LICENSE AGREEMENTS	12 Months Ended
Dec. 31, 2017
License Agreement Disclosure [Abstract]
LICENSE AGREEMENTS	4. LICENSE AGREEMENTS Janssen Biotech, Inc. Collaboration and License Agreement On November 13, 2014, we and Janssen entered into the Collaboration Agreement under which we granted to Janssen exclusive worldwide rights to develop and commercialize imetelstat for all human therapeutic uses, including hematologic myeloid malignancies. Upon the effectiveness of the Collaboration Agreement, we received $35,000,000 from Janssen as an upfront payment, which we classified as deferred revenue upon receipt. Under the Collaboration Agreement, Janssen is wholly responsible for the development, manufacturing, seeking regulatory approval for and commercialization of, imetelstat worldwide. Janssen is currently conducting two clinical trials of imetelstat: a Phase 2 trial in myelofibrosis, referred to as IMbark, and a Phase 2/3 trial in myelodysplastic syndromes, referred to as IMerge. Development costs for IMbark and IMerge are being shared between us and Janssen on a 50/50 basis. Additionally, under the terms of the Collaboration Agreement, we remain responsible for prosecuting, at Janssen’s direction, the patents licensed to Janssen at the time we entered into the Collaboration Agreement, with costs shared between us and Janssen on a 50/50 basis. The cost‑sharing arrangement with Janssen began in January 2015. As of December 31, 2017, accrued collaboration charges of $1,702,000 on our balance sheet represent the net amount owed to Janssen for our proportionate share of development costs incurred by Janssen under the Collaboration Agreement for the three months ended December 31, 2017. Following completion of the protocol-specified primary analysis of IMbark by Janssen, if completed, we expect Janssen to notify us of their decision, or a Continuation Decision, as to whether they elect to maintain the license rights granted to them under the Collaboration Agreement and continue to advance the development of imetelstat in any indication. In the event that IMbark is terminated early, or placed on clinical hold or suspended by a regulatory authority for an extended period of time, then Janssen must instead notify us of their Continuation Decision by the date that is approximately 24 months after the initiation of IMerge. 4. LICENSE AGREEMENTS (Continued) In the event that Janssen provides an affirmative Continuation Decision, we then would have an option, or the U.S. Opt‑In Rights, to share further U.S. development and promotion costs, including our share of development costs incurred to date by Janssen beyond IMbark or IMerge, in exchange for higher tiered royalty rates and higher future development and regulatory milestone payments if imetelstat is successfully developed and approved. If we exercise the U.S. Opt‑In Rights, then we and Janssen would share U.S. development and promotion costs beyond IMbark and IMerge on a 20/80 basis (Geron 20%, Janssen 80%), we would receive a $65,000,000 milestone payment, or the Continuation Fee, at the time of an affirmative Continuation Decision, and would be eligible to receive additional potential payments of up to $470,000,000 for the achievement of certain development and regulatory milestones, up to $350,000,000 for the achievement of certain sales milestones, and tiered royalties ranging from a mid‑teens up to low twenties percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen. In addition, if we exercise the U.S. Opt‑In Rights, we then would also have a separate option, or the U.S. Co‑Promotion Option, to provide 20% of the U.S. selling effort with our sales force personnel, in lieu of funding 20% of U.S. promotion costs, upon regulatory approval and commercial launch of imetelstat in the United States. Such co‑promotion would be conducted under a Janssen prepared promotion plan, and in accordance with a co‑promotion agreement to be agreed by the parties at the time of our exercise of the U.S. Co‑Promotion Option. We would be responsible for all costs associated with establishing and maintaining our sales force in any conduct of such co‑promotion. All product sales would be booked by Janssen. If we do not exercise the U.S. Opt‑In Rights, then all further development and promotion costs beyond IMbark and IMerge would be borne by Janssen, we would receive the $65,000,000 Continuation Fee at the time of an affirmative Continuation Decision plus a $70,000,000 payment, or the Full U.S. Rights Fee, for Janssen’s retention of full U.S. rights to imetelstat, and would be eligible to receive additional potential payments of up to $415,000,000 for the achievement of certain development and regulatory milestones, up to $350,000,000 for the achievement of certain sales milestones, and tiered royalties ranging from a double‑digit up to mid‑teens percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen. Under the terms of the Collaboration Agreement, we and Janssen have created a joint governance structure, including joint development and steering committees and working groups, to oversee and manage worldwide regulatory, development and manufacturing work under the joint clinical development plan and promotional activities (assuming we exercise the U.S. Opt‑In Rights) for imetelstat, with Janssen responsible for the operational execution of those activities. In addition, both we and Janssen may propose to the joint development committee imetelstat development for any new indications not then provided for in the joint clinical development plan and if we and Janssen agree such development should be conducted outside of the joint clinical development plan, both we and Janssen would be entitled to independently undertake such development at the developing party’s own cost, subject to the other party’s obligation to provide reimbursement for its specified portion of the development costs plus a premium following marketing approval of imetelstat in such newly proposed indication as a result of such independent development. In the event that we do not exercise the U.S. Opt‑In Rights following an affirmative Continuation Decision by Janssen, if any, the joint governance structure under the Collaboration Agreement would be dissolved, a joint oversight committee would monitor the progress of the collaboration, and we would have no further rights to conduct any independent imetelstat development. After an affirmative Continuation Decision by Janssen, the Collaboration Agreement would remain in effect until the expiration of the last‑to‑expire patent or the royalty obligations on sales of imetelstat cease, unless terminated earlier. If Janssen does not effect an affirmative Continuation Decision, then the Collaboration Agreement would terminate and all rights to the imetelstat program would revert to us. Janssen may terminate the Collaboration Agreement at any time for convenience or due to a safety‑related concern. If a notice of termination from Janssen occurs, we would be entitled to certain continued operational support and cost sharing under various circumstances and all rights to the imetelstat program would revert to us. 4. LICENSE AGREEMENTS (Continued) The terms of the Collaboration Agreement contain multiple deliverables, which included at inception: (i) exclusive worldwide rights to develop and commercialize imetelstat for all indications, (ii) transfer of know‑how and intellectual property, including our obligation to procure supply for manufacturing imetelstat for up to nine months after the effective date of the Collaboration Agreement, (iii) participation on the joint committees and working groups and (iv) potential participation in promoting imetelstat in the United States, if approved for commercial sale. We concluded the license for exclusive worldwide rights to develop and commercialize imetelstat has standalone value to Janssen based on the technical and financial resources of Janssen, including Janssen’s drug development experience, sizeable employee base with specific experience in hematologic malignancies, and sufficient capital to independently develop imetelstat on a global basis. Since Janssen has final decision‑making authority in the event a unanimous decision cannot be reached by the joint committees, we determined our participation on the joint committees does not represent a non‑contingent deliverable under the Collaboration Agreement. In addition, we determined our potential participation in promoting imetelstat in the United States does not represent a non‑contingent deliverable because such participation is uncertain and dependent on imetelstat being approved for commercial sale, which is not within our control. Accordingly, we determined delivery of the license rights granted by us to Janssen, together with our performance of certain technology transfer‑related activities under the Collaboration Agreement, represents the sole non‑contingent deliverable under the Collaboration Agreement associated with the upfront payment. Therefore, we accounted for our delivery of the imetelstat license rights and our performance of the technology transfer‑related activities as a single unit of accounting. During the third quarter of 2015, we completed performance of the technology transfer‑related activities to Janssen as outlined under the Collaboration Agreement. Combining this performance with the delivery of the imetelstat license rights, we fully recognized the $35,000,000 upfront payment from Janssen as collaboration revenue on our statements of operations in the third quarter of 2015. We have determined that each of the additional potential milestone payments to us under the Collaboration Agreement, including: (i) the Continuation Fee at the time of an affirmative Continuation Decision, (ii) the Full U.S. Rights Fee, if we do not exercise the U.S. Opt‑In Rights and (iii) payments based on the achievement of certain development, regulatory or sales milestones, represent contingent payments. Consequently, we will recognize revenue for these payments in their entirety upon successful accomplishment of the respective milestone. Royalties on future product sales of imetelstat, if successfully commercialized under the Collaboration Agreement, will