Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2019
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. Certain prior year amounts were reclassified to conform to current year presentation.
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 June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which simplifies the accounting for share-based payments to nonemployees 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 adopted this standard beginning January 1, 2019 and its adoption did not materially impact the Company's consolidated financial position or results of operations. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurements, which eliminates, adds or modifies certain disclosure requirements for fair value measurements. Entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year, with early adoption permitted to adopt either the entire standard or only the provisions that eliminate or modify the requirements. The Company is evaluating the effect of adopting this pronouncement. In August 2018, the FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year, with early adoption permitted, including adoption in any interim period. The Company is evaluating the effect of adopting this pronouncement. In June 2016, the FASB ASU 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments as modified by subsequently issued ASU 2018-19. This ASU requires estimating credit losses for certain financial instruments, including trade receivables, held at the reporting date based on historical experience, current conditions and reasonable forecasts. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. The Company is evaluating the effect of adopting this pronouncement.
Revenue	The Company’s revenue generated by its operating subsidiaries is comprised of sales of MRO products as well as other industrial and business supplies that are sold by the IPG segment. IPG also has 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 first quarter of 2019 and 2018, respectively. 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 March 31, 2019 and March 31, 2018. The Company offers customers rights to return product within a certain time, usually 30 days. The Company estimates its sales returns liability quarterly, based upon its historical returns rates, as a percentage of historical sales for the trailing twelve-month period.