| Document and Entity Information | Nov. 15, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 15, 2021 |
| Entity Registrant Name | GSE SYSTEMS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-14785 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000944480 |
| Title of 12(b) Security | Common Stock, $.01 Par Value |
| Trading Symbol | GVP |
| Security Exchange Name | NASDAQ |
