Document and Entity Information	6 Months Ended
	Jun. 30, 2012	Aug. 03, 2012 Common Stock Class A	Aug. 03, 2012 Common Stock Class B
Entity Registrant Name	COMPX INTERNATIONAL INC
Entity Central Index Key	0001049606
Document Type	10-Q
Document Period End Date	Jun. 30, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		2,392,107	10,000,000