v3.20.2

Earnings Per Share (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2020
Earnings Per Share [Abstract] |
Schedule of Earnings Per Share, Basic and Diluted | The share information used to compute basic and diluted EPS attributable to Arconic Corporation common shareholders was as follows (shares in millions):
|  | Second quarter ended June 30, |  |  |  | Six months ended June 30, |  |
| ​ | 2020 | ​ | 2019 |  | 2020 | ​ | 2019
Weighted-average shares outstanding – basic | ​ | 109 |  |  | 109 |  |  | 109 |  |  | 109 |
Effect of dilutive share equivalents: | ​ |  |  |  |  |  |  |
Stock options |  | — |  |  | — |  |  | — |  |  | — |
Stock units |  | — |  |  | — |  |  | — |  |  | — |
Weighted-average shares outstanding – diluted |  | 109 |  |  | 109 |  |  | 109 |  |  | 109 |

X
- References No definition available. + Details
Name: | us-gaap_EarningsPerShareAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration