Property and Equipment, net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 75,794	$ 63,335
Accumulated depreciation	(23,881)	(21,175)
Total property and equipment, net	51,913	42,160
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	1,472	727
Furniture, Fixtures and Other [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	3,420	3,416
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	27,956	25,353
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	25,977	25,473
Construction Work in Process [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 16,969	$ 8,366