Related Party Transactions - Receivables from and Payables to Affiliates (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current receivables from affiliates:
Receivable from affiliates	$ 4.5	$ 7.3
Current payables to affiliates:
Payable to affiliates	27.6	20.4
Contran
Current receivables from affiliates:
Contran trade items	1.7	0.4
Current payables to affiliates:
Contran income taxes	8.3	4.0
Noncurrent payable to affiliates:
Contran - income taxes	50.4	56.3
Louisiana Pigment Company
Current receivables from affiliates:
Receivable from affiliates		4.7
Current payables to affiliates:
Payable to affiliates	19.3	16.4
VALHI, INC. | Contran | Credit Facility
Noncurrent payable to affiliates:
Payables to affiliate included in long-term debt	270.7	313.0
Other
Current receivables from affiliates:
Receivable from affiliates	$ 2.8	$ 2.2