Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Long-term debt
Total debt	$ 998.0	$ 960.5
Less current maturities	26.9	9.5
Total long-term debt	971.1	951.0
VALHI, INC.
Long-term debt
Total debt	538.3	513.8
VALHI, INC. | Contran Credit Facility
Long-term debt
Total debt	288.3	263.8
VALHI, INC. | Notes Payable, Other Payables | Snake River
Long-term debt
Total debt	250.0	250.0
Kronos Worldwide, Inc. | Revolving North American credit facility
Long-term debt
Total debt	18.5
Kronos Worldwide, Inc. | 2014 Term Loan
Long-term debt
Total debt	336.4	338.0
WCS | Financing Capital Lease Obligation
Long-term debt
Total debt	64.4	65.6
Tremont | Promissory Note
Long-term debt
Total debt	17.1	17.1
BMI | Bank note payable
Long-term debt
Total debt	8.6	9.3
LandWell | Unsecured Debt
Long-term debt
Total debt	3.1	3.1
Other Subsidiary | Other
Long-term debt
Total debt	11.6	13.6
Subsidiary
Long-term debt
Total debt	$ 459.7	$ 446.7