Property and equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total, at cost	$ 12,557	$ 12,250
Accumulated depreciation	(4,984)	(4,243)
Total, net	7,573	8,007
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Total, at cost	5,660	5,655
Lab equipment [Member]
Property Plant And Equipment [Line Items]
Total, at cost	5,145	4,833
Computer equipment [Member]
Property Plant And Equipment [Line Items]
Total, at cost	978	942
Furniture and office equipment [Member]
Property Plant And Equipment [Line Items]
Total, at cost	459	459
Vehicles [Member]
Property Plant And Equipment [Line Items]
Total, at cost	296	296
Asset under construction [Member]
Property Plant And Equipment [Line Items]
Total, at cost	$ 19	$ 65