Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Sales	$ 271,498	$ 304,296	$ 285,892
Cost of goods sold	157,022	171,196	155,278
Gross profit	114,476	133,100	130,614
Operating expenses:
Research and development and engineering	22,393	23,454	22,297
Selling, general and administrative	65,584	67,877	64,535
Amortization of purchased intangible assets	2,650	3,515	4,436
Restructuring, restatement related costs, post-emergence fees and other	8,842	2,406	3,319
Total operating expenses	99,469	97,252	94,587
Income from operations	15,007	35,848	36,027
Interest expense, net	(2,788)	(12,977)	(19,829)
Foreign exchange transaction gains (losses), net	(1,267)	172	204
Other income (expense), net	582	1,177	1,781
Income from continuing operations before reorganization items and income taxes	11,534	24,220	18,183
Reorganization items	0	0	(26,156)
Income (loss) from continuing operations before income taxes	11,534	24,220	(7,973)
Income tax provision (benefit)	(10,940)	2,544	11,952
Income (loss) from continuing operations	22,474	21,676	(19,925)
Income (loss) from discontinued operations, net of tax	(5,151)	7,325	19,286
Gain on disposal of discontinued operations, net of tax	2,255
Consolidated net income (loss)	19,578	29,001	(639)
Less: Net income attributable to noncontrolling interest	(40)	(28)	(48)
Net income (loss) attributable to GSI Group Inc.	19,538	28,973	(687)
Earnings (Loss) per common share from continuing operations:
Basic	$ 0.66	$ 0.65	$ (0.84)
Diluted	$ 0.66	$ 0.64	$ (0.84)
Earnings (Loss) per common share from discontinued operations:
Basic	$ (0.08)	$ 0.22	$ 0.81
Diluted	$ (0.08)	$ 0.22	$ 0.81
Earnings (Loss) per common share attributable to GSI Group Inc.:
Basic	$ 0.58	$ 0.87	$ (0.03)
Diluted	$ 0.58	$ 0.86	$ (0.03)
Weighted average common shares outstanding-basic	33,775	33,481	23,703
Weighted average common shares outstanding-diluted	33,936	33,589	23,703
Amounts attributable to GSI Group Inc.:
Income (loss) from continuing operations	22,434	21,648	(19,973)
Income (loss) from discontinued operations	(2,896)	7,325	19,286
Net income (loss) attributable to GSI Group Inc.	$ 19,538	$ 28,973	$ (687)