Description of Business, Basis of Presentation, and Operating Segment	12 Months Ended
Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Basis of Presentation, and Operating Segment	Description of Business, Basis of Presentation, and Operating Segment (a)Description of Business Endologix, Inc. (the “Company”) is a Delaware corporation with corporate headquarters in Irvine, California and production facilities located in Irvine and Santa Rosa, California. The Company develops, manufactures, markets, and sells innovative medical devices for the treatment of aortic disorders. The Company’s products are intended for the treatment of abdominal aortic aneurysms (“AAA”). The Company’s AAA products are built on two platforms: (1) traditional minimally-invasive endovascular repair (“EVAR”) and (2) endovascular sealing (“EVAS”), the Company’s innovative solution for sealing the aneurysm sac while maintaining blood flow through two blood flow lumens. The Company’s current EVAR products include the Ovation® Abdominal Stent Graft System (“Ovation”), Endologix AFX Endovascular AAA System (“AFX”), the VELA™ Proximal Endograft System (“VELA”) and the Endologix IntuiTrak Endovascular AAA System (“IntuiTrak”). The Company’s current EVAS product is the Nellix Endovascular Aneurysm Sealing System (“Nellix EVAS System”). Sales of the Company’s EVAR and EVAS platforms (including extensions and accessories) to hospitals in the United States and Europe, and to third-party international distributors, provide the sole source of the Company’s reported revenue. (b) Basis of Presentation The accompanying Consolidated Financial Statements in this Annual Report on Form 10-K have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and with the rules and regulations of the United States Securities and Exchange Commission (“SEC”). These financial statements include the financial position, results of operations, and cash flows of the Company, including its subsidiaries, all of which are wholly-owned. All inter-company accounts and transactions have been eliminated in consolidation. For years ended December 31, 2017, 2016, and 2015 there were no related party transactions. In August 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-15, “Disclosure of Uncertainties About an Entity's Ability to Continue as a Going Concern.” ASU 2014-15 explicitly requires management to assess an entity's ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. ASU 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. The new standard is effective for all entities in the first annual period ending after December 15, 2016 and for annual periods and interim periods thereafter. We have adopted the guidance for the year ended December 31, 2016. The adoption of ASU 2014-15 did not impact our disclosures. In April 2015, the FASB issued ASU No. 2015-03, "Simplifying the Presentation of Debt Issuance Costs", which requires debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts. The ASU was effective for the Company on January 1, 2016. The Company adopted ASU 2015-03, "Simplifying the Presentation of Debt Issuance Costs" during the first quarter of 2016, utilizing retrospective application as permitted. As a result, the Company reclassified debt issuance costs from other assets to reduce the convertible notes as of December 31, 2015 and 2016. In conjunction with the Company’s adoption of ASU 2015-03, the Company also adopted an update thereof or ASU 2015-15 “Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of Credit Arrangements.” As a result, the Company classified debt issuance costs related to a line-of-credit arrangement as other assets. In September 2015, the FASB issued ASU No. 2015-16, “Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments,” which requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The new guidance also requires that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The guidance is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The Company adopted this standard and has applied it to amounts related to the TriVascular acquisition. In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” which requires an entity to measure inventory within the scope of the amendment at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. We adopted this new accounting standard prospectively in the first quarter of 2017. This new accounting standard did not have a significant impact on our consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which modifies certain aspects of the accounting for share-based payment transactions, including income taxes, classification of awards, and classification in the statement of cash flows. We adopted this standard effective January 1, 2017. As a result, excess tax benefits are no longer recorded in additional paid-in capital and instead are applied against taxes payable or recognized in the consolidated statements of operations. In addition, our income tax expense and associated effective tax rate will be impacted by fluctuations in stock price between the grant dates and vesting dates of equity awards. We also determined that there were no significant changes to disclosure or financial statement presentation and changes in accounting for excess tax benefits and deficiencies were not material as a result of adoption. In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU No. 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The FASB agreed to a one-year deferral of the revenue recognition standard's effective date for all entities. The new revenue standard is effective for us on January 1, 2018. Early application is permitted, but not before the original effective date, which would have been January 1, 2017 for us. The new revenue standard permits the use of either the full retrospective or modified retrospective transition method; these methods may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of initial application. Accordingly, in 2016, we established a cross-functional implementation team to analyze the impact of the new revenue standard. This preliminary analysis included the review of an initial sample of contracts, as well as reviewing current accounting policies and customary business practices to identify potential differences that would result from applying the requirements of the new standard to our revenue contracts. We currently expect revenue related to the completion of an EVAR or EVAS procedure in hospitals and shipments to distributors of our products, to remain substantially unchanged. As part of our review, we separated revenue streams into portfolios of contracts with similar characteristics and selected samples thereof, as we do not expect the financial statement effects to differ materially when applying this approach to individual contracts. In addition, we are in the process of implementing appropriate changes to our business processes, systems and controls to support recognition and disclosure under the new revenue standard. We currently expect to adopt the new revenue standard in our first quarter of 2018 utilizing the modified retrospective adoption method. We continue to expect that the new revenue standard will not have a material impact on the amount and timing of revenue recognized in our consolidated financial statements; we also currently do not expect to have an adjustment to the opening balance of retained earnings under the modified retrospective adoption method in our first quarter of 2018 financial statements. We are also in the process of reviewing the expansion of our disclosures relating to the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with our customers, as required by the new revenue standard. We are continuing to evaluate our impact and will continue to monitor any modifications or interpretations communicated by the FASB that may impact any of our final assessments. (c) Operating Segment The Company has one operating and reporting segment that is focused exclusively on the development, manufacture, marketing, and sale of EVAR and EVAS products for the treatment of aortic disorders. For the year ended December 31, 2017, all of the Company's revenue and related expenses were solely attributable to these activities. Substantially all of the Company's long-lived assets are located in the United States.

