Segment information - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Revenues From External Customers And Long Lived Assets [Line Items]
Depreciation and amortization	$ 1,868	$ 1,846
CompX
Revenues From External Customers And Long Lived Assets [Line Items]
Depreciation and amortization	$ 1,900	$ 1,800

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (b)
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-Topic 230
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Name:	us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration