Income Taxes - Components of Net Deferred Tax Liability (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Tax effect of temporary differences related to:
Inventories	$ 0.5	$ 0.4
Accrued OPEB costs	0.2	0.3
Accrued pension costs	0.5	0.5
Accrued employee benefits	1.3	1.1
Accrued environmental liabilities	26.7	29.1
Other accrued liabilities and deductible differences	0.2
Adjusted gross deferred tax assets (liabilities)	29.4	31.4
Netting of items by tax jurisdiction	(29.4)	(31.4)
Marketable securities	(7.0)	(3.6)
Property and equipment	(2.7)	(2.6)
Goodwill	(1.7)	(1.7)
Other taxable differences	(2.3)	(2.3)
Investment in Kronos Worldwide, Inc.	(59.8)	(55.0)
Adjusted gross deferred tax assets (liabilities)	(73.5)	(65.2)
Netting of items by tax jurisdiction	29.4	31.4
Net noncurrent deferred tax liability	$ (44.1)	$ (33.8)