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License and Collaboration Agreements - Additional Information (Detail) - USD ($) |  |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
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Feb. 13, 2018 | Jan. 01, 2018 | Aug. 23, 2017 | Apr. 30, 2018 | Oct. 31, 2017 | Sep. 30, 2017 | Jan. 31, 2017 | Sep. 30, 2016 | Mar. 31, 2016 | Jun. 30, 2014 | Oct. 31, 2010 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2015 | Dec. 31, 2013 | Dec. 31, 2007 | Jan. 09, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Performance obligation recognized |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 77,500,000 | $ 95,300,000 |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  | $ 1,700,000,000 |  |  |  |  |  |  |  |  | 1,700,000,000 |  |  |  |  |  |
Deferred revenue, current portion |  |  |  |  |  |  |  |  |  |  |  | 5,517,000 |  |  |  | $ 13,892,000 |  |  |  |  | 5,517,000 | 13,892,000 |  |  |  |  |
Deferred revenue, less current portion |  |  |  |  |  |  |  |  |  |  |  | 2,554,000 |  |  |  | 10,744,000 |  |  |  |  | 2,554,000 | 10,744,000 |  |  |  |  |
Upfront and milestone payments received from license agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 |  |  |  |  |  |
Accounts receivable |  |  |  |  |  |  |  |  |  |  |  | 36,802,000 |  |  |  | 43,213,000 |  |  |  |  | 36,802,000 | 43,213,000 |  |  |  |  |
Development milestones received |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16,565,000 |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | 8,071,000 |  |  |  | 24,636,000 |  |  |  |  | 8,071,000 | 24,636,000 |  |  |  |  |
Revenue recognized from contracts with customers |  |  |  |  |  |  |  |  |  |  |  | 33,862,000 | $ 29,218,000 | $ 23,315,000 | $ 28,222,000 | 39,826,000 | $ 27,762,000 | $ 1,087,717,000 | $ 38,018,000 |  | 114,617,000 | 1,193,323,000 | $ 307,711,000 |  |  |  |
bempegaldesleukin | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront and milestone payments received from license agreements |  |  |  | $ 1,000,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum total additional cash payments receivable upon achievement of certain development and regulatory milestones |  |  |  | 1,400,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
bempegaldesleukin | Nektar's | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eligible additional cash payments receivable upon achievement of certain sales milestones |  |  |  | $ 350,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ADYNOVATE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales milestone revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 |  |  |  |  |
BMS Collaboration Agreement | bempegaldesleukin | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Global commercialization profits and losses sharing percentage | 65.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing production costs | 65.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
BMS Collaboration Agreement | bempegaldesleukin | Nektar's | Opdivo |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing development costs | 32.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
BMS Collaboration Agreement | bempegaldesleukin | Nektar's | Opdivo and Yervoy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing development costs | 22.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
NKTR-358 | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | 1,300,000 |  |  |  |  |  |  |  |  | $ 1,300,000 |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  | $ 150,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing in Phase 2 development costs |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory milestones payment, description |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 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. |  |  |  |  |  |
AstraZeneca-Kirin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of upfront payment, market access milestones, royalties and sales milestones |  |  |  |  |  |  |  |  | 40.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly | NKTR-358 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing in Phase 2 development costs |  |  | 75.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bristol-Myers Squibb | Purchase Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares issued (in shares) |  |  |  | 8,284,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock consideration received |  |  |  | $ 850,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bristol-Myers Squibb | bempegaldesleukin | Research and development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reimbursement of expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 105,400,000 | 62,500,000 | 7,800,000 |  |  |  |
Bristol-Myers Squibb | BMS Collaboration Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts receivable |  |  |  |  |  |  |  |  |  |  |  | 24,000,000.0 |  |  |  | 19,000,000.0 |  |  |  |  | 24,000,000.0 | 19,000,000.0 |  |  |  |  |
Bristol-Myers Squibb | BMS Collaboration Agreement | Purchase Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total consideration received under agreements |  |  |  | 1,850,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated fair value of shares |  |  |  | $ 790,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Closing date price of common stock (in usd per share) |  |  |  | $ 99.36 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining amount allocated to transaction price |  |  |  | $ 1,059,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future development, regulatory and sales milestones |  |  |  | $ 1,800,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bristol-Myers Squibb | BMS Collaboration Agreement | bempegaldesleukin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Global commercialization profits and losses sharing percentage | 35.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing production costs | 35.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount recognized for granting licenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,059,800,000 |  |  |  |  |
