Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Income Statement (Detail) (Kronos, USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Kronos
Schedule Of Equity Method Investments [Line Items]
Net sales	$ 414.8	$ 419.1	$ 1,278.4	$ 1,363.8
Cost of sales	319.1	371.9	1,008.4	1,303.1
Income (loss) from operations	47.9	(37.0)	118.2	(131.6)
Net income (loss)	$ 31.9	$ (29.9)	$ 79.3	$ (104.9)