Basis of Presentation - Additional Information (Detail)	9 Months Ended
Sep. 30, 2024	Jul. 31, 2024
Aluminum Segment [Member]
Basis Of Presentation [Line Items]
Ownership interest in joint venture	55.00%
AWAC [Member] \| Alcoa Corporation [Member]
Basis Of Presentation [Line Items]
Ownership interest percentage		60.00%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant