Basis of Presentation	3 Months Ended
Apr. 01, 2016
Accounting Policies [Abstract]
Basis of Presentation	1. Basis of Presentation GSI Group Inc. and its subsidiaries (collectively referred to as the “Company”, “we”, “us”, “our”) design, develop, manufacture and sell precision photonic and motion control components and subsystems to Original Equipment Manufacturers (“OEMs”) in the medical and advanced industrial markets. Our highly engineered enabling technologies include CO2 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, 2015. In the opinion of management, these interim consolidated financial statements include all adjustments and accruals of a normal and recurring nature necessary to fairly state 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 Company has a 41% ownership interest in Laser Quantum Ltd. (“Laser Quantum”), a privately held company located in the United Kingdom. The Company records 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 for each quarterly period 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 revenue 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 Share-Based Compensation In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which amends the accounting for employee share-based payment transactions to require recognition of the tax effects resulting from the settlement of stock-based awards as income tax expense or benefit in the income statement in the reporting period in which they occur. In addition, the ASU requires that all tax-related cash flows resulting from share-based payments, including the excess tax benefits related to the settlement of stock-based awards, be classified as cash flows from operating activities in the statement of cash flows. This ASU also requires that cash paid through directly withholding shares for tax-withholding purposes be classified as a financing activity in the statement of cash flows. In addition, this ASU allows companies to make an accounting policy election to either estimate the number of awards that are expected to vest, consistent with current U.S. GAAP, or account for forfeitures when they occur. The new standard is effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently evaluating the impact of the new standard on our consolidated financial statements. Leases In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842),” which provides comprehensive lease accounting guidance. The standard requires entities to recognize lease assets and liabilities on the balance sheet and to disclose key information about leasing arrangements. ASU 2016-02 will become effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact of the new standard on our consolidated financial statements. Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern In August 2014, the FASB issued 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 consolidated 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 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. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers – Deferral of the Effective Date,” which defers the effective date of ASU 2014-09 by one year, with the option of early adoption as of the original effective date. The amendment in ASU 2015-14 will result in ASU 2014-09 being effective for annual and interim reporting periods beginning after December 15, 2017. The Company is currently evaluating the impact of the new standard on our consolidated financial statements.

1. Basis of Presentation

GSI Group Inc. and its subsidiaries (collectively referred to as the “Company”, “we”, “us”, “our”) design, develop, manufacture and sell precision photonic and motion control components and subsystems to Original Equipment Manufacturers (“OEMs”) in the medical and advanced industrial markets. Our highly engineered enabling technologies include CO2 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, 2015. In the opinion of management, these interim consolidated financial statements include all adjustments and accruals of a normal and recurring nature necessary to fairly state 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 Company has a 41% ownership interest in Laser Quantum Ltd. (“Laser Quantum”), a privately held company located in the United Kingdom. The Company records 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 for each quarterly period 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 revenue 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

Share-Based Compensation

In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which amends the accounting for employee share-based payment transactions to require recognition of the tax effects resulting from the settlement of stock-based awards as income tax expense or benefit in the income statement in the reporting period in which they occur. In addition, the ASU requires that all tax-related cash flows resulting from share-based payments, including the excess tax benefits related to the settlement of stock-based awards, be classified as cash flows from operating activities in the statement of cash flows. This ASU also requires that cash paid through directly withholding shares for tax-withholding purposes be classified as a financing activity in the statement of cash flows. In addition, this ASU allows companies to make an accounting policy election to either estimate the number of awards that are expected to vest, consistent with current U.S. GAAP, or account for forfeitures when they occur. The new standard is effective for annual reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently evaluating the impact of the new standard on our consolidated financial statements.

Leases

In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842),” which provides comprehensive lease accounting guidance. The standard requires entities to recognize lease assets and liabilities on the balance sheet and to disclose key information about leasing arrangements. ASU 2016-02 will become effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the impact of the new standard on our consolidated financial statements.

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

In August 2014, the FASB issued 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 consolidated 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 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. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers – Deferral of the Effective Date,” which defers the effective date of ASU 2014-09 by one year, with the option of early adoption as of the original effective date. The amendment in ASU 2015-14 will result in ASU 2014-09 being effective for annual and interim reporting periods beginning after December 15, 2017. The Company is currently evaluating the impact of the new standard on our consolidated financial statements.