Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1 – Summary of significant accounting policies: Organization. We (NYSE MKT: CIX) are 87% owned by NL Industries, Inc. (NYSE: NL) at December 31, 2016. We manufacture and sell component products (security products and recreational marine components). At December 31, 2016, Valhi, Inc. (NYSE: VHI) owns 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation owns 93% 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. Unless otherwise indicated, references in this report to “we,” “us,” or “our” refer to CompX International Inc. and its subsidiaries, taken as a whole. Management estimates. In preparing our financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at each balance sheet date and the reported amounts of our revenues and expenses during each reporting period. Actual results may differ significantly from previously estimated amounts under different assumptions or conditions. Principles of consolidation. Our consolidated financial statements include the accounts of CompX International Inc. and our wholly-owned subsidiaries. We eliminate all material intercompany accounts and balances. Fiscal year. Our fiscal year end is always the Sunday closest to December 31, and our operations are reported on a 52 or 53-week fiscal year. Each of the years ended December 31, 2014 and 2016 consisted of 52 weeks. The year ended December 31, 2015 consisted of 53 weeks. For presentation purposes, annual and quarterly information in the consolidated financial statements and accompanying notes are presented as ended on March 31, June 30, September 30 and December 31, as applicable. The actual date of our fiscal years ended December 31, 2014, 2015 and 2016 are December 28, 2014, January 3, 2016 and January 1, 2017, respectively. Cash and cash equivalents. We classify as cash and cash equivalents, bank time deposits and government and commercial notes and bills with original maturities of three months or less. Net sales. We record sales when products are shipped and title and other risks and rewards of ownership have passed to the customer. Amounts charged to customers for shipping and handling are not material. Sales are stated net of price, early payment and distributor discounts and volume rebates. We report any tax assessed by a governmental authority that we collect from our customers that is both imposed on and concurrent with our revenue producing activities (such as sales and use taxes) on a net basis (meaning we do not recognize these taxes either in our revenues or in our costs and expenses). Accounts receivable. We provide an allowance for doubtful accounts for known and estimated potential losses arising from our sales to customers based on a periodic review of these accounts. Inventories and cost of sales. We state inventories at the lower of cost or market, net of allowance for obsolete and slow-moving inventories. We generally base inventory costs for all inventory categories on average cost that approximates the first-in, first-out method. Inventories include the costs for raw materials, the cost to manufacture the raw materials into finished goods and overhead. Depending on the inventory’s stage of completion, our manufacturing costs can include the costs of packing and finishing, utilities, maintenance and depreciation, shipping and handling, and salaries and benefits associated with our manufacturing process. We allocate fixed manufacturing overhead costs based on normal production capacity. Unallocated overhead costs resulting from periods with abnormally low production levels are charged to expense as incurred. As inventory is sold to third parties, we recognize the cost of sales in the same period that the sale occurs. We periodically review our inventory for estimated obsolescence or instances when inventory is no longer marketable for its intended use, and we record any write-down, equal to the difference between the cost of inventory and its estimated net realizable value, based on assumptions about alternative uses, market conditions and other factors. Selling, general and administrative expenses; advertising costs. Selling, general and administrative expenses include costs related to marketing, sales, distribution, research and development and administrative functions such as accounting, treasury and finance, and includes costs for salaries and benefits, travel and entertainment, promotional materials and professional fees. We expense advertising and research and development costs as incurred. Advertising costs were not significant in 2014, 2015 or 2016. Goodwill. Goodwill represents the excess of cost over fair value of individual net assets acquired in business combinations. Goodwill is not subject to periodic amortization. We evaluate goodwill for impairment annually or when circumstances indicate the carrying value may not be recoverable. See Note 5. Property and equipment; depreciation expense. We state property and equipment, including purchased computer software for internal use, at cost. We compute depreciation of property and equipment for financial reporting purposes principally by the straight-line method over the estimated useful lives of 15 to 40 years for buildings and 3 to 20 years for equipment and software. We use accelerated depreciation methods for income tax purposes, as permitted. Depreciation expense was $3.5 million in each of 2014 and 2015 and $3.7 million in 2016. Upon sale or retirement of an asset, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is recognized in income currently. Expenditures for maintenance, repairs and minor renewals are expensed; expenditures for major improvements are capitalized. We perform impairment tests when events or changes in circumstances indicate the carrying value may not be recoverable. We consider all relevant factors. We perform the impairment test by comparing the estimated future undiscounted cash flows associated with the asset to the asset’s net carrying value to determine if impairment exists. Employee benefit plans. We maintain various defined contribution plans in which we make contributions based on matching or other formulas. Defined contribution plan expense approximated $2.3 million in 2014, $2.4 million in 2015 and $2.6 million in 2016. Self-insurance. We are partially self-insured for workers’ compensation and certain employee health benefits and self-insured for most environmental issues. We purchase coverage in order to limit our exposure to any significant levels of workers’ compensation or employee health benefit claims. We accrue self-insured losses based upon estimates of the aggregate liability for uninsured claims incurred using certain actuarial assumptions followed in the insurance industry and our own historical claims experience. Income taxes. We, and our parent NL, are members of the Contran Tax Group. We have been and currently are a part of the consolidated tax returns filed by Contran for U.S. federal purposes as well as for certain U.S. state jurisdictions. As a member of the Contran Tax Group, we are jointly and severally liable for the federal income tax liability of Contran and the other companies included in the Contran Tax Group for all periods in which we are included in the Contran Tax Group. See Note 10. As a member of the Contran Tax Group, we are a party to a tax sharing agreement which provides that we compute our provision for U.S. income taxes on a separate-company basis. Pursuant to the tax sharing agreement, we make payments to or receive payments from NL in amounts we would have paid to or received from the U.S. Internal Revenue Service or the applicable state tax authority had we not been a member of the Contran Tax Group. The separate company provisions and payments are computed using the tax elections made by Contran. We made net cash payments for income taxes to NL of $4.4 million in 2014, $4.7 million in 2015 and $4.6 million in 2016. Deferred income tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the income tax and financial reporting carrying amounts of assets and liabilities. Deferred income tax assets and liabilities for each tax-paying jurisdiction in which we operate are netted and presented as either a noncurrent deferred income tax asset or liability, as applicable. We periodically evaluate our deferred tax assets in the various taxing jurisdictions in which we operate and adjust any related valuation allowance based on the estimate of the amount of deferred tax assets which we believe do not meet the more-likely-than-not recognition criteria. See Notes 7 and 12. We record a reserve for uncertain tax positions for tax positions where we believe it is more-likely-than-not our position will not prevail with the applicable tax authorities. Our reserve for uncertain tax positions was nil in each of 2015 and 2016.

