Consolidated Statements Of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Consolidated net income (loss)	$ 19,578		$ 29,001		$ (639)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	(1,510)	[1]	241	[1]	701	[1]
Net unrealized gains and reclassifications of investments, net of tax					(568)	[2]
Pension liability adjustments, net of tax	(3,215)	[3]	(1,836)	[3]	(132)	[3]
Total other comprehensive income (loss)	(4,725)		(1,595)		1
Total consolidated comprehensive income (loss)	14,853		27,406		(638)
Less: Comprehensive income attributable to noncontrolling interest	(40)		(28)		(48)
Comprehensive income (loss) attributable to GSI Group Inc.	$ 14,813		$ 27,378		$ (686)

[1] The tax effect on the component of comprehensive income was $1,942 in 2012 and was nominal for the years ended 2011 and 2010.

[2] The tax effect on the component of comprehensive income was $0.

[3] The tax effect on the component of comprehensive income was $829 in 2012 and was nominal for the years ended 2011 and 2010.