License and Collaborations - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2017	Dec. 31, 2022	Mar. 31, 2022
License And Collaboration Agreements [Line Items]
Liabilities classified as noncurrent	$ 144,000,000		$ 144,000,000			$ 140,000,000
Shared costs classified as other noncurrent assets	109,000,000		109,000,000			114,000,000
Total collaboration and license revenues	29,000,000	$ 27,000,000	54,000,000	$ 45,000,000
Research and Development
License And Collaboration Agreements [Line Items]
Reimbursement from related party for shared costs	34,000,000	36,000,000	67,000,000	66,000,000
WuXi Biologics License Agreement | anti-CD39 | Research and Development
License And Collaboration Agreements [Line Items]
Development milestone expense	0	0	1,000,000	2,000,000
WuXi Biologics License Agreement | Maximum | anti-PD-1
License And Collaboration Agreements [Line Items]
Clinical, regulatory and commercialization milestone payments					$ 375,000,000
WuXi Biologics License Agreement | Maximum | anti-CD39
License And Collaboration Agreements [Line Items]
Additional clinical, regulatory and commercialization milestone payments			14,000,000
Abmuno License Agreement
License And Collaboration Agreements [Line Items]
Additional clinical, regulatory and commercialization milestone payments			88,000,000
AstraZeneca Agreement
License And Collaboration Agreements [Line Items]
Liabilities classified as noncurrent	10,000,000		10,000,000			5,000,000
Development cost recorded within research and development expenses	3,000,000	1,000,000	$ 5,000,000	2,000,000
Taiho Agreement | Taiho Pharmaceutical Co., Ltd
License And Collaboration Agreements [Line Items]
Option period					5 years
Option ending period					2022-09
Non refundable and non creditable cash payments					$ 35,000,000
Range of royalties receivable on net sales			high single-digits to mid-teens
Royalties payable description			Royalties will be payable by product and country commencing on the first commercial sale and ending upon the later of: (a) 10 years; and (b) expiration of the last-to-expire valid claim of our patents covering the manufacture, use or sale.
Total collaboration and license revenues		$ 1,000,000		$ 3,000,000
Reimbursement of research and development expense	2,000,000		$ 2,000,000
Deferred revenue							$ 0
Taiho Agreement | Taiho Pharmaceutical Co., Ltd | Minimum
License And Collaboration Agreements [Line Items]
Payment for option exercise					3,000,000
Taiho Agreement | Taiho Pharmaceutical Co., Ltd | Maximum
License And Collaboration Agreements [Line Items]
Contingent milestone payments receivable					145,000,000
Payment for option exercise					15,000,000
Additional clinical and regulatory milestone payments receivable					$ 130,000,000
Option License And Collaboration Agreement [Member]
License And Collaboration Agreements [Line Items]
Shared costs classified as other noncurrent assets	5,000,000		5,000,000			2,000,000
Deferred revenue	$ 433,000,000		$ 433,000,000			$ 452,000,000