Financial Instruments - Financial Instruments not Carried at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Kronos Worldwide, Inc. | Term Loan | 2014 Term Loan
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	$ 338.0	$ 340.9
Long term debt, fair value	309.5	341.5
VALHI, INC. | Contran Credit Facility
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	263.8	223.7
Long term debt, fair value	263.8	223.7
VALHI, INC. | Term Loan | Snake River
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	250.0	250.0
Long term debt, fair value	250.0	250.0
WCS | Fixed Rate Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	65.6	67.1
Long term debt, fair value	65.6	67.1
Tremont | Promissory Note
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	17.1	17.4
Long term debt, fair value	17.1	17.4
BMI | Bank note payable
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	9.3	10.2
Long term debt, fair value	9.4	10.3
LandWell | Unsecured Debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	3.1	3.1
Long term debt, fair value	3.1	3.1
Reported Value Measurement
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash equivalents	229.1	280.3
Deferred payment obligation	8.8	8.5
Portion at Fair Value Measurement
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash equivalents	229.1	280.3
Deferred payment obligation	$ 8.8	$ 8.5