Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 28, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
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
Entity Shell Company	false
Entity Public Float			$ 37,342,565
Entity Common Stock, Shares Outstanding		20,980,811
Auditor Firm ID	57
Auditor Name	DIXON HUGHES GOODMAN LLP
Auditor Location	Tysons, Virginia