Marketable Securities - Additional Information (Detail) (Valhi Inc, Common stock [Member], USD $) In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Valhi Inc | Common stock [Member]
Schedule Of Available For Sale Securities [Line Items]
Outstanding common stock	1.7	1.7
Quoted market price of per share	$ 19.96	$ 12.50