Financial Instruments and Commodity Contracts - Summary of Gross Fair Values of Financial Instruments and Commodity Contracts (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024
Assets
Derivative Assets, Current	$ 91	$ 45
Derivative Asset, Noncurrent	2	1
Liabilities
Derivative Liabilities, Current	(201)	(144)
Derivative Liabilities, Noncurrent	(5)	(5)
Net Fair Value Assets/Liabilities	(113)	(103)
Designated as Hedging Instrument
Assets
Derivative Assets, Current	26	8
Derivative Asset, Noncurrent	0	1
Liabilities
Derivative Liabilities, Current	(124)	(73)
Derivative Liabilities, Noncurrent	(4)	(4)
Net Fair Value Assets/Liabilities	(102)	(68)
Designated as Hedging Instrument \| Cash flow hedges \| Metal Contracts
Assets
Derivative Assets, Current	21	3
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	(89)	(56)
Derivative Liabilities, Noncurrent	0	(2)
Net Fair Value Assets/Liabilities	(68)	(55)
Designated as Hedging Instrument \| Cash flow hedges \| Currency Exchange Contracts
Assets
Derivative Assets, Current	1	4
Derivative Asset, Noncurrent	0	1
Liabilities
Derivative Liabilities, Current	(33)	(13)
Derivative Liabilities, Noncurrent	(3)	0
Net Fair Value Assets/Liabilities	(35)	(8)
Designated as Hedging Instrument \| Cash flow hedges \| Energy Contracts
Assets
Derivative Assets, Current	1	1
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	(2)	(4)
Derivative Liabilities, Noncurrent	0	0
Net Fair Value Assets/Liabilities	(1)	(3)
Designated as Hedging Instrument \| Cash flow hedges \| Interest Rate Swap
Assets
Derivative Assets, Current	0	0
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	0	0
Derivative Liabilities, Noncurrent	(1)	(2)
Net Fair Value Assets/Liabilities	(1)	(2)
Designated as Hedging Instrument \| Net investment hedges \| Currency Exchange Contracts
Assets
Derivative Assets, Current	3
Derivative Asset, Noncurrent	0
Liabilities
Derivative Liabilities, Current	0
Derivative Liabilities, Noncurrent	0
Net Fair Value Assets/Liabilities	3
Not Designated as Hedging Instrument
Assets
Derivative Assets, Current	65	37
Derivative Asset, Noncurrent	2	0
Liabilities
Derivative Liabilities, Current	(77)	(71)
Derivative Liabilities, Noncurrent	(1)	(1)
Net Fair Value Assets/Liabilities	(11)	(35)
Not Designated as Hedging Instrument \| Metal Contracts
Assets
Derivative Assets, Current	46	30
Derivative Asset, Noncurrent	2	0
Liabilities
Derivative Liabilities, Current	(59)	(53)
Derivative Liabilities, Noncurrent	(1)	(1)
Net Fair Value Assets/Liabilities	(12)	(24)
Not Designated as Hedging Instrument \| Currency Exchange Contracts
Assets
Derivative Assets, Current	19	6
Derivative Asset, Noncurrent	0	0
Liabilities
Derivative Liabilities, Current	(18)	(17)
Derivative Liabilities, Noncurrent	0	0
Net Fair Value Assets/Liabilities	$ 1	(11)
Not Designated as Hedging Instrument \| Energy Contracts
Assets
Derivative Assets, Current		1
Derivative Asset, Noncurrent		0
Liabilities
Derivative Liabilities, Current		(1)
Derivative Liabilities, Noncurrent		0
Net Fair Value Assets/Liabilities		$ 0

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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-Paragraph 2
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Section 50
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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