Related party transactions - Receivables from and Payables to Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Current receivables from affiliates:
Current receivables from affiliates	$ 0.8	$ 17.5
Current payables to affiliates:
Other liabilities, primarily current	17.1	30.1
Payables to affiliate included in long-term debt:
Valhi - Contran credit facility	563.4	546.5
Long-term debt	484.4	545.8
Related Party
Current receivables from affiliates:
Current receivables from affiliates	0.8	17.5
Current payables to affiliates:
Other liabilities, primarily current	17.1	30.1
Payables to affiliate included in long-term debt:
Long-term debt	98.3	93.4
Contran
Current receivables from affiliates:
Contran trade items	0.2	0.2
Current payables to affiliates:
Contran income taxes	16.9	10.2
Contran | Contran
Noncurrent payable to affiliates:
Contran - income taxes		18.5
Louisiana Pigment Company
Current receivables from affiliates:
Current receivables from affiliates		16.9
Current payables to affiliates:
Other liabilities, primarily current		19.9
VALHI, INC. | Contran | Credit Facility.
Payables to affiliate included in long-term debt:
Valhi - Contran credit facility	44.6	93.4
Kronos | Contran | Term loan
Payables to affiliate included in long-term debt:
Kronos - Contran Term Loan	53.7
Other Affiliates
Current receivables from affiliates:
Current receivables from affiliates	$ 0.6	$ 0.4