Description of Business, Basis of Presentation, and Operating Segment

(a)Description of Business

Endologix, Inc. (the “Company”) is a Delaware corporation with corporate headquarters in Irvine, California and production facilities located in Irvine and Santa Rosa, California. The Company develops, manufactures, markets, and sells innovative medical devices for the treatment of aortic disorders. The Company’s products are intended for the treatment of abdominal aortic aneurysms (“AAA”). The Company’s AAA products are built on two platforms: (1) traditional minimally-invasive endovascular repair (“EVAR”) and (2) endovascular sealing (“EVAS”), the Company’s innovative solution for sealing the aneurysm sac while maintaining blood flow through two blood flow lumens. The Company’s current EVAR products include the Ovation® Abdominal Stent Graft System (“Ovation”), Endologix AFX Endovascular AAA System (“AFX”), the VELA™ Proximal Endograft System (“VELA”) and the Endologix IntuiTrak Endovascular AAA System (“IntuiTrak”). The Company’s current EVAS product is the Nellix Endovascular Aneurysm Sealing System (“Nellix EVAS System”). Sales of the Company’s EVAR and EVAS platforms (including extensions and accessories) to hospitals in the United States and Europe, and to third-party international distributors, provide the sole source of the Company’s reported revenue.

(b) Basis of Presentation

The accompanying Consolidated Financial Statements in this Annual Report on Form 10-K have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and with the rules and regulations of the United States Securities and Exchange Commission (“SEC”). These financial statements include the financial position, results of operations, and cash flows of the Company, including its subsidiaries, all of which are wholly-owned. All inter-company accounts and transactions have been eliminated in consolidation. For years ended December 31, 2017, 2016, and 2015 there were no related party transactions.

