Noncontrolling Interest in Subsidiaries - Noncontrolling Interest in Subsidiaries (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 330.0	$ 358.1
Kronos Worldwide, Inc.
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	242.2	267.0
NL
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	74.4	77.8
CompX
Noncontrolling interest in net assets:
Noncontrolling interest in subsidiaries	$ 13.4	$ 13.3