Commitments and Contingencies - Additional Information (Detail) In Millions, unless otherwise specified	1 Months Ended				3 Months Ended	9 Months Ended		9 Months Ended
	Jul. 13, 2010 USD ($)	May 27, 2010	Nov. 20, 2009	Apr. 18, 2006 EUR (€)	Sep. 30, 2005	Sep. 28, 2012 USD ($)	May 06, 2011 EUR (€)	Sep. 28, 2012 Internal Revenue Service (IRS)	Apr. 05, 2010 Internal Revenue Service (IRS) USD ($)	May 06, 2011 SCGI EUR (€)	May 06, 2011 GSI Group GmbH EUR (€)
Commitments and Contingencies Disclosure [Line Items]
Annual rental payment						$ 1.5
Extended lease term						May 2013 to May 2019
Filed for bankruptcy protection date			Nov. 20, 2009		Jul. 07, 2005
Actions taken		On May 27, 2010, the Bankruptcy Court entered an order confirming and approving the plan of reorganization (the "Final Chapter 11 Plan").		On April 18, 2006, the commercial court of Le Creusot (France) ordered GSI France to pay approximately 0.7 million Euros to SCGI in the context of a claim filed by SCGI that a Laserdyne 890 system delivered in 1999 had unresolved technical problems.
Payment to settle claim filed, minimum				0.7						0.7
Payment to settle claim filed, maximum							3.1
Payment in the respect of a claim filed											2.4
IRS filed amended proofs of claim date								April 5, 2010
IRS filed aggregate claims									7.7
IRS Claims	On July 13, 2010, the Company filed a complaint, GSI Group Corporation v. United States of America, in Bankruptcy Court in an attempt to recover refunds totaling approximately $18.8 million in federal income taxes the Company asserts it overpaid to the IRS relating to tax years 2000 through 2008, together with applicable interest.
Amount of claim we filed with the IRS for federal income taxes overpaid	$ 18.8