Noncontrolling Interest in Subsidiaries - Schedule of Noncontrolling Interest in Net Income of Subsidiaries (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	$ 18.0	$ 9.7
Kronos Worldwide, Inc.
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	11.1	3.8
NL
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	3.2	2.3
CompX
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	0.6	0.6
BMI
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	1.2	1.1
LandWell
Noncontrolling interest in net income of subsidiaries:
Noncontrolling interest in net income of subsidiaries	$ 1.9	$ 1.9