Long-term debt - Valhi Contran Credit Facility - Additional Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($)
Debt Instrument [Line Items]
Repayments of credit facility	$ 148.9
VALHI, INC. \| Contran Credit Facility
Debt Instrument [Line Items]
Line of credit maximum borrowing capacity	$ 150.0
Interest rate spread	1.00%
Debt instrument, Interest rate at period end	8.50%
Debt due date, start date	Dec. 31, 2026
Debt instrument, interest rate during period	9.27%
Borrowings	$ 0.0
Repayments of credit facility	48.8
Amount available for borrowing	$ 105.4

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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