Accounts and Other Receivables, Net - Components of Accounts and Other Receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade accounts receivable:
VAT and other receivables	$ 20.7	$ 18.6
Allowance for doubtful accounts	(1.5)	(0.8)
Total	332.7	254.3
Trade Accounts Receivable | Kronos Worldwide, Inc.
Trade accounts receivable:
Accounts receivable	301.4	224.8
Trade Accounts Receivable | CompX
Trade accounts receivable:
Accounts receivable	10.5	10.4
Trade Accounts Receivable | BMI and LandWell
Trade accounts receivable:
Accounts receivable	$ 1.6	$ 1.3