Noncontrolling Interest in Subsidiaries - Noncontrolling Interest in Net Assets of Subsidiaries (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 335.2	$ 328.9
Kronos Worldwide, Inc.
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	230.0	226.6
NL Industries
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	81.7	75.7
CompX International
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	22.9	22.5
BMI
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	3.5	8.3
LandWell
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ (2.9)	$ (4.2)