Organization and Basis of Presentation - Additional Information (Detail)	Mar. 31, 2021
Contran \| Valhi Incorporation
Basis Of Presentation And Significant Accounting Policies [Line Items]
Parent company ownership interest	92.00%

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant