Noncontrolling Interest in Subsidiaries - Schedule of Noncontrolling Interest in Net Income of Subsidiaries (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	$ 2.9	$ 14.4	$ 4.1	$ 32.4
Kronos Worldwide, Inc.
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries			(4.5)	19.8
NL
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries			(1.7)	8.3
CompX
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries			1.3	1.5
BMI
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries			3.5	(1.9)
LandWell
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries			$ 5.5	$ 4.7