Financial Instruments and Commodity Contracts - Gain (Loss) Reclassification (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Income tax provision (benefit)	$ (60)	$ (54)
Net income	150	156
Total cash flow hedging derivatives	(151)	233
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	(122)	66
Income tax provision (benefit)	32	(19)
Net income	(90)	47
Total cash flow hedging derivatives	(154)	233
Cash flow hedges | Energy Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total cash flow hedging derivatives	0	(1)
Cash flow hedges | Energy Contracts | Cost of Goods Sold
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	(2)	(1)
Cash flow hedges | Metal Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total cash flow hedging derivatives	(120)	226
Cash flow hedges | Metal Contracts | Cost of Goods Sold
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision		1
Cash flow hedges | Metal Contracts | Net Sales
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	(116)	69
Cash flow hedges | Currency Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total cash flow hedging derivatives	(36)	8
Cash flow hedges | Currency Exchange Contracts | Cost of Goods Sold
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision		3
Cash flow hedges | Currency Exchange Contracts | Net Sales
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	(4)	(5)
Cash flow hedges | Currency Exchange Contracts | Depreciation and Amortization
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	(1)	(1)
Cash flow hedges | Currency Exchange Contracts | Interest Expense and Amortization of Debt Issuance Costs
Derivative Instruments, Gain (Loss) [Line Items]
Income before income tax provision	1
Cash flow hedges | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Total cash flow hedging derivatives	$ 2	$ 0