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Licenses, Asset Acquisitions and Contingent Consideration - Additional Information (Details) - USD ($) |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended
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May 11, 2020 | Sep. 21, 2018 | Jun. 24, 2018 | Jan. 04, 2018 | Oct. 02, 2017 | May 31, 2019 | Sep. 30, 2018 | Jun. 30, 2018 | Jan. 31, 2018 | Oct. 31, 2017 | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  | $ 20,000,000.0 |  |  | $ 275,000 | $ 0 | $ 18,080,000 | $ 2,000,000
GB002 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  |  |  |  | 0 | 0 | 0 | 0
GB001 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  |  |  |  | 0 | 0 | 0 | 0
GB004 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  |  |  |  | 275,000 | 0 | 15,275,000 | 0
GB1275 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  |  |  |  | 0 | $ 0 | 0 | $ 1,000,000
Pulmokine, Inc. | License Agreement | GB002 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Product license term |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |
Upfront payment |  |  |  |  |  |  |  |  |  | $ 5,500,000 |  |  |  |
Milestones accrued |  |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Pulmokine, Inc. | License Agreement | GB002 | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Development and regulatory milestone payments, payable |  |  |  |  | $ 63,000,000.0 |  |  |  |  |  |  |  |  |
Commercial milestone payments, payable |  |  |  |  | 45,000,000.0 |  |  |  |  |  |  |  |  |
Sales milestone payments, payable |  |  |  |  | $ 190,000,000.0 |  |  |  |  |  |  |  |  |
AA Biopharma Inc. | GB001 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
In process research and development |  |  |  |  |  |  |  |  | $ 19,300,000 |  |  |  |  |
AA Biopharma Inc. | GB001 | Common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business acquisition, aggregate number of shares issued (in shares) |  |  |  | 1,101,278 |  |  |  |  |  |  |  |  |  |
AA Biopharma Inc. | GB001 | Series Seed Convertible Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business acquisition, aggregate number of shares issued (in shares) |  |  |  | 20,000,000 |  |  |  |  |  |  |  |  |  |
Aerpio Pharmaceuticals, Inc. | License Agreement | GB004 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront payment | $ 15,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Milestones accrued |  |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Participation rights |  |  | 20.00% |  |  |  |  |  |  |  |  |  |  |
Aerpio Pharmaceuticals, Inc. | License Agreement | GB004 | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Development and regulatory milestone payments, payable | 40,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Sales milestone payments, payable | $ 50,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Adhaere Pharmaceuticals, Inc. | GB1275 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Milestones accrued |  |  |  |  |  |  |  |  |  |  | $ 0 |  | $ 0 |
In process research and development |  |  |  |  |  |  | $ 7,500,000 |  |  |  |  |  |  |
Upfront payment, purchase consideration paid |  | $ 7,500,000 |  |  |  |  |  |  |  |  |  |  |  |
Milestones payment |  |  |  |  |  | $ 1,000,000.0 |  |  |  |  |  |  |  |
Adhaere Pharmaceuticals, Inc. | GB1275 | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory, development and sales milestone payments payable |  | $ 62,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |

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