Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Long-term debt
Total debt	$ 598.1	$ 653.0
Less current maturities	(16.4)	(3.1)
Total long-term debt	581.7	649.9
VALHI, INC. | Contran Credit Facility
Long-term debt
Total debt	153.4	172.9
Kronos Worldwide, Inc. | 3.75% Senior Secured Notes due September 15, 2025 | Kronos International, Inc
Long-term debt
Total debt	415.1	448.8
BMI | Bank loan | Western Alliance Bank
Long-term debt
Total debt	14.3	15.4
LandWell | Unsecured Debt | Western Alliance Bank
Long-term debt
Total debt	13.2	13.5
Other Subsidiary | Other
Long-term debt
Total debt	2.1	2.4
Subsidiary
Long-term debt
Total debt	$ 444.7	$ 480.1