Organization and Basis of Presentation	6 Months Ended
Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	Note 1 – Organization and basis of presentation: Organization. We (NYSE American: CIX) are 87% owned by NL Industries, Inc. (NYSE: NL) at June 30, 2018. We manufacture and sell component products (security products and recreational marine components). At June 30, 2018, Valhi, Inc. (NYSE: VHI) owns 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation owns 92% of Valhi’s outstanding common stock. All of Contran’s outstanding voting stock is held by a family trust established for the benefit of Lisa K. Simmons and Serena Simmons Connelly and their children, for which Ms. Simmons and Ms. Connelly are co-trustees, or is held directly by Ms. Simmons and Ms. Connelly or entities related to them. Consequently, Ms. Simmons and Ms. Connelly may be deemed to control Contran, Valhi, NL and us. At our 2018 annual meeting of stockholders held May 23, 2018, our stockholders approved our second amended and restated certificate of incorporation, which among other things added a right for each holder of shares of our Class B common stock, at its option, to convert any or all of those shares into the same number of shares of our Class A common stock. The shares of our Class A and Class B common stock are identical in all respects, except for certain voting rights and certain conversion rights in respect of the shares of Class B common stock. Holders of our shares of Class B common stock are entitled to ten votes per share for election of our directors, and one vote per share on all other matters presented to our stockholders for their approval. Holders of our shares of Class A common stock are entitled to one vote per share on all matters presented to our stockholders for their approval. Our second amended and restated certificate of incorporation became effective on July 17, 2018 when we filed such certificate with the Delaware Secretary of State. Immediately after such effectiveness, NL, which owned all of the 10,000,000 issued and outstanding shares of our Class B common stock, converted such Class B shares into 10,000,000 shares of our Class A common stock. This conversion eliminated the dual-class voting structure with respect to election of our directors, providing for equal voting rights with respect to the election of directors for all shares of common stock and providing for uniform and equivalent corporate governance rights to all holders of our common stock. The rights of holders of Class A common stock were not otherwise affected, and the conversion does not affect the calculation of our earnings per share and has no impact on our consolidated financial position, results of operations or liquidity. Following such conversion, our authorized capital stock consists of 20,000,000 shares of Class A common stock (of which 12,435,557 shares are issued and outstanding), 10,000,000 shares of Class B common stock (none of which are issued and outstanding) and 1,000 shares of preferred stock (none of which are issued and outstanding). The second amended and restated certificate of incorporation does not permit the reissuance or resale of any of the shares of Class B common stock which were converted, and we expect our board of directors will take action in the near term to eliminate the 10,000,000 shares of Class B common stock currently authorized by the second amended and restated certificate of incorporation. Basis of presentation. Consolidated in this Quarterly Report are the results of CompX International Inc. and its subsidiaries. The unaudited Condensed Consolidated Financial Statements contained in this Quarterly Report have been prepared on the same basis as the audited Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 that we filed with the Securities and Exchange Commission (“SEC”) on February 28, 2018 (the “2017 Annual Report”). In our opinion, we have made all necessary adjustments (which include only normal recurring adjustments) in order to state fairly, in all material respects, our consolidated financial position, results of operations and cash flows as of the dates and for the periods presented. We have condensed the Consolidated Balance Sheet at December 31, 2017 contained in this Quarterly Report as compared to our audited Consolidated Financial Statements at that date, and we have omitted certain information and footnote disclosures (including those related to the Consolidated Balance Sheet at December 31, 2017) normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Our results of operations for the interim periods ended June 30, 2018 may not be indicative of our operating results for the full year. The Condensed Consolidated Financial Statements contained in this Quarterly Report should be read in conjunction with our 2017 Consolidated Financial Statements contained in our 2017 Annual Report. Our operations are reported on a 52 or 53-week year. For presentation purposes, annual and quarterly information in the Condensed Consolidated Financial Statements and accompanying notes are presented as ended June 30, 2017, December 31, 2017 and June 30, 2018. The actual dates of our annual and quarterly periods are July 2, 2017, December 31, 2017 and July 1, 2018, respectively. Unless otherwise indicated, references in this report to “we”, “us” or “our” refer to CompX International Inc. and its subsidiaries, taken as a whole.

