Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Balance Sheet (Detail) - Kronos - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Equity Method Investments [Line Items]
Current assets	$ 690.5	$ 710.8
Property and equipment, net	446.6	429.5
Investment in TiO2 joint venture	79.8	82.9
Other noncurrent assets	24.6	19.5
Total assets	1,241.5	1,242.7
Current liabilities	206.5	201.7
Long-term debt	336.0	337.2
Accrued pension and postretirement benefits	210.3	209.4
Other noncurrent liabilities	33.8	32.5
Stockholders' equity	454.9	461.9
Total liabilities and stockholders' equity	$ 1,241.5	$ 1,242.7