Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating losses	$ 43,626	$ 14,442	$ 306
Tax credits, net	9,196	1,131
Amortization	6,597	6,267	1,588
Lease liability	2,329
Accrued compensation	1,476	834
Stock-based compensation	1,388		1
Other	383	154
Total gross deferred tax assets	64,995	22,828	1,895
Deferred tax liabilities:
Right of use asset	(2,164)
Property, plant and equipment	(57)	(16)
Stock-based compensation		(1,057)
Total gross deferred tax liabilities	(2,221)	(1,073)
Valuation allowance	$ (62,774)	$ (21,755)	$ (1,895)