Financial Instruments and Commodity Contracts (Summary of Gross Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024
Assets
Derivative Assets, Current	$ 176	$ 45
Derivative Asset, Noncurrent	5	1
Liabilities
Derivative Liabilities, Current	(106)	(144)
Derivative Liabilities, Noncurrent	(7)	(5)
Derivative Assets (Liabilities), at Fair Value, Net	68	(103)
Derivatives designated as hedging instruments:
Assets
Derivative Assets, Current	106	8
Derivative Asset, Noncurrent	4	1
Liabilities
Derivative Liabilities, Current	(33)	(73)
Derivative Liabilities, Noncurrent	(6)	(4)
Derivative Assets (Liabilities), at Fair Value, Net	71	(68)
Derivatives designated as hedging instruments: \| Cash flow hedges \| Metal contracts
Assets
Derivative Assets, Current	89	3
Derivative Asset, Noncurrent	4	0
Liabilities
Derivative Liabilities, Current	(5)	(56)
Derivative Liabilities, Noncurrent	0	(2)
Derivative Assets (Liabilities), at Fair Value, Net	88	(55)
Derivatives designated as hedging instruments: \| Cash flow hedges \| Currency exchange contracts
Assets
Derivative Assets, Current	6	4
Derivative Asset, Noncurrent	0	1
Liabilities
Derivative Liabilities, Current	(27)	(13)
Derivative Liabilities, Noncurrent	(1)	0
Derivative Assets (Liabilities), at Fair Value, Net	(22)	(8)
Derivatives designated as hedging instruments: \| Cash flow hedges \| Energy contracts
Assets
Derivative Assets, Current	6	1
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	(1)	(4)
Derivative Liabilities, Noncurrent	0	0
Derivative Assets (Liabilities), at Fair Value, Net	5	(3)
Derivatives designated as hedging instruments: \| Cash flow hedges \| Interest rate swap contracts
Assets
Derivative Assets, Current	0	0
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	0	0
Derivative Liabilities, Noncurrent	(5)	(2)
Derivative Assets (Liabilities), at Fair Value, Net	(5)	(2)
Derivatives designated as hedging instruments: \| Net investment hedges \| Currency exchange contracts
Assets
Derivative Assets, Current	5
Derivative Asset, Noncurrent	0
Liabilities
Derivative Liabilities, Current	0
Derivative Liabilities, Noncurrent	0
Derivative Assets (Liabilities), at Fair Value, Net	5
Derivatives not designated as hedging instruments:
Assets
Derivative Assets, Current	70	37
Derivative Asset, Noncurrent	1	0
Liabilities
Derivative Liabilities, Current	(73)	(71)
Derivative Liabilities, Noncurrent	(1)	(1)
Derivative Assets (Liabilities), at Fair Value, Net	(3)	(35)
Derivatives not designated as hedging instruments: \| Metal contracts
Assets
Derivative Assets, Current	58	30
Derivative Asset, Noncurrent	1	0
Liabilities
Derivative Liabilities, Current	(56)	(53)
Derivative Liabilities, Noncurrent	(1)	(1)
Derivative Assets (Liabilities), at Fair Value, Net	2	(24)
Derivatives not designated as hedging instruments: \| Currency exchange contracts
Assets
Derivative Assets, Current	12	6
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	(17)	(17)
Derivative Liabilities, Noncurrent	0	0
Derivative Assets (Liabilities), at Fair Value, Net	(5)	(11)
Derivatives not designated as hedging instruments: \| Energy contracts
Assets
Derivative Assets, Current		1
Derivative Asset, Noncurrent		0
Liabilities
Derivative Liabilities, Current		(1)
Derivative Liabilities, Noncurrent		0
Derivative Assets (Liabilities), at Fair Value, Net		$ 0
Derivatives not designated as hedging instruments: \| Cash flow hedges \| Energy contracts
Assets
Derivative Assets, Current	0
Derivative Asset, Noncurrent	0
Liabilities
Derivative Liabilities, Current	0
Derivative Liabilities, Noncurrent	0
Derivative Assets (Liabilities), at Fair Value, Net	$ 0

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Section 50
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-Publisher FASB
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480463/815-10-45-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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-Section 50
-Paragraph 2
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-Publisher FASB
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