Accounts and other receivables, net - Components of Accounts and Other Receivables (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Trade accounts receivable:
VAT and other receivables	$ 37.7	$ 45.9
Refundable income taxes	3.2	1.3
Allowance for doubtful accounts	(4.3)	(3.9)
Total	379.2	327.8
Trade Accounts Receivable | Kronos
Trade accounts receivable:
Trade Accounts receivable	320.9	269.2
Trade Accounts Receivable | CompX
Trade accounts receivable:
Trade Accounts receivable	17.0	14.2
Trade Accounts Receivable | BMI/LandWell
Trade accounts receivable:
Trade Accounts receivable	1.2	0.3
Contran | Income taxes
Trade accounts receivable:
Receivables from affiliates	3.2
Contran | Trade items
Trade accounts receivable:
Receivables from affiliates	0.1	0.2
Other | Trade items
Trade accounts receivable:
Receivables from affiliates	$ 0.2	$ 0.6