Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts payable:
Accounts payable	$ 228.5	$ 199.4
Current accrued liabilities:
Deferred income	88.8	110.7
Employee benefits	36.2	34.4
Accrued sales discounts and rebates	22.5	25.6
Accrued development costs	15.1	5.6
Interest	5.1	4.9
Operating lease liabilities	$ 3.9	$ 3.8
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Environmental remediation and related costs	$ 3.7	$ 3.8	$ 3.5
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Other	$ 45.0	$ 54.8
Total	220.3	243.6
Noncurrent accrued liabilities:
Accrued development costs	42.3	48.1
Deferred income	15.5	25.9
Insurance claims and expenses	14.9	18.7
Operating lease liabilities	$ 18.6	$ 17.4
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Total	Total
Other postretirement benefits	$ 7.4	$ 7.1
Employee benefits	4.9	4.8
Reserve for uncertain tax positions		0.3
Other	7.8	6.7
Total	111.4	129.0
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	218.7	177.2
CompX
Accounts payable:
Accounts payable	3.1	3.5
BMI/LandWell
Accounts payable:
Accounts payable	$ 6.7	$ 18.7