License and Collaboration Agreements - Additional Information (Details)		1 Months Ended							3 Months Ended	12 Months Ended				52 Months Ended	53 Months Ended
	Jul. 13, 2020 USD ($) Program $ / shares shares	Jan. 31, 2022 USD ($)	Nov. 30, 2021 USD ($) Program	Feb. 28, 2021 USD ($) $ / shares shares	Jan. 31, 2021 USD ($) $ / shares shares	Nov. 30, 2019 USD ($)	Sep. 30, 2017 USD ($)	Aug. 31, 2017 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 30, 2021 USD ($)	Jul. 31, 2020 USD ($)
License And Collaboration Agreements [Line Items]
Issuance of common stock											$ 326,246,000
Option continuation payment due upon second anniversary of agreement										$ 100,000,000				$ 100,000,000	$ 100,000,000
Cost sharing receivable, current										744,595,000	1,049,000			744,595,000	744,595,000
Total collaboration and license revenues										382,882,000	77,517,000	$ 15,000,000
Deferred revenue recognized										202,082,000	7,000,000	7,000,000
Development expense										256,348,000	159,348,000	78,481,000
Remaining capitalized fees at closing										3,800,000
Fees allocated among performance obligations										8,300,000
Gilead Collaboration Agreement
License And Collaboration Agreements [Line Items]
Option payment upon achievement of certain development milestones	$ 150,000
Option payment upon completion of certain IND-enabling activities	60,000,000
Increase (decrease) in R&D expense										(24,900,000)	(3,400,000)
Purchase Agreement
License And Collaboration Agreements [Line Items]
Direct offering cost	1,900,000
Amended Gilead Collaboration Agreement
License And Collaboration Agreements [Line Items]
Upfront cash payment										725,000,000
Maximum ownership percentage of outstanding common stock remain unchanged					35.00%
Issuance of common stock					$ 220,300,000
Issuance of common stock, shares | shares					5,650,000
Shares issued, price per share | $ / shares					$ 39.00
Removeal of option continuation payment under agreement			$ 100,000,000
Initial transaction price										890,100,000
Deferred Revenue										165,100,000				165,100,000	165,100,000
Number of exercise option to programs | Program			3
Amended Gilead Collaboration Agreement | Subsequent Event
License And Collaboration Agreements [Line Items]
Option payment received		$ 725,000,000
Quemliclustat Option, and R&D Activities Agreement
License And Collaboration Agreements [Line Items]
Option payment upon achievement of certain development milestones										200,000,000
Total collaboration and license revenues										0
Deferred Revenue										175,600,000				175,600,000	175,600,000
R&D activities for Domvanalimab
License And Collaboration Agreements [Line Items]
Total collaboration and license revenues										0
Deferred Revenue										34,500,000				34,500,000	34,500,000
R&D and Commercialization Activities for Zimberelimab Monotherapy
License And Collaboration Agreements [Line Items]
Deferred revenue related to development and commercialization services										9,700,000				9,700,000	9,700,000
Total collaboration and license revenues										1,100,000
Deferred Revenue										10,100,000				10,100,000	10,100,000
Access Rights related to Research and Development Pipeline
License And Collaboration Agreements [Line Items]
Total collaboration and license revenues										30,900,000	15,400,000
AstraZeneca Agreement
License And Collaboration Agreements [Line Items]
Development cost recorded within research and development expenses										1,000,000.0	0
Gilead
License And Collaboration Agreements [Line Items]
Fee incurred to third party upon receipt of option exercise payments										4,500,000
Gilead | Gilead Collaboration Agreement
License And Collaboration Agreements [Line Items]
Upfront cash payment	$ 175,000,000
Collaboration term for current and future clinical programs	10 years
Contingent milestone payments receivable	$ 300,000,000
Option continuation payment receivable upon fourth anniversary of agreement	100,000,000
Option continuation payment receivable upon sixth anniversary of agreement	100,000,000
Option continuation payment receivable upon eighth anniversary of agreement	$ 100,000,000																$ 100,000,000
Additional collaboration term for programs entering clinical development prior to end of collaboration term	3 years
Option fee per program for all other programs entering clinical development to exercise option	$ 150,000,000
Number of research programs | Program	2
Option payment upon achievement of certain development milestones	$ 250,000,000
Deferred revenue related to etrumadenant option																$ 127,000,000.0
Option payment upon achievement of certain development milestones	$ 275,000,000
Deferred revenue related to domvanalimab option																36,700,000
Current and future programs exclusive access period	10 years
Performance obligation period	4 years
Contractual obligation remaining amount not obligated to pay	$ 300,000,000
Deferred revenue related to research and development pipeline										120,200,000				120,200,000	120,200,000	$ 91,700,000
Consultant and legal fees	7,300,000
Capitalized costs										3,800,000	1,200,000
