Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts payable:
Accounts payable	$ 163.6	$ 228.5
Current accrued liabilities:
Deferred income	50.8	88.8
Employee benefits	43.8	36.2
Accrued sales discounts and rebates	23.6	22.5
Accrued development costs	19.1	15.1
Accrued litigation settlement	16.4	11.8
Environmental remediation and related costs	4.1	3.7
Operating lease liabilities	$ 3.7	$ 3.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Interest	$ 2.2	$ 5.1
Other	61.5	45.0
Total	401.3	490.7
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	155.2	218.7
CompX
Accounts payable:
Accounts payable	3.3	3.1
BMI/LandWell
Accounts payable:
Accounts payable	5.1	6.7
Contran | Income Taxes Payable
Current accrued liabilities:
Other	$ 12.5	10.2
Louisiana Pigment Company
Current accrued liabilities:
Other		$ 19.9