Bristol-Myers Squibb | BMS Collaboration Agreement | bempegaldesleukin | Opdivo |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing development costs | 67.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bristol-Myers Squibb | BMS Collaboration Agreement | bempegaldesleukin | Opdivo and Yervoy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sharing development costs | 78.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bristol-Myers Squibb | Clinical Trial Agreement | bempegaldesleukin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of out-of-pocket costs to be reimbursed by partner |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baxalta Incorporated / Takeda |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 |  |  |  |  |  | $ 10,000,000.0 |  |  |  |  |
Baxalta Incorporated / Takeda | Hemophilia |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received under right to sublicense agreement |  |  |  |  | $ 12,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baxalta Incorporated / Takeda | Hemophilia | European Union |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront and milestone payments received from license agreements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 |  |  |  |  |  |
Additional upfront and milestone payments recognized from license agreements |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Phase 1 Clinical Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  | 17,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Drug Product Development |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  | 6,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional development and regulatory milestones |  |  | $ 250,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of regulatory milestones payments will be reduced under certain conditions |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of regulatory milestones payments will be reduced if conditions occur |  |  | 75.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Nektar's | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of funding phase 3 development costs on an indication by indication basis borne |  |  | 25.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | Nektar's | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of funding phase 3 development costs on an indication by indication basis borne |  |  | 0.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | License |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  | $ 125,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Eli Lilly and Company | NKTR-358 | License | ASC 606 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue recognized from contracts with customers |  | $ 125,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amgen, Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  |  | $ 50,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amgen, Inc. | ASC 606 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | 4,200,000 |  |  |  |  |  |  |  |  | 4,200,000 |  |  |  |  |  |
Ophthotech Corporation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Advance payment from collaboration partner |  |  |  |  |  |  | $ 12,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ophthotech Corporation | Reagent Shipments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Advance payment from collaboration partner for reagent shipments |  |  |  |  |  |  | $ 10,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ophthotech Corporation | Minimum Purchase Requirement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Advance payment from collaboration partner |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,300,000 |  |  |  |
Ophthotech Corporation | Fovista |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recognition of remaining deferred revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 18,000,000.0 |  |  |  |  |  |  |
Ophthotech Corporation | Fovista | Novartis Pharma AG |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  | $ 19,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bayer Healthcare LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40,000,000.0 |
Bayer Healthcare LLC | Performance-based Milestone Payments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 30,000,000.0 |  |
Recognition of remaining deferred revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 16,800,000 |  |  |  |  |  |  |  |  |  |  |
AstraZeneca AB | MOVANTIK and MOVENTIG | Upfront Payment Arrangement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 385,000,000.0 |  |  |
AstraZeneca AB | AstraZeneca-Kirin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |
Received upfront and milestone payment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,600,000 |  |  |  |
Percentage of upfront payment, market access milestone payments, royalties and sales milestone payments from sublicense agreement retained by our collaboration partner |  |  |  |  |  |  |  |  | 60.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
AstraZeneca AB |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  | 40,000,000.0 |  |  |  |  |  |  |  |  | 40,000,000.0 |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | 4,000,000.0 |  |  |  |  |  |  |  |  | 4,000,000.0 |  |  |  |  |  |
Terminated Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  |  |  | $ 2,000,000.0 |  |  |  |  |  |  |  |  | $ 2,000,000.0 |  |  |  |  |  |
Milestone One | Subsequent Event | BMS Collaboration Agreement | bempegaldesleukin | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25,000,000.0
Milestone Two | Subsequent Event | BMS Collaboration Agreement | bempegaldesleukin | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25,000,000.0
Milestone Three | Subsequent Event | BMS Collaboration Agreement | bempegaldesleukin | Nektar's |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future additional payments for development milestones |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 75,000,000.0

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