Novanta (NOVT) 10-Q 5 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 27, 2013	Oct. 28, 2013
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	27-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'GSIG	'
Entity Registrant Name	'GSI GROUP INC	'
Entity Central Index Key	'0001076930	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	33,960,019

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current Assets	'	'
Cash and cash equivalents	$53,690	$65,788
Accounts receivable, net of allowance of $823 and $374, respectively	58,829	42,652
Inventories	65,073	52,801
Income taxes receivable	3,906	16,540
Deferred tax assets	6,675	7,583
Prepaid expenses and other current assets	6,610	5,486
Assets of discontinued operations	'	17,618
Total current assets	194,783	208,468
Property, plant and equipment, net	32,702	32,338
Deferred tax assets	1,997	3,884
Other assets	9,074	8,172
Intangible assets, net	68,265	40,020
Goodwill	71,087	44,578
Total assets	377,908	337,460
Current Liabilities	'	'
Current portion of long-term debt	7,500	7,500
Accounts payable	27,100	18,824
Income taxes payable	2,983	3,317
Deferred revenue	947	316
Deferred tax liabilities	399	402
Accrued expenses and other current liabilities	22,334	18,962
Liabilities of discontinued operations	624	5,605
Total current liabilities	61,887	54,926
Long-term debt	70,875	42,500
Deferred tax liabilities	927	255
Income taxes payable	1,993	1,764
Other liabilities	8,958	9,809
Total liabilities	144,640	109,254
Commitments and Contingencies (Note 14)	'	'
Stockholders' Equity:	'	'
Common shares, no par value; Authorized shares: unlimited; Issued and outstanding: 33,959 and 33,796, respectively	423,856	423,856
Additional paid-in capital	25,157	21,924
Accumulated deficit	-205,221	-208,222
Accumulated other comprehensive loss	-10,963	-9,749
Total GSI Group Inc. stockholders' equity	232,829	227,809
Noncontrolling interest	439	397
Total stockholders' equity	233,268	228,206
Total liabilities and stockholders' equity	$377,908	$337,460

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accounts receivable, allowance	$823	$374
Common shares, no par value	'	'
Common shares, Issued	33,959	33,796
Common shares, outstanding	33,959	33,796

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Sales	$85,484	$69,520	$253,905	$205,085
Cost of sales	49,693	40,667	150,452	117,884
Gross profit	35,791	28,853	103,453	87,201
Operating expenses:	'	'	'	'
Research and development and engineering	6,585	5,545	19,988	16,933
Selling, general and administrative	20,075	16,125	60,933	49,174
Amortization of purchased intangible assets	1,772	663	5,625	1,988
Restructuring costs and other	1,641	2,728	5,893	7,396
Total operating expenses	30,073	25,061	92,439	75,491
Income from operations	5,718	3,792	11,014	11,710
Interest income (expense), net	-839	-656	-2,649	-2,143
Foreign exchange transaction gains (losses), net	-1,637	-685	-866	-957
Other income (expense), net	540	167	1,201	399
Income from continuing operations before income taxes	3,782	2,618	8,700	9,009
Income tax provision	1,610	563	4,217	1,410
Income from continuing operations	2,172	2,055	4,483	7,599
Loss from discontinued operations, net of tax	-113	-4,570	-848	-3,834
Loss on disposal of discontinued operations, net of tax	-281	'	-592	'
Consolidated net income (loss)	1,778	-2,515	3,043	3,765
Less: Net (income) loss attributable to noncontrolling interest	12	-19	-42	-45
Net income (loss) attributable to GSI Group Inc.	$1,790	($2,534)	$3,001	$3,720
Earnings per common share from continuing operations:	'	'	'	'
Basic	$0.06	$0.06	$0.13	$0.22
Diluted	$0.06	$0.06	$0.13	$0.22
Loss per common share from discontinued operations:	'	'	'	'
Basic	($0.01)	($0.13)	($0.04)	($0.11)
Diluted	($0.01)	($0.13)	($0.04)	($0.11)
Earnings (loss) per common share attributable to GSI Group Inc.:	'	'	'	'
Basic	$0.05	($0.07)	$0.09	$0.11
Diluted	$0.05	($0.07)	$0.09	$0.11
Weighted average common shares outstanding-basic	34,102	33,803	34,058	33,755
Weighted average common shares outstanding-diluted	34,417	33,912	34,325	33,914

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012
Consolidated net income (loss)	$1,778		($2,515)		$3,043		$3,765
Other comprehensive income (loss):	'		'		'		'
Foreign currency translation adjustments, net of tax	3,765	[1]	2,070	[1]	-2,015	[1]	1,924	[1]
Pension liability adjustments, net of tax	-371	[2]	120	[2]	801	[2]	612	[2]
Total other comprehensive income (loss)	3,394		2,190		-1,214		2,536
Total consolidated comprehensive income (loss)	5,172		-325		1,829		6,301
Less: Comprehensive (income) loss attributable to noncontrolling interest	12		-19		-42		-45
Comprehensive income (loss) to GSI Group Inc.	$5,184		($344)		$1,787		$6,256
[1]	The tax effect on the component of comprehensive income was zero and $1.3 million for the three and nine months ended September 27, 2013, respectively. The impact for the three and nine months ended September 28, 2012 was not material.
[2]	The tax effect on the component of comprehensive income was not material for all periods presented. See Note 4 for the total amount of pension liability adjustments reclassified out of accumulated other comprehensive loss.

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2013	Sep. 27, 2013
Foreign currency translation adjustments - Tax effect on component of comprehensive income	$0	$1.30

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Cash flows from operating activities:	'	'
Consolidated net income	$3,043	$3,765
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	15,305	10,429
Share-based compensation	4,212	3,479
Deferred income taxes	2,130	-657
Earnings from equity investment	-1,181	-364
Loss on disposal of business	592	'
Non-cash interest expense	735	796
Non-cash restructuring charges	179	3,599
Other non-cash items	1,079	91
Changes in operating assets and liabilities:	'	'
Accounts receivable	-7,097	-5,766
Inventories	470	-62
Income taxes receivable and prepaid income taxes	12,523	122
Prepaid expenses and other current assets	1,927	1,813
Deferred revenue	-842	-2,975
Accounts payable, accrued expenses, income taxes payable and other current liabilities	1,164	6,183
Other non-current assets and liabilities	209	1,046
Cash provided by operating activities	34,448	21,499
Cash flows from investing activities:	'	'
Purchases of property, plant and equipment	-3,073	-3,734
Acquisition of business	-82,653	'
Proceeds from the sale of property, plant and equipment	4,615	283
Proceeds from sale of business, net of transaction costs of $1,060	8,190	'
Cash used in investing activities	-72,921	-3,451
Cash flows from financing activities:	'	'
Proceeds from issuance of debt	60,000	'
Repayments of long-term debt	-5,625	-7,500
Repayments of borrowings under the revolving credit facility	-26,000	-13,000
Payments for debt issuance costs	-145	-92
Payments of withholding taxes from stock-based awards	-820	-100
Capital lease payments	-608	-596
Cash provided by (used in) financing activities	26,802	-21,288
Effect of exchange rates on cash and cash equivalents	-427	1,268
Decrease in cash and cash equivalents	-12,098	-1,972
Cash and cash equivalents, beginning of period	65,788	54,835
Cash and cash equivalents, end of period	53,690	52,863
Supplemental disclosure of cash flow information:	'	'
Cash paid for interest	1,674	1,441
Cash paid for income taxes	1,935	686
Income tax refunds received	$12,607	$222

Consolidated_Statements_of_Cas1

Consolidated Statements of Cash Flows (Parenthetical) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013
Proceeds from sale of business, transaction costs	$1,060

Nature_of_Operations_and_Summa

Nature of Operations and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 27, 2013
Nature of Operations and Summary of Significant Accounting Policies	'
	1. Nature of Operations and Summary of Significant Accounting Policies
	GSI Group Inc. and its subsidiaries (collectively referred to as the “Company”) design, develop, manufacture and sell precision photonics and motion control components and sub-systems for applications demanding extremely high levels of performance. The Company’s technology is targeted primarily at Original Equipment Manufacturers (“OEMs”) for incorporation into products and systems for a wide range of applications in major markets including: medical, industrial, electronics and scientific.
	The accompanying unaudited consolidated financial statements have been prepared in U.S. dollars and in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”), applied on a consistent basis. The accounting policies underlying these unaudited consolidated financial statements are those set forth in Note 3 to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. Those policies are not presented herein, except to the extent that new policies have been adopted, or there is material current period activity or changes to the Company’s policies.
	The interim consolidated financial statements include the accounts of the Company and its 50% owned joint venture, Excel Laser Technology Private Limited (“Excel SouthAsia JV”). Intercompany transactions and balances have been eliminated. During the second quarter of 2013, the Company’s ownership percentage in a privately held company located in the United Kingdom, Laser Quantum Ltd. (“Laser Quantum”) increased from 25.1% to 41.2% as a result of a share buy-back program by Laser Quantum. The Company continues to record the results of this entity under the equity method as it does not have a controlling interest in the entity.
	The Company’s unaudited interim financial statements are prepared on a quarterly basis ending on the Friday closest to the end of the calendar quarter, with the exception of the fourth quarter which always ends on December 31.
	The unaudited interim consolidated financial statements have been prepared pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”), the instructions to Form 10-Q and the provisions of Regulation S-X pertaining to interim financial statements. Accordingly, certain information and footnote disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. The interim consolidated financial statements and notes included in this report should be read in conjunction with the financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. In the opinion of management, these interim consolidated financial statements include all significant adjustments and accruals of a normal and recurring nature necessary for a fair presentation of the results of the interim periods presented. The results for interim periods are not necessarily indicative of results to be expected for the full year or for any future periods.
	Use of Estimates
	The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of sales and expenses during the reporting periods. The Company evaluates its estimates based on historical experience, current conditions and various other assumptions that it believes are reasonable under the circumstances. Estimates and assumptions are reviewed on an on-going basis and the effects of revisions are reflected in the period in which they are deemed to be necessary. Actual results could differ significantly from those estimates.
	Reclassifications and Adjustments
	As discussed in Note 15, the Company realigned its segment presentation during the first quarter of 2013 in light of the acquisition of NDS Surgical Imaging, LLC and NDS Surgical Imaging KK as well as restructuring activities. As a result, prior period segment information included in the consolidated statements has been reclassified to conform to the current period presentation.
	Beginning in 2008, the Company did not properly recognize deferred tax liabilities associated with certain permanent intercompany loans and did not consider these deferred tax liability amounts when determining the realizability of its deferred tax assets and thereby recorded excess valuation allowances beginning in 2009. The Company identified and corrected this immaterial error of $0.7 million income tax benefit related to prior years during the three months ended March 29, 2013. During the three months ended June 28, 2013, the Company identified and corrected an immaterial error of $0.3 million income tax provision related to the deferred tax effect of a foreign statutory to U.S. GAAP difference in a prior year income tax provision calculation. These error corrections resulted in a net $0.4 million income tax benefit allocated to income from continuing operations for the nine months ended September 27, 2013. The net correction had no effect on income from continuing operations before income taxes or cash flows for any periods presented. The Company evaluated these errors considering both qualitative and quantitative factors pursuant to SEC Staff Accounting Bulletin No. 108, “Considering the Effects of Prior year Misstatements When Quantifying Misstatements in Current Year Financial Statements,” and concluded that these adjustments were not material to the prior years’ consolidated financial statements. The Company also does not believe these adjustments will be material to the 2013 results.
	Recent Accounting Pronouncements
	In July 2012, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standard Update (“ASU”) 2012-02, “Testing Indefinite-Lived Intangible Assets for Impairment”. Similar to goodwill impairment testing guidance, the revised standard allows entities to use a qualitative approach to test indefinite-lived intangible assets for impairment. ASU 2012-02 permits entities to perform a qualitative assessment by considering events and circumstances which would impact the fair value of the entity’s indefinite-lived intangible assets to determine whether it is more likely than not that the fair value of the entity’s indefinite-lived intangible assets are impaired. An entity is not required to calculate the fair value of an indefinite-lived intangible asset and perform the quantitative impairment test unless the entity determines that it is more likely than not the asset is impaired. The revised standard is effective for annual and interim impairment tests performed for fiscal years beginning after September 15, 2012, with early adoption permitted. The Company adopted ASU 2012-02 in its annual impairment test performed as of the beginning of the second fiscal quarter. The adoption did not have any impact on the Company’s consolidated financial statements.
	In January 2013, the FASB issued ASU 2013-02, “Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Comprehensive Income”. Under ASU 2013-02, an entity is required to provide information about the amounts reclassified out of accumulated other comprehensive income (loss) by component. In addition, an entity is required to present, either on the face of the financial statements or in the notes, significant amounts reclassified out of accumulated other comprehensive income (loss) by the respective line items of net income, but only if the amount reclassified is required to be reclassified in its entirety in the same reporting period. For amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional details about those amounts. ASU 2013-02 does not change the current requirements for reporting net income or other comprehensive income (loss) in the financial statements. The standard was effective for interim periods beginning after December 15, 2012. The adoption of this amendment did not have a material impact on the Company’s consolidated financial statements.
	In March 2013, the FASB issued ASU 2013-05, “Foreign Currency Matters (Topic 830): Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity”. ASU 2013-05 provides clarification regarding whether ASC 810-10, “Consolidation – Overall” or ASC 830-30, “Foreign Currency Matters—Translation of Financial Statements,” applies to the release of cumulative translation adjustments into net income when a reporting entity either sells a part or all of its investment in a foreign entity or ceases to have a controlling financial interest in a subsidiary or group of assets that constitute a business within a foreign entity. The revised standard is effective for reporting periods beginning after December 15, 2013, with early adoption permitted. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.
	In July 2013, the FASB issued ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists”. ASU 2013-11 requires, unless certain conditions exists, an unrecognized tax benefit or a portion of an unrecognized tax benefit be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar to a tax loss or a tax credit carryforward. ASU 2013-11 is effective prospectively for reporting periods beginning after December 15, 2013. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 27, 2013
Discontinued Operations	'
	2. Discontinued Operations
	In June 2012, the Company committed to a plan for the sale of the Semiconductor Systems operating segment, sold under the GSI brand name, and Laser Systems product lines, sold under the Control Laser and Baublys brand names. The Company began accounting for these businesses as discontinued operations beginning in the second quarter of 2012. The Company included all current and historical results of these businesses in loss from discontinued operations, net of tax, in the accompanying consolidated statements of operations. The Company classified the assets and liabilities of discontinued operations for both the current and prior year in the consolidated balance sheets as current assets and current liabilities, respectively. The Company’s consolidated statements of cash flows included the cash flows from both continuing and discontinued operations.
	As discussed below, the Company settled final net working capital adjustments with the buyers of both the Laser Systems and Semiconductor Systems businesses, resulting in a loss on sale, net of tax, of $0.3 million during the three months ended September 27, 2013.
	Laser Systems
	In October 2012, the Company sold certain assets and liabilities of the Laser Systems business for $7.0 million to Hans Laser, subject to closing working capital adjustments, and recorded a $2.3 million gain in the consolidated statements of operations during the fiscal year ended December 31, 2012. In September 2013, we paid $0.4 million to Hans Laser as the final net working capital adjustment.
	The Company retained the Orlando facility which was used to manufacture Laser Systems products and is currently leasing the facility to Hans Laser under an operating agreement which was extended through October 2014. As of the end of the second quarter of 2013, it was determined that it was no longer probable that the facility would be sold within the next twelve months and, as a result, the facility was reclassified from assets of discontinued operations to property, plant and equipment.
	Semiconductor Systems
	In May 2013, the Company consummated the sale of certain assets and liabilities of the Semiconductor Systems business to Electro Scientific Industries, Inc. (“ESI”) for $8.0 million in cash, subject to closing working capital adjustments. The Company recognized a $0.3 million loss on the sale, net of tax, in the consolidated statements of operations during the six months ended June 28, 2013. In September 2013, the Company settled final net working capital adjustments with ESI for $1.7 million in favor of the Company, resulting in an adjusted selling price of $9.7 million for the sale.
	The major components of the assets and liabilities of discontinued operations as of September 27, 2013 and December 31, 2012 are as follows (in thousands):
		September 27,			December 31,
		2013			2012
	Accounts receivable, net	$	—		$	2,981
	Inventories		—			8,231
	Other assets		—			694
	Property, plant and equipment		—			5,712
	Assets of discontinued operations	$	—		$	17,618
	Accounts payable, accrued expenses and other current liabilities	$	—		$	3,474
	Deferred revenue		—			1,570
	Other liabilities		624			561
	Liabilities of discontinued operations	$	624		$	5,605
	Other liabilities of discontinued operations as of September 27, 2013 primarily relate to accrued severance owed to former Semiconductor Systems employees and cash owed ESI for trade receivables collected by the Company on behalf of ESI.
	The following table presents the operating results which are reported as discontinued operations in the Company’s consolidated statements of operations (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Sales from discontinued operations	$	—		$	9,618		$	9,090		$	38,342
	Loss from discontinued operations before income taxes	$	(152	)	$	(4,825	)	$	(1,294	)	$	(3,973	)
	Loss from discontinued operations, net of tax	$	(113	)	$	(4,570	)	$	(848	)	$	(3,834	)
	Loss on disposal of discontinued operations, net of tax	$	(281	)	$	—		$	(592	)	$	—

