XML 34 R24.htm IDEA: XBRL DOCUMENT v3.25.1

Organization and basis of presentation - Additional Information (Detail)	Mar. 31, 2025
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%

X

- Definition

Basis of presentation and significant accounting policies.

+ References

No definition available.

+ Details

Name:	cix_BasisOfPresentationAndSignificantAccountingPoliciesLineItems
Namespace Prefix:	cix_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- Details

Name:	dei_LegalEntityAxis=cix_NLIndustriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_OwnershipAxis=cix_CompXInternationalIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=cix_ValhiIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_OwnershipAxis=cix_NLIndustriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=cix_ContranCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_OwnershipAxis=cix_ValhiIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: