Quarterly Results of Operations - Schedule of Quarterly Results of Operations (Parenthetical) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred income taxes expense (benefit)									$ (115.9)	$ (245.8)	$ (26.4)
Loss on prepayment of debt						$ 7.1				7.1
Current income tax expense provisional pursuant to transition tax					$ 76.2
Deferred income tax benefit from change in enacted tax rate		$ (59.7)							$ (60.6)	77.1
Valuation allowance										$ (205.4)	$ (2.2)
Gain on sale of land per diluted share				$ 0.03
Charge on litigation settlement expense recognized per diluted share			$ 62
Current cash tax income tax expense per diluted share related to GILTI	$ 4.0
Canada - Germany APA
U.S. – Canada APA						(11.8)
Non Cash Deferred Income Tax Benefit | Deferred Income Tax Liability | U.S. Federal Corporate Income Tax Rate
Deferred income tax benefit from change in enacted tax rate					77.1
Aggregate provisional non-cash deferred income tax expense					5.3
Valuation Allowance of Deferred Tax Assets | One Non-U.S. subsidiary | Expected Future Periods Net Operating Loss Utilization | Non Cash Deferred Income Tax Benefit
Valuation allowance					(18.7)
Kronos Worldwide, Inc.
Non-cash deferred income tax benefit per diluted share		$ 112
Kronos Worldwide, Inc. | Valuation Allowance of Deferred Tax Assets | Germany and Belgium | Expected Future Periods Net Operating Loss Utilization | Non Cash Deferred Income Tax Benefit
Deferred income taxes expense (benefit)					(16.3)	$ (7.8)		$ (5.0)
Kronos Worldwide, Inc. | Valuation Allowance of Deferred Tax Assets | One Non-U.S. subsidiary | Expected Future Periods Net Operating Loss Utilization | Non Cash Deferred Income Tax Benefit
Deferred income taxes expense (benefit)							$ 157.6
Valuation allowance					$ (18.7)
Amalgamated Sugar Company LLC
Gain on securities transaction recognized per diluted share		$ 12.5