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Commitments and contingencies - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Feb. 28, 2025 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) site	Sep. 30, 2024 USD ($)
Commitments and contingencies
Litigation settlement final payment with accrued interest					$ 1,600
Accrual for reasonably estimable environmental remediation and related matters			$ 69,278		13,135
Litigation settlement amount	$ 151,100
Litigation settlement amount payable		$ 56,100
Litigation settlement interest		500
Litigation settlement from other party		$ 9,600
Aggregate income			$ 31,400
Insurance recoveries				$ 1,100		$ 1,317
Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments and contingencies
Accrual for reasonably estimable environmental remediation and related matters					$ 13,000
Number of sites associated with remediation and related costs | site					29
Number of sites currently not able to reasonably estimate a range of costs | site					5
Maximum | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments and contingencies
Upper end range, estimate costs for remediation and related matters					$ 38,000
Lead Pigment Litigation
Commitments and contingencies
First installment payment under the litigation.					$ 16,700

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