Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts payable:
Accounts payable	$ 144.7	$ 111.5
Current accrued liabilities:
Employee benefits	30.6	37.5
Operating lease liabilities	6.2
Accrued sales discounts and rebates	33.7	29.7
Deferred income	10.3	28.3
Environmental remediation and related costs	4.5	6.5	$ 6.8
Interest	5.2	5.2
Other	40.0	33.6
Total	130.5	140.8
Noncurrent accrued liabilities:
Other postretirement benefits	10.5	10.3
Operating lease liabilities	22.2
Reserve for uncertain tax positions	13.6	19.1
Deferred income	47.4	15.8
Employee benefits	6.0	7.1
Insurance claims and expenses	11.0	8.1
Deferred payment obligation	9.9	9.6
Accrued development costs	8.3	7.5
Other	8.2	9.9
Total	137.1	87.4
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	137.2	103.2
CompX
Accounts payable:
Accounts payable	2.5	3.2
BMI/LandWell
Accounts payable:
Accounts payable	3.7	2.9
NL
Accounts payable:
Accounts payable	0.9	1.6
Other
Accounts payable:
Accounts payable	$ 0.4	$ 0.6