Long-Term Debt (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($) Right	Dec. 31, 2014 USD ($)
Performance Bond Abstract
Number of Standby Letters of Credit | Right	13
Number of Surety Bonds | Right	1
Letter of Credit and Surety Bonds	$ 3,600
Number of Performance and Bid Bonds issued in relation to contracts | Right	12
Number of stand by letters of credit deposited in escrow accounts | Right	13
Restricted cash and investments	$ 3,600	$ 4,200
Susquehanna Bank [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Principal amount of the line of credit	$ 7,500
Line of Credit Facility, Affiliated Borrower	GSE Systems, Inc. and GSE Performance Solutions, Inc.
Line of Credit Facility, Interest Rate Description	Working capital advances bear interest at a rate equal to the Wall Street Journal Prime Rate of Interest, floating with a floor of 4 1/2%
Line of credit facility term	2 years
Expiration date of credit agreement	Jun. 30, 2016
Minimum Cash Balance Requirement	$ 3,000
Susquehanna Bank [Member] | Revolving Credit Facility [Member] | Minimum tangible capital base [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms	Must Exceed $10.5 million
Line of Credit Facility, Covenant Compliance	$10.9 million
Susquehanna Bank [Member] | Revolving Credit Facility [Member] | Quick Ratio [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Covenant Terms	Must Exceed 1.00 : 1.00
Line of Credit Facility, Covenant Compliance	1.43 : 1.00
IberiaBank [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Principal amount of the line of credit	$ 1,000
Line of Credit Facility, Affiliated Borrower	Hyperspring, LLC
Line of Credit Facility, Interest Rate Description	interest is payable monthly at the rate of 1.00 percentage points over the prime rate of interest as published in the money rate section of the Wall Street Journal
Line of Credit Facility, Interest Rate During Period	4.25%
Line of Credit Facility, Collateral	The line is secured by all accounts of Hyperspring and guaranteed by GSE Systems, Inc.
Line of credit facility term	1 year
Expiration date of credit agreement	Jul. 06, 2016
Line of Credit Facility, Fair Value of Amount Outstanding	$ 0	$ 339