License and Collaboration Agreements	6 Months Ended
License and Collaboration Agreements	Jun. 30, 2022
License And Collaboration Agreements [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements We have entered into various collaboration agreements including license agreements and collaborative research, development and commercialization agreements with various pharmaceutical and biotechnology companies. Under these collaboration arrangements, we are entitled to receive license fees, upfront payments, milestone and other contingent payments, royalties, sales milestone payments, and payments for the manufacture and supply of our proprietary PEGylation materials and/or reimbursement for research and development activities. We generally include our costs of performing these services in research and development expense, except for costs for product sales to our collaboration partners which we include in cost of goods sold. We analyze our agreements to determine whether we should account for the agreements within the scope of ASC 808, and, if so, we analyze whether we should account for any elements under ASC 606. There have been no material changes to our collaboration agreements in the three and six months ended June 30, 2022, other than as described below for our Strategic Collaboration Agreement with BMS and Note 4 regarding SFJ. Bristol-Myers Squibb Company (BMS): Bempegaldesleukin, also referred to as NKTR-214 On February 13, 2018, we entered into a Strategic Collaboration Agreement (the BMS Collaboration Agreement) and a Share Purchase Agreement with BMS, both of which became effective on April 3, 2018. Pursuant to the BMS Collaboration Agreement, we and BMS have jointly developed bempegaldesleukin in combination with BMS’s Opdivo®. The parties share the internal and external development costs for bempegaldesleukin in combination regimens based on each party’s relative ownership interest in the compounds included in the regimens. In accordance with the agreement, the parties share development costs for bempegaldesleukin in combination with Opdivo®, 67.5% of costs to BMS and 32.5% to Nektar. The parties share costs for the manufacturing and commercialization of bempegaldesleukin, 35% of the costs to BMS and 65% to Nektar. Upon the effective date of the BMS Collaboration Agreement in April 2018, BMS paid us a non-refundable upfront cash payment of $1.0 billion and purchased 8,284,600 shares of our common stock pursuant to the Share Purchase Agreement for total additional cash consideration of $850.0 million. In 2020, we received non-refundable milestone payments of $50.0 million in aggregate for the first patient, first visit in the registrational trials in muscle-invasive bladder cancer and adjuvant melanoma. As discussed in Note 1, on March 14, 2022, we announced our registrational trial in metastatic melanoma did not meet its primary endpoints and that BMS and we decided to discontinue the trials in metastatic melanoma and adjuvant melanoma. On April 14, 2022, we announced that our registrational trials in each of renal cell carcinoma and cisplatin-ineligible, locally advanced or metastatic urothelial cancer did not meet their respective primary endpoints. Due to these results, BMS and we decided that these studies and all other ongoing studies in the program will be discontinued. The decision to terminate the program does not affect the cost-sharing provisions under the BMS Collaboration Agreement. However, without further development of bempegaldesleukin, we will no longer be eligible for the development, regulatory and sales milestones under the arrangement. We determined that the BMS Collaboration Agreement falls within the scope of ASC 808. As mentioned above, BMS shares certain percentages of development costs incurred by us and we share certain percentages of development costs incurred by BMS. We consider these activities to represent collaborative activities under ASC 808 and we recognize such cost sharing proportionately with the performance of the underlying services. We recognized BMS’ reimbursement of our expenses as a reduction of research and development expense and our reimbursement of BMS’ expenses as research and development expense. As discussed in Note 8, beginning in the three months ended June 30, 2022, we began reporting clinical trial, other third-party costs and employee costs for the bempegaldesleukin program in Restructuring, impairment and other costs of program. Accordingly, during the three months ended June 30, 2022, we recorded $7.6 million, as a reduction of such expense for the net reimbursement from BMS. During the six months ended June 30, 2022, we recorded $24.9 million as a reduction of research and development expense for the net reimbursement from BMS, reflecting the reimbursement recorded in the three months ended March 31, 2022. For the three and six months ended June 30, 2021, we recorded $24.8 million and $51.4 million, respectively, as a reduction of research and development expense for the net reimbursement from BMS. As of June 30, 2022, we have recorded an unbilled receivable of $7.4 million from BMS in accounts receivable in our Condensed Consolidated Balance Sheet. Eli Lilly and Company (Lilly): NKTR-358 On July 23, 2017, we entered into a worldwide license agreement (the Lilly Agreement) with Eli Lilly and Company (Lilly) to co-develop NKTR-358, a novel immunological drug candidate that we invented, pursuant to which we received an initial payment of $150.0 million and are eligible for up to $250.0 million in additional development and regulatory milestones. We are currently in Phase 1B and Phase 2 development, where we share costs with 75% of the costs borne by Lilly and 25% of the costs borne by us. Lilly is responsible for the costs of Phase 3 development, but we retain the option to contribute up to 25% of the costs of Phase 3 development on an indication-by-indication basis in order for us to achieve the maximum royalty level under the Lilly Agreement, and further, if approved, we will have the opportunity to receive a royalty rate up to the low twenties based upon our Phase 3 development cost contribution and the level of annual global product sales. Lilly will be responsible for all costs of global commercialization, and we will have an option to co-promote in the U.S. under certain conditions. A portion of the development milestones may be reduced by 50% under certain conditions, related to the final formulation of the approved product and the timing of prior approval (if any) of competitive products with a similar mechanism of action, which could reduce these milestone payments by 75% if both conditions occur. The Lilly Agreement will continue until Lilly no longer has any royalty payment obligations or, if earlier, the termination of the agreement in accordance with its terms. The Lilly Agreement may be terminated by Lilly for convenience, and may also be terminated under certain other circumstances, including material breach. Although we are entitled to significant development milestones under this arrangement, through June 30, 2022, we have excluded such milestones from the transaction price due to the significant uncertainties involved with clinical development. We re-evaluate the transaction price at each reporting period and as uncertain events are resolved or other changes in circumstances occur. Other We have other collaboration agreements that have resulted in commercialized products for our collaborations partners. Under these agreements, we may sell our proprietary PEGylation materials for use in these products, and we are entitled to receive royalties based on net sales of these products as well as sales milestones. As discussed in Note 5, we have sold our rights to receive royalties from these other collaboration agreements. Our non-cash royalty revenue which totaled $16.3 million and $33.8 million for the three and six months ended June 30, 2022 and totaled $20.5 million and $39.3 million for the three and six months ended June 30, 2021, respectively, represents revenue for granting licenses which we had satisfied in prior periods. Additionally, we have a collaboration agreement for a product under development, under which we are entitled to up to a total of $40.0 million of regulatory milestones, as well as sales milestones upon achievement of annual sales targets and royalties based on net sales of commercialized products, if any. However, given the current phase of development of the potential product under this collaboration agreement, we cannot estimate the probability or timing of achieving these milestones, and, therefore, have excluded all development milestones from the transaction price for this agreement.