be recognized as revenue when earned. Janssen Pharmaceuticals, Inc. License Agreement On September 15, 2016, we entered into the License Agreement with Janssen Pharmaceuticals whereby we granted to Janssen Pharmaceuticals an exclusive worldwide license, or the Exclusive License, under our proprietary patents for the research, development and commercialization of products based on specialized oligonucleotide backbone chemistry and novel amidates for ribonucleic acid interference, or RNAi, for the prevention, treatment and/or diagnosis of any and all human disorders, excluding cancers originating from the blood or bone marrow, and products whose predominant or primary mechanism of action is telomerase inhibition. In addition to the Exclusive License, we granted to Janssen Pharmaceuticals a non‑exclusive worldwide license, or the Non‑Exclusive License, under our patents covering the synthesis of monomers, which are the building blocks of oligonucleotides, and certain know‑how necessary for the research, development and commercialization of products under the Exclusive License. The patent rights under the Non‑Exclusive License are also licensed exclusively to Janssen under the Collaboration Agreement, as described in the section above titled “Janssen Biotech, Inc. Collaboration and License Agreement”, for the development and commercialization of imetelstat, and the License Agreement with Janssen Pharmaceuticals expressly excludes, and is subject to, the rights and licenses granted to Janssen under the Collaboration Agreement. Under the terms of the License Agreement, Janssen Pharmaceuticals, at its sole expense, is required to use reasonable efforts to perform research, development and commercialization activities to obtain at least one licensed product to be researched, developed and commercialized under the License Agreement. We remain responsible for prosecuting the patent rights under the Exclusive License, with reasonable input provided by Janssen Pharmaceuticals, and the costs for such prosecution will be shared between us and Janssen Pharmaceuticals on a 50/50 basis. In addition, we remain responsible for prosecuting the patent rights under the Non‑Exclusive License, as set forth under the terms of the Collaboration Agreement with Janssen. 4. LICENSE AGREEMENTS (Continued) Under the terms of the License Agreement, we received $5,000,000 from Janssen Pharmaceuticals as a non‑refundable upfront payment. We are also eligible to receive additional potential payments of up to an aggregate maximum total of $75,000,000 for the achievement of certain development and regulatory milestones and tiered royalties in the low single digit percentage range on worldwide net sales of each licensed product commercialized under the License Agreement in any countries where there are valid claims under the patent rights licensed to Janssen Pharmaceuticals. The License Agreement will remain in effect until the expiration of the last‑to‑expire patent, unless terminated earlier. Janssen Pharmaceuticals may also terminate the License Agreement at will upon prior written notice to us. In the event of an early termination of the License Agreement, all licenses to Janssen Pharmaceuticals would terminate. The terms of the License Agreement contain multiple deliverables, which included at inception the transfer of: (i) license rights under the Exclusive License and (ii) license rights and certain know‑how under the Non‑Exclusive License. We concluded the License Agreement has standalone value to Janssen Pharmaceuticals based on Janssen Pharmaceuticals’ technical and financial resources, including drug development experience, sizeable employee base with specific knowledge of oligonucleotide chemistry, and sufficient capital to independently research, develop and commercialize products under the License Agreement on a global basis. Accordingly, we have determined delivery of the license rights granted by us to Janssen Pharmaceuticals under the Exclusive License and Non‑Exclusive License, together with the transfer of certain know‑how under the Non‑Exclusive License, represents the sole non‑contingent deliverable under the License Agreement associated with the upfront payment. Therefore, we accounted for our delivery of the license rights and transfer of know‑how under the License Agreement as a single unit of accounting. During the third quarter of 2016, we completed the delivery of the license rights and transfer of know‑how to Janssen Pharmaceuticals under the License Agreement. Accordingly, we fully recognized the $5,000,000 upfront payment from Janssen Pharmaceuticals as license fee revenue on our statements of operations in the third quarter of 2016. We have determined that each of the additional potential development and regulatory milestone payments to us under the License Agreement represent contingent payments. Consequently, we will recognize revenue for these payments in their entirety upon successful accomplishment of the respective milestone. Royalties on potential future product sales under the License Agreement will be recognized as revenue when earned.

