Noncontrolling Interest in Subsidiaries - Noncontrolling Interest in Net Assets of Subsidiaries (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 333.5	$ 328.9
Kronos Worldwide, Inc.
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	225.1	226.6
NL Industries
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	75.8	75.7
CompX International
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	20.4	22.5
BMI
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	7.1	8.3
LandWell
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 5.1	$ (4.2)