfactory completion of the future closure of the Copano facility in accordance with all applicable laws and regulations. On June 7, 2018, Sherwin filed a notice of dismissal in the suit against Reynolds; the dismissal was immediately effective as no court order was required. At the time the agreements were signed by all parties, the Company had a reserve of $29 for its proportionate share of environmental-related matters at both the Sherwin refinery site and the Copano facility based on the terms of the divestiture of the Sherwin refinery in 2000 (see Sherwin, TX in Environmental Matters above). While Reynolds no longer has any responsibility for environmental-related matters at the Sherwin refinery site, it assumed additional responsibility for environmental-related matters at the Copano facility ($9 – see above). In management’s judgment, the $38 reserve as of December 31, 2018 is sufficient to satisfy the Company’s revised responsibilities and obligations under the settlement agreements. Upon changes in facts or circumstances, a change to the reserve may be required. Suralco—On December 16, 2016, Boskalis International B.V. (Boskalis) initiated a binding arbitration proceeding against Suriname Aluminum Company, LLC (Suralco), an AWAC company, seeking $47 plus prejudgment interest and associated taxes in connection with a dispute arising under a contract for mining services in Suriname between Boskalis and Suralco. Boskalis asserted four separate claims under the contract. In February 2018, the arbitration hearing was held before a three-person panel under the rules of the International Chamber of Commerce. The panel issued its decision on May 29, 2018, finding in favor of Boskalis on two claims and against Boskalis on two claims. For the two claims on which Boskalis prevailed, the panel awarded Boskalis $29, including prejudgment interest of $3. The award is final and cannot be appealed. Accordingly, Alcoa Corporation recorded a charge of $29 ($17 after noncontrolling interest), including $26 in Cost of goods sold and $3 in Interest expense on the accompanying Statement of Consolidated Operations. On June 6, 2018, the Company made the $29 cash payment to Boskalis closing this matter. The claim that represented the majority of the arbitration award centered around a contract provision requiring Suralco to make a “true up” payment at the end of the contract in the event that Suralco was unable to receive delivery of the full contract quantity, thus allowing Boskalis to recover its fixed production costs and a suitable return on its investment. While Suralco argued that all required deliveries had been made during the amended contract term and that no “true up” payment was required because a “true up” would amount to a double payment for bauxite deliveries after the initial contract term, Boskalis argued that the deliveries were not made within the original contract term and thus, a “true up” payment was required. On the basis of its analysis of the facts and applicable law, management concluded that the likelihood of an unfavorable decision on Boskalis’ claims was remote (25% or less). Throughout the course of the proceeding, and even after the conclusion of the hearing, management’s judgment of the likelihood of an unfavorable outcome remained the same. General. In addition to the matters discussed above, various other lawsuits, claims, and proceedings have been or may be instituted or asserted against Alcoa Corporation, including those pertaining to environmental, safety and health, commercial, tax, product liability, intellectual property infringement, employment, and employee and retiree benefit matters, and other actions and claims arising out of the normal course of business. While the amounts claimed in these other matters may be substantial, the ultimate liability is not readily determinable because of the considerable uncertainties that exist. Accordingly, it is possible that the Company’s liquidity or results of operations in a particular period could be materially affected by one or more of these other matters. However, based on facts currently available, management believes that the disposition of these other matters that are pending or asserted will not have a material adverse effect, individually or in the aggregate, on the financial position of the Company. Commitments Purchase Obligations. Alcoa Corporation is party to unconditional purchase obligations for energy that expire between 2028 and 2037. Commitments related to these contracts total $151 in 2019, $209 in 2020, $213 in 2021, $217 in 2022, $223 in 2023, and $2,718 thereafter. Expenditures under these contracts totaled $169 in 2018, $199 in 2017, and $181 in 2016. Additionally, the Company has entered into other purchase commitments for energy, raw materials, and other goods and services, which total $1,886 in 2019, $1,312 in 2020, $1,229 in 2021, $1,313 in 2022, $1,315 in 2023, and $11,302 thereafter. AofA has a gas supply agreement to power its three alumina refineries in Western Australia beginning in July 2020 for a 12-year period. The terms of this agreement required AofA to make a prepayment of $500 in two installments, the first of which was made in June 2015 for $300. The second installment of $200 was made in April 2016 and was included in (Increase) in noncurrent assets on the accompanying Statement of Consolidated Cash Flows. At December 31, 2018 and 2017, Alcoa Corporation has an asset of $458 (A$654) and $510 (A$654), respectively, which was included in Other noncurrent assets (see Note S) on the accompanying Consolidated Balance Sheet. Operating Leases. Certain land and buildings, alumina refinery process control technology, plant equipment, vehicles, and computer equipment are under operating lease agreements. Total expense for all leases was $102 in 2018, $101 in 2017, and $90 in 2016. Under long-term operating leases, minimum annual lease payments (undiscounted) are $74 in 2019, $56 in 2020, $42 in 2021, $11 in 2022, $5 in 2023, and $21 thereafter. Guarantees of Third Parties. At December 31, 2018, the Company has maximum potential future payments for guarantees issued on behalf of a third party of $60. These guarantees expire at various times between 2018 and 2021 and relate to project financing for the aluminum complex in Saudi Arabia (see Note H). Bank Guarantees and Letters of Credit. Alcoa Corporation has outstanding bank guarantees and letters of credit related to, among others, energy contracts, environmental obligations, legal and tax matters, outstanding debt, leasing obligations, workers compensation, and customs duties. The total amount committed under these instruments, which automatically renew or expire at various dates between 2019 and 2022, was $373 (includes $136 issued under a standby letter of credit agreement —see below) at December 31, 2018. Additionally, Arconic has outstanding bank guarantees and letters of credit related to the Company in the amount of $29 at December 31, 2018. In the event Arconic would be required to perform under any of these instruments, Arconic would be indemnified by Alcoa Corporation in accordance with the Separation and Distribution Agreement. Likewise, the Company has outstanding bank guarantees and letters of credit related to Arconic in the amount of $15 at December 31, 2018. In the event Alcoa Corporation would be required to perform under any of these instruments, the Company would be indemnified by Arconic in accordance with the Separation and Distribution Agreement. In August 2017, Alcoa Corporation entered into a standby letter of credit agreement, which expires on August 17, 2019 (extended in August 2018), with three financial institutions. The agreement provides for a $150 facility, which will be used by the Company for matters in the ordinary course of business. Alcoa Corporation’s obligations under this facility will be secured in the same manner as obligations under the Company’s Second Amended Revolving Credit Agreement (see Note L). Additionally, this facility contains similar representations and warranties and affirmative, negative, and financial covenants as the Company’s Second Amended Revolving Credit Agreement (see Note L). As of December 31, 2018, letters of credit aggregating $136 were issued under this facility. Surety Bonds. Alcoa Corporation has outstanding surety bonds primarily related to tax matters, contract performance, workers compensation, environmental-related matters, and customs duties. The total amount committed under these bonds, which automatically renew or expire at various dates, mostly in 2019, was $40 at December 31, 2018. Additionally, Arconic has outstanding surety bonds related to the Company in the amount of $16 at December 31, 2018. In the event Arconic would be required to perform under any of these instruments, Arconic would be indemnified by Alcoa Corporation in accordance with the Separation and Distribution Agreement. Likewise, the Company has outstanding surety bonds related to Arconic in the amount of $2 at December 31, 2018. In the event Alcoa Corporation would be required to perform under any of these instruments, the Company would be indemnified by Arconic in accordance with the Separation and Distribution Agreement.

Contingencies and Commitments

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

R. Contingencies and Commitments

Unless specifically described to the contrary, all matters within Note R are the full responsibility of Alcoa Corporation pursuant to the Separation and Distribution Agreement. Additionally, the Separation and Distribution Agreement provides for cross-indemnities between the Company and Arconic for claims subject to indemnification.

Contingencies

Litigation.

Italy 148—Beginning in 2006, ParentCo and the Italian Energy Authority (Autorità di Regolazione per Energia Reti e Ambiente, formerly l’Autorità per l’Energia Elettrica, il Gas e il Sistema Idrico, the “Energy Authority”) had been in a dispute regarding the calculation of a drawback applied to a portion of the price of power under a special tariff received by Alcoa Trasformazioni S.r.l. (“Trasformazioni,” previously a subsidiary of ParentCo; now a subsidiary of Alcoa Corporation). This dispute arose as a result of a resolution (148/2004) issued in 2004 by the Energy Authority that changed the method for calculating the drawback. Through 2009, Trasformazioni continued to receive the power price drawback for its Portovesme and Fusina smelters in accordance with the original resolution (204/1999), at which time the European Commission declared all such special tariffs to be impermissible “state aid.” Between 2006 and 2014, several judicial hearings occurred related to continuous appeals filed by both ParentCo and the Energy Authority regarding the dispute on the calculation of the drawback; a hearing on the latest appeal was scheduled for May 2018 (see below). Additionally, between 2012 and 2013, Trasformazioni received multiple letters from the agency responsible for making and collecting payments on behalf of the Energy Authority demanding payment for the difference in the drawback calculation between the two resolutions. The latest such demand was for $97 (€76), including interest, and allegedly included consideration of a third resolution (44/2012) issued in 2012 on the calculation of the drawback; Trasformazioni rejected this demand.

In the meantime, as a result of the conclusion of the European Commission Matter in January 2016 (see Note R to the Consolidated Financial Statements in Part II Item 8 of Alcoa Corporation’s Annual Report on Form 10-K for the year ended December 31, 2017), ParentCo’s management modified its outlook with respect to a portion of the then-pending legal proceedings related to the drawback dispute. As such, a charge of $37 (€34) was recorded in Restructuring and other charges for the year ended December 31, 2015 to establish a partial reserve for this matter.

In December 2017, through an agreement with the Energy Authority, Alcoa Corporation settled this matter for $18 (€15) (paid in January 2018). Accordingly, the Company recorded a reduction of $22 (€19) (the U.S. dollar amount reflects the effects of foreign currency movements since 2015) to its previously established reserve in Restructuring and other charges (see Note D) on the accompanying Statement of Consolidated Operations. In January 2018, subsequent to making the previously referenced payment, Alcoa Corporation and the respective state attorney in Italy filed a joint request with the Regional Administrative Court for Lombardy to have this matter formally dismissed. On October 9, 2018, the court formally dismissed the case and this matter is now closed.