4. LICENSE AGREEMENTS

Janssen Biotech, Inc. Collaboration and License Agreement

On November 13, 2014, we and Janssen entered into the Collaboration Agreement under which we granted to Janssen exclusive worldwide rights to develop and commercialize imetelstat for all human therapeutic uses, including hematologic myeloid malignancies. Upon the effectiveness of the Collaboration Agreement, we received $35,000,000 from Janssen as an upfront payment, which we classified as deferred revenue upon receipt.

Under the Collaboration Agreement, Janssen is wholly responsible for the development, manufacturing, seeking regulatory approval for and commercialization of, imetelstat worldwide. Janssen is currently conducting two clinical trials of imetelstat: a Phase 2 trial in myelofibrosis, referred to as IMbark, and a Phase 2/3 trial in myelodysplastic syndromes, referred to as IMerge. Development costs for IMbark and IMerge are being shared between us and Janssen on a 50/50 basis. Additionally, under the terms of the Collaboration Agreement, we remain responsible for prosecuting, at Janssen’s direction, the patents licensed to Janssen at the time we entered into the Collaboration Agreement, with costs shared between us and Janssen on a 50/50 basis. The cost‑sharing arrangement with Janssen began in January 2015. As of December 31, 2017, accrued collaboration charges of $1,702,000 on our balance sheet represent the net amount owed to Janssen for our proportionate share of development costs incurred by Janssen under the Collaboration Agreement for the three months ended December 31, 2017.

Following completion of the protocol-specified primary analysis of IMbark by Janssen, if completed, we expect Janssen to notify us of their decision, or a Continuation Decision, as to whether they elect to maintain the license rights granted to them under the Collaboration Agreement and continue to advance the development of imetelstat in any indication. In the event that IMbark is terminated early, or placed on clinical hold or suspended by a regulatory authority for an extended period of time, then Janssen must instead notify us of their Continuation Decision by the date that is approximately 24 months after the initiation of IMerge.

4. LICENSE AGREEMENTS (Continued)

In the event that Janssen provides an affirmative Continuation Decision, we then would have an option, or the U.S. Opt‑In Rights, to share further U.S. development and promotion costs, including our share of development costs incurred to date by Janssen beyond IMbark or IMerge, in exchange for higher tiered royalty rates and higher future development and regulatory milestone payments if imetelstat is successfully developed and approved. If we exercise the U.S. Opt‑In Rights, then we and Janssen would share U.S. development and promotion costs beyond IMbark and IMerge on a 20/80 basis (Geron 20%, Janssen 80%), we would receive a $65,000,000 milestone payment, or the Continuation Fee, at the time of an affirmative Continuation Decision, and would be eligible to receive additional potential payments of up to $470,000,000 for the achievement of certain development and regulatory milestones, up to $350,000,000 for the achievement of certain sales milestones, and tiered royalties ranging from a mid‑teens up to low twenties percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen. In addition, if we exercise the U.S. Opt‑In Rights, we then would also have a separate option, or the U.S. Co‑Promotion Option, to provide 20% of the U.S. selling effort with our sales force personnel, in lieu of funding 20% of U.S. promotion costs, upon regulatory approval and commercial launch of imetelstat in the United States. Such co‑promotion would be conducted under a Janssen prepared promotion plan, and in accordance with a co‑promotion agreement to be agreed by the parties at the time of our exercise of the U.S. Co‑Promotion Option. We would be responsible for all costs associated with establishing and maintaining our sales force in any conduct of such co‑promotion. All product sales would be booked by Janssen. If we do not exercise the U.S. Opt‑In Rights, then all further development and promotion costs beyond IMbark and IMerge would be borne by Janssen, we would receive the $65,000,000 Continuation Fee at the time of an affirmative Continuation Decision plus a $70,000,000 payment, or the Full U.S. Rights Fee, for Janssen’s retention of full U.S. rights to imetelstat, and would be eligible to receive additional potential payments of up to $415,000,000 for the achievement of certain development and regulatory milestones, up to $350,000,000 for the achievement of certain sales milestones, and tiered royalties ranging from a double‑digit up to mid‑teens percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen.

