Noncontrolling Interest in Subsidiaries - Noncontrolling Interest in Net Assets of Subsidiaries (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 342.4	$ 348.2
Kronos Worldwide, Inc.
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	230.6	239.3
NL Industries
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	77.0	79.0
CompX International
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	21.0	20.6
BMI
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	8.6	6.9
LandWell
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 5.2	$ 2.4