Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Payable to affiliates:
Litigation settlement	$ 60.0
Employee benefits	28.0	$ 36.3
Deferred income	22.8	28.3
Accrued sales discounts and rebates	19.2	14.3
Environmental remediation and related costs	19.6	6.8
Interest	5.4	5.5
Other	39.4	33.6
Total	337.1	257.1
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	120.6	107.9
CompX
Accounts payable:
Accounts payable	3.0	2.3
BMI and LandWell
Accounts payable:
Accounts payable	2.8	3.7
NL
Accounts payable:
Accounts payable	0.7	1.8
Other
Accounts payable:
Accounts payable	0.4	0.4
Contran | Income Taxes Payable
Payable to affiliates:
Payable to affiliates	2.7
LPC | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	$ 12.5	$ 16.2