Organization and Basis of Presentation	12 Months Ended
Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Eleven Biotherapeutics, Inc. (the “Company”), a Delaware corporation formed on February 25, 2008, is a biologics oncology company primarily focused on designing, engineering and developing targeted protein therapeutics ("TPTs"). The Company's TPTs are single protein therapeutics composed of targeting moieties genetically fused via linker domains to cytotoxic protein payloads that are produced through the Company's proprietary one-step manufacturing process. The Company targets tumor cell surface antigens that allow for rapid internalization into the targeted cancer cell and have limited expression on normal cells. The Company has designed its TPTs to overcome the fundamental efficacy and safety challenges inherent in existing antibody drug conjugates ("ADCs"), where a payload is chemically attached to a targeting antibody. Liquidity The Company has financed its operations to date primarily through private placements of its common stock and preferred stock, and convertible bridge notes, venture debt borrowings, its initial public offering ("IPO"), secondary offerings, sales effected in an "at-the-market" offering, and the License Agreement with Roche. As of December 31, 2017, the Company had cash and cash equivalents totaling approximately $14.7 million, net working capital of $10.3 million and an accumulated deficit of $152.3 million. In August 2014, FASB issued ASU 2014‑15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern ("ASU 2015-14"). Under the new standard, management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved by the Company’s board of directors ("Board") before the date that the financial statements are issued. This standard was adopted by the Company at December 31, 2016. The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain profitable operations. The Company is subject to a number of risks similar to other early-stage life science companies, including, but not limited to, successful discovery and development of its product candidates, raising additional capital with favorable terms, development by its competitors of new technological innovations, protection of proprietary technology and market acceptance of the Company’s products. The successful discovery and development of product candidates requires substantial working capital which may not be available to the Company on favorable terms or not at all. To date, the Company has no revenue from product sales and management expects continuing operating losses in the future. As of December 31, 2017, the Company had available cash and cash equivalents of $14.7 million, and raised an additional $9.0 million in estimated net proceeds upon the issuance of common stock and warrants in follow–on offerings in March 2018, which it believes is not sufficient to fund the Company's current operating plan for at least twelve months after the date the consolidated financial statements are issued. Management expects to seek additional funds through equity or debt financings or through additional collaboration, licensing transactions or other sources. The Company may be unable to obtain equity or debt financings or enter into additional collaboration or licensing transactions and, if necessary, the Company will be required to implement cost reduction strategies. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Organization and Basis of Presentation

Eleven Biotherapeutics, Inc. (the “Company”), a Delaware corporation formed on February 25, 2008, is a biologics oncology company primarily focused on designing, engineering and developing targeted protein therapeutics ("TPTs"). The Company's TPTs are single protein therapeutics composed of targeting moieties genetically fused via linker domains to cytotoxic protein payloads that are produced through the Company's proprietary one-step manufacturing process. The Company targets tumor cell surface antigens that allow for rapid internalization into the targeted cancer cell and have limited expression on normal cells. The Company has designed its TPTs to overcome the fundamental efficacy and safety challenges inherent in existing antibody drug conjugates ("ADCs"), where a payload is chemically attached to a targeting antibody.

Liquidity

The Company has financed its operations to date primarily through private placements of its common stock and preferred stock, and convertible bridge notes, venture debt borrowings, its initial public offering ("IPO"), secondary offerings, sales effected in an "at-the-market" offering, and the License Agreement with Roche. As of December 31, 2017, the Company had cash and cash equivalents totaling approximately $14.7 million, net working capital of $10.3 million and an accumulated deficit of $152.3 million.

In August 2014, FASB issued ASU 2014‑15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern ("ASU 2015-14"). Under the new standard, management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved by the Company’s board of directors ("Board") before the date that the financial statements are issued. This standard was adopted by the Company at December 31, 2016.

The future success of the Company is dependent on its ability to develop its product candidates and ultimately upon its ability to attain profitable operations. The Company is subject to a number of risks similar to other early-stage life science companies, including, but not limited to, successful discovery and development of its product candidates, raising additional capital with favorable terms, development by its competitors of new technological innovations, protection of proprietary technology and market acceptance of the Company’s products. The successful discovery and development of product candidates requires substantial working capital which may not be available to the Company on favorable terms or not at all.

To date, the Company has no revenue from product sales and management expects continuing operating losses in the future. As of December 31, 2017, the Company had available cash and cash equivalents of $14.7 million, and raised an additional $9.0 million in estimated net proceeds upon the issuance of common stock and warrants in follow–on offerings in March 2018, which it believes is not sufficient to fund the Company's current operating plan for at least twelve months after the date the consolidated financial statements are issued. Management expects to seek additional funds through equity or debt financings or through additional collaboration, licensing transactions or other sources. The Company may be unable to obtain equity or debt financings or enter into additional collaboration or licensing transactions and, if necessary, the Company will be required to implement cost reduction strategies. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.