Subsequent Events	9 Months Ended
Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsA new five-year labor agreement for our Grundartangi aluminum smelter was ratified by the employees on October 22, 2020. The agreement is retroactive to January 1, 2020 and continues through December 31, 2024.On October 20, 2020, we issued a notice to employees at our Mt. Holly, South Carolina aluminum smelter of our intent to curtail the Mt. Holly plant operations by no later than December 31, 2020 when our current power contracts at Mt. Holly expire, if we are unable to secure a competitively priced power arrangement to deliver energy to the plant. The announcement was made pursuant to the Worker Adjustment and Retraining Notification Act.

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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