Consolidated leverage ratio maximum.

No definition available.

Name:	gsig_ConsolidatedLeverageRatioMaximum
Namespace Prefix:	gsig_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Credit facility limitations on restricted payments minimum required availability for borrowing under senior credit facility.

+ References

No definition available.

+ Details

Name:	gsig_CreditFacilityLimitationsOnRestrictedPaymentsMinimumRequiredAvailabilityForBorrowingUnderSeniorCreditFacility
Namespace Prefix:	gsig_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instruments maturity date month and year.

+ References

No definition available.

+ Details

Name:	gsig_DebtInstrumentsMaturityDateMonthAndYear
Namespace Prefix:	gsig_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility accordion feature.

+ References

No definition available.

+ Details

Name:	gsig_LineOfCreditFacilityAccordionFeature
Namespace Prefix:	gsig_
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

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-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 210.5-02.22(a)(1))

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

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ 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

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Details

Name:	gsig_AmendmentAxis=gsig_FourthAmendmentMember
Namespace Prefix:
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Balance Type:
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- Details

Name:	gsig_AmendmentAxis=gsig_ThirdAmendmentMember
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:	us-gaap_DebtInstrumentAxis=gsig_SeniorSecuredCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_StatementScenarioAxis=gsig_ForPermittedAcquisitionsAndStockRepurchasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Debt - Additional Information (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended		12 Months Ended
	Dec. 27, 2012	Sep. 13, 2013	Dec. 31, 2014	Feb. 10, 2014
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 125.0
Revolving credit facility maturity year	2017-12
Credit facility accordion feature		50.0
Third Amendment
Debt Instrument [Line Items]
Credit facility accordion feature		100.0
Maximum consolidated leverage ratio		275.00%
Fourth Amendment
Debt Instrument [Line Items]
Maximum consolidated leverage ratio			300.00%
Restricted Payments \| Fourth Amendment
Debt Instrument [Line Items]
Maximum consolidated leverage ratio		225.00%	250.00%
Eurodollar Rate \| Minimum
Debt Instrument [Line Items]
Variable interest rate			2.00%
Eurodollar Rate \| Maximum
Debt Instrument [Line Items]
Variable interest rate			3.00%
Base Rate \| Minimum
Debt Instrument [Line Items]
Variable interest rate			1.00%
Base Rate \| Maximum
Debt Instrument [Line Items]
Variable interest rate			2.00%
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	75.0
Debt instrument maturity period	5 years
Available for borrowings capacity			95.0
Revolving Credit Facility \| Fourth Amendment
Debt Instrument [Line Items]
Maximum borrowing capacity				175.0
Credit facility accordion feature			100.0
Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Unused Commitment Fees Percentage			0.25%
Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Unused Commitment Fees Percentage			0.625%
Term Loans
Debt Instrument [Line Items]
Maximum borrowing capacity	50.0
Debt instrument maturity period	5 years
Senior Secured Credit Facility
Debt Instrument [Line Items]
Debt instrument interest rate			2.90%
Limitations on restricted payments, minimum available for borrowing			25.0