Long-Term Debt - Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Long-term debt
Total debt	$ 936.8	$ 752.5
Less current maturities	11.8	10.7
Total long-term debt	925.0	741.8
VALHI, INC.
Long-term debt
Total debt	471.6	456.5
VALHI, INC. | Notes Payable, Other Payables | Snake River
Long-term debt
Total debt	250.0	250.0
VALHI, INC. | Line of Credit | Contran
Long-term debt
Total debt	221.6	206.5
Kronos Worldwide, Inc. | Notes Payable, Other Payables | Contran
Long-term debt
Total debt		170.0
Kronos Worldwide, Inc. | Bank note payable | 2014 Term Loan
Long-term debt
Total debt	346.7
Kronos Worldwide, Inc. | Domestic Line of Credit
Long-term debt
Total debt		11.1
WCS | Capital Lease Obligations
Long-term debt
Financing capital lease	67.5	68.6
WCS | Unsecured Debt
Long-term debt
Total debt	2.4	2.4
Tremont | Secured Debt
Long-term debt
Total debt	17.4	19.1
BMI | Bank note payable
Long-term debt
Total debt	10.5	11.2
LandWell | Unsecured Debt
Long-term debt
Total debt	3.1	3.1
Other Subsidiary | Other
Long-term debt
Total debt	17.6	10.5
Subsidiary
Long-term debt
Total debt	$ 465.2	$ 296.0