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Environmental remediation work completion period.

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Investments in environmental offsets associated cash outlays expected year.

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Investments in environmental offsets ending year.

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Investments in environmental offsets impacts caused by minining developement and Conservation programs.

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Investments in environmental offsets starting year.

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Number of remediation projects.

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Amount of expense for newly incurred environmental loss contingencies. Includes, but is not limited to, remediation expense and interest accretion.

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Amount of expense (reversal of expense) which increases (decreases) the accrual for environmental loss contingencies from revisions in estimates to existing obligations. Excludes changes related to business acquisitions, divestitures, or currency movement.

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Amount of cash outflow to settle environmental loss contingencies.

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Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable in twelve months or in the next operating cycle if longer.

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Contingencies - Additional Information (Detail) $ in Millions, $ in Millions	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) Project	Jun. 30, 2026 AUD ($) Project	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Loss Contingencies [Line Items]
Liabilities incurred	$ 5	$ 13	$ 9		$ 13	$ 85
Reversals of previously recorded liabilities	6		6			2
Payments against the reserve	10	5	16		13	25
Remediation reserve balance, current	$ 76		$ 76			$ 76
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Current		Other Liabilities, Current			Other Liabilities, Current
Active or future remediation for significant sites	$ 215		$ 215			$ 202
Accrued environmental reserves	285		285			282	$ 220
Restructuring and Other Charges, Net [Member] \| Ongoing Remediation Work [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities	(3)		(4)
Restructuring and Other Charges, Net [Member] \| Site Remediation at Previously Closed Site [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities	6		6
Cost of Goods Sold [Member] \| Ongoing Remediation Work [Member]
Loss Contingencies [Line Items]
Liabilities incurred	2		$ 5
Australia [Member] \| Cost of Goods Sold [Member] \| Investigation of Potential Contamination [Member]
Loss Contingencies [Line Items]
Liabilities incurred		8			8
Huntly Australia [Member]
Loss Contingencies [Line Items]
Investments in environmental offsets starting year			2019	2019
Investments in environmental offsets ending year			2025	2025
Investments in environmental offsets impacts caused by minining developement and Conservation programs			$ 38	$ 55
Investments in environmental offsets associated cash outlays expected year			2026	2026
Massena, New York [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period			8 years	8 years
Addy, Washington [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period			3 years	3 years
Addy, Washington [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period			5 years	5 years
Other Sites [Member]
Loss Contingencies [Line Items]
Number of remediation projects \| Project			28	28
Accrued environmental reserves	$ 70		$ 70			$ 80
Other Sites [Member] \| Cost of Goods Sold [Member] \| Ongoing Remediation Work [Member]
Loss Contingencies [Line Items]
Liabilities incurred		$ 3			$ 3