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Business Segment Information - Additional Information (Detail) | Mar. 31, 2021
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Kronos Worldwide, Inc. | Valhi Incorporation |
Segment Reporting Information [Line Items] |
Direct ownership percentage by parent | 50.00%
Kronos Worldwide, Inc. | NL |
Segment Reporting Information [Line Items] |
Indirect controlling interest in subsidiary | 30.00%
NL | Valhi Incorporation |
Segment Reporting Information [Line Items] |
Direct ownership percentage by parent | 83.00%
LandWell | Valhi Incorporation |
Segment Reporting Information [Line Items] |
Direct ownership percentage by parent | 27.00%
LandWell | BMI |
Segment Reporting Information [Line Items] |
Indirect controlling interest in subsidiary | 50.00%
BMI | Valhi Incorporation |
Segment Reporting Information [Line Items] |
Direct ownership percentage by parent | 63.00%

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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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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | instant

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Controlling interest in subsidiary held indirectly through controlled subsidiary of parent. + References No definition available. + Details
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Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
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Namespace Prefix: |
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- Details
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- Details
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- Details
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- Details
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- Details
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- Details
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