Also in December 2017, as part of a separate but related agreement to the above, the Company agreed to transfer ownership of the Portovesme smelter (permanently closed in 2014) to Invitalia, an Italian government agency responsible for managing economic development. Under the provisions of the agreement, the Company will retain the responsibility for environmental-related obligations associated with decommissioning the Portovesme smelter (see below). The agreement further provides that the Company may be relieved of such obligations upon Invitalia exercising an option to receive a cash payment of $23 (€20) from the Company. Additionally, this agreement included a framework for the future settlement of a groundwater remediation project related to the Portovesme site (see Fusina and Portovesme, Italy in Environmental Matters below). In February 2018, the Company completed the transfer of ownership of the Portovesme smelter to Invitalia. The carrying value of the assets related to the Portovesme site were previously written down to zero as a direct result of ParentCo’s decision in 2014 to decommission the facility.

In mid-2018, Invitalia sold the Portovesme smelter to SiderAlloys International S.A., a Switzerland company, which intends to restart the facility. In June 2018, Invitalia gave notice to the Company that it was exercising its option under the December 2017 agreement to receive the cash payment thereby releasing the Company from responsibility of all environmental-related obligations associated with a future decommissioning of the Portovesme smelter. The cash payment will be made in three installments, one in each of 2018 (paid $8 (€7) on June 18), 2019, and 2020. Accordingly, Alcoa Corporation recognized a $15 net benefit in Restructuring and other charges (see Note D) on the accompanying Statement of Consolidated Operations, comprised of (i) a $38 reversal of previously accrued asset retirement obligations ($36) and environmental reserves ($2) related to the Company’s former decommissioning plan for the Portovesme smelter, and (ii) a $23 charge to establish a liability for the planned cash payment to Invitalia.

Environmental Matters. Alcoa Corporation participates in environmental assessments and cleanups at several locations. These include owned or operating facilities and adjoining properties, previously owned or operating facilities and adjoining properties, and waste sites, including Superfund (Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)) sites.

A liability is recorded for environmental remediation when a cleanup program becomes probable and the costs can be reasonably estimated. As assessments and cleanups proceed, the liability is adjusted based on progress made in determining the extent of remedial actions and related costs. The liability can change substantially due to factors such as, among others, the nature and extent of contamination, changes in remedial requirements, and technological changes.

Alcoa Corporation’s remediation reserve balance was $280 and $294 at December 31, 2018 and 2017 (of which $44 and $36 was classified as a current liability), respectively, and reflects the most probable costs to remediate identified environmental conditions for which costs can be reasonably estimated.

In 2018, the remediation reserve was increased by $16 due to an increase of $9 related to the former Sherwin location (see below), a reversal of $2 (recorded in Restructuring and other charges) related to the Portovesme location (unrelated to the matter below – see Italy 148 in Litigation above), and a net charge of $9 ($7 and $2 were recorded in Cost of goods sold and Restructuring and other charges, respectively) associated with several sites. In 2017, the remediation reserve was increased by $1 due to a charge of $8 related to the planned demolition of the Rockdale smelter (see Note D), a combined reduction of $6 related to the Baie Comeau and Mosjøen locations (see below), a reversal of $4 related to the restart of the Warrick smelter (see Note D), and a net charge of $3 associated with several other sites. In 2016, the remediation reserve was increased by $39 due to a charge of $26 related to the planned demolition of the Suriname refinery and permanent closure of the related bauxite mines (see Note D) and a net charge of $13 associated with several other sites. Of the changes to the remediation reserve in 2017 and 2016, $4 and $26, respectively, was recorded in Restructuring and other charges, while the remainder was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations.

Payments related to remediation expenses applied against the reserve were $25, $48, and $32 in 2018, 2017, and 2016, respectively. These amounts include expenditures currently mandated, as well as those not required by any regulatory authority or third party. In 2018, the change in the reserve also reflects a decrease of $6 due to the effects of foreign currency translation and an increase of $1 for reclassifications made between this reserve and the Company’s liability for asset retirement obligations. In 2017, the change in the reserve also reflects an increase of $17, including $11 due to the effects of foreign currency translation and $5 for the reclassification of an amount previously included in Asset retirement obligations on Alcoa Corporation’s Consolidated Balance Sheet as of December 31, 2016. In 2016, the change in the reserve also reflects an increase for each of the following: $60 of obligations transferred from ParentCo in connection with the Separation Transaction on November 1, 2016, including Sherwin and East St. Louis described below; $17 for the reclassification of amounts included in other reserves within Other noncurrent liabilities and deferred credits on Alcoa Corporation’s Consolidated Balance Sheet as of December 31, 2015; and $5 due to the effects of foreign currency translation.

The Separation and Distribution Agreement includes provisions for the assignment or allocation of environmental liabilities between Alcoa Corporation and Arconic, including certain remediation obligations associated with environmental matters. In general, the respective parties are responsible for the environmental matters associated with their operations, and with the properties and other assets assigned to each. Additionally, the Separation and Distribution Agreement lists environmental matters with a shared responsibility between the two companies with an allocation of responsibility and the lead party responsible for management of each matter. For matters assigned to Alcoa Corporation and Arconic under the Separation and Distribution Agreement, the companies have agreed to indemnify each other in whole or in part for environmental liabilities arising from operations prior to the Separation Date.

The following description provides details regarding the current status of certain significant reserves related to current or former Alcoa Corporation sites. With the exception of the Fusina, Italy matter, Alcoa Corporation assumed full responsibility of the matters described below.

