Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Payable to affiliates:
Employee benefits	$ 27.2	$ 34.6
Deferred income	16.6	19.8
Accrued sales discounts and rebates	13.6	23.0
Environmental remediation and related costs	10.1	10.2
Other	40.6	40.4
Total	253.0	310.2
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	97.2	121.4
CompX
Accounts payable:
Accounts payable	3.6	3.9
WCS
Accounts payable:
Accounts payable	1.0	1.4
Other
Accounts payable:
Accounts payable	1.9	2.5
BMI and LandWell
Accounts payable:
Accounts payable	3.4	7.0
Contran | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	26.2	26.1
LPC | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	$ 11.6	$ 19.9