Nature of Operations and Summary of Significant Accounting Policies - Additional information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Jun. 28, 2013	Mar. 29, 2013	Sep. 27, 2013
Significant Accounting Policies [Line Items]
Minority interest ownership percentage			50.00%
Equity method investment previous ownership percentage on Laser Quantum		25.10%
Equity method investment ownership percentage on Laser Quantum	41.20%
Net income tax benefit from the error correction	$ 0.3	$ 0.7	$ 0.4

Name:	gsig_SignificantAccountingPoliciesLineItems
Namespace Prefix:	gsig_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Definition

Resulting effect of restatement to correct an error, after tax effects, on the net income of prior periods for the year in which any adjustments are first made. In statements containing more than one period, discloses the effects for each period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22663-107794

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22658-107794

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28359718&loc=d3e22644-107794

+ Details

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

- Definition

Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

+ References

No definition available.

+ Details

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