Business_Combinations

Business Combinations	9 Months Ended
	Sep. 27, 2013
Business Combinations	'
	3. Business Combinations
	On January 15, 2013, the Company acquired 100% of the outstanding membership interests of NDS Surgical Imaging, LLC and 100% of the outstanding stock of NDS Surgical Imaging KK (collectively, “NDS”) from NDSSI Holdings, LLC and NDS Surgical Imaging, Inc. for $82.7 million in cash consideration, subject to customary closing working capital adjustments. In October 2013, we finalized the closing working capital adjustments with the seller for $1.9 million, resulting in an adjusted purchase price of $80.8 million. In addition, a total of $5.4 million held in escrow after the payments of closing working capital adjustments can be utilized as indemnification for certain representations and warranty claims against the seller until the expiration of the escrow arrangement in July 2014. The Company expects the addition of NDS will enable the Company to leverage its existing medical OEM sales channels and expertise in color measurement technology. The Company recognized acquisition-related costs which are included in restructuring costs and other in the consolidated statements of operations, as follows (in thousands):
		Three Months		Nine Months		Cumulative
		Ended		Ended		Costs
		September 27,		September 27,		September 27,
		2013		2013		2013
	Acquisition-related charges	$	45	$	1,131	$	1,816
	The acquisition of NDS has been accounted for as a business combination. The allocation of the purchase price is based upon a valuation of assets and liabilities acquired. Assets acquired and liabilities assumed have been recorded at their estimated fair values as of the acquisition date. The fair values of intangible assets were based on valuations using an income approach, with estimates and assumptions provided by management of NDS and the Company. The excess of the purchase price over the tangible assets, identifiable intangible assets and assumed liabilities was recorded as goodwill. The Company’s estimates and assumptions in determining the estimated fair values of certain assets and liabilities are subject to change within the measurement period (up to one year from the acquisition date). The purchase price allocation is preliminary and the primary areas of the purchase price allocation that are not yet finalized relate to income taxes, the fair value of certain liabilities and the amount of resulting goodwill.
	Based upon a preliminary valuation, the total purchase price was allocated as follows (in thousands):
		Purchase Price
		Allocation
	Accounts receivable	$	10,327
	Inventory		14,144
	Property and equipment		2,426
	Intangible assets		37,817
	Other assets		1,782
	Goodwill		26,509
	Total assets acquired		93,005
	Accounts payable		4,768
	Accrued expenses		6,217
	Deferred tax liabilities		315
	Other liabilities assumed		932
	Total liabilities assumed		12,232
	Total net assets acquired	$	80,773
	During the third quarter of 2013, the Company made adjustments to the preliminary purchase price allocation related to the finalization of closing working capital and adjustments to certain tangible and intangible assets, resulting in a decrease to goodwill of $2.4 million.
	The preliminary fair value of intangible assets is comprised of the following (in thousands):
		Estimated Fair		Weighted Average
		Value		Amortization
				Period
	Customer relationships	$	22,294		20 years
	Developed technology		6,689		10 years
	Trademarks and tradenames		7,565		20 years
	Backlog		1,269		1 year
	Total	$	37,817
	The preliminary purchase price allocation resulted in $26.5 million of goodwill and $37.8 million of identifiable intangible assets, the majority of which are expected to be deductible for tax purposes. As a result, the Company recorded deferred tax liabilities of $0.3 million in purchase accounting, equal to the tax effect of the amount of certain acquired intangible assets other than goodwill. Intangible assets are being amortized over their weighted average useful lives primarily based upon the pattern in which economic benefits related to such assets are expected to be realized. The resulting amount of goodwill reflects our expectations of the following synergistic benefits: (1) the potential growth due to additional financial resources to spend on research and development activities, increase of sales resources and the ability to enhance product offerings; (2) the potential to sell NDS products into our customer base and to sell the Company’s products into NDS’s customer base; and (3) our intention to leverage our expertise in light and color measurement.
	The results of the NDS operations have been included in the consolidated statements of operations since the acquisition date. NDS contributed sales of $14.6 million and $49.7 million for the three and nine months ended September 27, 2013, respectively, and losses from continuing operations before income taxes of $1.5 million and $2.5 million for the three and nine months ended September 27, 2013, respectively. The losses from continuing operations before income taxes for both periods include amortization of the purchase price allocation adjustments.
	The following unaudited pro forma information presents the combined financial results for the Company and NDS as if the acquisition of NDS had been completed as of January 1, 2012 (in thousands, except per share information):
		Three Months Ended				Nine Months Ended
		September 27,		September 28,		September 27,		September 28,
		2013		2012		2013		2012
	Sales	$	85,484	$	88,838	$	254,997	$	267,373
	Income from continuing operations, net of tax	$	2,881	$	2,194	$	5,826	$	8,513
	Earnings per share - Basic	$	0.08	$	0.06	$	0.17	$	0.25
	Earnings per share - Diluted	$	0.08	$	0.06	$	0.17	$	0.25
	The pro forma information presented below includes the effects of acquisition accounting, including amortization charges from acquired intangible assets, interest expense on borrowings in connection with the acquisition, acquisition-related charges, and the related tax effects as though the acquisition had been consummated as of the beginning of 2012. These pro forma results exclude the impact of transaction costs included in the historical results and the related tax effects. The pro forma financial information is presented for comparative purposes only and is not necessarily indicative of the results of operations that actually would have been achieved if the acquisition had taken place at the beginning of 2012.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 27, 2013
Accumulated Other Comprehensive Loss	'
	4. Accumulated Other Comprehensive Loss
	The components of accumulated other comprehensive loss is as follows (in thousands):
		Total accumulated other			Foreign currency			Pension liability
		comprehensive loss			translation adjustments			adjustments
	Balance at December 31, 2012	$	(9,749	)	$	1,299		$	(11,048	)
	Other comprehensive income (loss) before reclassifications		(1,796	)		(2,015	)		219
	Amounts reclassified from other comprehensive loss		582			—			582
	Balance at September 27, 2013	$	(10,963	)	$	(716	)	$	(10,247	)
	Reclassification of pension liability adjustments out of accumulated other comprehensive loss and into net income for the nine months ended September 27, 2013 was included in selling, general and administrative costs in the consolidated statements of operations.