General—The Company is in the process of decommissioning various plants in several countries. As a result, redeveloping these sites for reuse or returning the land to a natural state requires the performance of certain remediation activities. In aggregate, the majority of these activities will be completed at various times in the future with the latest expected to be in 2026, after which ongoing monitoring and other activities will be required. At December 31, 2018 and 2017, the reserve balance associated with these activities was $132 and $150, respectively.

Sherwin, TX—In connection with ParentCo’s sale of the Sherwin alumina refinery, which was required to be divested as part of ParentCo’s acquisition of Reynolds Metals Company in 2000, ParentCo agreed to retain responsibility for the remediation of the then-existing environmental conditions, as well as a pro rata share of the final closure of the active bauxite residue waste disposal areas (known as the Copano facility). All ParentCo obligations regarding the Sherwin refinery and Copano facility were transferred from ParentCo to Alcoa Corporation as part of the Separation Transaction on November 1, 2016. Since October 2016, Reynolds Metals Company, a subsidiary of Alcoa Corporation, had been involved in a legal dispute with the owner of Sherwin related to the allocation of responsibility for the environmental obligations at this site. In April 2018, Reynolds Metals Company reached a settlement agreement with the owner of Sherwin, as well as a separate agreement with the Texas Commission on Environmental Quality, that revised the environmental responsibilities and obligations for each related to the Sherwin refinery site and Copano facility. These agreements became effective on May 21, 2018. Accordingly, the Company increased the reserve associated with this matter by $9 to reflect certain incremental obligations under the agreements. At December 31, 2018 and 2017, the reserve balance associated with this matter was $38 and $29, respectively. In management’s judgment, the Company’s reserve as of December 31, 2018 is sufficient to satisfy the provisions of the settlement agreements. Upon changes in facts or circumstances, a change to the reserve may be required. See “Sherwin” in the Other section below for a complete description of this matter.

Baie Comeau, Quebec, Canada—Alcoa Corporation has a remediation project related to known polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) contained in sediments of the Anse du Moulin bay, which is near the Company’s Baie Comeau smelter. The project, which was approved by the Quebec Ministry of Sustainable Development, Environment, Wildlife and Parks through a final ministerial decree issued in July 2015, is aimed at dredging and capping of the contaminated sediments. The project work began in April 2017 and was virtually completed in December 2017. At the end of 2017, the Company decreased the reserve for Baie Comeau by $4 to reflect the final cost estimate of the remaining work and the subsequent monitoring program, which is expected to last through 2023. At December 31, 2018 and 2017, the reserve balance associated with this matter was $3 and $5, respectively.

Fusina and Portovesme, Italy—The following matters are in regards to an order issued in 2004 to Alcoa Trasformazioni S.r.l. (“Trasformazioni”) (Trasformazioni is now a subsidiary of Alcoa Corporation and owns the Fusina smelter and Portovesme smelter (until February 2017 – see Italy 148 in Litigation above) sites, and Fusina Rolling S.r.l., a new ParentCo subsidiary, now owns the Fusina rolling operations) by the Italian Ministry of Environment and Protection of Land and Sea (the “MOE”) for the development of a clean-up plan related to soil and groundwater contamination in excess of allowable limits under legislative decree and, for only the Fusina site, to institute emergency actions and pay natural resource damages.

For the Fusina site, Trasformazioni has a soil and groundwater remediation project, which was approved by the MOE through a final ministerial decree issued in August 2014. Additionally, under an administrative agreement reached in February 2014 with the MOE, Trasformazioni is required to make annual payments over a 10-year period for groundwater emergency containment and natural resource damages related to the Fusina site. Trasformazioni began work on the soil remediation project in October 2017 and expects to complete the project by the end of 2019. The MOE assumed the responsibility for the execution of the groundwater remediation/emergency containment in accordance with the February 2014 settlement agreement, as part of a regional effort by the MOE, and project work is slated to begin in 2020. At December 31, 2018 and 2017, the reserve balance associated with all of the foregoing Fusina-related matters (excluding a portion related to the rolling operations – see below) was $5 and $8, respectively.

Effective with the Separation Transaction, Arconic retained the portion of Trasformazioni’s obligation related to the Fusina rolling operations. Specifically, under the Separation and Distribution Agreement, Trasformazioni, and with it the Fusina properties, were assigned to Alcoa Corporation. Fusina Rolling S.r.l., entered into a lease agreement for the portion of property that included the rolling operations. Pursuant to the Separation and Distribution Agreement, the liabilities at Fusina described above were allocated between Alcoa Corporation (Trasformazioni) and Arconic (Fusina Rolling S.r.l.).

For the Portovesme site, Trasformazioni has a soil remediation project, which was approved by the MOE through a final ministerial decree issued in October 2015. Project work on the soil remediation project commenced in mid-2016 and is expected to be completed by the end of 2019. Additionally, Trasformazioni, along with four other entities that operated in the same industrial park, have submitted a groundwater remediation project, which was preliminarily approved in 2010 by the MOE. Since that time, the parties have performed additional studies and work to be incorporated into the final remedial design. In December 2017, a framework for the future settlement of the groundwater remediation project was included within an agreement to transfer the ownership of the Portovesme smelter to an Italian government agency (see Italy 148 in Litigation above). The MOE has confirmed its acceptance of the proposal set out in the framework; however, the total cost of the groundwater remediation project will not be determined until the final remedial design is completed in mid-2019. The ultimate outcome of this matter may result in a change to the existing reserve for Portovesme. At December 31, 2018 and 2017, the reserve balance associated with all of the foregoing Portovesme-related matters was $12 and $16, respectively.

