Fixed Assets, net - Schedule of Fixed Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation and amortization	$ (8,773)	$ (8,494)
Total	7,432	7,579
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	2,959	2,836
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	2,225	2,225
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 11,021	$ 11,012