Fair Value Measurements and Financial Instruments - Financial Instruments not Carried at Fair Value (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash equivalents	$ 280,900,000	$ 186,800,000
Deferred payment obligation	8,400,000	8,200,000
Noncontrolling interest, Carrying amount	369,900,000	391,500,000
Valhi stockholders' equity, Carrying amount	590,500,000	601,300,000
Cash, cash equivalents and restricted cash equivalents, Fair value	280,900,000	186,800,000
Deferred payment obligation, Fair value	8,400,000	8,200,000
Noncontrolling interest, Fair value	2,177,200,000	5,916,700,000
Kronos Worldwide, Inc.
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Noncontrolling interest, Carrying amount	241,000,000	241,900,000
Noncontrolling interest, Fair value	355,100,000	431,600,000
Kronos Worldwide, Inc. | Term Loan
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, Carrying amount	347,500,000
Debt instrument, Fair value	351,700,000
Kronos Worldwide, Inc. | Note Payable | Contran
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument		170,000,000
Debt instrument, Fair value		170,000,000
Kronos Worldwide, Inc. | Bank Credit Facility
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Variable rate credit facility, Carrying amount		11,100,000
Variable rate credit facility, Fair value		11,100,000
Snake River | Fixed Rate Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, Carrying amount	250,000,000	250,000,000
Debt instrument, Fair value	250,000,000	250,000,000
WCS | Fixed Rate Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, Carrying amount	71,600,000	72,400,000
Debt instrument, Fair value	71,600,000	72,400,000
Valhi | Credit Facility | Contran
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Variable rate credit facility, Carrying amount	215,000,000	206,500,000
Variable rate credit facility, Fair value	215,000,000	206,500,000
Tremont | Promissory Note
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument	17,400,000	19,100,000
Debt instrument, Fair value	17,400,000	19,100,000
BMI | Bank note payable
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument	10,800,000	11,200,000
Debt instrument, Fair value	10,800,000	11,200,000
LandWell | City of Henderson
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument	3,100,000	3,100,000
Debt instrument, Fair value	3,100,000	3,100,000
NL
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Noncontrolling interest, Carrying amount	57,800,000	74,500,000
Noncontrolling interest, Fair value	77,000,000	92,600,000
CompX
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Noncontrolling interest, Carrying amount	14,100,000	13,600,000
Noncontrolling interest, Fair value	$ 17,200,000	$ 23,100,000