Income Taxes - Summary of components of the Company's net deferred tax assets (Detail) - USD ($) $ in Thousands  | 
Dec. 31, 2020  | 
Dec. 31, 2019  | 
|---|---|---|
| Deferred tax assets: | ||
| Net operating loss carryforwards | $ 72,785 | $ 42,051 | 
| Research and development credits | 13,499 | 7,759 | 
| Accruals and reserves | 493 | 551 | 
| Property and equipment | 811 | 474 | 
| Stock-based compensation | 649 | 418 | 
| Total deferred tax assets | 88,237 | 51,253 | 
| Valuation allowance | (88,237) | (51,115) | 
| Net deferred tax assets | 0 | 138 | 
| Deferred tax liabilities | ||
| Intangibles | 0 | (138) | 
| Total deferred tax liabilities | 0 | (138) | 
| Net deferred tax assets | $ 0 | $ 0 | 
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- References No definition available. 
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- References No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from property, plant, and equipment. No definition available. 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from reserves and accruals. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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