Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenues:
Total revenues	$ 28	$ 145
Operating expenses:
Research and development (Includes $5 and $16 of net recoveries from a related party)	122	109
General and administrative	28	32
Impairment of long-lived assets	0	20
Total operating expenses	150	161
Loss from operations	(122)	(16)
Non-operating income (expense):
Interest and other income, net	11	13
Interest expense	(1)	(1)
Total non-operating income, net	10	12
Loss before income taxes	(112)	(4)
Income tax expense	0	0
Net loss	$ (112)	$ (4)
Net loss per share, basic (in dollars per share)	$ (1.14)	$ (0.05)
Net loss per share, diluted (in dollars per share)	$ (1.14)	$ (0.05)
Shares used to compute loss per share, basic (in shares)	98.4	86.2
Shares used to compute loss per share, diluted (in shares)	98.4	86.2
License and Development Services Revenue
Revenues:
Total revenues	$ 20	$ 135
Other Collaboration Revenue
Revenues:
Total revenues	$ 8	$ 10