Nature of Operations and Summary of Significant Accounting Policies	9 Months Ended
Sep. 26, 2014
Accounting Policies [Abstract]
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 photonic and motion control components and subsystems to Original Equipment Manufacturers (OEM’s) in the medical equipment and advanced industrial technology markets. Our highly engineered enabling technologies include laser sources, laser scanning and beam delivery products, optical data collection and machine vision technologies, medical visualization and informatics solutions and precision motion control products. We specialize in collaborating with OEM customers to adapt our component and subsystem technologies to deliver highly differentiated performance in their applications. The accompanying unaudited interim consolidated financial statements have been prepared in U.S. dollars and 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, 2013. In the opinion of management, these interim consolidated financial statements include all 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. The interim consolidated financial statements include the accounts of the Company and its 50% owned joint venture, Excel Laser Technology Private Limited (the “India JV”), which is reported as discontinued operations in the Company’s consolidated statements of operations. 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 approximately 25% to 41% 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. 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. Recent Accounting Pronouncements Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern In August 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) 2014-15, "Presentation of Financial Statements - Going Concern (Subtopic 205-40)," which requires management to assess a company’s ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. ASU 2014-15 will be effective for annual reporting periods ending after December 15, 2016. Early application is permitted. The Company does not expect the adoption of ASU 2014-15 to have an impact on the Company’s financial statements. Revenue from Contracts with Customers In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers”, which provides guidance for revenue recognition. ASU 2014-09 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) 605, “Revenue Recognition,” and requires entities to recognize revenue in a way that depicts the transfer of goods or services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 will be effective for annual and interim reporting periods beginning after December 15, 2016. Early adoption is not permitted. Upon adoption, an entity may apply the new guidance either retrospectively to each prior reporting period presented or retrospectively only to customer contracts not yet completed as of the date of adoption with the cumulative effect of initially applying the standard recognized in beginning retained earnings at the date of the initial application. The Company is currently evaluating the impact of the new standard on the Company’s financial statements. Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity.” ASU 2014-08 provides guidance on determining when disposals can be presented as discontinued operations. ASU 2014-08 requires that only disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results should be presented as discontinued operations. A strategic shift may include a disposal of a major line of business, a major equity method investment or a major part of an entity. Additionally, ASU 2014-08 requires expanded disclosures regarding discontinued operations. ASU 2014-08 will be effective prospectively for reporting periods beginning after December 15, 2014, with early adoption permitted. The Company will adopt this pronouncement in January 2015. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.

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 photonic and motion control components and subsystems to Original Equipment Manufacturers (OEM’s) in the medical equipment and advanced industrial technology markets. Our highly engineered enabling technologies include laser sources, laser scanning and beam delivery products, optical data collection and machine vision technologies, medical visualization and informatics solutions and precision motion control products. We specialize in collaborating with OEM customers to adapt our component and subsystem technologies to deliver highly differentiated performance in their applications.

The accompanying unaudited interim consolidated financial statements have been prepared in U.S. dollars and 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, 2013. In the opinion of management, these interim consolidated financial statements include all 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.

The interim consolidated financial statements include the accounts of the Company and its 50% owned joint venture, Excel Laser Technology Private Limited (the “India JV”), which is reported as discontinued operations in the Company’s consolidated statements of operations. 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 approximately 25% to 41% 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.

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.

Recent Accounting Pronouncements

Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern

In August 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) 2014-15, "Presentation of Financial Statements - Going Concern (Subtopic 205-40)," which requires management to assess a company’s ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. ASU 2014-15 will be effective for annual reporting periods ending after December 15, 2016. Early application is permitted. The Company does not expect the adoption of ASU 2014-15 to have an impact on the Company’s financial statements.

Revenue from Contracts with Customers

In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers”, which provides guidance for revenue recognition. ASU 2014-09 supersedes the revenue recognition requirements in Accounting Standards Codification (“ASC”) 605, “Revenue Recognition,” and requires entities to recognize revenue in a way that depicts the transfer of goods or services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 will be effective for annual and interim reporting periods beginning after December 15, 2016. Early adoption is not permitted. Upon adoption, an entity may apply the new guidance either retrospectively to each prior reporting period presented or retrospectively only to customer contracts not yet completed as of the date of adoption with the cumulative effect of initially applying the standard recognized in beginning retained earnings at the date of the initial application. The Company is currently evaluating the impact of the new standard on the Company’s financial statements.

Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity

In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity.” ASU 2014-08 provides guidance on determining when disposals can be presented as discontinued operations. ASU 2014-08 requires that only disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results should be presented as discontinued operations. A strategic shift may include a disposal of a major line of business, a major equity method investment or a major part of an entity. Additionally, ASU 2014-08 requires expanded disclosures regarding discontinued operations. ASU 2014-08 will be effective prospectively for reporting periods beginning after December 15, 2014, with early adoption permitted. The Company will adopt this pronouncement in January 2015. The adoption of this amendment is not expected to have a material impact on the Company’s consolidated financial statements.