Accounts and Other Receivables - Accounts and Other Receivables (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Allowance for doubtful accounts	$ (1.2)	$ (1.4)
Total	340.7	346.5
Trade receivables
Accounts Notes And Loans Receivable [Line Items]
Accounts and other receivables	318.5	301.4
Recoverable VAT and other receivables
Accounts Notes And Loans Receivable [Line Items]
Accounts and other receivables	20.1	19.0
Other
Accounts Notes And Loans Receivable [Line Items]
Receivable from affiliates	$ 3.3	3.2
Refundable income taxes
Accounts Notes And Loans Receivable [Line Items]
Refundable income taxes		0.1
Valhi | Income taxes, net
Accounts Notes And Loans Receivable [Line Items]
Receivable from affiliates		15.3
Louisiana Pigment Company, L.P. ("LPC'')
Accounts Notes And Loans Receivable [Line Items]
Receivable from affiliates		$ 8.9