Mosjøen, Norway—Alcoa Corporation has a remediation project related to known PAHs in the sediments located in the harbor and extending out into the fjord, which are near the Company’s Mosjøen smelter. The project, which was approved by the Norwegian Environmental Agency through a final order issued in June 2015, is aimed at dredging and capping of the contaminated sediments. In order to allow for the sediment dredging in the harbor, the project also includes stabilization of the wharf. Project work commenced in early 2016 and the main portion of such work was completed in the second half of 2017. At that time, the Company reexamined its cost estimate for the remaining project work, resulting in a reduction of the reserve associated with this matter by $2. In mid-2018, the remaining project work was completed. At December 31, 2018, there is a small reserve balance for required ongoing reporting and monitoring activities. At December 31, 2017, the reserve balance associated with this matter was $2.

East St. Louis, IL—Alcoa Corporation has an ongoing remediation project related to an area used for the disposal of bauxite residue from ParentCo’s former alumina refining operations. The project, which was selected by the U.S. Environmental Protection Agency (EPA) in a Record of Decision issued in July 2012 and approved in a consent decree entered as final in February 2014 by the U.S. Department of Justice, is aimed at implementing a soil cover over the affected area. As a result, ParentCo began the project work in March 2014; the fieldwork on a majority of this project was completed by the end of June 2016. A completion report was approved by the EPA in September 2016 and this matter, for the completed portion of the project, transitioned into a long-term (approximately 30 years) inspection, maintenance, and monitoring program. Fieldwork for the remaining portion of the project is expected to be completed in 2020, at which time it would also transition into a long-term inspection, maintenance, and monitoring program. This obligation was transferred from ParentCo to Alcoa Corporation as part of the Separation Transaction on November 1, 2016. At December 31, 2018 and 2017, the reserve balance associated with this matter was $3 and $4, respectively.

Tax.

Spain—In July 2013, following a corporate income tax audit covering the 2006 through 2009 tax years, an assessment was received as a result of Spain’s tax authorities disallowing certain interest deductions claimed by a former Spanish consolidated tax group previously owned by ParentCo. The following month, ParentCo filed an appeal of this assessment in Spain’s Central Tax Administrative Court. In conjunction with this appeal, as required under Spanish tax law, ParentCo provided financial assurance in this matter in the form of both a bank guarantee (Arconic) and a lien secured with the San Ciprian smelter (Alcoa Corporation) to Spain’s tax authorities. In January 2015, Spain’s Central Tax Administrative Court denied ParentCo’s appeal of this assessment. Two months later, ParentCo filed an appeal of the assessment in Spain’s National Court (the “National Court”). The amount of this assessment, including interest, was $152 (€131) as of June 30, 2018.

On July 6, 2018, the National Court denied ParentCo’s appeal of the assessment; however, the decision includes a requirement that Spain’s tax authorities issue a new assessment, which considers available net operating losses of the former Spanish consolidated tax group from prior tax years that can be utilized during the assessed tax years. Spain’s tax authorities will not issue a new assessment until this matter is resolved; however, based on estimated calculations completed by Arconic and Alcoa Corporation (collectively, the “Companies”), the amount of the new assessment, including applicable interest, is expected to be in the range of $25 to $61 (€21 to €53) after consideration of available net operating losses and tax credits. Under the Tax Matters Agreement related to the Separation Transaction, Arconic and Alcoa Corporation are responsible for 51% and 49%, respectively, of the assessed amount in the event of an unfavorable outcome. On July 12, 2018, the Companies sent a letter to the National Court seeking clarification on one part of the decision. A response was received from the National Court on October 1, 2018, resulting in no change to its July 6, 2018 decision. On November 8, 2018, the Companies filed a petition for appeal to Spain’s Supreme Court, to which Spain’s tax authorities have filed their opposition.

Notwithstanding the petition for appeal, based on a review of the bases on which the National Court decided this matter, Alcoa Corporation management no longer believes that the Companies are more likely than not (greater than 50%) to prevail in this matter. Accordingly, Alcoa Corporation recorded a charge of $30 (€26) in Provision for income taxes on the accompanying Statement of Consolidated Operations to establish a liability for its 49% share of the estimated loss in this matter, representing management’s best estimate at this time. As indicated above, at a future point in time, the Companies will receive an updated assessment from Spain’s tax authorities, which may result in a change to management’s estimate following further analysis.

Separately, in January 2017, the National Court issued a decision in favor of the former Spanish consolidated tax group related to a similar assessment for the 2003 through 2005 tax years, effectively making that assessment null and void. Additionally, in August 2017, in lieu of receiving a formal assessment, the Companies reached a settlement with Spain’s tax authorities for the 2010 through 2013 tax years that had been under audit for a similar matter. Alcoa Corporation’s share of this settlement was not material to the Company’s Consolidated Financial Statements. The ultimate outcomes related to the 2003 through 2005 and the 2010 through 2013 tax years are not indicative of the potential ultimate outcome of the assessment for the 2006 through 2009 tax years due to procedural differences. Also, it is possible that the Companies may receive similar assessments for tax years subsequent to 2013; however, management does not expect any such assessment, if received, to be material to Alcoa Corporation’s Consolidated Financial Statements.

