Related Party Transactions - Current Receivables and Payables to Affiliates (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current receivables from affiliates:
Receivable from affiliate	$ 1,767	$ 14
Current payables to affiliates:
Payable to affiliates	429	1,717
Other - Trade Items
Current receivables from affiliates:
Receivable from affiliate		14
Current payables to affiliates:
Payable to affiliates	429	211
Valhi | Income Taxes
Current receivables from affiliates:
Receivable from affiliate	$ 1,767
Current payables to affiliates:
Payable to affiliates		$ 1,506