Under the terms of the Collaboration Agreement, we and Janssen have created a joint governance structure, including joint development and steering committees and working groups, to oversee and manage worldwide regulatory, development and manufacturing work under the joint clinical development plan and promotional activities (assuming we exercise the U.S. Opt‑In Rights) for imetelstat, with Janssen responsible for the operational execution of those activities. In addition, both we and Janssen may propose to the joint development committee imetelstat development for any new indications not then provided for in the joint clinical development plan and if we and Janssen agree such development should be conducted outside of the joint clinical development plan, both we and Janssen would be entitled to independently undertake such development at the developing party’s own cost, subject to the other party’s obligation to provide reimbursement for its specified portion of the development costs plus a premium following marketing approval of imetelstat in such newly proposed indication as a result of such independent development. In the event that we do not exercise the U.S. Opt‑In Rights following an affirmative Continuation Decision by Janssen, if any, the joint governance structure under the Collaboration Agreement would be dissolved, a joint oversight committee would monitor the progress of the collaboration, and we would have no further rights to conduct any independent imetelstat development.

After an affirmative Continuation Decision by Janssen, the Collaboration Agreement would remain in effect until the expiration of the last‑to‑expire patent or the royalty obligations on sales of imetelstat cease, unless terminated earlier. If Janssen does not effect an affirmative Continuation Decision, then the Collaboration Agreement would terminate and all rights to the imetelstat program would revert to us. Janssen may terminate the Collaboration Agreement at any time for convenience or due to a safety‑related concern. If a notice of termination from Janssen occurs, we would be entitled to certain continued operational support and cost sharing under various circumstances and all rights to the imetelstat program would revert to us.

4. LICENSE AGREEMENTS (Continued)

The terms of the Collaboration Agreement contain multiple deliverables, which included at inception: (i) exclusive worldwide rights to develop and commercialize imetelstat for all indications, (ii) transfer of know‑how and intellectual property, including our obligation to procure supply for manufacturing imetelstat for up to nine months after the effective date of the Collaboration Agreement, (iii) participation on the joint committees and working groups and (iv) potential participation in promoting imetelstat in the United States, if approved for commercial sale. We concluded the license for exclusive worldwide rights to develop and commercialize imetelstat has standalone value to Janssen based on the technical and financial resources of Janssen, including Janssen’s drug development experience, sizeable employee base with specific experience in hematologic malignancies, and sufficient capital to independently develop imetelstat on a global basis. Since Janssen has final decision‑making authority in the event a unanimous decision cannot be reached by the joint committees, we determined our participation on the joint committees does not represent a non‑contingent deliverable under the Collaboration Agreement. In addition, we determined our potential participation in promoting imetelstat in the United States does not represent a non‑contingent deliverable because such participation is uncertain and dependent on imetelstat being approved for commercial sale, which is not within our control. Accordingly, we determined delivery of the license rights granted by us to Janssen, together with our performance of certain technology transfer‑related activities under the Collaboration Agreement, represents the sole non‑contingent deliverable under the Collaboration Agreement associated with the upfront payment. Therefore, we accounted for our delivery of the imetelstat license rights and our performance of the technology transfer‑related activities as a single unit of accounting. During the third quarter of 2015, we completed performance of the technology transfer‑related activities to Janssen as outlined under the Collaboration Agreement. Combining this performance with the delivery of the imetelstat license rights, we fully recognized the $35,000,000 upfront payment from Janssen as collaboration revenue on our statements of operations in the third quarter of 2015.

We have determined that each of the additional potential milestone payments to us under the Collaboration Agreement, including: (i) the Continuation Fee at the time of an affirmative Continuation Decision, (ii) the Full U.S. Rights Fee, if we do not exercise the U.S. Opt‑In Rights and (iii) payments based on the achievement of certain development, regulatory or sales milestones, represent contingent payments. Consequently, we will recognize revenue for these payments in their entirety upon successful accomplishment of the respective milestone. Royalties on future product sales of imetelstat, if successfully commercialized under the Collaboration Agreement, will be recognized as revenue when earned.

