Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Income Statement (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule Of Equity Method Investments [Line Items]
Net sales	$ 443.5	$ 481.1	$ 863.6	$ 944.7
Cost of sales	349.7	471.5	689.3	931.2
Income (loss) from operations	44.3	(47.7)	70.3	(94.6)
Net income (loss)	$ 33.1	$ (33.9)	$ 47.4	$ (75.0)