Earnings_per_Share

Earnings per Share	9 Months Ended
	Sep. 27, 2013
Earnings per Share	'
	5. Earnings per Share
	Basic earnings per common share is computed by dividing net income by the weighted average number of common shares outstanding during the period. For diluted earnings per common share, the denominator also includes the dilutive effect of outstanding restricted stock units determined using the treasury stock method. For periods in which net losses are generated, the dilutive potential common shares are excluded from the calculation of diluted earnings per share as the effect would be anti-dilutive.
	The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share amounts):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Numerators:
	Consolidated net income		$	2,172		$	2,055		$	4,483		$	7,599
	Less: (income) loss attributable to noncontrolling interest			12			(19	)		(42	)		(45	)
	Income from continuing operations			2,184			2,036			4,441			7,554
	Loss from discontinued operations			(394	)		(4,570	)		(1,440	)		(3,834	)
	Net income (loss) attributable to GSI Group Inc.		$	1,790		$	(2,534	)	$	3,001		$	3,720
	Denominators:
	Weighted average common shares outstanding—basic			34,102			33,803			34,058			33,755
	Dilutive potential common shares (1)			315			109			267			159
	Weighted average common shares outstanding—diluted			34,417			33,912			34,325			33,914
	Antidilutive common shares excluded from above			37			424			327			141
	Basic Earnings (Loss) per Common Share:
	From continuing operations		$	0.06		$	0.06		$	0.13		$	0.22
	From discontinued operations		$	(0.01	)	$	(0.13	)	$	(0.04	)	$	(0.11	)
	Basic earnings (loss) per share attributable to GSI Group Inc.		$	0.05		$	(0.07	)	$	0.09		$	0.11
	Diluted Earnings (Loss) per Common Share:
	From continuing operations		$	0.06		$	0.06		$	0.13		$	0.22
	From discontinued operations		$	(0.01	)	$	(0.13	)	$	(0.04	)	$	(0.11	)
	Diluted earnings (loss) per share attributable to GSI Group Inc.		$	0.05		$	(0.07	)	$	0.09		$	0.11
	(1)	Due to the Company’s net loss attributable to GSI Group Inc. for the three months ended September 28, 2012, all potentially dilutive shares were excluded as their effect would have been anti-dilutive.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 27, 2013
Fair Value Measurements	'
	6. Fair Value Measurements
	ASC 820, “Fair Value Measurements,” establishes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the third is considered unobservable:
		•		Level 1: Quoted prices for identical assets or liabilities in active markets which the Company can access.
		•		Level 2: Observable inputs other than those described in Level 1.
		•		Level 3: Unobservable inputs.
	The Company’s cash equivalents are investments in money market accounts, which represent the only asset the Company measures at fair value on a recurring basis. The Company determines the fair value of our cash equivalents using a market approach based on quoted prices in active markets. The fair values of cash, accounts receivable, income taxes receivable, accounts payable, income taxes payable, accrued expenses and other current liabilities approximate their carrying values because of their short-term nature.
	The following table summarizes the fair values of our financial assets as of September 27, 2013 (in thousands):
			Fair Value		Quoted Prices in		Significant Other		Significant Other
					Active Markets for		Observable Inputs		Unobservable
					Identical Assets		(Level 2)		Inputs
					(Level 1)				(Level 3)
	Assets
	Cash equivalents		$	3,143	$	3,143	$	—	$	—
	The following table summarizes the fair values of our financial assets as of December 31, 2012 (in thousands):
			Fair Value		Quoted Prices in		Significant Other		Significant Other
					Active Markets for		Observable		Unobservable
					Identical Assets		Inputs		Inputs
					(Level 1)		(Level 2)		(Level 3)
	Assets
	Cash equivalents		$	2,511	$	2,511	$	—	$	—
	See Note 9 to Consolidated Financial Statements for discussion of the estimated fair value of the Company’s outstanding debt.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 27, 2013
Goodwill and Intangible Assets	'
	7. Goodwill and Intangible Assets
	Goodwill
	Goodwill is recorded when the consideration for a business combination exceeds the fair value of net tangible and identifiable intangible assets and liabilities acquired. The Company tests its goodwill balances annually as of the beginning of the second quarter or more frequently if indicators are present or changes in circumstances suggest that impairment may exist. The Company performed its annual goodwill impairment test at the beginning of the second quarter and noted no impairment of goodwill. As of the date of our most recent annual impairment test, the fair value of our medical components reporting unit exceeded its carrying value by approximately 10%. The gap between the fair value and the carrying value is relatively small for this reporting unit because our recent NDS acquisition constitutes the majority of the reporting unit.
	The following table summarizes changes in goodwill for the nine months ended September 27, 2013 (in thousands):
		September 27,
		2013
	Balance at beginning of the period	$	44,578
	Goodwill acquired from NDS acquisition		26,509
	Balance at end of period	$	71,087
	Goodwill acquired from the NDS acquisition is reflected in the Precision Technologies segment. Goodwill by reportable segment as of September 27, 2013 is as follows (in thousands):
		Reportable Segment						Total
		Laser			Precision
		Products			Technologies
	Goodwill	$	84,592		$	118,149		$	202,741
	Accumulated impairment of goodwill		(54,099	)		(77,555	)		(131,654	)
	Total	$	30,493		$	40,594		$	71,087
	Goodwill by reportable segment as of December 31, 2012, as restated to conform to the current period segment presentation, is as follows (in thousands):
		Reportable Segment						Total
		Laser			Precision
		Products			Technologies
	Goodwill	$	84,592		$	91,640		$	176,232
	Accumulated impairment of goodwill		(54,099	)		(77,555	)		(131,654	)
	Total	$	30,493		$	14,085		$	44,578
	Intangible Assets
	Intangible assets as of September 27, 2013 and December 31, 2012, respectively, are summarized as follows (in thousands):
		September 27, 2013									December 31, 2012
		Gross Carrying			Accumulated			Net Carrying			Gross Carrying		Accumulated			Net Carrying
		Amount			Amortization			Amount			Amount		Amortization			Amount
	Amortizable intangible assets:
	Patents and acquired technologies	$	68,294		$	(54,778	)	$	13,516		$	61,667	$	(50,904	)	$	10,763
	Customer relationships		55,517			(22,911	)		32,606			33,245		(18,981	)		14,264
	Customer backlog		3,623			(3,516	)		107			2,355		(2,355	)		—
	Trademarks, trade names and other		13,331			(4,322	)		9,009			5,780		(3,814	)		1,966
	Amortizable intangible assets		140,765			(85,527	)		55,238			103,047		(76,054	)		26,993
	Non-amortizable intangible assets:
	Trade names		13,027			—			13,027			13,027		—			13,027
	Totals	$	153,792		$	(85,527	)	$	68,265		$	116,074	$	(76,054	)	$	40,020
	Definite-lived intangible assets are amortized on either a straight-line basis or an economic benefits basis over their remaining useful life. Amortization expense, by classification, in the consolidated statements of operations is summarized as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Amortization expense – cost of sales	$	1,343		$	791		$	3,937		$	2,373
	Amortization expense – operating expenses		1,772			663			5,625			1,988
	Total amortization expense	$	3,115		$	1,454		$	9,562		$	4,361
	Estimated amortization expense for each of the five succeeding years and thereafter as of September 27, 2013, is as follows (in thousands):
	Year Ending December 31,	Cost of Sales			Operating			Total
					Expenses
	2013 (remainder of year)	$	1,343		$	1,645		$	2,988
	2014		4,953			6,041			10,994
	2015		3,310			5,444			8,754
	2016		1,965			5,050			7,015
	2017		1,573			4,720			6,293
	Thereafter		372			18,822			19,194
	Total	$	13,516		$	41,722		$	55,238

Supplementary_Balance_Sheet_In

Supplementary Balance Sheet Information	9 Months Ended
	Sep. 27, 2013
Supplementary Balance Sheet Information	'
	8. Supplementary Balance Sheet Information
	The following tables provide the details of selected balance sheet items as of the periods indicated (in thousands):
	Inventories
		September 27,			December 31,
		2013			2012
	Raw materials	$	38,328		$	30,554
	Work-in-process		12,419			11,959
	Finished goods		11,200			8,023
	Demo and consigned inventory		3,126			2,265
	Total inventories	$	65,073		$	52,801
	Accrued Expenses and Other Current Liabilities
		September 27,			December 31,
		2013			2012
	Accrued compensation and benefits	$	7,489		$	6,655
	Accrued warranty		3,658			2,777
	Customer deposits		1,573			3,033
	Other		9,614			6,497
	Total	$	22,334		$	18,962
	Accrued Warranty
		Nine Months Ended
		September 27,			September 28,
		2013			2012
	Balance at beginning of the period	$	2,777		$	3,035
	Provision charged to cost of sales		1,399			1,958
	Acquisition related warranty accrual		998			—
	Use of provision		(1,517	)		(2,191	)
	Foreign currency exchange rate changes		1			50
	Balance at end of period	$	3,658		$	2,852

Debt

Debt	9 Months Ended
	Sep. 27, 2013
Debt	'
	9. Debt
	Debt consisted of the following (in thousands):
		September 27,		December 31,
		2013		2012
	Senior Credit Facilities – term loan	$	44,375	$	50,000
	Senior Credit Facilities – revolving credit facility		34,000		—
	Total Senior Credit Facilities	$	78,375	$	50,000
	Senior Credit Facilities
	The Company’s amended and restated senior secured credit agreement (the “Amended and Restated Credit Agreement”) provides for a $50.0 million, 5-year, term loan facility due in quarterly installments of $1.9 million beginning in January 2013 and a $75.0 million, 5-year, revolving credit facility (collectively, the “Senior Credit Facilities”) that matures in December 2017. Quarterly installments due in the next twelve months amount to $7.5 million and are classified as a current liability in the consolidated balance sheet. On September 13, 2013, we entered into a third amendment to the Amended and Restated Credit Agreement (the “Third Amendment”). The Third Amendment increases the accordion feature provided in the Amended and Restated Credit Agreement from uncommitted $50.0 million to uncommitted $100.0 million in aggregate of our revolving credit facility and term loan.
	The Company is required to satisfy certain financial and non-financial covenants under the Amended and Restated Credit Agreement. The Company is in compliance with these covenants as of September 27, 2013.
	Fair Value of Debt
	As of September 27, 2013 and December 31, 2012, the outstanding balance of the Company’s Senior Credit Facilities approximated their fair value based on current rates available to the Company for debt of the same maturity, and is classified as Level 2 within the fair value hierarchy.

ShareBased_Compensation

Share-Based Compensation	9 Months Ended
	Sep. 27, 2013
Share-Based Compensation	'
	10. Share-Based Compensation
	The table below summarizes activities relating to restricted stock units issued and outstanding under the 2010 Incentive Award Plan during the nine months ended September 27, 2013:
		Restricted			Weighted
		Stock Units			Average Grant
		(In thousands)			Date Fair Value
	Unvested at December 31, 2012		804		$	10.9
	Granted		424		$	9.61
	Vested		(250	)	$	11.54
	Forfeited		(23	)	$	10.92
	Unvested at September 27, 2013		955		$	10.16
	Expected to vest as of September 27, 2013		938
	The total fair value of restricted stock units that vested during the nine months ended September 27, 2013 was $2.4 million based on the market price of the underlying stock on the day of vesting.
	Share-Based Compensation Expense
	The table below summarizes share-based compensation expense recorded in the consolidated statements of operations under the 2010 Incentive Award Plan (in thousands):
		Three Months Ended					Nine Months Ended
		September 27,			September 28,		September 27,		September 28,
		2013			2012		2013		2012
	Selling, general and administrative	$	1,264		$	1,102	$	3,993	$	3,342
	Research and development and engineering		48			31		129		80
	Cost of sales		32			23		90		57
	Restructuring and other		—			51		—		51
	Total share-based compensation expense	$	1,344		$	1,207	$	4,212	$	3,530
	The expense recorded during the nine months ended September 27, 2013 and September 28, 2012 includes $0.5 million and $0.6 million, respectively, related to deferred stock units granted to the members of the Company’s Board of Directors, pursuant to the Company’s 2010 Incentive Award Plan. The expense associated with the respective deferred stock units was recognized in full on the respective date of grant, as the deferred stock units were fully vested and nonforfeitable on the date of grant.

Employee_Benefit_Plans

Employee Benefit Plans	9 Months Ended
	Sep. 27, 2013
Employee Benefit Plans	'
	11. Employee Benefit Plans
	The net periodic pension cost for the U.K. defined benefit pension plan includes the following components (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Components of the net periodic pension cost:
	Interest cost	$	355		$	343		$	1,064		$	1,028
	Expected return on plan assets		(346	)		(315	)		(1,037	)		(943	)
	Amortization of actuarial loss		167			98			501			293
	Net periodic pension cost	$	176		$	126		$	528		$	378

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 27, 2013
Income Taxes	'
	12. Income Taxes
	The Company determines its estimated annual effective tax rate at the end of each successive interim period based on facts known at that time. The estimated annual effective tax rate is applied to the year-to-date pre-tax income at the end of each interim period. The tax effect of significant unusual items is reflected in the period in which they occur. Since the Company is incorporated in Canada, it is required to use Canada’s blended statutory tax rate of 26.0% in the determination of the estimated annual effective tax rate.
	The Company’s reported effective tax rate on income from continuing operations of 42.6% for the three months ended September 27, 2013 differs from the expected Canadian blended statutory rate of 26.0% primarily due to income earned in jurisdictions with varying tax rates and losses in jurisdictions with a valuation allowance which are not benefitted in the income tax provision in the current period. The Company’s reported effective tax rate on income from continuing operations of 48.5% for the nine months ended September 27, 2013 differs from the expected Canadian blended statutory rate of 26.0% primarily due to income earned in jurisdictions with varying tax rates and losses in jurisdictions with a valuation allowance which are not benefitted in the income tax provision in the current period. The Company’s reported effective tax rate on income from continuing operations for the three and nine months ended September 28, 2012 of 21.5% and 15.7%, respectively, differs from the current period effect tax rates due to the utilization of valuation allowances in the prior year comparable periods.
	The Company maintains a valuation allowance on some of its deferred tax assets in certain jurisdictions. A valuation allowance is required when, based upon an assessment of various factors, including recent operating loss history, anticipated future earnings, and prudent and reasonable tax planning strategies, it is more likely than not that some portion of the deferred tax assets will not be realized.
	In conjunction with the Company’s ongoing review of its actual results and anticipated future earnings, the Company continuously reassesses the possibility of releasing the remaining valuation allowance currently in place on its deferred tax assets. A release would be reported as a reduction to income tax expense without any impact on cash flows in the quarter in which it is released.
	During the fourth quarter of 2012, the Company reached a settlement agreement with the IRS and Department of Justice regarding the IRS audit for the 2000 through 2008 tax years. This settlement was accepted by the Congressional Joint Committee on Taxation during the second quarter of 2013. During the third quarter of 2013, the Company received cash refunds from the IRS of $12.5 million and continues to record an income tax receivable of $0.3 million as of September 27, 2013. In addition, the Company expects to realize the benefit relating to the carryback and carryforward of certain net operating losses in 2014, which will result in the refund of tax payments made in the carryback periods and lower income tax payments in the carryforward periods.
	On September 13, 2013, the IRS released final tangible property regulations under Sections 162(a) and 263(a) of the Internal Revenue Code of 1986 (the “Code”), regarding the deduction and capitalization of expenditures related to tangible property. In addition, the IRS proposed regulations under Section 168 of the Code regarding dispositions of tangible property. These final and proposed regulations will be effective for the Company’s fiscal year ending December 31, 2014. Transition guidance providing the procedural rules to comply with such regulations is expected to be released in the near term. The Company is in the process of reviewing the regulations and the related impact on its consolidated financial statements.

