Related Party Transactions - Additional Information (Detail) - USD ($)
$ in Millions |
1 Months Ended |
12 Months Ended |
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Feb. 28, 2021 |
Dec. 31, 2020 |
Jul. 31, 2018 |
Mar. 31, 2021 |
Mar. 31, 2020 |
Mar. 31, 2019 |
| Series F-1 Redeemable Convertible Preferred Stock [Member] |
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| Related Party Transaction [Line Items] |
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| Temporary equity shares issued during the period shares |
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4,755,037
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| Glaxosmithkline Agreement [Member] | Glaxosmith Kline [Member] | Series F-1 Redeemable Convertible Preferred Stock [Member] |
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| Related Party Transaction [Line Items] |
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| Temporary equity shares issued during the period shares |
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17,291,066
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| Business collaborations, percentage of voting rights |
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10.00%
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10.00%
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10.00%
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| Early Exercise Of Unvested Stock Options [Member] | Chief Executive Officer [Member] | Share-based Payment Arrangement, Option [Member] | Two Thousand And Six Equity Incentive Plan [Member] |
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| Related Party Transaction [Line Items] |
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| Share based compensation by share based payment arrangement early accelarated vesting of unrecognized shares |
7,111,979
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| Share based compensation by share based payment arrangement unrecognized stock compensation expense recognized |
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$ 40.4
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