Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Balance Sheet (Detail) - Kronos - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 781.2	$ 886.2
Property and equipment, net	431.3	479.7
Investment in TiO2 joint venture	81.4	89.0
Other noncurrent assets	18.8	187.6
Total assets	1,312.7	1,642.5
Current liabilities	204.7	237.9
Long-term debt	342.9	344.7
Accrued pension and postretirement benefits	219.1	245.2
Other noncurrent liabilities	38.3	33.6
Stockholders' equity	507.7	781.1
Total liabilities and stockholders' equity	$ 1,312.7	$ 1,642.5