Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts payable:
Accounts payable	$ 231.3	$ 250.0
Current accrued liabilities:
Employee benefits	38.0	37.8
Accrued development costs	25.2	30.0
Deferred income	25.9	28.2
Accrued sales discounts and rebates	25.1	27.6
Interest	14.2	11.4
Accrued severance cost	8.8	0.9
Operating lease liabilities	$ 4.2	$ 3.5
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current	Accrued Liabilities, Current
Payables to affiliates	$ 1.4	$ 17.1
Accrued litigation settlement		16.4
Other	57.2	59.7
Total	198.6	199.1
Other noncurrent liabilities
Accrued development costs	16.1	26.8
Operating lease liabilities	$ 15.7	$ 17.1
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Total	Total
Insurance claims and expenses	$ 16.1	$ 16.6
Deferred income	2.9	11.8
Asset retirement obligations	14.7	14.3
Other postretirement benefits	6.4	6.7
Employee benefits	4.6	4.5
Earn-out liability		4.3
Other	0.5	0.6
Total	77.0	102.7
Kronos Worldwide
Accounts payable:
Accounts payable	224.0	232.4
CompX
Accounts payable:
Accounts payable	2.7	3.7
BMI/LandWell
Accounts payable:
Accounts payable	2.6	8.0
Other
Accounts payable:
Distributions payable to noncontrolling interest	2.0	5.9
Contran
Accounts payable:
Income taxes payable current		16.9
Contran - other	$ 0.1	$ 0.2