Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Payable to affiliates:
Accrued litigation settlement	$ 11.9	$ 11.8
Employee benefits	36.3	37.5
Operating lease liabilities	6.3	6.7
Accrued sales discounts and rebates	14.9	30.2
Deferred income	18.2	20.1
Environmental remediation and related costs	3.5	3.4
Interest	1.5	5.7
Other	32.7	39.4
Total	291.9	300.0
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	132.0	111.0
CompX
Accounts payable:
Accounts payable	3.1	2.6
BMI and LandWell
Accounts payable:
Accounts payable	5.4	3.6
Other
Accounts payable:
Accounts payable	0.4	0.4
Contran | Income Taxes Payable
Payable to affiliates:
Payable to affiliates	8.9	8.3
Louisiana Pigment Company, L.P. ("LPC")
Payable to affiliates:
Payable to affiliates	$ 16.8	$ 19.3