Segment Information - Schedule of Sales by Product Division (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation Of Revenue [Line Items]
Sales	$ 3,369	$ 2,599
Aluminum [Member]
Disaggregation Of Revenue [Line Items]
Sales	1,955	1,661
Alumina [Member]
Disaggregation Of Revenue [Line Items]
Sales	1,211	890
Bauxite [Member]
Disaggregation Of Revenue [Line Items]
Sales	242	61
Energy [Member]
Disaggregation Of Revenue [Line Items]
Sales	33	33
Other [Member]
Disaggregation Of Revenue [Line Items]
Sales	$ (72)	$ (46)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Alcoa Corp 10-Q