Brazil (AWAB)—In March 2013, AWAB was notified by the Brazilian Federal Revenue Office (RFB) that approximately $110 (R$220) of value added tax credits previously claimed are being disallowed and a penalty of 50% assessed. Of this amount, AWAB received $41 (R$82) in cash in May 2012. The value-added tax credits were claimed by AWAB for both fixed assets and export sales related to the Juruti bauxite mine and São Luís refinery expansion. The RFB has disallowed credits they allege belong to the consortium in which AWAB owns an interest and should not have been claimed by AWAB. Credits have also been disallowed as a result of challenges to apportionment methods used, questions about the use of the credits, and an alleged lack of documented proof. AWAB presented defense of its claim to the RFB on April 8, 2013. If AWAB is successful in this administrative process, the RFB would have no further recourse. If unsuccessful in this process, AWAB has the option to litigate at a judicial level. Separately from AWAB’s administrative appeal, in June 2015, new tax law was enacted repealing the provisions in the tax code that were the basis for the RFB assessing a 50% penalty in this matter. As such, the estimated range of reasonably possible loss is $0 to $27 (R$103), whereby the maximum end of the range represents the portion of the disallowed credits applicable to the export sales and excludes the 50% penalty. Additionally, the estimated range of disallowed credits related to AWAB’s fixed assets is $0 to $30 (R$117), which would increase the net carrying value of AWAB’s fixed assets if ultimately disallowed. It is management’s opinion that the allegations have no basis; however, at this time, the Company is unable to reasonably predict an outcome for this matter.

Brazil (Alumínio)—Between 2000 and 2002, Alumínio sold approximately 2,000 metric tons of metal per month from its Poços de Caldas facility, located in the State of Minas Gerais (the “State”), Brazil, to Alfio, a customer also located in the State. Sales in the State were exempted from value-added tax (VAT) requirements. Alfio subsequently sold metal to customers outside of the State, but did not pay the required VAT on those transactions. In July 2002, Alumínio received an assessment from State auditors on the theory that Alumínio should be jointly and severally liable with Alfio for the unpaid VAT. In June 2003, the administrative tribunal found Alumínio liable, and Alumínio filed a judicial case in the State in February 2004 contesting the finding. In May 2005, the Court of First Instance found Alumínio solely liable, and a panel of a State appeals court confirmed this finding in April 2006. Alumínio filed a special appeal to the Superior Tribunal of Justice (STJ) in Brasilia (the federal capital of Brazil) later in 2006. In 2011, the STJ (through one of its judges) reversed the judgment of the lower courts, finding that Alumínio should neither be solely nor jointly and severally liable with Alfio for the VAT, which ruling was then appealed by the State. In August 2012, the STJ agreed to have the case reheard before a five-judge panel. On February 21, 2017, the lead judge of the STJ issued a ruling confirming that Alumínio should be held liable in this matter. On March 16, 2017, Alumínio filed an appeal to have its case reheard before the five-judge panel as originally agreed to by the STJ in August 2012. Separately, in June 2017, the State opened a tax amnesty program. At the end of August 2017, Alumínio elected to submit this matter for consideration into the amnesty program, which the State approved. As a result, under the terms of the amnesty program, this matter was settled for $8 (R$25). In 2017, a charge for the settlement amount was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. Prior to submitting this matter for consideration into the amnesty program, the assessment, including penalties and interest, totaled $46 (R$145). This matter is now closed.

Other.

Reynolds—On January 11, 2016, Sherwin Alumina Company, LLC (“Sherwin”), the current owner of a refinery previously owned by ParentCo (see below), and one of its affiliate entities, filed bankruptcy petitions in Corpus Christi, Texas for reorganization under Chapter 11 of the U.S. Bankruptcy Code. Sherwin informed the bankruptcy court that it intends to cease operations because it is not able to continue its bauxite supply agreement. On November 23, 2016, the bankruptcy court approved Sherwin’s plans for cessation of its operations. On February 16, 2017, Sherwin filed a bankruptcy Chapter 11 Plan (the “Plan”) and, on February 17, 2017, the court approved that Plan.

In 2000, ParentCo acquired Reynolds Metals Company (“Reynolds,” a subsidiary of Alcoa Corporation), which included an alumina refinery in Gregory, Texas. As a condition of the Reynolds acquisition, ParentCo was required to divest this alumina refinery. In accordance with the terms of the divestiture in 2000, ParentCo agreed to retain responsibility for certain environmental obligations (see Sherwin, TX in Environmental Matters above) and assigned to the buyer an Energy Services Agreement (“ESA”) with Gregory Power Partners (“Gregory Power”) for purchase of steam and electricity by the refinery.

Through the bankruptcy proceedings, the owner of Sherwin exercised its right under the U.S. Bankruptcy Code to reject the agreement from 2000 containing the previously mentioned retained responsibility, which had the effect of terminating all rights and responsibilities of the parties to the agreement.

As a result of Sherwin’s initial bankruptcy filing, separate legal actions were initiated against Reynolds by Gregory Power and Sherwin as described below.

