Quarterly Results of Operations - Schedule of Quarterly Results of Operations (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Non-cash income tax benefit recognized related to completion of audit						$ 3.2
Provision (benefit) for income taxes related to previous periods					$ 1.2
Insurance recoveries							$ 3.7	$ 10.4	$ 9.4
Deferred income taxes							85.7	$ 10.0	$ (114.8)
Kronos Worldwide, Inc. | Direct investment in subsidiary excess carrying amount
Deferred income taxes	$ 29.3	$ 29.3	$ 29.3
German and Belgium | Kronos Worldwide, Inc.
Non-cash deferred income tax expense	6.4	2.3	150.3
Employee Severance | Chemicals
Restructuring charges	$ 0.2	$ 0.4	$ 21.1				$ 21.7
Attributable to Parent Net of Tax
Insurance recoveries				$ 3.0	$ 7.3