Janssen Pharmaceuticals, Inc. License Agreement

On September 15, 2016, we entered into the License Agreement with Janssen Pharmaceuticals whereby we granted to Janssen Pharmaceuticals an exclusive worldwide license, or the Exclusive License, under our proprietary patents for the research, development and commercialization of products based on specialized oligonucleotide backbone chemistry and novel amidates for ribonucleic acid interference, or RNAi, for the prevention, treatment and/or diagnosis of any and all human disorders, excluding cancers originating from the blood or bone marrow, and products whose predominant or primary mechanism of action is telomerase inhibition.

In addition to the Exclusive License, we granted to Janssen Pharmaceuticals a non‑exclusive worldwide license, or the Non‑Exclusive License, under our patents covering the synthesis of monomers, which are the building blocks of oligonucleotides, and certain know‑how necessary for the research, development and commercialization of products under the Exclusive License. The patent rights under the Non‑Exclusive License are also licensed exclusively to Janssen under the Collaboration Agreement, as described in the section above titled “Janssen Biotech, Inc. Collaboration and License Agreement”, for the development and commercialization of imetelstat, and the License Agreement with Janssen Pharmaceuticals expressly excludes, and is subject to, the rights and licenses granted to Janssen under the Collaboration Agreement.

Under the terms of the License Agreement, Janssen Pharmaceuticals, at its sole expense, is required to use reasonable efforts to perform research, development and commercialization activities to obtain at least one licensed product to be researched, developed and commercialized under the License Agreement. We remain responsible for prosecuting the patent rights under the Exclusive License, with reasonable input provided by Janssen Pharmaceuticals, and the costs for such prosecution will be shared between us and Janssen Pharmaceuticals on a 50/50 basis. In addition, we remain responsible for prosecuting the patent rights under the Non‑Exclusive License, as set forth under the terms of the Collaboration Agreement with Janssen.

4. LICENSE AGREEMENTS (Continued)

Under the terms of the License Agreement, we received $5,000,000 from Janssen Pharmaceuticals as a non‑refundable upfront payment. We are also eligible to receive additional potential payments of up to an aggregate maximum total of $75,000,000 for the achievement of certain development and regulatory milestones and tiered royalties in the low single digit percentage range on worldwide net sales of each licensed product commercialized under the License Agreement in any countries where there are valid claims under the patent rights licensed to Janssen Pharmaceuticals.

The License Agreement will remain in effect until the expiration of the last‑to‑expire patent, unless terminated earlier. Janssen Pharmaceuticals may also terminate the License Agreement at will upon prior written notice to us. In the event of an early termination of the License Agreement, all licenses to Janssen Pharmaceuticals would terminate.

The terms of the License Agreement contain multiple deliverables, which included at inception the transfer of: (i) license rights under the Exclusive License and (ii) license rights and certain know‑how under the Non‑Exclusive License. We concluded the License Agreement has standalone value to Janssen Pharmaceuticals based on Janssen Pharmaceuticals’ technical and financial resources, including drug development experience, sizeable employee base with specific knowledge of oligonucleotide chemistry, and sufficient capital to independently research, develop and commercialize products under the License Agreement on a global basis. Accordingly, we have determined delivery of the license rights granted by us to Janssen Pharmaceuticals under the Exclusive License and Non‑Exclusive License, together with the transfer of certain know‑how under the Non‑Exclusive License, represents the sole non‑contingent deliverable under the License Agreement associated with the upfront payment. Therefore, we accounted for our delivery of the license rights and transfer of know‑how under the License Agreement as a single unit of accounting. During the third quarter of 2016, we completed the delivery of the license rights and transfer of know‑how to Janssen Pharmaceuticals under the License Agreement. Accordingly, we fully recognized the $5,000,000 upfront payment from Janssen Pharmaceuticals as license fee revenue on our statements of operations in the third quarter of 2016.

We have determined that each of the additional potential development and regulatory milestone payments to us under the License Agreement represent contingent payments. Consequently, we will recognize revenue for these payments in their entirety upon successful accomplishment of the respective milestone. Royalties on potential future product sales under the License Agreement will be recognized as revenue when earned.