Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Long-term debt
Total debt	$ 1,000.8	$ 965.0
Less current maturities	7.6	7.8
Total long-term debt	993.2	957.2
VALHI, INC.
Long-term debt
Total debt	528.9	528.9
VALHI, INC. | Contran Credit Facility
Long-term debt
Total debt	278.9	278.9
VALHI, INC. | Notes Payable, Other Payables | Snake River
Long-term debt
Total debt	250.0	250.0
Kronos Worldwide, Inc. | North American Revolving Credit Facility
Long-term debt
Total debt	26.0
Kronos Worldwide, Inc. | 2014 Term Loan
Long-term debt
Total debt	335.4	335.9
WCS | Financing Capital Lease Obligation
Long-term debt
Total debt	63.6	64.0
Tremont | Promissory Note
Long-term debt
Total debt	14.5	14.5
BMI | Bank note payable | Meadows Bank
Long-term debt
Total debt		8.4
BMI | Bank loan | Western Alliance Bank
Long-term debt
Total debt	19.5
LandWell | Unsecured Debt
Long-term debt
Total debt	2.9	2.9
Other Subsidiary | Other
Long-term debt
Total debt	10.0	10.4
Subsidiary
Long-term debt
Total debt	$ 471.9	$ 436.1