Restructuring_Costs_and_Other

Restructuring Costs and Other	9 Months Ended
	Sep. 27, 2013
Restructuring Costs and Other	'
	13. Restructuring Costs and Other
	The following table summarizes restructuring costs and other expenses in the accompanying consolidated statements of operations (in thousands):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	2011 restructuring		$	85		$	974		$	2,316		$	5,626
	2012 restructuring			—			1,711			—			1,711
	2013 restructuring			1,443			—			2,370			—
	Germany restructuring			—			43			8			59
	Total restructuring charges		$	1,528		$	2,728		$	4,694		$	7,396
	Total acquisition related charges			113			—			1,199			—
	Total restructuring costs and other		$	1,641		$	2,728		$	5,893		$	7,396
	2011 Restructuring
	In November 2011, the Company announced a strategic initiative (“2011 restructuring”), which aimed to consolidate operations to reduce our cost structure and improve operational efficiency. As part of this initiative, the Company eliminated facilities through consolidation of certain manufacturing, sales and distribution facilities and exit of businesses. The Company completed the 2011 restructuring plan during the nine months ended September 27, 2013. The Company records restructuring charges (benefits), as necessary, related to this plan for changes in estimates for facilities that were exited as part of the 2011 restructuring plan.
	Presented below are actual cash charges, including severance and relocation costs, facility closure costs and consulting costs and non-cash charges related to accelerated depreciation for changes in estimated useful lives of certain long-lived assets for which the Company exited with respect to the 2011 restructuring plan (in thousands):
			Three Months Ended						Nine Months Ended						Cumulative
															Costs for Plan
			September 27,			September 28,			September 27,			September 28,			September 27,
			2013			2012			2013			2012			2013
	Cash charges (benefits)		$	(40	)	$	974		$	1,850		$	3,735		$	7,020
	Non-cash charges			125			—			466			1,891			3,320
	Total restructuring costs		$	85		$	974		$	2,316		$	5,626		$	10,340
	The following table summarizes restructuring costs for each segment and unallocated corporate costs related to the 2011 restructuring plan (in thousands):
			Three Months Ended						Nine Months Ended						Cumulative
															Costs for Plan
			September 27,			September 28,			September 27,			September 28,			September 27,
			2013			2012			2013			2012			2013
	Laser Products		$	75		$	371		$	2,044		$	4,335		$	8,119
	Precision Technologies			—			452			53			652			746
	Unallocated restructuring costs(1)			10			151			219			639			1,475
	Total restructuring costs		$	85		$	974		$	2,316		$	5,626		$	10,340
	(1)	Represents consulting and severance restructuring costs related to corporate and shared service functions.
	2013 Restructuring
	During the first half of 2013, the Company initiated a plan following our acquisition of NDS to integrate the NDS business into our operating structure and further reduce manufacturing and operating costs across businesses to leverage our infrastructure and further integrate our product lines. The Company incurred $1.3 million and $2.2 million of cash related charges during the three and nine months ended September 27, 2013, respectively, related to this plan primarily related to exit costs associated with a facility exited during the first quarter of 2013, employee severance and an officer severance. The Company expects to incur between $0.2 million and $0.5 million of remaining cash charges related to this plan for the remainder of 2013.
	The following table summarizes restructuring costs for each segment and unallocated corporate costs related to the 2013 restructuring plan (in thousands):
			Three Months			Nine Months
			Ended			Ended
			September 27,			September 27,
			2013			2013
	Laser Products		$	767		$	938
	Precision Technologies			437			1,138
	Unallocated restructuring costs(1)			239			294
	Total restructuring costs		$	1,443		$	2,370
	(1)	Represents consulting and severance restructuring costs related to corporate and shared service functions.
	Rollforward of Accrued Expenses Related to Restructuring
	The following table summarizes the accrual activities, by component, related to the Company’s restructuring plans recorded in the accompanying consolidated balance sheets (in thousands):
			Total			Severance			Facility			Accelerated			Other
												Depreciation
	Balance at December 31, 2012		$	2,030		$	1,304		$	489		$	—		$	237
	Restructuring charges			4,694			2,374			1,349			66			905
	Cash payments			(4,361	)		(2,428	)		(996	)		—			(937	)
	Acquired lease obligation			128			—			128			—			—
	Non-cash write-offs and other adjustments			(147	)		21			21			(66	)		(123	)
	Balance at September 27, 2013		$	2,344		$	1,271		$	991		$	—		$	82
	In accordance with the guidance in ASC 420, “Exit or Disposal Cost Obligations,” the Company records lease termination accruals based on market estimates, including the time period for which facilities will remain vacant, sublease terms, sublease rates and discount rates. The Company reviews prior estimates and current market data available to determine the appropriate value of these liabilities at period end.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 27, 2013
Commitments and Contingencies	'
	14. Commitments and Contingencies
	Operating Leases
	The Company leases certain equipment and facilities under operating lease agreements. Excluding leases acquired as a result of the NDS acquisition, there have been no material changes to the Company’s operating leases through September 27, 2013 from those discussed in Note 15 to Consolidated Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012. Future minimum lease payments under the existing operating leases for NDS are as follows (in thousands):
	Year Ending December 31,	Operating Leases
	2013 (remainder of year)	$	327
	2014		1,223
	2015		84
	Thereafter		—
	Total	$	1,634
	Purchase Commitments
	There have been no material changes to the Company’s purchase commitments from those discussed in Note 15 to Consolidated Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012.
	Legal Proceedings
	During the third quarter of 2005, the Company’s French subsidiary, GSI Lumonics SARL (“GSI France”), filed for bankruptcy protection, which was granted on July 7, 2005. On April 18, 2006, the commercial court of Le Creusot (France) ordered GSI France to pay approximately 0.7 million Euros to SCGI in the context of a claim filed by SCGI that a Laserdyne 890 system delivered in 1999 had unresolved technical problems. No appeal was lodged. On May 6, 2011, GSI Group Ltd. was served with summons from the official receiver of GSI France demanding that GSI Group Ltd. and the Company’s German subsidiary, GSI Group GmbH, appear before the Paris commercial court. GSI Group GmbH was subsequently served with a separate summons from the official receiver. The cases against GSI Group Ltd. and GSI Group GmbH were subsequently combined into a single case (docket number 2011/088718). The receiver claimed (i) that the bankruptcy proceedings initiated against GSI France in 2005 should be extended to GSI Group Ltd. and GSI Group GmbH on the ground that GSI France’s decisions were actually made by GSI Group Ltd. and that GSI Group GmbH made financial advances for no consideration, which would reveal in both cases confusion of personhood, or (ii) alternatively, that GSI Group Ltd. be ordered to pay approximately 3.1 million Euros (i.e. the aggregate of GSI France’s liabilities, consisting primarily of approximately 0.7 million Euros to SCGI and approximately 2.4 million Euros to GSI Group GmbH) on the ground that GSI Group Ltd. is liable in tort for having disposed of GSI France’s assets freely and for having paid all of GSI France’s debts except for the liability to SCGI. On June 19, 2012, the receiver withdrew its claim with respect to extending the bankruptcy proceedings to GSI Group Ltd. and GSI Group GmbH. On September 4, 2013, the Paris commercial court dismissed the receiver’s tort claims in whole on the ground that the action was time-barred. On October 9, 2013, the receiver lodged an appeal before the court of appeals of Paris. The calendar of the proceedings before the court of appeals of Paris has not yet been determined. The Company currently does not believe a loss is probable. Accordingly, no accrual has been made in the Company’s accompanying consolidated financial statements with respect to this claim.
	The Company is also subject to various legal proceedings and claims that arise in the ordinary course of business. The Company does not believe that the outcome of these claims will have a material adverse effect upon its financial condition or results of operations but there can be no assurance that any such claims, or any similar claims, would not have a material adverse effect upon its financial condition or results of operations.
	IRS Claim
	On April 5, 2010, the IRS filed amended proofs of claim aggregating approximately $7.7 million with the United States Bankruptcy Court for Delaware (the “Bankruptcy Court”) as part of the Company’s proceedings under Chapter 11 of the Bankruptcy Code. On July 13, 2010, the Company filed a complaint, GSI Group Corporation v. United States of America, in Bankruptcy Court in an attempt to recover refunds totaling approximately $18.8 million in federal income taxes the Company asserts it overpaid to the IRS relating to tax years 2000 through 2009, together with applicable interest. The complaint includes an objection to the IRS proofs of claim which the Company believes are not allowable claims and should be expunged in their entirety.
	During the fourth quarter of 2012, the Company reached a settlement agreement with the IRS and Department of Justice regarding the IRS audit for the 2000 through 2008 tax years. This settlement was accepted by the Congressional Joint Committee on Taxation during the second quarter of 2013. During the third quarter of 2013, the Company received cash refunds from the IRS of $12.5 million. The Company continues to record an income tax receivable of $0.3 million as of September 27, 2013. In addition, the Company expects to realize the benefit relating to the carryback and carryforward of certain net operating losses in 2014, which will result in the refund of tax payments made in the carryback periods and lower income tax payments in the carryforward periods.
	Guarantees and Indemnifications
	In the normal course of its operations, the Company executes agreements that provide for indemnification and guarantees to counterparties in transactions such as business dispositions, sale of assets, sale of products and operating leases. Additionally, the by-laws of the Company require it to indemnify certain current or former directors, officers, and employees of the Company against expenses incurred by them in connection with each proceeding in which he or she is involved as a result of serving or having served in certain capacities. Indemnification is not available with respect to a proceeding as to which it has been adjudicated that the person did not act in good faith in the reasonable belief that the action was in the best interests of the Company. On June 5, 2009, the Board of Directors of the Company approved a form of indemnification agreement to be implemented by the Company with respect to its directors and officers. The form of indemnification agreement provides, among other things, that each director and officer of the Company who signs the indemnification agreement shall be indemnified to the fullest extent permitted by applicable law against all expenses, judgments, fines and amounts paid in settlement actually and reasonably incurred by such officer or director in connection with any proceeding by reason of his or her relationship with the Company. In addition, the form of indemnification agreement provides for the advancement of expenses incurred by such director or officer in connection with any proceeding covered by the indemnification agreement, subject to the conditions set forth therein and to the extent such advancement is not prohibited by law. The indemnification agreement also sets out the procedures for determining entitlement to indemnification, the requirements relating to notice and defense of claims for which indemnification is sought, the procedures for enforcement of indemnification rights, the limitations on and exclusions from indemnification, and the minimum levels of directors’ and officers’ liability insurance to be maintained by the Company.

Segment_Information

Segment Information	9 Months Ended
	Sep. 27, 2013
Segment Information	'
	15. Segment Information
	Reportable Segments
	The Company evaluates the performance of, and allocates resources to, its segments based on sales, gross profit and operating profit. The Company reports assets on a consolidated basis to the chief operating decision maker, which is the Chief Executive Officer. The Company’s reportable segments have been identified based on commonality of end markets, customers, applications and technologies amongst the Company’s individual product lines, which is consistent with the Company’s operating structure, associated management structure, and management compensation programs.
	The Company previously operated in three reportable segments: Laser Products, Precision Motion and Technologies and Semiconductor Systems. The Company divested its Semiconductor Systems and Laser Systems businesses in May 2013 and October 2012, respectively. As a result, these businesses have been reported as discontinued operations in the consolidated financial statements.
	As a result of the NDS acquisition and restructuring activities, the Company realigned its reportable segments during the first quarter of 2013 into two segments: Laser Products and Precision Technologies. The segment realignment resulted in the scanning solutions product line being moved to the Laser Products segment and added NDS to the Precision Technologies segment. The segment realignment was based on the following factors: (i) customers and sales channel overlap; (ii) commonality amongst customer applications; (iii) allocation of resources, as the Company has a Group President for each of its two reportable segments who is held accountable for the overall results of the respective segment; (iv) consistency with the structure of the Company’s senior management non-equity incentive program for each segment’s senior management; (v) grouping together those product lines whose organizational and operating cost structures we expect will be consolidated in the future; and (vi) meetings between the chief operating decision maker and the two segment Group Presidents to review the operating performance of each segment and to allocate resources.
	Reportable segment financial information has been revised based on the circumstances outlined above. The remaining reportable segments and their principal activities consist of the following:
	Laser Products
	The Laser Products segment designs, manufactures and markets photonics-based solutions to customers worldwide. The segment serves highly demanding photonics-based applications such as cutting, welding, marking, medical diagnosis and treatment, and scientific research. The vast majority of the segment’s product offerings are sold to OEMs. The segment sells these products both directly utilizing a highly technical sales force and indirectly through resellers and distributors.
	Precision Technologies
	The Precision Technologies segment designs, manufactures and markets medical visualization solutions and imaging informatics products, medical printers, optical encoders, air bearing spindles, and light and color measurement instrumentation to customers worldwide. The vast majority of the segment’s product offerings are sold to OEMs. The segment sells these products both directly utilizing a highly technical sales force and indirectly through resellers and distributors.
	Reportable Segment Financial Information
	Sales, gross profit, gross profit margin and operating income by reportable segments are as follows (in thousands):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Sales
	Laser Products		$	50,340		$	48,369		$	142,519		$	138,828
	Precision Technologies			35,144			21,151			111,386			66,257
	Total		$	85,484		$	69,520		$	253,905		$	205,085
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Gross Profit
	Laser Products		$	20,882		$	19,245		$	56,857		$	56,683
	Precision Technologies			14,964			9,903			46,759			31,230
	Corporate (1)			(55	)		(295	)		(163	)		(712	)
	Total		$	35,791		$	28,853		$	103,453		$	87,201
	(1)	Corporate costs primarily represent unallocated overhead.
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Gross Profit Margin
	Laser Products			41.5	%		39.8	%		39.9	%		40.8	%
	Precision Technologies			42.6	%		46.8	%		42	%		47.1	%
	Total			41.9	%		41.5	%		40.7	%		42.5	%
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Operating Income
	Laser Products		$	7,653		$	5,379		$	16,258		$	13,313
	Precision Technologies			2,754			3,689			11,032			14,208
	Corporate, shared services and unallocated (2)			(4,689	)		(5,276	)		(16,276	)		(15,811	)
	Total		$	5,718		$	3,792		$	11,014		$	11,710
	(2)	Corporate and shared services costs primarily represent corporate and shared service function costs which are not allocated to the operating segments, including restructuring and all acquisition related costs.

