Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 12,636	$ 4,843
Less accumulated depreciation	(1,652)	(1,049)
Property and equipment, net	10,984	3,794
Lab and Office Equipment Under and Financing Right of Use Asset
Property Plant And Equipment [Line Items]
Total property and equipment	2,771	2,751
Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	1,478	919
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	89	71
Furniture & Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	861	104
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	6,820	545
Assets Not Yet in Service
Property Plant And Equipment [Line Items]
Total property and equipment	$ 617	$ 453