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Sole-Source Cost-Sharing Agreement and Cooperative Research and Development Agreement - Additional Information (Details) - USAMRMC - USD ($) | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jul. 31, 2015 | Sep. 30, 2017 | Dec. 31, 2018
Schedule Of Cost Sharing Agreement And Cooperative Research And Development Agreement [Line Items] |  |  |
Expiration date of original contract |  |  | Dec. 31, 2016
Reimbursement received |  |  | $ 3,000,000
Cooperative Research and Development Agreement |  |  |
Schedule Of Cost Sharing Agreement And Cooperative Research And Development Agreement [Line Items] |  |  |
Expiration year of original contract |  | 2018 |
Extended expiration date of original contract |  | Dec. 31, 2021 |
Maximum |  |  |
Schedule Of Cost Sharing Agreement And Cooperative Research And Development Agreement [Line Items] |  |  |
Reimbursed trial cost | $ 3,000,000 |  |

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