Nature_of_Operations_and_Summa1

Nature of Operations and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 27, 2013
Use of Estimates	'
	Use of Estimates
	The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of sales and expenses during the reporting periods. The Company evaluates its estimates based on historical experience, current conditions and various other assumptions that it believes are reasonable under the circumstances. Estimates and assumptions are reviewed on an on-going basis and the effects of revisions are reflected in the period in which they are deemed to be necessary. Actual results could differ significantly from those estimates.
Reclassifications and Adjustments	'
	Reclassifications and Adjustments
	As discussed in Note 15, the Company realigned its segment presentation during the first quarter of 2013 in light of the acquisition of NDS Surgical Imaging, LLC and NDS Surgical Imaging KK as well as restructuring activities. As a result, prior period segment information included in the consolidated statements has been reclassified to conform to the current period presentation.
	Beginning in 2008, the Company did not properly recognize deferred tax liabilities associated with certain permanent intercompany loans and did not consider these deferred tax liability amounts when determining the realizability of its deferred tax assets and thereby recorded excess valuation allowances beginning in 2009. The Company identified and corrected this immaterial error of $0.7 million income tax benefit related to prior years during the three months ended March 29, 2013. During the three months ended June 28, 2013, the Company identified and corrected an immaterial error of $0.3 million income tax provision related to the deferred tax effect of a foreign statutory to U.S. GAAP difference in a prior year income tax provision calculation. These error corrections resulted in a net $0.4 million income tax benefit allocated to income from continuing operations for the nine months ended September 27, 2013. The net correction had no effect on income from continuing operations before income taxes or cash flows for any periods presented. The Company evaluated these errors considering both qualitative and quantitative factors pursuant to SEC Staff Accounting Bulletin No. 108, “Considering the Effects of Prior year Misstatements When Quantifying Misstatements in Current Year Financial Statements,” and concluded that these adjustments were not material to the prior years’ consolidated financial statements. The Company also does not believe these adjustments will be material to the 2013 results.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In July 2012, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standard Update (“ASU”) 2012-02, “Testing Indefinite-Lived Intangible Assets for Impairment”. Similar to goodwill impairment testing guidance, the revised standard allows entities to use a qualitative approach to test indefinite-lived intangible assets for impairment. ASU 2012-02 permits entities to perform a qualitative assessment by considering events and circumstances which would impact the fair value of the entity’s indefinite-lived intangible assets to determine whether it is more likely than not that the fair value of the entity’s indefinite-lived intangible assets are impaired. An entity is not required to calculate the fair value of an indefinite-lived intangible asset and perform the quantitative impairment test unless the entity determines that it is more likely than not the asset is impaired. The revised standard is effective for annual and interim impairment tests performed for fiscal years beginning after September 15, 2012, with early adoption permitted. The Company adopted ASU 2012-02 in its annual impairment test performed as of the beginning of the second fiscal quarter. The adoption did not have any impact on the Company’s consolidated financial statements.
	In January 2013, the FASB issued ASU 2013-02, “Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Comprehensive Income”. Under ASU 2013-02, an entity is required to provide information about the amounts reclassified out of accumulated other comprehensive income (loss) by component. In addition, an entity is required to present, either on the face of the financial statements or in the notes, significant amounts reclassified out of accumulated other comprehensive income (loss) by the respective line items of net income, but only if the amount reclassified is required to be reclassified in its entirety in the same reporting period. For amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional details about those amounts. ASU 2013-02 does not change the current requirements for reporting net income or other comprehensive income (loss) in the financial statements. The standard was effective for interim periods beginning after December 15, 2012. The adoption of this amendment did not have a material impact on the Company’s consolidated financial statements.
	In March 2013, the FASB issued ASU 2013-05, “Foreign Currency Matters (Topic 830): Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity”. ASU 2013-05 provides clarification regarding whether ASC 810-10, “Consolidation – Overall” or ASC 830-30, “Foreign Currency Matters—Translation of Financial Statements,” applies to the release of cumulative translation adjustments into net income when a reporting entity either sells a part or all of its investment in a foreign entity or ceases to have a controlling financial interest in a subsidiary or group of assets that constitute a business within a foreign entity. The revised standard is effective for reporting periods beginning after December 15, 2013, with early adoption permitted. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.
	In July 2013, the FASB issued ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists”. ASU 2013-11 requires, unless certain conditions exists, an unrecognized tax benefit or a portion of an unrecognized tax benefit be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar to a tax loss or a tax credit carryforward. ASU 2013-11 is effective prospectively for reporting periods beginning after December 15, 2013. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 27, 2013
Components of Assets and Liabilities and Operating Results Historically Included Segment	'
	The major components of the assets and liabilities of discontinued operations as of September 27, 2013 and December 31, 2012 are as follows (in thousands):
		September 27,			December 31,
		2013			2012
	Accounts receivable, net	$	—		$	2,981
	Inventories		—			8,231
	Other assets		—			694
	Property, plant and equipment		—			5,712
	Assets of discontinued operations	$	—		$	17,618
	Accounts payable, accrued expenses and other current liabilities	$	—		$	3,474
	Deferred revenue		—			1,570
	Other liabilities		624			561
	Liabilities of discontinued operations	$	624		$	5,605
	The following table presents the operating results which are reported as discontinued operations in the Company’s consolidated statements of operations (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Sales from discontinued operations	$	—		$	9,618		$	9,090		$	38,342
	Loss from discontinued operations before income taxes	$	(152	)	$	(4,825	)	$	(1,294	)	$	(3,973	)
	Loss from discontinued operations, net of tax	$	(113	)	$	(4,570	)	$	(848	)	$	(3,834	)
	Loss on disposal of discontinued operations, net of tax	$	(281	)	$	—		$	(592	)	$	—

Business_Combinations_Tables

Business Combinations (Tables)	9 Months Ended
	Sep. 27, 2013
Acquisition Related Costs Recognized in Consolidated Statements of Operations	'
	The Company recognized acquisition-related costs which are included in restructuring costs and other in the consolidated statements of operations, as follows (in thousands):
		Three Months		Nine Months		Cumulative
		Ended		Ended		Costs
		September 27,		September 27,		September 27,
		2013		2013		2013
	Acquisition-related charges	$	45	$	1,131	$	1,816
Summary of Fair Values of Assets Acquired and Liabilities Assumed Purchase Price Allocation	'
	Based upon a preliminary valuation, the total purchase price was allocated as follows (in thousands):
		Purchase Price
		Allocation
	Accounts receivable	$	10,327
	Inventory		14,144
	Property and equipment		2,426
	Intangible assets		37,817
	Other assets		1,782
	Goodwill		26,509
	Total assets acquired		93,005
	Accounts payable		4,768
	Accrued expenses		6,217
	Deferred tax liabilities		315
	Other liabilities assumed		932
	Total liabilities assumed		12,232
	Total net assets acquired	$	80,773
Fair Value of Intangible Assets	'
	The preliminary fair value of intangible assets is comprised of the following (in thousands):
		Estimated Fair		Weighted Average
		Value		Amortization
				Period
	Customer relationships	$	22,294		20 years
	Developed technology		6,689		10 years
	Trademarks and tradenames		7,565		20 years
	Backlog		1,269		1 year
	Total	$	37,817
Unaudited Pro forma Information	'
	The following unaudited pro forma information presents the combined financial results for the Company and NDS as if the acquisition of NDS had been completed as of January 1, 2012 (in thousands, except per share information):
		Three Months Ended				Nine Months Ended
		September 27,		September 28,		September 27,		September 28,
		2013		2012		2013		2012
	Sales	$	85,484	$	88,838	$	254,997	$	267,373
	Income from continuing operations, net of tax	$	2,881	$	2,194	$	5,826	$	8,513
	Earnings per share - Basic	$	0.08	$	0.06	$	0.17	$	0.25
	Earnings per share - Diluted	$	0.08	$	0.06	$	0.17	$	0.25

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 27, 2013
Components of Accumulated Other Comprehensive Loss	'
	The components of accumulated other comprehensive loss is as follows (in thousands):
		Total accumulated other			Foreign currency			Pension liability
		comprehensive loss			translation adjustments			adjustments
	Balance at December 31, 2012	$	(9,749	)	$	1,299		$	(11,048	)
	Other comprehensive income (loss) before reclassifications		(1,796	)		(2,015	)		219
	Amounts reclassified from other comprehensive loss		582			—			582
	Balance at September 27, 2013	$	(10,963	)	$	(716	)	$	(10,247	)

Earnings_per_Share_Tables

Earnings per Share (Tables)	9 Months Ended
	Sep. 27, 2013
Computation of Basic and Diluted Earnings Per Share	'
	The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share amounts):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Numerators:
	Consolidated net income		$	2,172		$	2,055		$	4,483		$	7,599
	Less: (income) loss attributable to noncontrolling interest			12			(19	)		(42	)		(45	)
	Income from continuing operations			2,184			2,036			4,441			7,554
	Loss from discontinued operations			(394	)		(4,570	)		(1,440	)		(3,834	)
	Net income (loss) attributable to GSI Group Inc.		$	1,790		$	(2,534	)	$	3,001		$	3,720
	Denominators:
	Weighted average common shares outstanding—basic			34,102			33,803			34,058			33,755
	Dilutive potential common shares (1)			315			109			267			159
	Weighted average common shares outstanding—diluted			34,417			33,912			34,325			33,914
	Antidilutive common shares excluded from above			37			424			327			141
	Basic Earnings (Loss) per Common Share:
	From continuing operations		$	0.06		$	0.06		$	0.13		$	0.22
	From discontinued operations		$	(0.01	)	$	(0.13	)	$	(0.04	)	$	(0.11	)
	Basic earnings (loss) per share attributable to GSI Group Inc.		$	0.05		$	(0.07	)	$	0.09		$	0.11
	Diluted Earnings (Loss) per Common Share:
	From continuing operations		$	0.06		$	0.06		$	0.13		$	0.22
	From discontinued operations		$	(0.01	)	$	(0.13	)	$	(0.04	)	$	(0.11	)
	Diluted earnings (loss) per share attributable to GSI Group Inc.		$	0.05		$	(0.07	)	$	0.09		$	0.11
	(1)	Due to the Company’s net loss attributable to GSI Group Inc. for the three months ended September 28, 2012, all potentially dilutive shares were excluded as their effect would have been anti-dilutive.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 27, 2013
Fair Value of Asset Measured on Recurring and Nonrecurring Basis	'
	The following table summarizes the fair values of our financial assets as of September 27, 2013 (in thousands):
		Fair Value		Quoted Prices in		Significant Other		Significant Other
				Active Markets for		Observable Inputs		Unobservable
				Identical Assets		(Level 2)		Inputs
				(Level 1)				(Level 3)
	Assets
	Cash equivalents	$	3,143	$	3,143	$	—	$	—
	The following table summarizes the fair values of our financial assets as of December 31, 2012 (in thousands):
		Fair Value		Quoted Prices in		Significant Other		Significant Other
				Active Markets for		Observable		Unobservable
				Identical Assets		Inputs		Inputs
				(Level 1)		(Level 2)		(Level 3)
	Assets
	Cash equivalents	$	2,511	$	2,511	$	—	$	—

