Furniture, Equipment and Leasehold Improvements, Net - Additional Information (Detail) - USD ($) $ in Thousands  | 
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2021  | 
Mar. 31, 2020  | 
Dec. 31, 2020  | 
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| Property Plant And Equipment [Line Items] | |||
| Depreciation expense | $ 281 | $ 273 | |
| Leased assets write off | 82 | ||
| Accumulated depreciation | 10,471 | $ 10,190 | |
| Leased Assets | |||
| Property Plant And Equipment [Line Items] | |||
| Accumulated depreciation | $ 64 | ||
| X | ||||||||||
- Definition Write off of leased assets. No definition available. 
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- Definition Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| 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 | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Details 
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