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Amount, after allowance, receivable from customers, clients, or other third-parties, and receivables classified as other due within one year or the normal operating cycle, if longer.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of income (expense) related to nonoperating activities, classified as other.

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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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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.

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Investment In and Advances to Non-Consolidated Affiliates and Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Mar. 31, 2024
Schedule of Equity Method Investments [Line Items]
Net sales	$ 4,295	$ 4,107	$ 8,482	$ 8,198
Other income	(65)	2	(125)	29
Parent Company
Schedule of Equity Method Investments [Line Items]
Net sales	1	1	1	1
Accounts receivable, net	$ 1		$ 1		$ 2
Aluminum Norf GmbH
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%
Ulsan Aluminum, Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%
Additional contributions	$ 3	$ 4	$ 12	$ 7
AluInfra Services SA
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%