Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2013	Jun. 29, 2012	Jun. 28, 2013	Jun. 29, 2012
Sales	$ 85,307	$ 70,379	$ 168,421	$ 135,565
Cost of sales	50,808	39,712	100,759	77,217
Gross profit	34,499	30,667	67,662	58,348
Operating expenses:
Research and development and engineering	6,782	5,615	13,403	11,388
Selling, general and administrative	20,618	16,841	40,858	33,049
Amortization of purchased intangible assets	1,617	663	3,853	1,325
Restructuring costs and other	1,135	2,451	4,252	4,668
Total operating expenses	30,152	25,570	62,366	50,430
Income from operations	4,347	5,097	5,296	7,918
Interest income (expense), net	(915)	(678)	(1,810)	(1,487)
Foreign exchange transaction gains (losses), net	(425)	620	771	(272)
Other income (expense), net	292	45	661	232
Income from continuing operations before income taxes	3,299	5,084	4,918	6,391
Income tax provision	2,457	617	2,607	847
Income from continuing operations	842	4,467	2,311	5,544
Income (loss) from discontinued operations, net of tax	(1,384)	414	(735)	736
Loss on disposal of discontinued operations, net of tax	(311)		(311)
Consolidated net income (loss)	(853)	4,881	1,265	6,280
Less: Net (income) attributable to noncontrolling interest	(18)	(8)	(54)	(26)
Net income (loss) attributable to GSI Group Inc.	$ (871)	$ 4,873	$ 1,211	$ 6,254
Earnings per common share from continuing operations:
Basic	$ 0.02	$ 0.13	$ 0.07	$ 0.16
Diluted	$ 0.02	$ 0.13	$ 0.07	$ 0.16
Earnings (loss) per common share from discontinued operations:
Basic	$ (0.05)	$ 0.01	$ (0.03)	$ 0.03
Diluted	$ (0.05)	$ 0.01	$ (0.03)	$ 0.02
Earnings (loss) per common share attributable to GSI Group Inc.:
Basic	$ (0.03)	$ 0.14	$ 0.04	$ 0.19
Diluted	$ (0.03)	$ 0.14	$ 0.04	$ 0.18
Weighted average common shares outstanding - basic	34,088	33,782	34,036	33,731
Weighted average common shares outstanding - diluted	34,285	33,953	34,279	33,915