Gregory Power: On January 26, 2016, Gregory Power delivered notice to Reynolds that Sherwin’s bankruptcy filing constitutes a breach of the ESA; on January 29, 2016, Reynolds responded that the filing does not constitute a breach. On September 16, 2016, Gregory Power filed a complaint in the bankruptcy case against Reynolds alleging breach of the ESA. In response to this complaint, on November 10, 2016, Reynolds filed both a motion to dismiss, including a jury demand, and a motion to withdraw the reference to the bankruptcy court based on the jury demand. On July 18, 2017, the district court ordered that any trial would be held to a jury in district court, but that the bankruptcy court would retain jurisdiction on all pre-trial matters. Since that time, Gregory Power filed an amended complaint to include Allied Alumina LLC (“Allied”), the successor to the original purchaser of the refinery from Reynolds. In September 2018, Reynolds and Allied filed their respective answers to the amended complaint, and Allied filed a cross complaint against Reynolds, which was answered by Reynolds on October 15, 2018. The court has yet to rule on several pending pretrial matters. At this time, Alcoa Corporation is unable to reasonably predict the ultimate outcome of this matter.

Sherwin: On October 4, 2016, the Texas Commission on Environmental Quality (TCEQ) filed suit against Sherwin in the bankruptcy proceeding seeking to hold Sherwin responsible for remediation of alleged environmental conditions at the Sherwin refinery site and related bauxite residue waste disposal areas (known as the Copano facility). On October 11, 2016, Sherwin filed a similar suit against Reynolds in the case. As provided in the Plan, Sherwin, including certain affiliated companies, and Reynolds had been negotiating an allocation among them as to the ownership of and responsibility for certain areas of the refinery and the Copano facility. In March 2018, Reynolds and Sherwin reached a settlement agreement that assigns to Reynolds all environmental liabilities associated with the Copano facility and assigns to Sherwin all environmental liabilities associated with the Sherwin refinery site. Additionally, Reynolds and the TCEQ reached an agreement that defines the operating and environmental steps required for the Copano facility, which Reynolds intends to operate for the purpose of managing materials other than bauxite residue waste, including third-party dredge material. The effectiveness and enforceability of each of these two agreements are pre-conditioned on the other being accepted by the bankruptcy court. A public notice and comment period on these agreements expired on April 26, 2018 without material affect to the documents. On June 5, 2018, the bankruptcy court accepted and entered the agreements into the judicial record as submitted (May 21, 2018 serves as the “effective date” for both agreements).

On June 5, 2018, the transaction between Sherwin and Reynolds was completed. Under the agreement with Sherwin, in exchange for assuming full responsibility for the environmental-related liabilities (see below related to the Company’s existing reserve) associated with the Copano facility, Reynolds assumed ownership of the land that comprises the Copano facility, as well as land that serves as a buffer around the Copano facility and other related assets. A third-party appraisal estimated the fair value of the land and other assets to be $16. Under the agreement with TCEQ, a portion of the Copano facility must be closed within 10 years and the remaining portion must be closed within 30 years, both timeframes began on the effective date. Also, Reynolds is required to install upgrades to certain dust control systems and repair certain structures and drainage systems at the Copano facility, and prepare and submit to TCEQ a preliminary groundwater assessment report (submitted on November 5, 2018) and a drinking water survey report (waived due to no evidence of a contaminant release) related to the Copano facility within 180 days of the effective date. Accordingly, the Company recognized $16 in properties, plants, and equipment, $9 in environmental remediation liabilities, and $7 in other related liabilities. Additionally, the Company paid $12 into a trust managed by the state of Texas as financial assurance of the Company’s performance in completing the required obligations. This amount will be returned to the Company upon satisfactory completion of the future closure of the Copano facility in accordance with all applicable laws and regulations. On June 7, 2018, Sherwin filed a notice of dismissal in the suit against Reynolds; the dismissal was immediately effective as no court order was required.

At the time the agreements were signed by all parties, the Company had a reserve of $29 for its proportionate share of environmental-related matters at both the Sherwin refinery site and the Copano facility based on the terms of the divestiture of the Sherwin refinery in 2000 (see Sherwin, TX in Environmental Matters above). While Reynolds no longer has any responsibility for environmental-related matters at the Sherwin refinery site, it assumed additional responsibility for environmental-related matters at the Copano facility ($9 – see above). In management’s judgment, the $38 reserve as of December 31, 2018 is sufficient to satisfy the Company’s revised responsibilities and obligations under the settlement agreements. Upon changes in facts or circumstances, a change to the reserve may be required.

Suralco—On December 16, 2016, Boskalis International B.V. (Boskalis) initiated a binding arbitration proceeding against Suriname Aluminum Company, LLC (Suralco), an AWAC company, seeking $47 plus prejudgment interest and associated taxes in connection with a dispute arising under a contract for mining services in Suriname between Boskalis and Suralco. Boskalis asserted four separate claims under the contract.

In February 2018, the arbitration hearing was held before a three-person panel under the rules of the International Chamber of Commerce. The panel issued its decision on May 29, 2018, finding in favor of Boskalis on two claims and against Boskalis on two claims. For the two claims on which Boskalis prevailed, the panel awarded Boskalis $29, including prejudgment interest of $3. The award is final and cannot be appealed. Accordingly, Alcoa Corporation recorded a charge of $29 ($17 after noncontrolling interest), including $26 in Cost of goods sold and $3 in Interest expense on the accompanying Statement of Consolidated Operations. On June 6, 2018, the Company made the $29 cash payment to Boskalis closing this matter.

