Noncontrolling Interest in Subsidiaries - Schedule of Noncontrolling Interest in Net Income of Subsidiaries (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	$ 1.2	$ 18.0
Kronos Worldwide, Inc.
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	(3.0)	11.1
NL
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	(1.1)	3.2
CompX
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	0.8	0.6
BMI
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	1.7	1.2
LandWell
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	$ 2.8	$ 1.9