Subsequent Events	3 Months Ended
Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	S. Subsequent Events In April 2023, the Company purchased group annuity contracts to transfer the obligation to pay the remaining retirement benefits of approximately 500 retirees and beneficiaries from certain Canadian defined benefit pension plans to an insurance company. The transfer of approximately $235 in both plan obligations and plan assets was completed on April 18, 2023. As a result, Alcoa will record a non-cash settlement loss of approximately $18 ($13 after-tax) in Restructuring and other charges, net on the Statement of Consolidated Operations in the second quarter of 2023.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI https://asc.fasb.org/topic&trid=2122774

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

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