Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Revenue	$ 3	$ 65
Operating expenses:
Research and development	43,174	44,630
General and administrative	13,494	19,279
Other operating income, net	(1,090)	(1,288)
Total operating expenses	55,578	62,621
Loss from operations	(55,575)	(62,556)
Interest income, net	6,819	4,497
Other income, net	1,090	1,100
Impairment of other investments	(13,001)	(10,000)
Total other loss, net	(5,092)	(4,403)
Net loss	(60,667)	(66,959)
Other comprehensive loss:
Net unrealized (loss) gain on marketable securities	(310)	3,720
Comprehensive loss	$ (60,977)	$ (63,239)
Net loss per common share, basic (in dollars per share)	$ (0.24)	$ (0.27)
Net loss per common share, diluted (in dollars per share)	$ (0.24)	$ (0.27)
Weighted-average shares used to compute net loss per common share, basic (in shares)	254,252	249,591
Weighted-average shares used to compute net loss per common share, diluted (in shares)	254,252	249,591