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Convertible Promissory Notes - Additional Information (Detail) $ / shares in Units, ¥ in Thousands, $ in Thousands | Feb. 03, 2018 CNY (¥) | Dec. 31, 2020 $ / shares shares | Feb. 03, 2018 USD ($) $ / shares | Oct. 31, 2016 $ / shares
--- | --- | --- | --- | ---
Debt Conversion [Line Items] |  |  |  |
Share price |  |  |  | $ 0.77
2018 Notes [Member] | Genexine Inc [Member] |  |  |  |
Debt Conversion [Line Items] |  |  |  |
Shares issued | shares |  | 900,000 |  |
Share price |  | $ 10 |  |
2018 Notes [Member] | Series A-3 Preferred Shares [Member] |  |  |  |
Debt Conversion [Line Items] |  |  |  |
Convertible promissory notes issued to Investors | ¥ | ¥ 59,704 |  |  |
Convertible Promissory Notes 2018 [Member] | Series B-1 Preferred Shares [Member] |  |  |  |
Debt Conversion [Line Items] |  |  |  |
Conversion price of debt instrument |  |  | $ 10 |
Convertible Promissory Notes 2018 [Member] | Series A-3 Preferred Shares [Member] |  |  |  |
Debt Conversion [Line Items] |  |  |  |
Maturity period of debt instrument | 36 months |  |  |
Convertible notes issued | $ |  |  | $ 9,000 |
Interest Rate |  |  | 0.00% |
Share price |  |  | $ 3.96 |

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