Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Long-term debt
Total debt	$ 1,106.7	$ 965.0
Less current maturities	3.9	7.8
Total long-term debt	1,102.8	957.2
VALHI, INC.
Long-term debt
Total debt	534.3	528.9
VALHI, INC. | Contran Credit Facility
Long-term debt
Total debt	284.3	278.9
VALHI, INC. | Notes Payable, Other Payables | Snake River
Long-term debt
Total debt	250.0	250.0
Kronos Worldwide, Inc. | 3.75% Senior Secured Notes due September 15, 2025 | Kronos International, Inc
Long-term debt
Total debt	464.2
Kronos Worldwide, Inc. | 2014 Term Loan
Long-term debt
Total debt		335.9
Waste Control Specialists | Financing Capital Lease Obligation
Long-term debt
Total debt	62.7	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	18.7
LandWell | Unsecured Debt
Long-term debt
Total debt	2.7	2.9
Other Subsidiary | Other
Long-term debt
Total debt	9.6	10.4
Subsidiary
Long-term debt
Total debt	$ 572.4	$ 436.1