v3.22.1

Restructuring and Other Charges - Restructuring and Other Charges by Segment (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2022 | Mar. 31, 2021
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | $ 5 | $ 1
Operating segments |  |
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | 1 | 1
Operating segments | Rolled Products |  |
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | 0 | 1
Operating segments | Building and Construction Systems |  |
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | 0 | (1)
Operating segments | Extrusions |  |
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | 1 | (1)
Corporate, Non-Segment |  |
Restructuring Cost and Reserve [Line Items] |  |
Restructuring and other charges (E) | $ 4 | $ 0

X
- Definition Restructuring, Settlement And Impairment Provisions, Including Gain (Loss) On Disposition Of Assets And Business + References No definition available. + Details
Name: | arnc_RestructuringSettlementAndImpairmentProvisionsIncludingGainLossOnDispositionOfAssetsAndBusiness
Namespace Prefix: | arnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RestructuringCostAndReserveLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=arnc_RolledProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=arnc_BuildingandConstructionSystemsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=arnc_ExtrusionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_CorporateNonSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |