Commitments and contingencies - Lead Pigment Litigation-NL and Environmental Matters and Litigation - Additional Information (Details)			1 Months Ended					3 Months Ended	12 Months Ended
	Feb. 10, 2025 USD ($) company	Jul. 24, 2019 USD ($) defendant installment	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) site	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2019 USD ($)	Jul. 25, 2019 USD ($)
Commitments And Contingent Liabilities [Line Items]
Litigation settlement									$ 16,400,000	$ 11,800,000
Long-term litigation settlement										16,100,000
Accrual for reasonably estimable environmental remediation and related matters									74,600,000	96,900,000	$ 97,300,000	$ 97,600,000
Insurance recoveries									1,400,000	3,000,000	2,800,000
Other Environmental Cleanup Matters
Commitments And Contingent Liabilities [Line Items]
Accrual for reasonably estimable environmental remediation and related matters									6,000,000
Raritan Bay Slag Superfund Site | Subsequent event
Commitments And Contingent Liabilities [Line Items]
Settlement amount	$ 151,100,000
Number of private companies to pay to resolve all federal and state law claims | company	22
N L Industries Inc
Commitments And Contingent Liabilities [Line Items]
Aggregate income									31,400,000
Insurance recoveries									1,400,000	500,000
N L Industries Inc | Subsequent event
Commitments And Contingent Liabilities [Line Items]
Litigation Settlement Interest								$ 500,000
Litigation settlement, current								9,600,000
Litigation Settlement, Amount Payable								$ 56,100,000
N L Industries Inc | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments And Contingent Liabilities [Line Items]
Accrual for reasonably estimable environmental remediation and related matters									$ 69,000,000
Number of sites associated with remediation and related costs | site									30
Number of sites for which NL not currently able to reasonably estimate range of costs									5
N L Industries Inc | Maximum | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments And Contingent Liabilities [Line Items]
Upper end range, estimate costs for remediation and related matters									$ 38,000,000
C A Lead Paint Litigation | N L Industries Inc
Commitments And Contingent Liabilities [Line Items]
Description of defendants									July 24, 2019, an order approving a global settlement agreement entered into among all of the plaintiffs and the three defendants remaining in the case (the Sherwin Williams Company, ConAgra Grocery Products and NL) was entered by the court and the case was dismissed with prejudice. The global settlement agreement provides that an aggregate $305 million will be paid collectively by the three co-defendants in full satisfaction of all claims resulting in a dismissal of the case with prejudice and the resolution of (i) all pending and future claims by the plaintiffs in the case, and (ii) all potential claims for contribution or indemnity between NL and its co-defendants in respect to the case.
Number of Defendant | defendant		3
Litigation settlement		$ 101,700,000
Settlement amount		305,000,000
Litigation settlement charge upon approval of settlement terms		25,000,000
Remaining litigation settlement charge		$ 76,700,000							$ 101,700,000
Number of annual installment payments | installment		6
Litigation payment			$ 12,000,000	$ 12,000,000	$ 12,000,000	$ 12,000,000	$ 12,000,000
Remaining litigation settlement charge due in first installment		$ 12,000,000
Remaining litigation settlement charge due in second installment		12,000,000
Remaining litigation settlement charge due in third installment		12,000,000
Remaining litigation settlement charge due in fourth installment		12,000,000
Remaining litigation settlement charge due in fifth installment		12,000,000	$ 12,000,000
Remaining litigation settlement charge due in sixth installment		$ 16,700,000
Discounted rate for estimated present value of remaining litigation amount									1.90%
Long-term litigation settlement									$ 96,300,000
Litigation settlement accrual payments													$ 25,000,000
Accretion expense									$ 500,000	$ 700,000	$ 900,000
C A Lead Paint Litigation | N L Industries Inc | Other Assets
Commitments And Contingent Liabilities [Line Items]
Escrow deposit														$ 9,000,000