Long-term debt - Valhi Contran Credit Facility - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Long-term debt
Repayments of credit facility	$ 649.8	$ 148.9
VALHI, INC. \| Contran Credit Facility
Long-term debt
Line of credit maximum borrowing capacity	$ 125.0
Interest rate spread	1.00%
Borrowings	$ 0.0
Repayments of credit facility	$ 21.0
Debt instrument, interest rate during period	7.37%
Debt instrument, Interest rate at period end	7.75%
Amount available for borrowing	$ 101.4

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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