Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2020
Summary of Significant Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation GSE Systems, Inc. is a leading provider of professional and technical engineering, staffing services and simulation software to clients in the power and process industries. References in this report to “GSE” or "we” and "our" are to GSE Systems, Inc. and our subsidiaries, collectively. The consolidated interim financial statements included herein have been prepared by GSE and are unaudited. In the opinion of the management, all adjustments and reclassifications of a normal and recurring nature necessary to present fairly the financial position, results of operations and cash flows for the periods presented, have been made. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") have been condensed or omitted. The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The accompanying balance sheet data for the year ended December 31, 2019 was derived from our audited financial statements, but it does not include all disclosures required by U.S. GAAP. The results of operations for interim periods are not necessarily an indication of the results for the full year. These consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the Securities and Exchange Commission on June 11, 2020. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as reported amounts of revenues and expenses during the reporting period. Our most significant estimates relate to revenue recognition on contracts with customers, allowance for doubtful accounts, product warranties, valuation of goodwill and intangible assets acquired including the determination of fair value in impairment tests, valuation of long-lived assets to be disposed of, valuation of contingent consideration issued in business acquisitions, valuation of stock-based compensation awards and the recoverability of deferred tax assets. Actual results of these, and other items not listed, could differ from these estimates and those differences could be material.
COVID-19	COVID-19 We began working remotely at the period end, due to the COVID-19 impact and continue to do so, available, and mandated by local, state and federal regulations. As a result, employees almost entirely work from home for the Performance Solutions segment, but for when required to be at the client site for essential project work. Performance Projects, since they are essential, for the most part continue without pause. For our staff augmentation, we have seen certain contract for NITC customers paused and or delayed as clients shrink their own on-premise workforces to the bare minimum in response to the pandemic; as a result the NITC business has seen its deployed billable employee base contract since the start of the pandemic. Although we cannot fully estimate the length or gravity of the impact of the COVID-19 outbreak at this time, we have experienced delays in commencing new projects, which has delayed or ability to recognize revenue. In addition, we have had order reductions or changes due to the pandemic. We expect the financial results for the fiscal year 2020 to be lower as a result of COVID-19.
Going Concern Consideration	Going Concern Consideration As a result of the COVID-19 pandemic, we are experiencing a negative impact on our financial position and results of operations. We are likely to continue to experience delays in commencing outstanding orders or loss of orders altogether, disruption of our business as a result of worker illness or mandated shutdowns, and this could impact our ability to maintain compliance with our debt covenants, our ability to refinance existing indebtedness and our ability to access new capital. We received $10 million from the Paycheck Protection Program ("PPP") and indicated without these funds, the risk of employee terminations, layoffs and other drastic cost reductions exists. While the PPP funds will provide us liquidity, these funds will not prevent us from potentially not meeting the minimum EBITDA covenant or other of our debt covenants in the future. Including the proceeds from the PPP, we believe we have sufficient cash to meet our operating requirement needs for at least the next twelve months; however since some of our loan covenants are related to operating performance, and our operating performance is being significantly impacted by the COVID-19 pandemic, we believe it is probable we will not remain in compliance with our debt covenants throughout the remainder of fiscal 2020. As a result of the expected debt covenant violation, we have classified our debt as short-term in our consolidated balance sheets as of March 31, 2020 and December 31, 2019, which creates substantial doubt regarding our ability to continue as a going concern.