Term of the interest rate that fluctuates over time as a result of an underlying benchmark interest rate or index.

No definition available.

Name:	gvp_DebtInstrumentTermOfVariableRate
Namespace Prefix:	gvp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the number of letters of credit on which the entity is contingently liable.

+ References

No definition available.

+ Details

Name:	gvp_NumberOfLettersOfCredit
Namespace Prefix:	gvp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Refers to the percentage of letter of credit fees per annum.

+ References

No definition available.

+ Details

Name:	gvp_PercentageOfLetterOfCreditFeesPerAnnum
Namespace Prefix:	gvp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	gvp_TermLoanAbstract
Namespace Prefix:	gvp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For indemnification assets recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the indemnification benefit which may be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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Name:	us-gaap_BusinessCombinationIndemnificationAssetsRangeOfOutcomesValueHigh
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Expenses paid for obtaining loans which includes expenses such as application and origination fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LoanProcessingFee
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LoansPayableToBank
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of current portion of long-term loans payable to bank due within one year or the operating cycle if longer.

+ References

+ Details

Name:	us-gaap_LoansPayableToBankCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the operating cycle if longer, excluding current portion.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Publisher FASB
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-Topic 942
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-Section S99
-Paragraph 1
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LongTermLoansFromBank
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtCurrentAndNoncurrentAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
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-Publisher FASB
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-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=gvp_CitizenSBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gvp_DelayedDrawTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=gvp_DPEngineeringLtdCoMember
Namespace Prefix:
Data Type:	na
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Period Type:

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Debt (Details) $ in Thousands			3 Months Ended
Debt (Details) $ in Thousands	Feb. 15, 2019 USD ($)	May 11, 2018 USD ($)	Mar. 31, 2019 USD ($) Letter	Dec. 31, 2018 USD ($)	Dec. 29, 2016 USD ($)
Line of Credit Facility [Abstract]
Number of letters of credit \| Letter			4
Long-term Debt, Current and Noncurrent [Abstract]
Long-term debt, net of discount				$ 8,512
Less: current portion of long-term debt				(1,902)
Long-term debt, less current portion				$ 6,610
LIBOR [Member]
Term Loan [Abstract]
Term of variable rate			1 month
Citizen's Bank [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Line of credit facility expiration period			3 years
Principal amount of the line of credit					$ 5,000
Line of credit facility term			5 years
Outstanding letter of credit balance			$ 0
Number of letters of credit \| Letter			4
Outstanding letter of credit balance			$ 1,900
Line of credit facility, remaining borrowing capacity			$ 3,100
Citizen's Bank [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Percentage of letter of credit fees per annum			1.25%
Citizen's Bank [Member] \| Revolving Credit Facility [Member] \| Maximum [Member]
Line of Credit Facility [Abstract]
Percentage of letter of credit fees per annum			2.00%
Delayed Draw Term Loan [Member]
Long-term Debt, Current and Noncurrent [Abstract]
Long-term debt, net of discount			$ 22,104
Less: current portion of long-term debt			(4,763)
Long-term debt, less current portion			$ 17,341
Delayed Draw Term Loan [Member] \| Minimum [Member]
Term Loan [Abstract]
Debt instrument, basis spread on variable rate			2.00%
Delayed Draw Term Loan [Member] \| Maximum [Member]
Term Loan [Abstract]
Debt instrument, basis spread on variable rate			2.75%
Delayed Draw Term Loan [Member] \| Citizen's Bank [Member] \| LIBOR [Member]
Term Loan [Abstract]
Term of variable rate			1 month
Delayed Draw Term Loan [Member] \| Citizen's Bank [Member] \| Minimum [Member]
Term Loan [Abstract]
Debt instrument, basis spread on variable rate			2.00%
Delayed Draw Term Loan [Member] \| Citizen's Bank [Member] \| Maximum [Member]
Line of Credit Facility [Abstract]
Line of credit facility expiration period			18 months
Term Loan [Abstract]
Debt instrument, basis spread on variable rate			2.75%
Delayed Draw Term Loan [Member] \| Citizen's Bank [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Principal amount of the line of credit		$ 25,000
DP Engineering Ltd, CO. [Member]
Term Loan [Abstract]
Cash purchase price	$ 13,500
Proceeds from issuance of debt	14,263
Earn-out amount	$ 5,000
DP Engineering Ltd, CO. [Member] \| Delayed Draw Term Loan [Member]
Line of Credit Facility [Abstract]
Line of credit facility term	5 years
DP Engineering Ltd, CO. [Member] \| Delayed Draw Term Loan [Member] \| LIBOR [Member]
Term Loan [Abstract]
Term of variable rate			1 month
DP Engineering Ltd, CO. [Member] \| Delayed Draw Term Loan [Member] \| Minimum [Member]
Term Loan [Abstract]
Debt instrument, basis spread on variable rate	2.00%
DP Engineering Ltd, CO. [Member] \| Delayed Draw Term Loan [Member] \| Maximum [Member]
Term Loan [Abstract]
Debt instrument, basis spread on variable rate	2.75%
True North Consulting, LLC [Member]
Term Loan [Abstract]
Cash purchase price		9,750
Proceeds from issuance of debt		10,300
True North Consulting, LLC [Member] \| Delayed Draw Term Loan [Member]
Line of Credit Facility [Abstract]
Line of credit facility term			5 years
Term Loan [Abstract]
Proceeds from issuance of debt		10,300
Repayments of debt		$ 500
Debt issuance costs			$ 70
Loan origination fees			$ 75
True North Consulting, LLC [Member] \| Delayed Draw Term Loan [Member] \| LIBOR [Member]
Term Loan [Abstract]
Term of variable rate			1 month