Accounts Payable and Accrued Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Payable to affiliates:
Employee benefits	$ 26.0	$ 34.6
Deferred income	23.0	19.8
Accrued workforce reduction costs	18.3
Accrued sales discounts and rebates	15.1	23.0
Environmental remediation and related costs	9.9	10.2
Other	40.8	40.4
Total	292.6	310.2
Kronos Worldwide, Inc.
Accounts payable:
Accounts payable	99.0	121.4
CompX
Accounts payable:
Accounts payable	2.9	3.9
WCS
Accounts payable:
Accounts payable	0.8	1.4
BMI and LandWell
Accounts payable:
Accounts payable	4.2	7.0
NL
Accounts payable:
Accounts payable	6.6	2.3
Other
Accounts payable:
Accounts payable	0.5	0.2
Contran | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	26.1	26.1
Contran | Income Taxes
Payable to affiliates:
Payable to affiliates	5.6
LPC | Trade Accounts Payables
Payable to affiliates:
Payable to affiliates	$ 13.8	$ 19.9