Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue:
Total revenue	$ 207,085	$ 21,098	$ 21,219
Type of Revenue [Extensible List]	Collaboration Revenue [Member]	Collaboration Revenue [Member]	Collaboration Revenue [Member]
Operating expenses:
Research and development	$ 189,407	$ 156,869	$ 100,528
General and administrative	55,038	59,403	35,095
Total operating expenses	244,445	216,272	135,623
Loss from operations	(37,360)	(195,174)	(114,404)
Other income, net	1,031	4,946	9,019
Net loss	(36,329)	(190,228)	(105,385)
Unrealized gain (loss) on marketable securities	(1,557)	472	184
Comprehensive loss	$ (37,886)	$ (189,756)	$ (105,201)
Net loss per share, basic and diluted	$ (0.45)	$ (2.45)	$ (1.71)
Shares used in computing net loss per share, basic and diluted	80,416,936	77,758,806	61,734,492