Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The accompanying condensed consolidated financial statements of Systemax Inc., with its subsidiaries, (the "Company") are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America are not required in these interim financial statements and have been condensed or omitted. All significant intercompany accounts and transactions have been eliminated in consolidation.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Public companies in the United States are subject to the accounting and reporting requirements of various authorities, including the Financial Accounting Standards Board (“FASB”) and the Securities and Exchange Commission (“SEC”). These authorities issue numerous pronouncements, most of which are not applicable to the Company’s current or reasonably foreseeable operating structure. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, which amends the guidance for the recognition of revenue from contracts with customers to transfer goods and services. The new revenue recognition standard is effective for interim and annual periods beginning on January 1, 2018. The new standard is required to be adopted using either a full-retrospective or a modified-retrospective approach. The Company adopted the new standard using the modified-retrospective approach beginning on January 1, 2018. There was no material impact to total revenues in our consolidated statements of income, accounting policies, business processes, internal controls or disclosures. See Note 2 of the Notes to condensed consolidated financial statements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) Targeted Improvements, which provides entities with an additional (and optional) transition method, in addition to the existing transition method, the modified retrospective approach, to adopt the new leases standard by allowing entities to initially apply the new leases standard, ASU 2016-02, Leases (Topic 842), at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. This additional transition method changes only when an entity is required to initially apply the transition requirements of the new leases standard; it does not change how those requirements apply, An entity's reporting for the comparative periods presented in the financial statements in which it adopts the new leases standard will continue to be in accordance with current GAAP. ASU 2016-02 related to leases that outlines a comprehensive lease accounting model and supersedes the current lease guidance. The new guidance requires lessees to recognize lease liabilities and corresponding right-of-use assets for all leases with lease terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. The new guidance will be effective for the Company starting in the first quarter of fiscal 2019. Early adoption is permitted. The Company is currently in the process of evaluating which method to adopt and the impact of the adoption of this standard on the consolidated financial statements. In March 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment. which eliminates the second step from the goodwill impairment test. An entity should perform its goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, but the loss cannot exceed the total amount of goodwill allocated to the reporting unit. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the effect of adopting this pronouncement. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718) Scope of Modification Accounting, which clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. This new guidance will be applied prospectively to awards modified on or after the adoption date. This standard is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The Company adopted this standard beginning January 1, 2018 and its adoption did not materially impact the Company's consolidated financial position or results of operations when implemented in the first quarter of 2018. In June 2018, the FASB issued ASU 2018-07, Improvements to Non employee Share-Based Payment Accounting, which simplifies the accounting for share-based payments to non employees by aligning it with the accounting for share-based payments to employees, with certain exceptions. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year, with early adoption permitted after adoption of ASU 2014-09. The Company is evaluating the effect of adopting this pronouncement.
Revenue	The Company’s revenue is generated by its operating subsidiaries and is primarily comprised of sales of maintenance, repair and operational (“MRO”) products as well as other industrial and business supplies that are sold by IPG and information and communications technology (“ICT”) products that are sold by ETG. Additionally, both IPG and ETG have revenues from related activities, such as freight and, to a lesser extent, services. The Company recognizes revenue when a sales arrangement with a customer exists through the Company’s invoicing or a contract, the performance obligations have been identified, the transaction price is fixed or determinable and the Company has satisfied its performance obligations. The Company’s standard terms, provided on its invoices as well as on its websites, are included in communications with the customer and have standard payment terms of 30 days. Certain customers may have extended payment terms that have been pre-approved by the Company’s credit department, but generally none extend longer than 120 days. The Company’s performance obligation is primarily a single obligation to deliver products. The Company’s performance obligations are satisfied when products are transferred to a customer in accordance with agreed upon shipping terms. Certain sales may include product and/or services that are distinct and accounted for as separate performance obligations. The Company’s performance obligations for services are satisfied when the services are rendered. The Company’s total service revenue is immaterial as it accounted for less than 1% of total revenue for the second quarter and six months ended June 30, 2018. The Company’s revenue is shown as “Net sales” in the accompanying Condensed Consolidated Statements of Operations and is measured as the determined transaction price, net of any variable consideration consisting primarily of rights to return product. The Company has elected to treat shipping and handling revenues as activities to fulfill its performance obligation. Billings for freight and shipping and handling are recorded in net sales and costs of freight and shipping and handling are recorded in cost of sales in the accompanying Condensed Consolidated Statements of Operations. The Company records a contract liability in cases where customers pay in advance of the Company satisfying its performance obligation. The Company did not have any material unsatisfied performance obligations or liabilities as of June 30, 2018. The Company offers customers rights to return product within a certain time, usually 30 days. The Company estimates is sales returns liability quarterly based upon its historical returns rates as a percentage of historical sales for the trailing twelve-month period.