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Subsequent Events - Additional information (Detail) $ / shares in Units, $ in Millions | 1 Months Ended | 9 Months Ended
--- | --- | ---
Dec. 31, 2020 USD ($) shares $ / shares | Sep. 30, 2020 USD ($)
Amendment Subscription Agreement With Hill House Entities [Member] |  |
Subsequent Event [Line Items] |  |
Number of share issued, ADS | shares | 8,712,124 |
Class of warrants or rights issued during the period | shares | 1,597,235 |
Proceeds from equity issuances | $ 125.0 |
AbbVie [Member] |  |
Subsequent Event [Line Items] |  |
Upfront payment received |  | $ 180.0
Subsequent Event [Member] | AbbVie [Member] |  |
Subsequent Event [Line Items] |  |
Upfront payment received | 180.0 |
Milestone payment receivable | $ 20.0 |
Subsequent Event [Member] | Genexine Inc [Member] | 2018 Notes [Member] |  |
Subsequent Event [Line Items] |  |
Conversion price of debt instrument | $ / shares | $ 10 |
Stock shares issued during period conversion of debt into equity | shares | 900,000 |

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