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 27, 2013
Summary of Changes in Goodwill	'
	The following table summarizes changes in goodwill for the nine months ended September 27, 2013 (in thousands):
		September 27,
		2013
	Balance at beginning of the period	$	44,578
	Goodwill acquired from NDS acquisition		26,509
	Balance at end of period	$	71,087
Goodwill by Reportable Segment	'
	Goodwill acquired from the NDS acquisition is reflected in the Precision Technologies segment. Goodwill by reportable segment as of September 27, 2013 is as follows (in thousands):
		Reportable Segment						Total
		Laser			Precision
		Products			Technologies
	Goodwill	$	84,592		$	118,149		$	202,741
	Accumulated impairment of goodwill		(54,099	)		(77,555	)		(131,654	)
	Total	$	30,493		$	40,594		$	71,087
	Goodwill by reportable segment as of December 31, 2012, as restated to conform to the current period segment presentation, is as follows (in thousands):
		Reportable Segment						Total
		Laser			Precision
		Products			Technologies
	Goodwill	$	84,592		$	91,640		$	176,232
	Accumulated impairment of goodwill		(54,099	)		(77,555	)		(131,654	)
	Total	$	30,493		$	14,085		$	44,578
Intangible Assets	'
	Intangible assets as of September 27, 2013 and December 31, 2012, respectively, are summarized as follows (in thousands):
		September 27, 2013									December 31, 2012
		Gross Carrying			Accumulated			Net Carrying			Gross Carrying		Accumulated			Net Carrying
		Amount			Amortization			Amount			Amount		Amortization			Amount
	Amortizable intangible assets:
	Patents and acquired technologies	$	68,294		$	(54,778	)	$	13,516		$	61,667	$	(50,904	)	$	10,763
	Customer relationships		55,517			(22,911	)		32,606			33,245		(18,981	)		14,264
	Customer backlog		3,623			(3,516	)		107			2,355		(2,355	)		—
	Trademarks, trade names and other		13,331			(4,322	)		9,009			5,780		(3,814	)		1,966
	Amortizable intangible assets		140,765			(85,527	)		55,238			103,047		(76,054	)		26,993
	Non-amortizable intangible assets:
	Trade names		13,027			—			13,027			13,027		—			13,027
	Totals	$	153,792		$	(85,527	)	$	68,265		$	116,074	$	(76,054	)	$	40,020
Amortization Expense of Intangible Assets	'
	Amortization expense, by classification, in the consolidated statements of operations is summarized as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Amortization expense – cost of sales	$	1,343		$	791		$	3,937		$	2,373
	Amortization expense – operating expenses		1,772			663			5,625			1,988
	Total amortization expense	$	3,115		$	1,454		$	9,562		$	4,361
Estimated Amortization Expense	'
	Estimated amortization expense for each of the five succeeding years and thereafter as of September 27, 2013, is as follows (in thousands):
	Year Ending December 31,	Cost of Sales			Operating			Total
					Expenses
	2013 (remainder of year)	$	1,343		$	1,645		$	2,988
	2014		4,953			6,041			10,994
	2015		3,310			5,444			8,754
	2016		1,965			5,050			7,015
	2017		1,573			4,720			6,293
	Thereafter		372			18,822			19,194
	Total	$	13,516		$	41,722		$	55,238

Supplementary_Balance_Sheet_In1

Supplementary Balance Sheet Information (Tables)	9 Months Ended
	Sep. 27, 2013
Inventories	'
	Inventories
		September 27,			December 31,
		2013			2012
	Raw materials	$	38,328		$	30,554
	Work-in-process		12,419			11,959
	Finished goods		11,200			8,023
	Demo and consigned inventory		3,126			2,265
	Total inventories	$	65,073		$	52,801
Accrued Expenses and Other Current Liabilities	'
	Accrued Expenses and Other Current Liabilities
		September 27,			December 31,
		2013			2012
	Accrued compensation and benefits	$	7,489		$	6,655
	Accrued warranty		3,658			2,777
	Customer deposits		1,573			3,033
	Other		9,614			6,497
	Total	$	22,334		$	18,962
Accrued Warranty	'
	Accrued Warranty
		Nine Months Ended
		September 27,			September 28,
		2013			2012
	Balance at beginning of the period	$	2,777		$	3,035
	Provision charged to cost of sales		1,399			1,958
	Acquisition related warranty accrual		998			—
	Use of provision		(1,517	)		(2,191	)
	Foreign currency exchange rate changes		1			50
	Balance at end of period	$	3,658		$	2,852

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 27, 2013
Debt	'
	Debt consisted of the following (in thousands):
		September 27,		December 31,
		2013		2012
	Senior Credit Facilities – term loan	$	44,375	$	50,000
	Senior Credit Facilities – revolving credit facility		34,000		—
	Total Senior Credit Facilities	$	78,375	$	50,000

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 27, 2013
Share Based Compensation Expense	'
	The table below summarizes share-based compensation expense recorded in the consolidated statements of operations under the 2010 Incentive Award Plan (in thousands):
		Three Months Ended					Nine Months Ended
		September 27,			September 28,		September 27,		September 28,
		2013			2012		2013		2012
	Selling, general and administrative	$	1,264		$	1,102	$	3,993	$	3,342
	Research and development and engineering		48			31		129		80
	Cost of sales		32			23		90		57
	Restructuring and other		—			51		—		51
	Total share-based compensation expense	$	1,344		$	1,207	$	4,212	$	3,530
2010 Incentive Award Plan	'
Restricted Stock Units Issued and Outstanding	'
	The table below summarizes activities relating to restricted stock units issued and outstanding under the 2010 Incentive Award Plan during the nine months ended September 27, 2013:
		Restricted			Weighted
		Stock Units			Average Grant
		(In thousands)			Date Fair Value
	Unvested at December 31, 2012		804		$	10.9
	Granted		424		$	9.61
	Vested		(250	)	$	11.54
	Forfeited		(23	)	$	10.92
	Unvested at September 27, 2013		955		$	10.16
	Expected to vest as of September 27, 2013		938

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 27, 2013
Net Periodic Cost for U.K Defined Benefit Pension Plan	'
	The net periodic pension cost for the U.K. defined benefit pension plan includes the following components (in thousands):
		Three Months Ended						Nine Months Ended
		September 27,			September 28,			September 27,			September 28,
		2013			2012			2013			2012
	Components of the net periodic pension cost:
	Interest cost	$	355		$	343		$	1,064		$	1,028
	Expected return on plan assets		(346	)		(315	)		(1,037	)		(943	)
	Amortization of actuarial loss		167			98			501			293
	Net periodic pension cost	$	176		$	126		$	528		$	378

Restructuring_Costs_and_Other_

Restructuring Costs and Other (Tables)	9 Months Ended
	Sep. 27, 2013
Summary of Restructuring Costs and Other Expense	'
	The following table summarizes restructuring costs and other expenses in the accompanying consolidated statements of operations (in thousands):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	2011 restructuring		$	85		$	974		$	2,316		$	5,626
	2012 restructuring			—			1,711			—			1,711
	2013 restructuring			1,443			—			2,370			—
	Germany restructuring			—			43			8			59
	Total restructuring charges		$	1,528		$	2,728		$	4,694		$	7,396
	Total acquisition related charges			113			—			1,199			—
	Total restructuring costs and other		$	1,641		$	2,728		$	5,893		$	7,396
Actual Cash and Non-Cash Charges of the Restructuring Plan	'
	Presented below are actual cash charges, including severance and relocation costs, facility closure costs and consulting costs and non-cash charges related to accelerated depreciation for changes in estimated useful lives of certain long-lived assets for which the Company exited with respect to the 2011 restructuring plan (in thousands):
			Three Months Ended						Nine Months Ended						Cumulative
															Costs for Plan
			September 27,			September 28,			September 27,			September 28,			September 27,
			2013			2012			2013			2012			2013
	Cash charges (benefits)		$	(40	)	$	974		$	1,850		$	3,735		$	7,020
	Non-cash charges			125			—			466			1,891			3,320
	Total restructuring costs		$	85		$	974		$	2,316		$	5,626		$	10,340
Summary of Accrual Activities by Components Related to Company's Restructuring Plans	'
	The following table summarizes the accrual activities, by component, related to the Company’s restructuring plans recorded in the accompanying consolidated balance sheets (in thousands):
			Total			Severance			Facility			Accelerated			Other
												Depreciation
	Balance at December 31, 2012		$	2,030		$	1,304		$	489		$	—		$	237
	Restructuring charges			4,694			2,374			1,349			66			905
	Cash payments			(4,361	)		(2,428	)		(996	)		—			(937	)
	Acquired lease obligation			128			—			128			—			—
	Non-cash write-offs and other adjustments			(147	)		21			21			(66	)		(123	)
	Balance at September 27, 2013		$	2,344		$	1,271		$	991		$	—		$	82
2011 Restructuring	'
Summary of Restructuring Costs for Each Segment and Unallocated Corporate Costs	'
	The following table summarizes restructuring costs for each segment and unallocated corporate costs related to the 2011 restructuring plan (in thousands):
			Three Months Ended						Nine Months Ended						Cumulative
															Costs for Plan
			September 27,			September 28,			September 27,			September 28,			September 27,
			2013			2012			2013			2012			2013
	Laser Products		$	75		$	371		$	2,044		$	4,335		$	8,119
	Precision Technologies			—			452			53			652			746
	Unallocated restructuring costs(1)			10			151			219			639			1,475
	Total restructuring costs		$	85		$	974		$	2,316		$	5,626		$	10,340
	(1)	Represents consulting and severance restructuring costs related to corporate and shared service functions.
2013 Restructuring	'
Summary of Restructuring Costs for Each Segment and Unallocated Corporate Costs	'
	The following table summarizes restructuring costs for each segment and unallocated corporate costs related to the 2013 restructuring plan (in thousands):
			Three Months			Nine Months
			Ended			Ended
			September 27,			September 27,
			2013			2013
	Laser Products		$	767		$	938
	Precision Technologies			437			1,138
	Unallocated restructuring costs(1)			239			294
	Total restructuring costs		$	1,443		$	2,370
	(1)	Represents consulting and severance restructuring costs related to corporate and shared service functions.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 27, 2013
Future Minimum Lease Payments Under Operating Leases	'
	Future minimum lease payments under the existing operating leases for NDS are as follows (in thousands):
	Year Ending December 31,	Operating Leases
	2013 (remainder of year)	$	327
	2014		1,223
	2015		84
	Thereafter		—
	Total	$	1,634

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 27, 2013
Sales Gross Profit Gross Profit Margin and Operating Income by Reportable Segments	'
	Sales, gross profit, gross profit margin and operating income by reportable segments are as follows (in thousands):
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Sales
	Laser Products		$	50,340		$	48,369		$	142,519		$	138,828
	Precision Technologies			35,144			21,151			111,386			66,257
	Total		$	85,484		$	69,520		$	253,905		$	205,085
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Gross Profit
	Laser Products		$	20,882		$	19,245		$	56,857		$	56,683
	Precision Technologies			14,964			9,903			46,759			31,230
	Corporate (1)			(55	)		(295	)		(163	)		(712	)
	Total		$	35,791		$	28,853		$	103,453		$	87,201
	(1)	Corporate costs primarily represent unallocated overhead.
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Gross Profit Margin
	Laser Products			41.5	%		39.8	%		39.9	%		40.8	%
	Precision Technologies			42.6	%		46.8	%		42	%		47.1	%
	Total			41.9	%		41.5	%		40.7	%		42.5	%
			Three Months Ended						Nine Months Ended
			September 27,			September 28,			September 27,			September 28,
			2013			2012			2013			2012
	Operating Income
	Laser Products		$	7,653		$	5,379		$	16,258		$	13,313
	Precision Technologies			2,754			3,689			11,032			14,208
	Corporate, shared services and unallocated (2)			(4,689	)		(5,276	)		(16,276	)		(15,811	)
	Total		$	5,718		$	3,792		$	11,014		$	11,710
	(2)	Corporate and shared services costs primarily represent corporate and shared service function costs which are not allocated to the operating segments, including restructuring and all acquisition related costs.

