Collaborative Research and License Agreements	3 Months Ended
Mar. 31, 2019
Research and Development [Abstract]
Collaborative Research and License Agreements	Collaborative Research and License Agreements Dermelix Collaboration On February 17, 2019, Exicure entered into a License and Development Agreement (the “Dermelix Collaboration”) with Dermelix, LLC d/b/a Dermelix Biotherapeutics (“Dermelix”). Pursuant to the Dermelix Collaboration, the Company granted to Dermelix exclusive, worldwide royalty-bearing license rights to, develop, manufacture, have manufactured, use and commercialize the Company’s spherical nucleic acid (“SNA”) technology for the treatment of Netherton Syndrome (“NS”) and, at Dermelix’s option, up to five additional specified orphan diseases that are within the dermatology field. Upon written notice to the Company, Dermelix may exercise its option at any time following the effective date of the Dermelix Collaboration until the date that is six (6) years from the date that the first collaboration SNA therapeutic achieves first dosing in humans in a Phase 1 clinical trial for NS. Dermelix will initially seek to develop a targeted therapy for the treatment of NS. Under the terms of the Dermelix Collaboration, the Company will be responsible for conducting the early stage development for each indication up to IND enabling toxicology studies. Dermelix will assume subsequent development, commercial activities and financial responsibility for such indications. Dermelix will pay the costs and expenses of development and commercialization of any licensed products under the Dermelix Collaboration, including the Company’s expenses incurred in connection with development activities and in accordance with the development budget. Under the terms of the Dermelix License Agreement, Exicure received an upfront payment of $1,000, to be applied against the initial $1,000 of the Company’s development expenses. If Dermelix exercises any of its option rights for additional indications, Dermelix will pay an option exercise fee equal to $1,000 for each exercised option (each, an “Option Exercise Fee”). Any Option Exercise Fee will be applied against the Company’s development expenses with respect to the particular indication for which the option was exercised. Pursuant to the Dermelix Collaboration, the Company shall have the right to pursue the development and commercialization of SNA technology for the treatment of orphan diseases which are neither NS nor one of the additional specified orphan diseases selected by Dermelix pursuant to its option rights. If the Company commences development activities of SNA technology for the treatment of such an orphan disease, the Company will notify Dermelix in writing of such development and Dermelix will have thirty (30) days following receipt of such notice to use one of its remaining option rights on such orphan disease. If Dermelix does not use one of its remaining option rights on such orphan disease, or has no option rights remaining, then the Company will have no further obligations to Dermelix with respect to the development of SNA therapeutics for such orphan disease and shall be free to continue commercialization and development activities with respect thereto. For each of NS as well as any additional licensed product for which Dermelix exercises one of its options, the Company shall be eligible to receive additional cash payments totaling up to $13,500 upon achievement of certain development and regulatory milestones and up to $152,500 upon achievement of certain sales milestones. The regulatory milestones are payable upon the initiation or completion of clinical trials, and regulatory approval in the United States and outside the United States, per program. The commercial sales milestones are payable upon achievement of specified aggregate annual product sales thresholds. In the event a therapeutic candidate subject to the collaboration results in commercial sales, the Company will receive low double-digit royalties on annual net sales for such licensed products. Dermelix Collaboration — Revenue Recognition The Company concluded that Dermelix is a customer in this arrangement, and as such the arrangement falls within the scope of the revenue recognition guidance. The Company identified performance obligations under the Dermelix Collaboration for the license of intellectual property for the NS therapeutic candidate and associated research and development services for the NS therapeutic candidate. The Company determined that the performance obligations were not separately identifiable and were not distinct or distinct within the context of the contract due to the specialized nature of the services to be provided by Exicure, specifically with respect to the Company’s expertise related to SNA technology, and the interdependent relationship between the performance obligations. As such, the Company concluded that there is a single identified performance obligation. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential development and regulatory milestone, which is considered variable consideration, was zero, as the achievement of those milestones is uncertain and highly susceptible to factors outside of the Company’s control. Accordingly, all such milestones were excluded from the transaction price. Management will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur and adjust the transaction price as necessary. Sales-based royalties, including commercial sales milestone payments based on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the royalties relate. The Company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Revenue associated with the performance obligation will be recognized as services are provided using a cost-to-cost measure of progress method. The transfer of control occurs over time and, in management’s judgment, this input method is the best measure of progress towards satisfying the performance obligation and reflects a faithful depiction of the transfer of goods and services. The Company recognized $25 of revenue under the Dermelix Collaboration during the three months ended March 31, 2019. The aggregate amount of the consideration received and the amount recognized as revenue as of March 31, 2019 relates to the Company’s wholly unsatisfied performance obligation. This amount is recorded as deferred revenue at March 31, 2019 and is $975 at March 31, 2019. As of March 31, 2019, the Company expected to recognize this amount as revenue in the second, third and fourth quarters of 2019 based on the related level of performance during those periods. Purdue Collaboration During the three months ended March 31, 2018, the Company recognized collaboration revenue of $36 which consisted entirely of research and development activities that were reimbursed by Purdue Pharma L.P. (“Purdue”) and is presented on a gross basis in the accompanying unaudited condensed consolidated statement of operations. See Note 14, Subsequent Events for recent developments regarding the Purdue Collaboration.

