CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 26, 2014	Sep. 27, 2013	Sep. 26, 2014	Sep. 27, 2013
Income Statement [Abstract]
Sales	$ 94,656	$ 79,858	$ 270,694	$ 234,698
Cost of sales	54,973	45,697	160,255	136,667
Gross profit	39,683	34,161	110,439	98,031
Operating expenses:
Research and development and engineering	7,735	6,031	21,117	17,962
Selling, general and administrative	21,512	19,006	62,540	57,069
Amortization of purchased intangible assets	2,843	1,772	7,463	5,625
Restructuring and acquisition related costs	771	1,553	1,949	4,724
Total operating expenses	32,861	28,362	93,069	85,380
Operating income from continuing operations	6,822	5,799	17,370	12,651
Interest income (expense), net	(1,453)	(841)	(3,665)	(2,660)
Foreign exchange transaction gains (losses), net	1,030	(1,723)	950	(963)
Other income (expense), net	733	542	1,733	1,204
Income from continuing operations before income taxes	7,132	3,777	16,388	10,232
Income tax provision	2,013	1,533	5,007	4,954
Income from continuing operations	5,119	2,244	11,381	5,278
Loss from discontinued operations, net of tax	(273)	(185)	(4,817)	(1,643)
Loss on disposal of discontinued operations, net of tax	(321)	(281)	(321)	(592)
Consolidated net income	4,525	1,778	6,243	3,043
Less: Net income (loss) attributable to noncontrolling interest		12	(10)	(42)
Net income attributable to GSI Group Inc.	$ 4,525	$ 1,790	$ 6,233	$ 3,001
Earnings per common share from continuing operations:
Basic	$ 0.15	$ 0.07	$ 0.33	$ 0.15
Diluted	$ 0.15	$ 0.07	$ 0.33	$ 0.15
Loss per common share from discontinued operations:
Basic	$ (0.02)	$ (0.02)	$ (0.15)	$ (0.07)
Diluted	$ (0.02)	$ (0.02)	$ (0.15)	$ (0.07)
Earnings per common share attributable to GSI Group Inc.:
Basic	$ 0.13	$ 0.05	$ 0.18	$ 0.08
Diluted	$ 0.13	$ 0.05	$ 0.18	$ 0.08
Weighted average common shares outstanding—basic	34,389	34,102	34,333	34,058
Weighted average common shares outstanding—diluted	34,793	34,417	34,725	34,325

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This element represents (i) restructuring charges, which are amounts charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a program that is planned and controlled by management, and materially changes either the scope of a business undertaken by an entity, or the manner in which that business is conducted; and (ii) acquisition-related costs, which are costs incurred to effect a business combination which costs have been expensed during the period. Such costs can include transaction costs such as banking, legal, accounting and other costs directly related to effect a business combination as well as external, incremental costs of integration planning that are directly related to a business combination, including costs associated with preparing for systems and other integration activities.