CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Consolidated net income (loss)	$ 29,001		$ (639)		$ (71,269)
Other comprehensive income (loss):
Foreign currency translation adjustments	241		701		2,706
Net unrealized gains and reclassifications of investments, net of tax			(568)	[1]	488	[1]
Pension liability adjustments, net of tax	(1,836)	[1]	(132)	[1]	(2,388)	[1]
Total other comprehensive income (loss), net of tax	(1,595)		1		806
Total consolidated comprehensive income (loss)	27,406		(638)		(70,463)
Less: Comprehensive income attributable to noncontrolling interest	(28)		(48)		(61)
Comprehensive income (loss) attributable to GSI Group Inc.	$ 27,378		$ (686)		$ (70,524)

[1] The tax effect on the component of comprehensive income (loss) is nominal for all periods presented.