Recently Adopted and Recently Issued Accounting Guidance	9 Months Ended
Sep. 30, 2020
Accounting Policies [Abstract]
Recently Adopted and Recently Issued Accounting Guidance	Recently Adopted and Recently Issued Accounting Guidance Adopted On January 1, 2020, Arconic Corporation adopted changes issued by the Financial Accounting Standards Board (FASB) to credit losses. This guidance added a new impairment model (known as the current expected credit loss (CECL) model), which is based on expected losses rather than incurred losses. Under this model, an entity is required to recognize an allowance equivalent to its estimate of expected credit losses. The CECL model applies to most debt instruments, trade receivables, lease receivables, financial guarantee contracts, and other loan commitments. This model does not have a minimum threshold for recognition of impairment losses and requires the measurement of expected credit losses on assets that have a low risk of loss. The adoption of this guidance did not have a material impact on the Consolidated Financial Statements. This guidance will need to be considered in future assessments of credit losses. Issued In March 2020, the FASB issued guidance that provides optional expedients and exceptions for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. These expedients and exceptions may be used when applying GAAP, if certain criteria are met, to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of such reform. The purpose of this guidance is to provide relief to entities from experiencing unintended accounting and/or financial reporting outcomes or consequences due to reference rate reform. This guidance became effective immediately on March 12, 2020 and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022, after which time the expedients and exceptions expire. As of September 30, 2020, the Company has not experienced any unintended outcomes or consequences of reference rate reform that would necessitate the adoption of this guidance. Additionally, the Company will not need to consider the application of this guidance related to its credit agreement, which is scheduled to mature on May 13, 2025 and provides a credit facility that is referenced to LIBOR in certain borrowing situations (see Note M), as the terms of such agreement currently provide for a replacement rate if LIBOR is discontinued by the end of 2021 as expected. That said, management will continue to closely monitor all potential instances of reference rate reform to determine if adoption of this guidance becomes necessary in the future.

On January 1, 2020, Arconic Corporation adopted changes issued by the Financial Accounting Standards Board (FASB) to credit losses. This guidance added a new impairment model (known as the current expected credit loss (CECL) model), which is based on expected losses rather than incurred losses. Under this model, an entity is required to recognize an allowance equivalent to its estimate of expected credit losses. The CECL model applies to most debt instruments, trade receivables, lease receivables, financial guarantee contracts, and other loan commitments. This model does not have a minimum threshold for recognition of impairment losses and requires the measurement of expected credit losses on assets that have a low risk of loss. The adoption of this guidance did not have a material impact on the Consolidated Financial Statements. This guidance will need to be considered in future assessments of credit losses.

In March 2020, the FASB issued guidance that provides optional expedients and exceptions for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. These expedients and exceptions may be used when applying GAAP, if certain criteria are met, to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of such reform. The purpose of this guidance is to provide relief to entities from experiencing unintended accounting and/or financial reporting outcomes or consequences due to reference rate reform. This guidance became effective immediately on March 12, 2020 and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022, after which time the expedients and exceptions expire. As of September 30, 2020, the Company has not experienced any unintended outcomes or consequences of reference rate reform that would necessitate the adoption of this guidance. Additionally, the Company will not need to consider the application of this guidance related to its credit agreement, which is scheduled to mature on May 13, 2025 and provides a credit facility that is referenced to LIBOR in certain borrowing situations (see Note M), as the terms of such agreement currently provide for a replacement rate if LIBOR is discontinued by the end of 2021 as expected. That said, management will continue to closely monitor all potential instances of reference rate reform to determine if adoption of this guidance becomes necessary in the future.