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Income Taxes - Components of Deferred Tax (Detail) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Deferred tax assets (liabilities): |  |
Net operating loss carryforwards | $ 32,664 | $ 23,650
Research and development credits | 11,765 | 8,124
Capitalized start-up and other costs | 68,859 | 45,374
Capitalized research and development costs | 79,562 | 48,917
Equity based compensation | 10,276 | 5,004
Accruals | 2,795 | 1,985
Other temporary differences | 36 | 27
Deferred tax assets before valuation allowance | 205,957 | 133,081
Valuation allowances | (205,957) | (133,081)
Net deferred tax assets | $ 0 | $ 0

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