Note 1 – Summary of significant accounting policies:

Organization. We (NYSE MKT: CIX) are 87% owned by NL Industries, Inc. (NYSE: NL) at December 31, 2016. We manufacture and sell component products (security products and recreational marine components). At December 31, 2016, Valhi, Inc. (NYSE: VHI) owns 83% of NL’s outstanding common stock and a wholly-owned subsidiary of Contran Corporation owns 93% 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.

Unless otherwise indicated, references in this report to “we,” “us,” or “our” refer to CompX International Inc. and its subsidiaries, taken as a whole.

Management estimates. In preparing our financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at each balance sheet date and the reported amounts of our revenues and expenses during each reporting period. Actual results may differ significantly from previously estimated amounts under different assumptions or conditions.

Principles of consolidation. Our consolidated financial statements include the accounts of CompX International Inc. and our wholly-owned subsidiaries. We eliminate all material intercompany accounts and balances.

Fiscal year. Our fiscal year end is always the Sunday closest to December 31, and our operations are reported on a 52 or 53-week fiscal year. Each of the years ended December 31, 2014 and 2016 consisted of 52 weeks. The year ended December 31, 2015 consisted of 53 weeks. For presentation purposes, annual and quarterly information in the consolidated financial statements and accompanying notes are presented as ended on March 31, June 30, September 30 and December 31, as applicable. The actual date of our fiscal years ended December 31, 2014, 2015 and 2016 are December 28, 2014, January 3, 2016 and January 1, 2017, respectively.

Cash and cash equivalents. We classify as cash and cash equivalents, bank time deposits and government and commercial notes and bills with original maturities of three months or less.

Net sales. We record sales when products are shipped and title and other risks and rewards of ownership have passed to the customer. Amounts charged to customers for shipping and handling are not material. Sales are stated net of price, early payment and distributor discounts and volume rebates. We report any tax assessed by a governmental authority that we collect from our customers that is both imposed on and concurrent with our revenue producing activities (such as sales and use taxes) on a net basis (meaning we do not recognize these taxes either in our revenues or in our costs and expenses).

Accounts receivable. We provide an allowance for doubtful accounts for known and estimated potential losses arising from our sales to customers based on a periodic review of these accounts.

