Long-term debt - Valhi Contran Credit Facility - Additional Information (Detail) - VALHI, INC. - Contran Credit Facility $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Borrowings of credit facility	$ 0.0
Repayments of credit facility	$ 28.0
Debt instrument, Interest rate at period end	9.50%
Line of credit maximum borrowing capacity	$ 150.0
Interest rate on outstanding borrowings	1.00%
Debt due date, start date	Dec. 31, 2025
Amount available for borrowing	$ 56.6
Debt instrument, interest rate during period	9.20%

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

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Earliest date the outstanding debt instruments are required to be repaid, in YYYY-MM-DD format.

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The effective interest rate at the end of the reporting period.

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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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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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