v3.20.1

Pension and Other Postretirement Benefits (Tables) | 3 Months Ended
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Mar. 31, 2020
Retirement Benefits [Abstract] |
Schedule of Expenses Related to Pension and Other Postretirement Benefits | The following table summarizes the total expenses recognized by Arconic Corporation related to the pension and other postretirement benefits described above:
​ | ​ | ​ | ​ | Pension benefits | ​ | Other postretirement benefits
​ | ​ | ​ | ​ | First quarter ended March 31, | ​ | First quarter ended March 31,
Type of Plan | ​ | Type of Expense | ​ | 2020 | ​ | 2019 | ​ | 2020 | ​ | 2019
Cumulative Direct Plans | ​ | Net periodic benefit cost | ​ | $ | 21 |  |  | $ | 1 |  |  | $ | 6 |  |  | $ | — |
Shared Plans | ​ | Multiemployer contribution | ​ | — |  |  | 16 |  |  | — |  |  | 5 |
Shared Plans | ​ | Cost allocation | ​ | (1 | ) |  | 5 |  |  | — |  |  | 1 |
​ | ​ | ​ | ​ | $ | 20 |  |  | $ | 22 |  |  | $ | 6 |  |  | $ | 6 |
Schedule of Components of Net Periodic Benefit Cost Classified as Direct Plans | The components of net periodic benefit cost for defined benefit plans classified as Cumulative Direct Plans were as follows:
First quarter ended March 31, | ​ | 2020 | ​ | 2019
Pension benefits |  |  |  |
Service cost | ​ | $ | 5 |  |  | $ | — |
Interest cost | ​ | 26 |  |  | 1 |
Expected return on plan assets | ​ | (40 | ) |  | (1 | )
Recognized net actuarial loss | ​ | 30 |  |  | 1 |
Net periodic benefit cost* | ​ | $ | 21 |  |  | $ | 1 |
Other postretirement benefits |  |  |  |
Service cost | ​ | $ | 1 |  |  | $ | — |
Interest cost | ​ | 4 |  |  | — |
Recognized net actuarial loss |  | 2 |  |  | — |
Amortization of prior service benefit | ​ | (1 | ) |  | — |
Net periodic benefit cost* | ​ | $ | 6 |  |  | $ | — |
​ __________________
* | Service cost was included within Cost of goods sold and all other cost components were included in Other expenses (income), net on the accompanying Statement of Combined Operations.

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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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