Commitments and Contingencies (Details) (USD $)	12 Months Ended
Dec. 31, 2014 Bond Contract Letter	Dec. 31, 2013
Operating Leases, Future Minimum Payments Due [Abstract]
2015	$ 1,163,000
2016	897,000
2017	823,000
2018	746,000
2019	612,000
Thereafter	1,867,000
Total	6,108,000
Rent Expense [Abstract]
Rent expense	1,400,000us-gaap_OperatingLeasesRentExpenseNet	1,100,000us-gaap_OperatingLeasesRentExpenseNet
Standby Letters of Credit, Bank Guarantees, Surety Bonds and Performance Bonds [Abstract]
Standby letters of credit and surety bonds	4,200,000
Number of standby letters of credit	12gvp_NumberOfStandbyLettersOfCredit
Number of surety bonds	1gvp_NumberOfSuretyBonds
Number of Bid Bonds Contract	11gvp_NumberOfBidBondsContract
Number of stand by letters of credit deposited in certificates of deposit	11
Restricted cash and investments	$ 4,200,000	$ 1,100,000

This item represents the number of bid bonds contract.

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Number of stand by letters of credit deposited in certificates of deposit.

+ References

No definition available.

+ Details

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- Definition

This item represents the number of surety bonds on which the entity is contingently liable.

+ References

No definition available.

+ Details

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Namespace Prefix:	gvp_
Data Type:	xbrli:integerItemType
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- Definition

Fair value of advance payment, lines of credit and performance bonds at the balance sheet date.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 3)

-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

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- Details

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- Definition

Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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- Definition

Amount of required minimum rental payments maturing in the forth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing after the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	instant

- Details

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Balance Type:	na
Period Type:	duration

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

+ Details

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Balance Type:	debit
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- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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