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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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Per share or per unit amount of equity securities issued.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Investment In and Advances to Non-Consolidated Affiliates and Related Party Transactions - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Dec. 23, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Mar. 31, 2025
Schedule of Equity Method Investments [Line Items]
Net sales		$ 4,186	$ 4,080	$ 13,647	$ 12,562
Other income		(381)	4	(426)	(121)
Return of capital to our common shareholder			35	35
Stock issued during period	$ 750
Stock issued during period (in shares)	5,000,000
Shares issued, price per share (in dollars per share)	$ 150
Additional Paid-in Capital
Schedule of Equity Method Investments [Line Items]
Return of capital to our common shareholder				35
Parent Company
Schedule of Equity Method Investments [Line Items]
Net sales			1	1	1
Accounts receivable, net		$ 1		$ 1		$ 1
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		$ 1	$ 6	$ 7	$ 18
AluInfra Services SA
Schedule of Equity Method Investments [Line Items]
Ownership percentage		50.00%		50.00%