Organization and Basis of Presentation - Additional Information (Detail) - $ / shares	1 Months Ended
Aug. 06, 2024	Jun. 30, 2024
Special dividend 2024 \| Class A Common Stock \| Subsequent Event [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Common stock dividends (in dollars per share)	$ 2.00
Dividend declared date	Aug. 06, 2024
Dividend record date	Aug. 19, 2024
Dividend Payable Date	Aug. 28, 2024
NL Industries \| CompX International Inc
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of ownership held by parent company		87.00%
Valhi Inc \| NL Industries
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of ownership held by parent company		83.00%
Contran Corporation \| Valhi Inc
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of ownership held by parent company		91.00%

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
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