Accounts Payable and Accrued Liabilities - Components of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts Payable And Accrued Liabilities [Line Items]
Accounts payable	$ 111.2	$ 137.2
Employee benefits	22.3	21.1
Accrued sales discounts and rebates	20.8	32.4
Operating lease liabilities	6.0	6.2
Other	34.9	40.8
Total	216.1	259.0
LPC
Accounts Payable And Accrued Liabilities [Line Items]
Payables to affiliate	16.3	16.4
Other
Accounts Payable And Accrued Liabilities [Line Items]
Payables to affiliate	0.1
Valhi | Income taxes
Accounts Payable And Accrued Liabilities [Line Items]
Payables to affiliate	$ 4.5	$ 4.9