Share-Based Payment and Related Stock Option Plan - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
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| Share-based Payment Arrangement [Abstract] | ||||||
| Total share-based compensation expense | $ 3,933 | $ 315 | $ 4,564 | $ 846 | $ 1,161 | $ 1,682 |
| Unrecognized compensation cost | $ 0 | $ 0 | $ 3,416 | $ 3,793 | ||
| Remaining recognition period (in years) | 2 years 8 months 12 days | 3 years 4 months 24 days | ||||
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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- References No definition available.
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- Definition Amount of cost not yet recognized for nonvested award under share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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