The claim that represented the majority of the arbitration award centered around a contract provision requiring Suralco to make a “true up” payment at the end of the contract in the event that Suralco was unable to receive delivery of the full contract quantity, thus allowing Boskalis to recover its fixed production costs and a suitable return on its investment. While Suralco argued that all required deliveries had been made during the amended contract term and that no “true up” payment was required because a “true up” would amount to a double payment for bauxite deliveries after the initial contract term, Boskalis argued that the deliveries were not made within the original contract term and thus, a “true up” payment was required. On the basis of its analysis of the facts and applicable law, management concluded that the likelihood of an unfavorable decision on Boskalis’ claims was remote (25% or less). Throughout the course of the proceeding, and even after the conclusion of the hearing, management’s judgment of the likelihood of an unfavorable outcome remained the same.

General. In addition to the matters discussed above, various other lawsuits, claims, and proceedings have been or may be instituted or asserted against Alcoa Corporation, including those pertaining to environmental, safety and health, commercial, tax, product liability, intellectual property infringement, employment, and employee and retiree benefit matters, and other actions and claims arising out of the normal course of business. While the amounts claimed in these other matters may be substantial, the ultimate liability is not readily determinable because of the considerable uncertainties that exist. Accordingly, it is possible that the Company’s liquidity or results of operations in a particular period could be materially affected by one or more of these other matters. However, based on facts currently available, management believes that the disposition of these other matters that are pending or asserted will not have a material adverse effect, individually or in the aggregate, on the financial position of the Company.

Commitments

Purchase Obligations. Alcoa Corporation is party to unconditional purchase obligations for energy that expire between 2028 and 2037. Commitments related to these contracts total $151 in 2019, $209 in 2020, $213 in 2021, $217 in 2022, $223 in 2023, and $2,718 thereafter. Expenditures under these contracts totaled $169 in 2018, $199 in 2017, and $181 in 2016. Additionally, the Company has entered into other purchase commitments for energy, raw materials, and other goods and services, which total $1,886 in 2019, $1,312 in 2020, $1,229 in 2021, $1,313 in 2022, $1,315 in 2023, and $11,302 thereafter.

AofA has a gas supply agreement to power its three alumina refineries in Western Australia beginning in July 2020 for a 12-year period. The terms of this agreement required AofA to make a prepayment of $500 in two installments, the first of which was made in June 2015 for $300. The second installment of $200 was made in April 2016 and was included in (Increase) in noncurrent assets on the accompanying Statement of Consolidated Cash Flows. At December 31, 2018 and 2017, Alcoa Corporation has an asset of $458 (A$654) and $510 (A$654), respectively, which was included in Other noncurrent assets (see Note S) on the accompanying Consolidated Balance Sheet.

Operating Leases. Certain land and buildings, alumina refinery process control technology, plant equipment, vehicles, and computer equipment are under operating lease agreements. Total expense for all leases was $102 in 2018, $101 in 2017, and $90 in 2016. Under long-term operating leases, minimum annual lease payments (undiscounted) are $74 in 2019, $56 in 2020, $42 in 2021, $11 in 2022, $5 in 2023, and $21 thereafter.

Guarantees of Third Parties. At December 31, 2018, the Company has maximum potential future payments for guarantees issued on behalf of a third party of $60. These guarantees expire at various times between 2018 and 2021 and relate to project financing for the aluminum complex in Saudi Arabia (see Note H).

Bank Guarantees and Letters of Credit. Alcoa Corporation has outstanding bank guarantees and letters of credit related to, among others, energy contracts, environmental obligations, legal and tax matters, outstanding debt, leasing obligations, workers compensation, and customs duties. The total amount committed under these instruments, which automatically renew or expire at various dates between 2019 and 2022, was $373 (includes $136 issued under a standby letter of credit agreement —see below) at December 31, 2018. Additionally, Arconic has outstanding bank guarantees and letters of credit related to the Company in the amount of $29 at December 31, 2018. In the event Arconic would be required to perform under any of these instruments, Arconic would be indemnified by Alcoa Corporation in accordance with the Separation and Distribution Agreement. Likewise, the Company has outstanding bank guarantees and letters of credit related to Arconic in the amount of $15 at December 31, 2018. In the event Alcoa Corporation would be required to perform under any of these instruments, the Company would be indemnified by Arconic in accordance with the Separation and Distribution Agreement.

In August 2017, Alcoa Corporation entered into a standby letter of credit agreement, which expires on August 17, 2019 (extended in August 2018), with three financial institutions. The agreement provides for a $150 facility, which will be used by the Company for matters in the ordinary course of business. Alcoa Corporation’s obligations under this facility will be secured in the same manner as obligations under the Company’s Second Amended Revolving Credit Agreement (see Note L). Additionally, this facility contains similar representations and warranties and affirmative, negative, and financial covenants as the Company’s Second Amended Revolving Credit Agreement (see Note L). As of December 31, 2018, letters of credit aggregating $136 were issued under this facility.

Surety Bonds. Alcoa Corporation has outstanding surety bonds primarily related to tax matters, contract performance, workers compensation, environmental-related matters, and customs duties. The total amount committed under these bonds, which automatically renew or expire at various dates, mostly in 2019, was $40 at December 31, 2018. Additionally, Arconic has outstanding surety bonds related to the Company in the amount of $16 at December 31, 2018. In the event Arconic would be required to perform under any of these instruments, Arconic would be indemnified by Alcoa Corporation in accordance with the Separation and Distribution Agreement. Likewise, the Company has outstanding surety bonds related to Arconic in the amount of $2 at December 31, 2018. In the event Alcoa Corporation would be required to perform under any of these instruments, the Company would be indemnified by Arconic in accordance with the Separation and Distribution Agreement.