Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Payable to affiliates:
Litigation settlement	$ 60.0
Employee benefits	38.5	$ 36.3
Deferred income	23.3	28.3
Accrued sales discounts and rebates	25.4	14.3
Environmental remediation and related costs	19.0	6.8
Interest	1.4	5.5
Other	35.8	33.6
Total	343.6	257.1
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	105.8	107.9
CompX
Accounts payable:
Accounts payable	3.3	2.3
BMI and LandWell
Accounts payable:
Accounts payable	3.8	3.7
NL
Accounts payable:
Accounts payable	2.6	1.8
Other
Accounts payable:
Accounts payable	0.4	0.4
Contran | Income Taxes Payable
Payable to affiliates:
Payable to affiliates	11.6
LPC | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	$ 12.7	$ 16.2