Income Taxes - Schedule of the Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses carryforwards	$ 90,534	$ 36,783
Intangible assets	14,165	17,107
Accruals and reserves	4,936	5,127
Research and development credits	11,031	5,753
Stock-based compensation	3,143	1,289
Lease liabilities	10,195	0
Other	160	210
Total deferred tax asset	134,164	66,269
Deferred tax liabilities:
Property and equipment	(119)	(73)
Section 481 (a) adjustment	(914)	0
Right-of-use asset	(7,363)	0
Unrealized gain/loss on investments	(346)	0
Less: valuation allowance	(125,245)	(66,196)
Net deferred tax assets	$ 177	$ 0