Noncontrolling interest in subsidiaries - Changes in Ownership Interest in Subsidiaries (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Noncontrolling Interest [Line Items]
Net income attributable to Valhi stockholders	$ 22.9	$ 71.5	$ 156.2	$ 161.9
Transfers from noncontrolling interest -
Issuance of subsidiaries common stock				0.4
Net income attributable to Valhi stockholders and change from noncontrolling interest in subsidiaries			$ 156.2	$ 162.3