Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Accounts payable:
Accounts payable	$ 139.2	$ 228.5
Current accrued liabilities:
Deferred income	50.4	88.8
Employee benefits	34.5	36.2
Accrued development costs	17.2	15.1
Accrued litigation settlement	11.9	11.8
Accrued sales discounts and rebates	18.1	22.5
Interest	11.9	5.1
Operating lease liabilities	$ 3.7	$ 3.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Environmental remediation and related costs	$ 3.9	$ 3.7
Other	43.7	45.0
Total	367.7	490.7
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	129.9	218.7
CompX
Accounts payable:
Accounts payable	3.8	3.1
BMI/LandWell
Accounts payable:
Accounts payable	5.5	6.7
Contran | Income Taxes Payable
Current accrued liabilities:
Other	14.8	10.2
Louisiana Pigment Company
Current accrued liabilities:
Other	$ 18.4	$ 19.9