Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accrued liabilities:
Employee benefits	$ 31.1	$ 24.7
Deferred income	23.2	21.8
Sales discounts and rebates	22.4	23.9
Environmental remediation and related costs	16.5	11.7
Reserve for uncertain tax positions	3.3
Workforce reduction costs	3.0	5.3
Other	36.8	30.4
Total	274.0	271.4
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	81.2	96.1
CompX
Accounts payable:
Accounts payable	3.5	2.7
WCS
Accounts payable:
Accounts payable	1.0	1.3
BMI and LandWell
Accounts payable:
Accounts payable	3.6	2.1
Other
Accounts payable:
Accounts payable	2.4	2.6
Contran | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	30.0	26.1
LPC | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	12.7	19.4
Interest Rate Swap
Accrued liabilities:
Hedging liabilities	$ 3.3	$ 3.3