Collaborative Research and License Agreements

Dermelix Collaboration

On February 17, 2019, Exicure entered into a License and Development Agreement (the “Dermelix Collaboration”) with Dermelix, LLC d/b/a Dermelix Biotherapeutics (“Dermelix”). Pursuant to the Dermelix Collaboration, the Company granted to Dermelix exclusive, worldwide royalty-bearing license rights to, develop, manufacture, have manufactured, use and commercialize the Company’s spherical nucleic acid (“SNA”) technology for the treatment of Netherton Syndrome (“NS”) and, at Dermelix’s option, up to five additional specified orphan diseases that are within the dermatology field. Upon written notice to the Company, Dermelix may exercise its option at any time following the effective date of the Dermelix Collaboration until the date that is six (6) years from the date that the first collaboration SNA therapeutic achieves first dosing in humans in a Phase 1 clinical trial for NS.

Dermelix will initially seek to develop a targeted therapy for the treatment of NS. Under the terms of the Dermelix Collaboration, the Company will be responsible for conducting the early stage development for each indication up to IND enabling toxicology studies. Dermelix will assume subsequent development, commercial activities and financial responsibility for such indications. Dermelix will pay the costs and expenses of development and commercialization of any licensed products under the Dermelix Collaboration, including the Company’s expenses incurred in connection with development activities and in accordance with the development budget. Under the terms of the Dermelix License Agreement, Exicure received an upfront payment of $1,000, to be applied against the initial $1,000 of the Company’s development expenses. If Dermelix exercises any of its option rights for additional indications, Dermelix will pay an option exercise fee equal to $1,000 for each exercised option (each, an “Option Exercise Fee”). Any Option Exercise Fee will be applied against the Company’s development expenses with respect to the particular indication for which the option was exercised.

Pursuant to the Dermelix Collaboration, the Company shall have the right to pursue the development and commercialization of SNA technology for the treatment of orphan diseases which are neither NS nor one of the additional specified orphan diseases selected by Dermelix pursuant to its option rights. If the Company commences development activities of SNA technology for the treatment of such an orphan disease, the Company will notify Dermelix in writing of such development and Dermelix will have thirty (30) days following receipt of such notice to use one of its remaining option rights on such orphan disease. If Dermelix does not use one of its remaining option rights on such orphan disease, or has no option rights remaining, then the Company will have no further obligations to Dermelix with respect to the development of SNA therapeutics for such orphan disease and shall be free to continue commercialization and development activities with respect thereto.

For each of NS as well as any additional licensed product for which Dermelix exercises one of its options, the Company shall be eligible to receive additional cash payments totaling up to $13,500 upon achievement of certain development and regulatory milestones and up to $152,500 upon achievement of certain sales milestones. The regulatory milestones are payable upon the initiation or completion of clinical trials, and regulatory approval in the United States and outside the United States, per program. The commercial sales milestones are payable upon achievement of specified aggregate annual product sales thresholds. In the event a therapeutic candidate subject to the collaboration results in commercial sales, the Company will receive low double-digit royalties on annual net sales for such licensed products.

Dermelix Collaboration — Revenue Recognition

The Company concluded that Dermelix is a customer in this arrangement, and as such the arrangement falls within the scope of the revenue recognition guidance. The Company identified performance obligations under the Dermelix Collaboration for the license of intellectual property for the NS therapeutic candidate and associated research and development services for the NS therapeutic candidate. The Company determined that the performance obligations were not separately identifiable and were not distinct or distinct within the context of the contract due to the specialized nature of the services to be provided by Exicure, specifically with respect to the Company’s expertise related to SNA technology, and the interdependent relationship between the performance obligations. As such, the Company concluded that there is a single identified performance obligation.

The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential development and regulatory milestone, which is considered variable consideration, was zero, as the achievement of those milestones is uncertain and highly susceptible to factors outside of the Company’s control. Accordingly, all such milestones were excluded from the transaction price. Management will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur and adjust the transaction price as necessary. Sales-based royalties, including commercial sales milestone payments based on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the royalties relate. The Company will recognize such revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Revenue associated with the performance obligation will be recognized as services are provided using a cost-to-cost measure of progress method. The transfer of control occurs over time and, in management’s judgment, this input method is the best measure of progress towards satisfying the performance obligation and reflects a faithful depiction of the transfer of goods and services.

The Company recognized $25 of revenue under the Dermelix Collaboration during the three months ended March 31, 2019. The aggregate amount of the consideration received and the amount recognized as revenue as of March 31, 2019 relates to the Company’s wholly unsatisfied performance obligation. This amount is recorded as deferred revenue at March 31, 2019 and is $975 at March 31, 2019. As of March 31, 2019, the Company expected to recognize this amount as revenue in the second, third and fourth quarters of 2019 based on the related level of performance during those periods.

Purdue Collaboration

During the three months ended March 31, 2018, the Company recognized collaboration revenue of $36 which consisted entirely of research and development activities that were reimbursed by Purdue Pharma L.P. (“Purdue”) and is presented on a gross basis in the accompanying unaudited condensed consolidated statement of operations. See Note 14, Subsequent Events for recent developments regarding the Purdue Collaboration.