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v3.21.1

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

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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
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Balance Type: | na
Period Type: | instant

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- Definition Basis of presentation and significant accounting policies. + References No definition available. + Details
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Namespace Prefix: | vhi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | srt_OwnershipAxis=vhi_ValhiIncorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |