Investment in Kronos Worldwide, Inc. - Selected Financial Information of Kronos Income Statement (Detail) - Kronos - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Equity Method Investments [Line Items]
Net sales	$ 1,731.1	$ 1,661.9	$ 1,729.0
Cost of sales	1,344.9	1,099.7	1,159.3
Income from operations	145.8	330.1	347.8
Income tax expense (benefit)	34.0	88.8	(48.8)
Net income	$ 87.1	$ 205.0	$ 354.5