Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Collaboration revenue	$ 18,549	$ 13,412	$ 36,963	$ 24,552
Type of Revenue [Extensible List]	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember
Operating expenses:
Research and development	$ 81,307	$ 48,023	$ 153,446	$ 92,873
General and administrative	20,351	12,168	41,093	24,668
Total operating expenses	101,658	60,191	194,539	117,541
Loss from operations	(83,109)	(46,779)	(157,576)	(92,989)
Other income:
Interest income	757	346	1,175	723
Change in fair value of stock price appreciation milestones	5,881	(8,700)	14,240	(7,956)
Other income:	366	0	366	0
Total other income (expense)	7,004	(8,354)	15,781	(7,233)
Net loss	(76,105)	(55,133)	(141,795)	(100,222)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities, net	(531)	174	(2,619)	(156)
Comprehensive loss	$ (76,636)	$ (54,959)	$ (144,414)	$ (100,378)
Earnings Per Share, Basic	$ (0.79)	$ (0.58)	$ (1.47)	$ (1.07)
Earnings Per Share, Diluted	$ (0.79)	$ (0.58)	$ (1.47)	$ (1.07)
Weighted Average Number of Shares Outstanding, Basic	96,704,413	94,326,648	96,524,968	93,881,734
Weighted Average Number of Shares Outstanding, Diluted	96,704,413	94,326,648	96,524,968	93,881,734