Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts payable:
Accounts payable	$ 116.1	$ 92.8
Current accrued liabilities:
Employee benefits	36.3	28.0
Accrued sales discounts and rebates	14.3	22.6
Deferred income	28.3	28.7
Environmental remediation and related costs	6.8	15.3	$ 11.7
Reserve for uncertain tax positions		3.3
Accrued workforce reduction costs	0.2	1.2
Interest	5.5	0.2
Other	33.4	23.3
Total	124.8	125.4
Noncurrent accrued liabilities:
Reserve for uncertain tax positions	16.5	35.7
Asset retirement obligations	1.6	1.3
Deferred income	15.7	12.6
Employee benefits	8.4	7.6
Insurance claims and expenses	9.1	9.5
Deferred payment obligation	9.3	9.0
Accrued development costs	6.1	5.0
Other	6.9	3.8
Total	73.6	84.5
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	107.9	84.9
CompX
Accounts payable:
Accounts payable	2.3	2.6
BMI/LandWell
Accounts payable:
Accounts payable	3.7	2.2
NL
Accounts payable:
Accounts payable	1.8	2.4
Other
Accounts payable:
Accounts payable	$ 0.4	0.7
Interest Rate Swap Contract
Current accrued liabilities:
Hedging liabilities		$ 2.8