| Document and Entity Information - USD ($) | 12 Months Ended | ||
| Dec. 31, 2023 | Mar. 31, 2024 | Jun. 30, 2023 | |
| Cover [Abstract] | |||
| Document Type | 10-K/A | ||
| Amendment Flag | true | ||
| Amendment Description | GSE Systems, Inc. (the “Company”) is filing this Amendment No. 1 (this “Amendment”) to its Annual Report on Form 10-K for the year ended December 31, 2023, as filed with the Securities and Exchange Commission on April 2, 2024 (the “Original Report”), solely to correct a clerical error in the number of outstanding shares of the Company’s common stock at March 31, 2024 set forth on the cover page of the Original Report. The correct number of shares of the Company’s common stock outstanding at March 31, 2024 was 3,239,355 as set forth on the cover page of this Amendment. Except as described above, no changes have been made to the Original Report. This Amendment does not modify, amend or update any financial information in the Original Report. This Amendment continues to speak as of the date of the Original Report, and the Company has not updated the disclosures contained therein to reflect any events that occurred at a date subsequent to the Original Report. | ||
| Document Annual Report | true | ||
| Document Period End Date | Dec. 31, 2023 | ||
| Current Fiscal Year End Date | --12-31 | ||
| Document Fiscal Year Focus | 2023 | ||
| Document Fiscal Period Focus | FY | ||
| Document Transition Report | false | ||
| Entity File Number | 001-14785 | ||
| Entity Registrant Name | GSE Systems, Inc. | ||
| Entity Central Index Key | 0000944480 | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity Tax Identification Number | 52-1868008 | ||
| Entity Address, Address Line One | 6940 Columbia Gateway Dr. | ||
| Entity Address, Address Line Two | Suite 470 | ||
| Entity Address, City or Town | Columbia | ||
| Entity Address, State or Province | MD | ||
| Entity Address, Postal Zip Code | 21046 | ||
| City Area Code | 410 | ||
| Local Phone Number | 970-7800 | ||
| Title of 12(b) Security | Common Stock, $0.01 Par Value | ||
| Trading Symbol | GVP | ||
| Security Exchange Name | NASDAQ | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | false | ||
| ICFR Auditor Attestation Flag | false | ||
| Document Financial Statement Error Correction [Flag] | false | ||
| Entity Shell Company | false | ||
| Entity Public Float | $ 8,928,827 | ||
| Entity Common Stock, Shares Outstanding | 3,239,355 | ||
| Auditor Firm ID | 686 | ||
| Auditor Name | FORVIS, LLP | ||
| Auditor Location | Tysons, VA |
