Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts payable:
Accounts payable	$ 111.5	$ 116.1
Current accrued liabilities:
Employee benefits	37.5	36.3
Accrued sales discounts and rebates	29.7	14.3
Deferred income	28.3	28.3
Environmental remediation and related costs	6.5	6.8	$ 15.3
Interest	5.2	5.5
Other	33.6	33.6
Total	140.8	124.8
Noncurrent accrued liabilities:
Other postretirement benefits	10.3	11.3
Reserve for uncertain tax positions	19.1	16.5
Deferred income	15.8	15.7
Employee benefits	7.1	8.4
Insurance claims and expenses	8.1	9.1
Deferred payment obligation	9.6	9.3
Accrued development costs	7.5	6.1
Other	9.9	8.5
Total	87.4	84.9
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	103.2	107.9
CompX
Accounts payable:
Accounts payable	3.2	2.3
BMI/LandWell
Accounts payable:
Accounts payable	2.9	3.7
NL
Accounts payable:
Accounts payable	1.6	1.8
Other
Accounts payable:
Accounts payable	$ 0.6	$ 0.4