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Commitments and Contingencies (Detail) - USD ($) | Dec. 31, 2020 | Dec. 31, 2019
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Loss Contingencies [Line Items] |  |
Purchase commitments related to contract manufacturing, clinical development and certain other items | $ 8,000,000.0 |
Legal Matters |  |
Loss Contingencies [Line Items] |  |
Litigation matters, liabilities | 0 | $ 0
Indemnification Obligation |  |
Loss Contingencies [Line Items] |  |
Litigation matters, liabilities | 0 | 0
Commercial Agreements |  |
Loss Contingencies [Line Items] |  |
Litigation matters, liabilities | 0 | $ 0
Merger and Acquisition Related Claims | Maximum |  |
Loss Contingencies [Line Items] |  |
Obligations under Director and Officer Indemnifications per incident | 10,000,000.0 |
Securities Related Claims |  |
Loss Contingencies [Line Items] |  |
Obligations under Director and Officer Indemnifications per incident | 10,000,000.0 |
Non-Securities Related Claims |  |
Loss Contingencies [Line Items] |  |
Obligations under Director and Officer Indemnifications per incident | $ 10,000,000.0 |

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