Inventories and cost of sales. We state inventories at the lower of cost or market, net of allowance for obsolete and slow-moving inventories. We generally base inventory costs for all inventory categories on average cost that approximates the first-in, first-out method. Inventories include the costs for raw materials, the cost to manufacture the raw materials into finished goods and overhead. Depending on the inventory’s stage of completion, our manufacturing costs can include the costs of packing and finishing, utilities, maintenance and depreciation, shipping and handling, and salaries and benefits associated with our manufacturing process. We allocate fixed manufacturing overhead costs based on normal production capacity. Unallocated overhead costs resulting from periods with abnormally low production levels are charged to expense as incurred. As inventory is sold to third parties, we recognize the cost of sales in the same period that the sale occurs. We periodically review our inventory for estimated obsolescence or instances when inventory is no longer marketable for its intended use, and we record any write-down, equal to the difference between the cost of inventory and its estimated net realizable value, based on assumptions about alternative uses, market conditions and other factors.

Selling, general and administrative expenses; advertising costs. Selling, general and administrative expenses include costs related to marketing, sales, distribution, research and development and administrative functions such as accounting, treasury and finance, and includes costs for salaries and benefits, travel and entertainment, promotional materials and professional fees. We expense advertising and research and development costs as incurred. Advertising costs were not significant in 2014, 2015 or 2016.

Goodwill. Goodwill represents the excess of cost over fair value of individual net assets acquired in business combinations. Goodwill is not subject to periodic amortization. We evaluate goodwill for impairment annually or when circumstances indicate the carrying value may not be recoverable. See Note 5.

Property and equipment; depreciation expense. We state property and equipment, including purchased computer software for internal use, at cost. We compute depreciation of property and equipment for financial reporting purposes principally by the straight-line method over the estimated useful lives of 15 to 40 years for buildings and 3 to 20 years for equipment and software. We use accelerated depreciation methods for income tax purposes, as permitted. Depreciation expense was $3.5 million in each of 2014 and 2015 and $3.7 million in 2016. Upon sale or retirement of an asset, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is recognized in income currently. Expenditures for maintenance, repairs and minor renewals are expensed; expenditures for major improvements are capitalized.

We perform impairment tests when events or changes in circumstances indicate the carrying value may not be recoverable. We consider all relevant factors. We perform the impairment test by comparing the estimated future undiscounted cash flows associated with the asset to the asset’s net carrying value to determine if impairment exists.

Employee benefit plans. We maintain various defined contribution plans in which we make contributions based on matching or other formulas. Defined contribution plan expense approximated $2.3 million in 2014, $2.4 million in 2015 and $2.6 million in 2016.

Self-insurance. We are partially self-insured for workers’ compensation and certain employee health benefits and self-insured for most environmental issues. We purchase coverage in order to limit our exposure to any significant levels of workers’ compensation or employee health benefit claims. We accrue self-insured losses based upon estimates of the aggregate liability for uninsured claims incurred using certain actuarial assumptions followed in the insurance industry and our own historical claims experience.

Income taxes. We, and our parent NL, are members of the Contran Tax Group. We have been and currently are a part of the consolidated tax returns filed by Contran for U.S. federal purposes as well as for certain U.S. state jurisdictions. As a member of the Contran Tax Group, we are jointly and severally liable for the federal income tax liability of Contran and the other companies included in the Contran Tax Group for all periods in which we are included in the Contran Tax Group. See Note 10.

As a member of the Contran Tax Group, we are a party to a tax sharing agreement which provides that we compute our provision for U.S. income taxes on a separate-company basis. Pursuant to the tax sharing agreement, we make payments to or receive payments from NL in amounts we would have paid to or received from the U.S. Internal Revenue Service or the applicable state tax authority had we not been a member of the Contran Tax Group. The separate company provisions and payments are computed using the tax elections made by Contran. We made net cash payments for income taxes to NL of $4.4 million in 2014, $4.7 million in 2015 and $4.6 million in 2016.

Deferred income tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the income tax and financial reporting carrying amounts of assets and liabilities. Deferred income tax assets and liabilities for each tax-paying jurisdiction in which we operate are netted and presented as either a noncurrent deferred income tax asset or liability, as applicable. We periodically evaluate our deferred tax assets in the various taxing jurisdictions in which we operate and adjust any related valuation allowance based on the estimate of the amount of deferred tax assets which we believe do not meet the more-likely-than-not recognition criteria. See Notes 7 and 12.

We record a reserve for uncertain tax positions for tax positions where we believe it is more-likely-than-not our position will not prevail with the applicable tax authorities. Our reserve for uncertain tax positions was nil in each of 2015 and 2016.