Note 1 – Organization and basis of presentation:

Organization. We (NYSE American: CIX) are 87% owned by NL Industries, Inc. (NYSE: NL) at June 30, 2018. We manufacture and sell component products (security products and recreational marine components). At June 30, 2018, Valhi, Inc. (NYSE: VHI) owns 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation owns 92% of Valhi’s outstanding common stock. All of Contran’s outstanding voting stock is held by a family trust established for the benefit of Lisa K. Simmons and Serena Simmons Connelly and their children, for which Ms. Simmons and Ms. Connelly are co-trustees, or is held directly by Ms. Simmons and Ms. Connelly or entities related to them. Consequently, Ms. Simmons and Ms. Connelly may be deemed to control Contran, Valhi, NL and us.

At our 2018 annual meeting of stockholders held May 23, 2018, our stockholders approved our second amended and restated certificate of incorporation, which among other things added a right for each holder of shares of our Class B common stock, at its option, to convert any or all of those shares into the same number of shares of our Class A common stock. The shares of our Class A and Class B common stock are identical in all respects, except for certain voting rights and certain conversion rights in respect of the shares of Class B common stock. Holders of our shares of Class B common stock are entitled to ten votes per share for election of our directors, and one vote per share on all other matters presented to our stockholders for their approval. Holders of our shares of Class A common stock are entitled to one vote per share on all matters presented to our stockholders for their approval. Our second amended and restated certificate of incorporation became effective on July 17, 2018 when we filed such certificate with the Delaware Secretary of State. Immediately after such effectiveness, NL, which owned all of the 10,000,000 issued and outstanding shares of our Class B common stock, converted such Class B shares into 10,000,000 shares of our Class A common stock. This conversion eliminated the dual-class voting structure with respect to election of our directors, providing for equal voting rights with respect to the election of directors for all shares of common stock and providing for uniform and equivalent corporate governance rights to all holders of our common stock. The rights of holders of Class A common stock were not otherwise affected, and the conversion does not affect the calculation of our earnings per share and has no impact on our consolidated financial position, results of operations or liquidity. Following such conversion, our authorized capital stock consists of 20,000,000 shares of Class A common stock (of which 12,435,557 shares are issued and outstanding), 10,000,000 shares of Class B common stock (none of which are issued and outstanding) and 1,000 shares of preferred stock (none of which are issued and outstanding). The second amended and restated certificate of incorporation does not permit the reissuance or resale of any of the shares of Class B common stock which were converted, and we expect our board of directors will take action in the near term to eliminate the 10,000,000 shares of Class B common stock currently authorized by the second amended and restated certificate of incorporation.

Basis of presentation. Consolidated in this Quarterly Report are the results of CompX International Inc. and its subsidiaries. The unaudited Condensed Consolidated Financial Statements contained in this Quarterly Report have been prepared on the same basis as the audited Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2017 that we filed with the Securities and Exchange Commission (“SEC”) on February 28, 2018 (the “2017 Annual Report”). In our opinion, we have made all necessary adjustments (which include only normal recurring adjustments) in order to state fairly, in all material respects, our consolidated financial position, results of operations and cash flows as of the dates and for the periods presented. We have condensed the Consolidated Balance Sheet at December 31, 2017 contained in this Quarterly Report as compared to our audited Consolidated Financial Statements at that date, and we have omitted certain information and footnote disclosures (including those related to the Consolidated Balance Sheet at December 31, 2017) normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Our results of operations for the interim periods ended June 30, 2018 may not be indicative of our operating results for the full year. The Condensed Consolidated Financial Statements contained in this Quarterly Report should be read in conjunction with our 2017 Consolidated Financial Statements contained in our 2017 Annual Report.

Our operations are reported on a 52 or 53-week year. For presentation purposes, annual and quarterly information in the Condensed Consolidated Financial Statements and accompanying notes are presented as ended June 30, 2017, December 31, 2017 and June 30, 2018. The actual dates of our annual and quarterly periods are July 2, 2017, December 31, 2017 and July 1, 2018, respectively. Unless otherwise indicated, references in this report to “we”, “us” or “our” refer to CompX International Inc. and its subsidiaries, taken as a whole.