Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Collaboration revenue	[1]	$ 33,053	$ 57,994	$ 43,103
Type of Revenue [Extensible List]		us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development		$ 229,807	$ 150,408	$ 108,413
General and administrative		71,096	44,169	41,058
Total operating expenses		300,903	194,577	149,471
Operating loss		(267,850)	(136,583)	(106,368)
Loss from equity method investments		1,325	0	0
Interest income		1,283	2,352	6,835
Total other (expense) income, net		42	2,352	6,835
Net loss		$ (267,892)	$ (134,231)	$ (99,533)
Net loss per share, basic and diluted		$ (3.78)	$ (2.40)	$ (2.11)
Weighted average shares outstanding, basic and diluted		70,894	55,987	47,247
Other comprehensive (loss) income:
Marketable Securities, Unrealized Gain (Loss), Total		$ (2,126)	$ (260)	$ 289
Other comprehensive loss from equity method investment		(507)	0	0
Comprehensive loss		$ (270,525)	$ (134,491)	$ (99,244)

[1]   (1) Including the following revenue from related party (see Notes 9 and 15):   $ 6,072     $ -     $ -