Subsequent Events	6 Months Ended
Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	R. Subsequent Events On July 28, 2021, Alcoa made the decision to permanently close the previously curtailed anode facility in Lake Charles, Louisiana, United States. The anode facility within the Lake Charles site has been fully curtailed since 2015. The Company expects to record restructuring and other charges of approximately $25 to $30 (pre- and after-tax) in the third quarter of 2021, comprised of asset impairments of approximately $20 and cash-based charges for closure and asset retirement obligations of approximately $5 to $10. The closure is expected to take approximately one year. The decision to permanently close the facility was made as part of the Company’s on-going portfolio review. The Company’s petroleum coke calciner located at the same site in Lake Charles will remain in operation, unaffected by the closure of the anode facility.

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 http://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 http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

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