Accounts and Other Receivables, Net - Components of Accounts and Other Receivables (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Trade accounts receivable:
VAT and other receivables	$ 23.4	$ 27.2
Refundable income taxes	5.4	5.7
Allowance for doubtful accounts	(2.0)	(1.9)
Total	362.8	342.3
Trade Accounts Receivable | Kronos Worldwide, Inc.
Trade accounts receivable:
Accounts receivable	314.7	294.8
Trade Accounts Receivable | CompX
Trade accounts receivable:
Accounts receivable	16.9	10.8
Trade Accounts Receivable | BMI and LandWell
Trade accounts receivable:
Accounts receivable	1.3	1.2
Contran | Trade Items
Trade accounts receivable:
Receivable from affiliates	0.4	1.7
Other | Trade Items
Trade accounts receivable:
Receivable from affiliates	$ 2.7	$ 2.8