Cost sharing receivable										4,900,000				4,900,000	4,900,000
Total collaboration and license revenues										0
Deferred revenue recognized										328,800,000
Deferred Revenue										218,700,000				218,700,000	218,700,000
Gilead | Gilead Collaboration Agreement | Prepaid Expenses and Other Current Assets
License And Collaboration Agreements [Line Items]
Cost sharing receivable, current										900,000				900,000	900,000
Gilead | Gilead Collaboration Agreement | Other Noncurrent Assets
License And Collaboration Agreements [Line Items]
Cost sharing receivable, noncurrent										4,000,000.0				4,000,000.0	4,000,000.0
Gilead | Gilead Collaboration Agreement | Maximum
License And Collaboration Agreements [Line Items]
Contingent milestone payments receivable	300,000,000
Potential regulatory approval milestones payment receivable related to domvanalimab	500,000,000
Gilead | Purchase Agreement
License And Collaboration Agreements [Line Items]
Issuance of common stock	200,000,000			$ 220,400,000						$ 220,296,000	107,468,000
Funds received for purchase of common stock											200,000,000
Purchase price of common stock allocation to performance obligation	$ 90,600,000										$ 90,600,000
Issuance of common stock, shares | shares	5,963,029			5,650,000							5,963,029
Shares issued, price per share | $ / shares	$ 33.54			$ 39.00							$ 33.54
Percentage of option to purchase maximum shares of common stock	35.00%
Period over common stock to be purchased	5 years
Percentage of premium purchase price of common stock	20.00%
Trailing days average closing price	5 days
Share Price | $ / shares	$ 33.54
Gilead | Purchase Agreement | May 2020 Public Offering
License And Collaboration Agreements [Line Items]
Shares issued, price per share | $ / shares											$ 27.50
Additional equity investment net of offering costs											$ 56,700,000
Additional equity investment shares issued | shares											2,200,000
Taiho Pharmaceutical Co., Ltd | Gilead Collaboration Agreement
License And Collaboration Agreements [Line Items]
Option period							5 years
Option ending period							2022-09
Payment for first option exercise			$ 15,000,000.0
Taiho Pharmaceutical Co., Ltd | Taiho Agreement
License And Collaboration Agreements [Line Items]
Non refundable and non creditable cash payments													$ 35,000,000.0
Payment for option exercise						$ 8,000,000.0								26,000,000.0
Range of royalties receivable on net sales										high single-digits to mid-teens
Royalties payable description										Royalties will be payable on a licensed product-by-licensed product and country-by-country basis during the period of time commencing on the first commercial sale of a licensed product in a country and ending upon the later of: (a) ten (10) years from the date of first commercial sale of such licensed product in such country; and (b) expiration of the last-to-expire valid claim of the Company’s patents covering the manufacture, use or sale or exploitation of such licensed product in such country (the Royalty Term).
Non-refundable, non-creditable upfront cash payments										$ 35,000,000
Estimated performance period										5 years
Clinical and regulatory milestones achieved										$ 0
Sales milestone or royalty revenue recognized										0
Deferred revenue, current										5,000,000.0	$ 7,000,000.0			$ 5,000,000.0	5,000,000.0
Deferred revenue, noncurrent											5,000,000.0
Taiho Pharmaceutical Co., Ltd | Taiho Agreement | Maximum
License And Collaboration Agreements [Line Items]
Contingent milestone payments receivable							$ 145,000,000.0
Payment for option exercise							15,000,000.0
Additional clinical and regulatory milestone payments receivable							130,000,000.0
Taiho Pharmaceutical Co., Ltd | Taiho Agreement | Minimum
License And Collaboration Agreements [Line Items]
Payment for option exercise							$ 3,000,000.0
WuXi Biologics License Agreement
License And Collaboration Agreements [Line Items]
Clinical and regulatory milestones achieved										$ 16,500,000
Range of tiered royalty payments on net sales										high single-digits to low teens
Milestone expense										$ 0	0
WuXi Biologics License Agreement | Forecast
License And Collaboration Agreements [Line Items]
Development milestone expense									$ 1,500,000
WuXi Biologics License Agreement | Research and Development
License And Collaboration Agreements [Line Items]
Upfront cash payment										500,000
Upfront and milestone payments															41,000,000.0
Milestone payments										10,000,000.0	5,000,000.0	7,500,000
Sub-license fees incurred										0	10,100,000	1,200,000			$ 11,300,000
WuXi Biologics License Agreement | Maximum
License And Collaboration Agreements [Line Items]
Clinical, regulatory and commercialization milestone payments								$ 375,000,000.0
Abmuno License Agreement
License And Collaboration Agreements [Line Items]
Upfront and milestone payments										14,600,000
Clinical, regulatory and commercialization remaining milestone payments										93,000,000.0
Milestone expense										5,000,000.0	3,000,000.0	0
Genentech
License And Collaboration Agreements [Line Items]
Development expense										$ 1,000,000.0	$ 500,000	$ 0