Nature_of_Operations_and_Summa2

Nature of Operations and Summary of Significant Accounting Policies - Additional information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Jun. 28, 2013	Mar. 29, 2013	Sep. 27, 2013
Significant Accounting Policies [Line Items]	'	'	'
Minority interest ownership percentage	'	'	50.00%
Equity method investment previous ownership percentage on Laser Quantum	'	25.10%	'
Equity method investment ownership percentage on Laser Quantum	41.20%	'	'
Net income tax benefit from the error correction	$0.30	$0.70	$0.40

Discontinued_Operations_Additi

Discontinued Operations - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended	1 Months Ended		1 Months Ended	6 Months Ended		3 Months Ended
	Sep. 27, 2013	Sep. 27, 2013	Oct. 31, 2012	Sep. 27, 2013	30-May-13	Jun. 28, 2013	Sep. 27, 2013	Sep. 27, 2013
			Laser Products	Laser Products	Semiconductor Systems	Semiconductor Systems	Semiconductor Systems	Semiconductor Systems
								Adjusted selling price
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'	'
Gain (Loss) on sale of business	($281,000)	($592,000)	$2,300,000	'	'	($300,000)	'	'
Sale of assets and liabilities	'	8,190,000	7,000,000	'	8,000,000	'	'	9,700,000
Settlement of closing working capital adjustments	'	'	'	$400,000	'	'	$1,700,000	'

Components_of_Assets_and_Liabi

Components of Assets and Liabilities (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Accounts receivable, net	'	$2,981
Inventories	'	8,231
Other assets	'	694
Property, plant and equipment	'	5,712
Assets of discontinued operations	'	17,618
Accounts payable, accrued expenses and other current liabilities	'	3,474
Deferred revenue	'	1,570
Other liabilities	624	561
Liabilities of discontinued operations	$624	$5,605

Operating_Results_Historically

Operating Results Historically Included Segment (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'
Sales from discontinued operations	'	$9,618	$9,090	$38,342
Loss from discontinued operations before income taxes	-152	-4,825	-1,294	-3,973
Loss from discontinued operations, net of tax	-113	-4,570	-848	-3,834
Loss on disposal of discontinued operations, net of tax	($281)	'	($592)	'

Business_Combinations_Addition

Business Combinations - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended		3 Months Ended	9 Months Ended
	Jan. 15, 2013	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Oct. 30, 2013	Jan. 15, 2013	Sep. 27, 2013	Sep. 27, 2013	Jan. 15, 2013	Jan. 15, 2013
						Subsequent Event	Maximum	NDS	NDS	NDS Surgical Imaging, LLC	NDS Surgical Imaging KK
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Ownership percentage	'	'	'	'	'	'	'	'	'	100.00%	100.00%
Cash consideration	$82,653,000	'	'	$82,653,000	'	'	'	'	'	'	'
Closing working capital adjustments	'	'	'	'	'	1,900,000	'	'	'	'	'
Adjusted purchase price	'	'	'	'	'	80,773,000	'	'	'	'	'
Escrow after the payments of closing working capital adjustments	'	'	'	'	'	5,400,000	'	'	'	'	'
Estimates and assumptions, measurement period	'	'	'	'	'	'	'1 year	'	'	'	'
Preliminary purchase price allocation related to the finalization of closing working capital and adjustments to tangible and intangible assets	'	2,400,000	'	'	'	'	'	'	'	'	'
Goodwill	26,509,000	'	'	26,509,000	'	'	'	'	'	'	'
Intangible assets	37,817,000	'	'	'	'	'	'	'	'	'	'
Deferred tax liabilities	315,000	'	'	'	'	'	'	'	'	'	'
Sales	'	85,484,000	69,520,000	253,905,000	205,085,000	'	'	14,600,000	49,700,000	'	'
Losses from continuing operations before income taxes	'	$3,782,000	$2,618,000	$8,700,000	$9,009,000	'	'	($1,500,000)	($2,500,000)	'	'

Acquisition_Related_Costs_Reco

Acquisition Related Costs Recognized in Consolidated Statements of Operations (Detail) (USD $)	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 27, 2013	Sep. 27, 2013	Sep. 27, 2013	Sep. 27, 2013
			NDS Acquisition	NDS Acquisition	Cumulative Costs
					NDS Acquisition
Redomestication [Line Items]	'	'	'	'	'
Acquisition-related charges	$113	$1,199	$45	$1,131	$1,816

Summary_of_Fair_Values_of_Asse

Summary of Fair Values of Assets Acquired and Liabilities Assumed Purchase Price Allocation (Detail) (USD $)	Sep. 27, 2013	Jan. 15, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]	'	'	'
Accounts receivable	'	$10,327	'
Inventory	'	14,144	'
Property and equipment	'	2,426	'
Intangible assets	'	37,817	'
Other assets	'	1,782	'
Goodwill	71,087	26,509	44,578
Total assets acquired	'	93,005	'
Accounts payable	'	4,768	'
Accrued expenses	'	6,217	'
Deferred tax liabilities	'	315	'
Other liabilities assumed	'	932	'
Total liabilities assumed	'	12,232	'
Total net assets acquired	'	$80,773	'

Fair_Value_of_Intangible_Asset

Fair Value of Intangible Assets (Detail) (USD $)	1 Months Ended
In Thousands, unless otherwise specified	Jan. 15, 2013
Acquired Finite-Lived Intangible Assets [Line Items]	'
Intangible assets	$37,817
Customer Relationships	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Intangible assets	22,294
Amortization Period of intangible assets	'20 years
Developed Technology	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Intangible assets	6,689
Amortization Period of intangible assets	'10 years
Trademarks and Trade Names	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Intangible assets	7,565
Amortization Period of intangible assets	'20 years
Backlog	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Intangible assets	$1,269
Amortization Period of intangible assets	'1 year

Unaudited_Pro_forma_Informatio

Unaudited Pro forma Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Business Combination, Pro Forma Information [Line Items]	'	'	'	'
Sales	$85,484	$88,838	$254,997	$267,373
Income from continuing operations, net of tax	$2,881	$2,194	$5,826	$8,513
Earnings per share - Basic	$0.08	$0.06	$0.17	$0.25
Earnings per share - Diluted	$0.08	$0.06	$0.17	$0.25

Components_of_Accumulated_Othe

Components of Accumulated Other Comprehensive Loss (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	($9,749)
Other comprehensive income (loss) before reclassifications	-1,796
Amounts reclassified from other comprehensive loss	582
Ending Balance	-10,963
Foreign currency translation adjustments	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	1,299
Other comprehensive income (loss) before reclassifications	-2,015
Ending Balance	-716
Pension liability adjustments	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Beginning Balance	-11,048
Other comprehensive income (loss) before reclassifications	219
Amounts reclassified from other comprehensive loss	582
Ending Balance	($10,247)

Computation_of_Basic_and_Dilut

Computation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended				9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012
Numerators:	'		'		'		'
Consolidated net income	$2,172		$2,055		$4,483		$7,599
Less: (income) loss attributable to noncontrolling interest	12		-19		-42		-45
Income from continuing operations	2,184		2,036		4,441		7,554
Loss from discontinued operations	-394		-4,570		-1,440		-3,834
Net income (loss) attributable to GSI Group Inc.	$1,790		($2,534)		$3,001		$3,720
Denominators:	'		'		'		'
Weighted average common shares outstanding-basic	34,102		33,803		34,058		33,755
Dilutive potential common shares	315	[1]	109	[1]	267	[1]	159	[1]
Weighted average common shares outstanding-diluted	34,417		33,912		34,325		33,914
Antidilutive common shares excluded from above	37		424		327		141
Basic Earnings (Loss) per Common Share:	'		'		'		'
From continuing operations	$0.06		$0.06		$0.13		$0.22
From discontinued operations	($0.01)		($0.13)		($0.04)		($0.11)
Basic earnings (loss) per share attributable to GSI Group Inc.	$0.05		($0.07)		$0.09		$0.11
Diluted Earnings (Loss) per Common Share:	'		'		'		'
From continuing operations	$0.06		$0.06		$0.13		$0.22
From discontinued operations	($0.01)		($0.13)		($0.04)		($0.11)
Diluted earnings (loss) per share attributable to GSI Group Inc.	$0.05		($0.07)		$0.09		$0.11
[1]	Due to the Company's net loss attributable to GSI Group Inc. for the three months ended September 28, 2012, all potentially dilutive shares were excluded as their effect would have been anti-dilutive.

Fair_Values_of_Financial_Asset

Fair Values of Financial Assets (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Cash equivalents	$3,143	$2,511
Fair Value, Inputs, Level 1	'	'
Assets	'	'
Cash equivalents	$3,143	$2,511

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 27, 2013
Goodwill And Intangible Assets [Line Items]	'
Goodwill impairment loss	$0
Medical Component	'
Goodwill And Intangible Assets [Line Items]	'
Reporting units in excess of carrying value	10.00%

Summary_of_Changes_in_Goodwill

Summary of Changes in Goodwill (Detail) (USD $)	1 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Jan. 15, 2013	Sep. 27, 2013
Goodwill [Line Items]	'	'
Balance at beginning of the period	'	$44,578
Goodwill acquired from NDS acquisition	26,509	26,509
Balance at end of period	$26,509	$71,087

Goodwill_By_Reportable_Segment

Goodwill By Reportable Segment (Detail) (USD $)	Sep. 27, 2013	Jan. 15, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Goodwill [Line Items]	'	'	'
Goodwill	$202,741	'	$176,232
Accumulated impairment of goodwill	-131,654	'	-131,654
Total	71,087	26,509	44,578
Laser Products	'	'	'
Goodwill [Line Items]	'	'	'
Goodwill	84,592	'	84,592
Accumulated impairment of goodwill	-54,099	'	-54,099
Total	30,493	'	30,493
Precision Technologies	'	'	'
Goodwill [Line Items]	'	'	'
Goodwill	118,149	'	91,640
Accumulated impairment of goodwill	-77,555	'	-77,555
Total	$40,594	'	$14,085

Intangible_Assets_Detail

Intangible Assets (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Amortizable intangible assets, gross carrying amount	$140,765	$103,047
Amortizable intangible assets, accumulated amortization	-85,527	-76,054
Amortizable intangible assets, net carrying amount	55,238	26,993
Gross carrying amount	153,792	116,074
Accumulated amortization	-85,527	-76,054
Net carrying amount	68,265	40,020
Patents and acquired technology	'	'
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Amortizable intangible assets, gross carrying amount	68,294	61,667
Amortizable intangible assets, accumulated amortization	-54,778	-50,904
Amortizable intangible assets, net carrying amount	13,516	10,763
Customer Relationships	'	'
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Amortizable intangible assets, gross carrying amount	55,517	33,245
Amortizable intangible assets, accumulated amortization	-22,911	-18,981
Amortizable intangible assets, net carrying amount	32,606	14,264
Customer Backlog	'	'
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Amortizable intangible assets, gross carrying amount	3,623	2,355
Amortizable intangible assets, accumulated amortization	-3,516	-2,355
Amortizable intangible assets, net carrying amount	107	'
Trademarks, trade names and other	'	'
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Amortizable intangible assets, gross carrying amount	13,331	5,780
Amortizable intangible assets, accumulated amortization	-4,322	-3,814
Amortizable intangible assets, net carrying amount	9,009	1,966
Trade Names	'	'
Schedule of Intangible Assets Disclosure [Line Items]	'	'
Non-amortizable intangible assets, gross carrying amount	13,027	13,027
Non-amortizable intangible assets, accumulated amortization	'	'
Non-amortizable intangible assets, net carrying amount	$13,027	$13,027

Amortization_Expense_of_Intang

Amortization Expense of Intangible Assets (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Finite Lived Intangible Assets Amortization Expense [Line Items]	'	'	'	'
Amortization	$3,115	$1,454	$9,562	$4,361
Cost of Sales	'	'	'	'
Finite Lived Intangible Assets Amortization Expense [Line Items]	'	'	'	'
Amortization	1,343	791	3,937	2,373
Operating Expense	'	'	'	'
Finite Lived Intangible Assets Amortization Expense [Line Items]	'	'	'	'
Amortization	$1,772	$663	$5,625	$1,988

Estimated_Amortization_Expense

Estimated Amortization Expense (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]	'	'
2013 (remainder of year)	$2,988	'
2014	10,994	'
2015	8,754	'
2016	7,015	'
2017	6,293	'
Thereafter	19,194	'
Amortizable intangible assets, net carrying amount	55,238	26,993
Cost of Sales	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
2013 (remainder of year)	1,343	'
2014	4,953	'
2015	3,310	'
2016	1,965	'
2017	1,573	'
Thereafter	372	'
Amortizable intangible assets, net carrying amount	13,516	'
Operating Expense	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
2013 (remainder of year)	1,645	'
2014	6,041	'
2015	5,444	'
2016	5,050	'
2017	4,720	'
Thereafter	18,822	'
Amortizable intangible assets, net carrying amount	$41,722	'

Inventories_Detail

Inventories (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Inventory [Line Items]	'	'
Raw materials	$38,328	$30,554
Work-in-process	12,419	11,959
Finished goods	11,200	8,023
Demo and consigned inventory	3,126	2,265
Total inventories	$65,073	$52,801

Accrued_Expenses_and_Other_Cur

Accrued Expenses and Other Current Liabilities (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012	Sep. 28, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Accrued Expenses and Other Current Liabilities [Line Items]	'	'	'	'
Accrued compensation and benefits	$7,489	$6,655	'	'
Accrued warranty	3,658	2,777	2,852	3,035
Customer deposits	1,573	3,033	'	'
Other	9,614	6,497	'	'
Total	$22,334	$18,962	'	'

Accrued_Warranty_Detail

Accrued Warranty (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012
Accrued Warranty [Line Items]	'	'
Balance at beginning of the period	$2,777	$3,035
Provision charged to cost of sales	1,399	1,958
Acquisition related warranty accrual	998	'
Use of provision	-1,517	-2,191
Foreign currency exchange rate changes	1	50
Balance at end of period	$3,658	$2,852

Debt_Detail

Debt (Detail) (Senior Credit Facilities, USD $)	Sep. 27, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Debt long term and short term	$78,375	$50,000
Term Loan	'	'
Debt Instrument [Line Items]	'	'
Debt long term and short term	44,375	50,000
Revolving Credit Facility	'	'
Debt Instrument [Line Items]	'	'
Debt long term and short term	$34,000	'

