Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Accounts payable:
Accounts payable	$ 250.0	$ 228.5
Current accrued liabilities:
Employee benefits	38.7	36.2
Accrued development costs	30.0	15.1
Deferred income	28.2	88.8
Accrued sales discounts and rebates	27.6	22.5
Interest	11.4	5.1
Operating lease liabilities	$ 3.5	$ 3.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Other	$ 59.7	$ 45.0
Total	199.1	216.6
Noncurrent accrued liabilities:
Accrued development costs	26.8	42.3
Operating lease liabilities	17.1	18.6
Insurance claims and expenses	16.6	14.9
Deferred income	11.8	15.5
Asset retirement obligations	14.3	7.2
Other postretirement benefits	6.7	7.4
Employee benefits	4.5	4.9
Earn-out liability	4.3
Other	0.6	0.6
Total	102.7	111.4
Kronos Worldwide
Accounts payable:
Accounts payable	232.4	218.7
CompX
Accounts payable:
Accounts payable	3.7	3.1
BMI/LandWell
Accounts payable:
Accounts payable	8.0	$ 6.7
Other
Accounts payable:
Distributions payable to noncontrolling interest	$ 5.9