Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total property and equipment	$ 13,010	$ 12,504
Less: accumulated depreciation	(3,427)	(1,958)
Property and equipment, net	9,583	10,546
Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	5,634	4,847
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	548	542
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	512	517
Software
Property Plant And Equipment [Line Items]
Total property and equipment	106	90
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 6,210	6,174
Construction in Process
Property Plant And Equipment [Line Items]
Total property and equipment		$ 334