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)	Sep. 27, 2013	Dec. 31, 2012	Sep. 27, 2013	Sep. 27, 2013	Sep. 27, 2013
			Term Loans	Revolving Credit Facilities	Revolving credit facility and term loan
					Third Amendment
Debt Instrument [Line Items]	'	'	'	'	'
Maximum borrowing capacity	'	'	$50,000,000	$75,000,000	$100,000,000
Debt instrument maturity period	'	'	'5 years	'5 years	'
Quarterly installments payable on term loan	'	'	1,900,000	'	'
Revolving credit facility maturity year	'	'	'	'2017-12	'
Current portion of long-term debt	$7,500,000	$7,500,000	'	'	'

Restricted_Stock_Units_Issued_

Restricted Stock Units Issued and Outstanding (Detail) (2010 Incentive Award Plan, Restricted Stock Units, USD $)	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2013
2010 Incentive Award Plan | Restricted Stock Units	'
Restricted Stock Units	'
Unvested Beginning Balance	804
Granted	424
Vested	-250
Forfeited	-23
Unvested Ending Balance	955
Expected to vest	938
Weighted Average Grant Date Fair Value	'
Unvested Beginning Balance	$10.90
Granted	$9.61
Vested	$11.54
Forfeited	$10.92
Unvested Ending Balance	$10.16

ShareBased_Compensation_Additi

Share-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Deferred Stock Units	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation expense	'	'	$500,000	$600,000
2010 Incentive Award Plan	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation expense	1,344,000	1,207,000	4,212,000	3,530,000
2010 Incentive Award Plan | Restricted Stock Units	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total fair value of restricted stock vested	'	'	$2,400,000	'

Share_Based_Compensation_Expen

Share Based Compensation Expense in Statements of Operations (Detail) (2010 Incentive Award Plan, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Share Based Compensation [Line Items]	'	'	'	'
Share based compensation expense	$1,344	$1,207	$4,212	$3,530
Selling, general and administrative	'	'	'	'
Share Based Compensation [Line Items]	'	'	'	'
Share based compensation expense	1,264	1,102	3,993	3,342
Research and development and engineering	'	'	'	'
Share Based Compensation [Line Items]	'	'	'	'
Share based compensation expense	48	31	129	80
Cost of Sales	'	'	'	'
Share Based Compensation [Line Items]	'	'	'	'
Share based compensation expense	32	23	90	57
Restructuring and other	'	'	'	'
Share Based Compensation [Line Items]	'	'	'	'
Share based compensation expense	'	$51	'	$51

Net_Periodic_Cost_for_UK_Defin

Net Periodic Cost for U.K Defined Benefit Pension Plan (Detail) (UNITED KINGDOM, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
UNITED KINGDOM	'	'	'	'
Components of the net periodic pension cost:	'	'	'	'
Interest cost	$355	$343	$1,064	$1,028
Expected return on plan assets	-346	-315	-1,037	-943
Amortization of actuarial loss	167	98	501	293
Net periodic pension cost	$176	$126	$528	$378

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Income Taxes [Line Items]	'	'	'	'
Effective tax rate on income from operations	42.60%	21.50%	48.50%	15.70%
Income tax refund received	'	'	$12,607,000	$222,000
CANADA	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Statutory tax rate	26.00%	'	26.00%	'
Internal Revenue Service (IRS)	'	'	'	'
Income Taxes [Line Items]	'	'	'	'
Income tax refund received	12,500,000	'	'	'
Income tax receivable	300,000	'	$300,000	'

Summary_of_Restructuring_Costs

Summary of Restructuring Costs and Other Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	$1,528	$2,728	$4,694	$7,396
Total acquisition related charges	113	'	1,199	'
Total restructuring costs and other	1,641	2,728	5,893	7,396
Germany Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	'	43	8	59
2011 Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	85	974	2,316	5,626
2012 Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	'	1,711	'	1,711
2013 Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	$1,443	'	$2,370	'

Restructuring_Costs_and_Other_1

Restructuring Costs and Other - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	$1,528,000	$2,728,000	$4,694,000	$7,396,000
2011 Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring plan	'	'	'In November 2011, the Company announced a strategic initiative ("2011 restructuring"), which aimed to consolidate operations to reduce our cost structure and improve operational efficiency. As part of this initiative, the Company eliminated facilities through consolidation of certain manufacturing, sales and distribution facilities and exit of businesses. The Company completed the 2011 restructuring plan during the nine months ended September 27, 2013.	'
Restructuring charges	85,000	974,000	2,316,000	5,626,000
2013 Restructuring	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	1,443,000	'	2,370,000	'
2013 Restructuring | Minimum	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Total cash cost expected under plan	'	'	200,000	'
2013 Restructuring | Maximum	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Total cash cost expected under plan	'	'	$500,000	'

Actual_Cash_and_NonCash_Charge

Actual Cash and Non-Cash Charges of the Restructuring Plan (Detail) (2011 Restructuring Plan, USD $)	3 Months Ended		9 Months Ended		23 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013
Restructuring Cost and Reserve [Line Items]	'	'	'	'	'
Total restructuring costs	$85	$974	$2,316	$5,626	'
Cumulative Costs for Plan	'	'	'	'	10,340
Cash Charges (Benefits)	'	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'	'
Total restructuring costs	-40	974	1,850	3,735	'
Cumulative Costs for Plan	'	'	'	'	7,020
Non-Cash Charges	'	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'	'
Total restructuring costs	125	'	466	1,891	'
Cumulative Costs for Plan	'	'	'	'	$3,320

Summary_of_Restructuring_Costs1

Summary of Restructuring Costs for Each Segment and Unallocated Corporate Costs (Detail) (USD $)	3 Months Ended				9 Months Ended				23 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	$1,528		$2,728		$4,694		$7,396		'
2013 Restructuring	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	1,443		'		2,370		'		'
2013 Restructuring | Laser Products	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	767		'		938		'		'
2013 Restructuring | Precision Technologies	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	437		'		1,138		'		'
2013 Restructuring | Unallocated Restructuring Costs	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	239	[1]	'		294	[1]	'		'
2011 Restructuring	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	85		974		2,316		5,626		'
Cumulative Costs for Plan	'		'		'		'		10,340
2011 Restructuring | Laser Products	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	75		371		2,044		4,335		'
Cumulative Costs for Plan	'		'		'		'		8,119
2011 Restructuring | Precision Technologies	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	'		452		53		652		'
Cumulative Costs for Plan	'		'		'		'		746
2011 Restructuring | Unallocated Restructuring Costs	'		'		'		'		'
Restructuring Cost and Reserve [Line Items]	'		'		'		'		'
Restructuring Costs	10	[1]	151	[1]	219	[1]	639	[1]	'
Cumulative Costs for Plan	'		'		'		'		$1,475	[1]
[1]	Represents consulting and severance restructuring costs related to corporate and shared service functions.

Summary_of_Accrual_Activities_

Summary of Accrual Activities by Components Related to Company's Restructuring Plans (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Accrued expense beginning balance	'	'	$2,030	'
Restructuring charges	1,528	2,728	4,694	7,396
Cash payments	'	'	-4,361	'
Non-cash write-offs and other adjustments	'	'	-147	'
Accrued expense ending balance	2,344	'	2,344	'
Restructuring Related Lease	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Acquired lease obligation	'	'	128	'
Employee Severance	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Accrued expense beginning balance	'	'	1,304	'
Restructuring charges	'	'	2,374	'
Cash payments	'	'	-2,428	'
Non-cash write-offs and other adjustments	'	'	21	'
Accrued expense ending balance	1,271	'	1,271	'
Facility	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Accrued expense beginning balance	'	'	489	'
Restructuring charges	'	'	1,349	'
Cash payments	'	'	-996	'
Non-cash write-offs and other adjustments	'	'	21	'
Accrued expense ending balance	991	'	991	'
Facility | Restructuring Related Lease	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Acquired lease obligation	'	'	128	'
Accelerated Depreciation and Impairment	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Restructuring charges	'	'	66	'
Non-cash write-offs and other adjustments	'	'	-66	'
Other Restructuring Charges	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Accrued expense beginning balance	'	'	237	'
Restructuring charges	'	'	905	'
Cash payments	'	'	-937	'
Non-cash write-offs and other adjustments	'	'	-123	'
Accrued expense ending balance	$82	'	$82	'

Future_Minimum_Lease_Payments_

Future Minimum Lease Payments Under Operating Leases (Detail) (USD $)	Sep. 27, 2013
In Thousands, unless otherwise specified
Operating Leases	'
2013 (remainder of year)	$327
2014	1,223
2015	84
Thereafter	'
Total minimum lease payments	$1,634

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	9 Months Ended				3 Months Ended	9 Months Ended			1 Months Ended	3 Months Ended
	Jul. 13, 2010	Sep. 27, 2013	Sep. 28, 2012	6-May-11	Apr. 18, 2006	Sep. 27, 2013	Sep. 27, 2013	Apr. 05, 2010	6-May-11	Apr. 18, 2006	Sep. 30, 2005
	USD ($)	USD ($)	USD ($)	EUR (€)	EUR (€)	Internal Revenue Service (IRS)	Internal Revenue Service (IRS)	Internal Revenue Service (IRS)	GSI Group GmbH	GSI's French Subsidiary	GSI's French Subsidiary
						USD ($)	USD ($)	USD ($)	EUR (€)
Commitments and Contingencies Disclosure [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Filed for bankruptcy protection date	'	'	'	'	'	'	'	'	'	'	7-Jul-05
Actions taken	'	'	'	'	'	'	'	'	'	'On April 18, 2006, the commercial court of Le Creusot (France) ordered GSI France to pay approximately 0.7 million Euros to SCGI in the context of a claim filed by SCGI that a Laserdyne 890 system delivered in 1999 had unresolved technical problems.	'
Payment to settle claim filed, minimum	'	'	'	'	€ 700,000	'	'	'	'	'	'
Payment to settle claim filed, maximum	'	'	'	3,100,000	'	'	'	'	'	'	'
Payment in the respect of a claim filed	'	'	'	'	'	'	'	'	2,400,000	'	'
IRS filed amended proofs of claim date	'	'	'	'	'	'	'April 5, 2010	'	'	'	'
IRS filed aggregate claims	'	'	'	'	'	'	'	7,700,000	'	'	'
IRS Claims	'On July 13, 2010, the Company filed a complaint, GSI Group Corporation v. United States of America, in Bankruptcy Court in an attempt to recover refunds totaling approximately $18.8 million in federal income taxes the Company asserts it overpaid to the IRS relating to tax years 2000 through 2009, together with applicable interest.	'	'	'	'	'	'	'	'	'	'
Amount of claim we filed with the IRS for federal income taxes overpaid	18,800,000	'	'	'	'	'	'	'	'	'	'
Income tax refund received	'	12,607,000	222,000	'	'	12,500,000	'	'	'	'	'
Income tax receivable	'	'	'	'	'	$300,000	$300,000	'	'	'	'

Segment_Information_Additional

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 29, 2013	Jun. 29, 2012
	Segment	Segment
Segment Reporting Information [Line Items]	'	'
Number of operating segments	2	3

Sales_Gross_Profit_and_Gross_P

Sales, Gross Profit and Gross Profit Margin by Reportable Segments (Detail) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012
Segment Reporting Information [Line Items]	'		'		'		'
Sales	$85,484		$69,520		$253,905		$205,085
Gross profit	35,791		28,853		103,453		87,201
Gross profit margin percentage	41.90%		41.50%		40.70%		42.50%
Laser Products	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Sales	50,340		48,369		142,519		138,828
Gross profit	20,882		19,245		56,857		56,683
Gross profit margin percentage	41.50%		39.80%		39.90%		40.80%
Precision Technologies	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Sales	35,144		21,151		111,386		66,257
Gross profit	14,964		9,903		46,759		31,230
Gross profit margin percentage	42.60%		46.80%		42.00%		47.10%
Corporate	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Gross profit	($55)	[1]	($295)	[1]	($163)	[1]	($712)	[1]
[1]	Corporate costs primarily represent unallocated overhead.

Operating_Income_by_Reportable

Operating Income by Reportable Segments (Detail) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2013		Sep. 28, 2012		Sep. 27, 2013		Sep. 28, 2012
Operating Income	'		'		'		'
Operating Income	$5,718		$3,792		$11,014		$11,710
Laser Products	'		'		'		'
Operating Income	'		'		'		'
Operating Income	7,653		5,379		16,258		13,313
Precision Technologies	'		'		'		'
Operating Income	'		'		'		'
Operating Income	2,754		3,689		11,032		14,208
Corporate, shared services and unallocated	'		'		'		'
Operating Income	'		'		'		'
Operating Income	($4,689)	[1]	($5,276)	[1]	($16,276)	[1]	($15,811)	[1]
[1]	Corporate and shared services costs primarily represent corporate and shared service function costs which are not allocated to the operating segments, including restructuring and all acquisition related costs.