In August 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-15, “Disclosure of Uncertainties About an Entity's Ability to Continue as a Going Concern.” ASU 2014-15 explicitly requires management to assess an entity's ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. ASU 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. The new standard is effective for all entities in the first annual period ending after December 15, 2016 and for annual periods and interim periods thereafter. We have adopted the guidance for the year ended December 31, 2016. The adoption of ASU 2014-15 did not impact our disclosures.

In April 2015, the FASB issued ASU No. 2015-03, "Simplifying the Presentation of Debt Issuance Costs", which requires debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts. The ASU was effective for the Company on January 1, 2016. The Company adopted ASU 2015-03, "Simplifying the Presentation of Debt Issuance Costs" during the first quarter of 2016, utilizing retrospective application as permitted. As a result, the Company reclassified debt issuance costs from other assets to reduce the convertible notes as of December 31, 2015 and 2016. In conjunction with the Company’s adoption of ASU 2015-03, the Company also adopted an update thereof or ASU 2015-15 “Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of Credit Arrangements.” As a result, the Company classified debt issuance costs related to a line-of-credit arrangement as other assets.

In September 2015, the FASB issued ASU No. 2015-16, “Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments,” which requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The new guidance also requires that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The guidance is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The Company adopted this standard and has applied it to amounts related to the TriVascular acquisition.

In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” which requires an entity to measure inventory within the scope of the amendment at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. We adopted this new accounting standard prospectively in the first quarter of 2017. This new accounting standard did not have a significant impact on our consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which modifies certain aspects of the accounting for share-based payment transactions, including income taxes, classification of awards, and classification in the statement of cash flows. We adopted this standard effective January 1, 2017. As a result, excess tax benefits are no longer recorded in additional paid-in capital and instead are applied against taxes payable or recognized in the consolidated statements of operations. In addition, our income tax expense and associated effective tax rate will be impacted by fluctuations in stock price between the grant dates and vesting dates of equity awards. We also determined that there were no significant changes to disclosure or financial statement presentation and changes in accounting for excess tax benefits and deficiencies were not material as a result of adoption.

In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU No. 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The FASB agreed to a one-year deferral of the revenue recognition standard's effective date for all entities. The new revenue standard is effective for us on January 1, 2018. Early application is permitted, but not before the original effective date, which would have been January 1, 2017 for us. The new revenue standard permits the use of either the full retrospective or modified retrospective transition method; these methods may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of initial application.

Accordingly, in 2016, we established a cross-functional implementation team to analyze the impact of the new revenue standard. This preliminary analysis included the review of an initial sample of contracts, as well as reviewing current accounting policies and customary business practices to identify potential differences that would result from applying the requirements of the new standard to our revenue contracts. We currently expect revenue related to the completion of an EVAR or EVAS procedure in hospitals and shipments to distributors of our products, to remain substantially unchanged. As part of our review, we separated revenue streams into portfolios of contracts with similar characteristics and selected samples thereof, as we do not expect the financial statement effects to differ materially when applying this approach to individual contracts. In addition, we are in the process of implementing appropriate changes to our business processes, systems and controls to support recognition and disclosure under the new revenue standard. We currently expect to adopt the new revenue standard in our first quarter of 2018 utilizing the modified retrospective adoption method. We continue to expect that the new revenue standard will not have a material impact on the amount and timing of revenue recognized in our consolidated financial statements; we also currently do not expect to have an adjustment to the opening balance of retained earnings under the modified retrospective adoption method in our first quarter of 2018 financial statements. We are also in the process of reviewing the expansion of our disclosures relating to the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with our customers, as required by the new revenue standard. We are continuing to evaluate our impact and will continue to monitor any modifications or interpretations communicated by the FASB that may impact any of our final assessments.

The Company has one operating and reporting segment that is focused exclusively on the development, manufacture, marketing, and sale of EVAR and EVAS products for the treatment of aortic disorders. For the year ended December 31, 2017, all of the Company's revenue and related expenses were solely attributable to these activities. Substantially all of the Company's long-lived assets are located in the United States.