Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands |
9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
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| Property, Plant and Equipment [Abstract] | ||||
| Depreciation | $ 392 | $ 182 | $ 287 | $ 0 |
| X | ||||||||||
- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- References No definition available.
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