Accumulated Other Comprehensive Loss - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 29, 2012	Jul. 01, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassified Accumulated Other Comprehensive Loss Into Net Income	$ 0.5	$ 0.1

Other Comprehensive Income Reclassification of Defined Benefit Plan net Transition Asset (Obligation) and Amortization Net Prior Service Cost Recognized in Net Periodic Benefit Cost Net of Tax

No definition available.

Name:	gsig_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlanNetTransitionAssetObligationAndAmortizationNetPriorServiceCostRecognizedInNetPeriodicBenefitCostNetOfTax
Namespace Prefix:	gsig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration