The amount of bank fee payable.

No definition available.

Name:	gvp_BankFeePayable
Namespace Prefix:	gvp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Term for deferred principal and interest payments.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Target value to be tested as part of a covenant.

+ References

No definition available.

+ Details

Name:	gvp_EBITDATarget
Namespace Prefix:	gvp_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Refers to the fixed charge coverage ratio.

+ References

No definition available.

+ Details

Name:	gvp_FixedChargeCoverageRatio
Namespace Prefix:	gvp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Refers to the leverage ratio.

+ References

No definition available.

+ Details

Name:	gvp_LeverageRatio
Namespace Prefix:	gvp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

As part of a covenant the Company agreed to maintain a minimum USA liquidity amount.

+ References

No definition available.

+ Details

Name:	gvp_Liquidity
Namespace Prefix:	gvp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

- References

No definition available.

+ Details

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

- 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

- Definition

Percentage of principal amount of loan guaranteed.

+ References

No definition available.

+ Details

Name:	gvp_PercentageOfPrincipalAmountOfLoanGuaranteed
Namespace Prefix:	gvp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of the total principal payments made during the annual reporting period.

+ References

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
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

Amount of the fee for available but unused credit capacity under the credit facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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=121572278&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 the required periodic payment applied to principal.

+ References

+ Details

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

- 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

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
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-Section S99
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- 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=121586364&loc=d3e3291-108585

+ Details

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

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

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-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Name:	us-gaap_RepaymentsOfLinesOfCredit
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_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_SixthAmendmentAndReaffirmationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_StatementScenarioAxis=us-gaap_ScenarioPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=gvp_PaycheckProtectionProgramCARESActMember
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:

Debt (Details) $ in Thousands			3 Months Ended				12 Months Ended
Debt (Details) $ in Thousands	May 11, 2018 USD ($)	Dec. 29, 2016 USD ($)	Mar. 31, 2021 USD ($) Letter	Mar. 29, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 15, 2020 USD ($)	Aug. 28, 2020 USD ($)	Jun. 30, 2020 USD ($)	Apr. 23, 2020	Apr. 17, 2020 USD ($)	Jan. 06, 2020 USD ($)
Line of Credit Facility [Abstract]
Repayments of debt							$ 18,500
Repayment on line of credit			$ 500			$ 0
LIBOR [Member]
Line of Credit Facility [Abstract]
Term of variable rate	1 month
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Line of credit facility expiration period		3 months
Line of credit		$ 5,000	4,250
Repayment on line of credit			500
Long-term debt			$ 2,500
Number of letters of credit \| Letter			3
Outstanding letter of credit balance			$ 933
Amount available at the reporting date			$ 300
Revolving Credit Facility [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Percentage of letter of credit fees per annum							1.25%
Revolving Credit Facility [Member] \| Maximum [Member]
Line of Credit Facility [Abstract]
Percentage of letter of credit fees per annum							2.00%
Sixth Amendment and Reaffirmation Agreement [Member]
Line of Credit Facility [Abstract]
EBITDA target																								$ 4,300
Accelerated principal payments						$ 1,000															$ 1,000			3,000
Debt issuance costs																								20
Sixth Amendment and Reaffirmation Agreement [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Liquidity																								$ 5,000
Seventh Amendment And Reaffirmation Agreement [Member]
Line of Credit Facility [Abstract]
Accelerated principal payments																					$ 500		$ 750
Debt issuance costs																							$ 50
Fixed charge coverage ratio																							1.25
Leverage ratio					2.50		2.50											3.00
Seventh Amendment And Reaffirmation Agreement [Member] \| Plan [Member]
Line of Credit Facility [Abstract]
Leverage ratio			2.25											2.25	2.25	2.25	2.25
Eighth Amendment and Reaffirmation Agreement [Member]
Line of Credit Facility [Abstract]
Debt issuance costs					$ 70		$ 70													$ 10
Bank fee payable																		$ 10,000
Eighth Amendment and Reaffirmation Agreement [Member] \| Plan [Member]
Line of Credit Facility [Abstract]
Leverage ratio			3.00		1.00		1.00				2.00	2.00	2.00	2.00	2.00	2.50	2.75
Eighth Amendment and Reaffirmation Agreement [Member] \| Minimum [Member]
Line of Credit Facility [Abstract]
Liquidity																			$ 3,500
Eighth Amendment and Reaffirmation Agreement [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Outstanding letter of credit balance					$ 9,100		$ 9,100											$ 700
Repayments of debt					$ 200
Ninth Amendment and Reaffirmation Agreement [Member]
Line of Credit Facility [Abstract]
Amendment fee amount							$ 25
Ninth Amendment and Reaffirmation Agreement [Member] \| Plan [Member]
Line of Credit Facility [Abstract]
Fixed charge coverage ratio			1.1					2.00	2.00	2.00	2.00	2.00	2.50	2.75	3.00	3.25	1.1
Ninth Amendment and Reaffirmation Agreement [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Liquidity				$ 2,500
Repayment on line of credit				500
Amount available at the reporting date				500
Periodic payment				$ 500
Ninth Amendment and Reaffirmation Agreement [Member] \| Revolving Credit Facility [Member] \| Plan [Member]
Line of Credit Facility [Abstract]
Line of credit			$ 4,250													$ 3,500	$ 3,750
Amount available at the reporting date															$ 75
PPP Loan [Member]
Line of Credit Facility [Abstract]
Long-term debt			$ 1,300
Paycheck Protection Program Loan [Abstract]
Maturity date			Apr. 23, 2022
Interest rate			1.00%																			1.00%
Term for deferred principal and interest payments			10 months
Percentage of principal amount of loan guaranteed			100.00%																			100.00%
Term Loan [Member]
Line of Credit Facility [Abstract]
Line of credit facility expiration period	18 months
Line of credit	$ 25,000
Line of credit facility term	5 years