Inventories - Schedule of Inventory Components (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Finished goods	$ 402	$ 385
Work-in-process	335	350
Bauxite and alumina	603	584
Purchased raw materials	862	923
Operating supplies	193	185
Inventories, total	$ 2,395	$ 2,427

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of products used directly or indirectly in the manufacturing or production process, which may or may not become part of the final product. May also include items used in the storage, presentation or transportation of physical goods.

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