Organization	9 Months Ended
Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization OvaScience, Inc., incorporated on April 5, 2011 as a Delaware corporation, is a company focused on the discovery and development of new treatment options for women and families struggling with infertility. As used in these consolidated financial statements, the terms “OvaScience,” “the Company,” “we,” “us,” and “our” refer to the business of OvaScience, Inc. and its wholly owned subsidiaries. To date OvaScience has been leveraging the breakthrough discovery of egg precursor, or EggPC^SM, cells to transform the treatment landscape for women's fertility. OvaScience's operations to date have been limited to organizing and staffing the company, business planning, raising capital, acquiring and developing our technology, identifying potential fertility treatments, developing the OvaPrime^SM treatment, the OvaTure^SM treatment and the AUGMENT^SM treatment, introducing AUGMENT in select international in vitro fertilization ("IVF") clinics and determining the regulatory and development path for OvaScience's fertility treatments. OvaScience has generated limited revenues to date, and does not anticipate significant revenues in the near term. In June 2017, OvaScience announced that it would continue to focus on advancing OvaPrime in clinical development and OvaTure in preclinical development and would discontinue ongoing efforts related to the AUGMENT treatment outside of North America. To better align its organization with these strategic priorities, OvaScience restructured its workforce and reduced its workforce by approximately 50%. On January 3, 2018, OvaScience announced a further restructuring of its organization and a workforce reduction of approximately 50%. On May 3, 2018, OvaScience announced that its Board of Directors had approved a corporate restructuring plan furthering its on-going efforts to effectively align its resources. On August 9, 2018, OvaScience announced that it had entered into a definitive agreement with Millendo Therapeutics, Inc. ("Millendo") under which Millendo will merge with OvaScience in an all-stock transaction. A wholly owned subsidiary of OvaScience will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience (the "Merger"). OvaScience and Millendo believe that the Merger, if finalized, will result in a specialty biopharmaceutical company focused on developing novel treatments for orphan endocrine diseases where current therapies do not exist or are insufficient. The transaction has been approved by the Boards of Directors of both companies. The Merger is expected to close in the fourth quarter of 2018, subject to the approval of OvaScience shareholders at a special shareholder meeting to be held on December 4, 2018, as well as other customary conditions. We are currently subject to a number of risks similar to other life science companies, including, but not limited to, risks associated with clinical and preclinical development, the need to develop and obtain marketing approval for certain of our fertility treatments, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of our fertility treatments and protection of proprietary technology, and the outcome of our exploration of strategic alternatives. If we do not successfully develop and commercialize any of our fertility treatments, we will be unable to generate treatment revenue or achieve profitability. As of September 30, 2018, we had an accumulated deficit of approximately $322.2 million. Liquidity We have incurred annual net operating losses in each year since our inception. We have generated limited treatment revenues related to our primary business purpose and have financed our operations primarily through private placements of our preferred stock, which was subsequently converted to common stock, and public sales of our common stock and interest income earned on cash, cash equivalents, and short-term investments balances. We have devoted substantially all of our financial resources and efforts to the research and development of our OvaPrime and OvaTure fertility treatments and the introduction of AUGMENT in select international IVF clinics. We expect to continue to incur operating losses for the next several years. We believe that our cash, cash equivalents and short-term investments of $46.4 million at September 30, 2018, will be sufficient to fund our current operating plan for at least the next 12 months from the date of filing this Form 10-Q. There can be no assurances, however, that the current operating plan will be achieved or that additional funding, if needed, will be available on terms acceptable to us, or at all.

Organization

OvaScience, Inc., incorporated on April 5, 2011 as a Delaware corporation, is a company focused on the discovery and development of new treatment options for women and families struggling with infertility. As used in these consolidated financial statements, the terms “OvaScience,” “the Company,” “we,” “us,” and “our” refer to the business of OvaScience, Inc. and its wholly owned subsidiaries. To date OvaScience has been leveraging the breakthrough discovery of egg precursor, or EggPC^SM, cells to transform the treatment landscape for women's fertility. OvaScience's operations to date have been limited to organizing and staffing the company, business planning, raising capital, acquiring and developing our technology, identifying potential fertility treatments, developing the OvaPrime^SM treatment, the OvaTure^SM treatment and the AUGMENT^SM treatment, introducing AUGMENT in select international in vitro fertilization ("IVF") clinics and determining the regulatory and development path for OvaScience's fertility treatments. OvaScience has generated limited revenues to date, and does not anticipate significant revenues in the near term. In June 2017, OvaScience announced that it would continue to focus on advancing OvaPrime in clinical development and OvaTure in preclinical development and would discontinue ongoing efforts related to the AUGMENT treatment outside of North America. To better align its organization with these strategic priorities, OvaScience restructured its workforce and reduced its workforce by approximately 50%. On January 3, 2018, OvaScience announced a further restructuring of its organization and a workforce reduction of approximately 50%. On May 3, 2018, OvaScience announced that its Board of Directors had approved a corporate restructuring plan furthering its on-going efforts to effectively align its resources. On August 9, 2018, OvaScience announced that it had entered into a definitive agreement with Millendo Therapeutics, Inc. ("Millendo") under which Millendo will merge with OvaScience in an all-stock transaction. A wholly owned subsidiary of OvaScience will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience (the "Merger"). OvaScience and Millendo believe that the Merger, if finalized, will result in a specialty biopharmaceutical company focused on developing novel treatments for orphan endocrine diseases where current therapies do not exist or are insufficient. The transaction has been approved by the Boards of Directors of both companies. The Merger is expected to close in the fourth quarter of 2018, subject to the approval of OvaScience shareholders at a special shareholder meeting to be held on December 4, 2018, as well as other customary conditions.

We are currently subject to a number of risks similar to other life science companies, including, but not limited to, risks associated with clinical and preclinical development, the need to develop and obtain marketing approval for certain of our fertility treatments, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of our fertility treatments and protection of proprietary technology, and the outcome of our exploration of strategic alternatives. If we do not successfully develop and commercialize any of our fertility treatments, we will be unable to generate treatment revenue or achieve profitability. As of September 30, 2018, we had an accumulated deficit of approximately $322.2 million.

Liquidity

We have incurred annual net operating losses in each year since our inception. We have generated limited treatment revenues related to our primary business purpose and have financed our operations primarily through private placements of our preferred stock, which was subsequently converted to common stock, and public sales of our common stock and interest income earned on cash, cash equivalents, and short-term investments balances.

We have devoted substantially all of our financial resources and efforts to the research and development of our OvaPrime and OvaTure fertility treatments and the introduction of AUGMENT in select international IVF clinics. We expect to continue to incur operating losses for the next several years.

We believe that our cash, cash equivalents and short-term investments of $46.4 million at September 30, 2018, will be sufficient to fund our current operating plan for at least the next 12 months from the date of filing this Form 10-Q. There can be no assurances, however, that the current operating plan will be achieved or that additional funding, if needed, will be available on terms acceptable to us, or at all.