Collaboration and License Agreements - Janssen Collaboration and Option Agreement (Details) - USD ($)				1 Months Ended	3 Months Ended		6 Months Ended
	May 26, 2022	Apr. 07, 2020	Apr. 02, 2020	Jun. 30, 2020	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2021
Collaboration agreement
Collaboration contract asset					$ 9,108,000		$ 9,108,000			$ 9,870,000
Revenue recognized					18,549,000	$ 13,412,000	36,963,000	$ 24,552,000
Janssen Biotech Inc
Collaboration agreement
Upfront, non-refundable and non-creditable payment			$ 50,000,000.0				50,000,000.0
Transaction price of the agreement			66,000,000.0
Equity premium			16,000,000.0
Non-refundable upfront payments recorded as deferred revenue			$ 66,000,000.0
Option exercise payment	$ 10,000,000.0
Cash received upon achievement of each milestone							3,000,000.0
Collaboration contract asset					15,600,000		15,600,000
Amortization of sublicense consideration					1,200,000	700,000	2,400,000	1,100,000
Revenue recognized					18,100,000	10,900,000	34,100,000	19,500,000
Deferred revenue					51,400,000		51,400,000
Deferred revenue classified as current					33,700,000		33,700,000
Research and development fees cash payments received							49,400,000
Total cash received upon achievement of milestone							6,000,000.0
Janssen Biotech Inc | Research And Development
Collaboration agreement
Revenue recognized					11,400,000	7,100,000	21,200,000	13,800,000
Janssen Biotech Inc | Upfront Fee and Equity Premium
Collaboration agreement
Revenue recognized					6,700,000	$ 3,800,000	12,900,000	$ 5,700,000
Janssen Biotech Inc | Sublicense Consideration
Collaboration agreement
Collaboration contract asset					$ 9,100		$ 9,100
Johnson Johnson Innovation J J D C Inc | Stock Purchase Agreement
Collaboration agreement
Issuance of common stock in conjunction with public offering (in shares)							1,600,000
Common stock per share					$ 31.00		$ 31.00
Aggregate purchase price of common stock							$ 50,000,000.0
Equity premium per share							$ 9.93
Aggregate equity premium on shares							$ 16,000,000.0
Proceeds from public offering of common stock, net of issuance costs							$ 34,000,000.0
Johnson Johnson Innovation J J D C Inc | Stock Purchase Agreement | Private Placement
Collaboration agreement
Issuance of common stock in conjunction with public offering (in shares)							50,000,000.0
Proceeds from public offering of common stock, net of issuance costs				$ 50,000,000.0
Share issue price (in dollars per share)				$ 28.31					$ 28.31
Issuance of common stock during period for private placements (in shares)									1,800,000
First Janssen Cancer Target | Maximum | Janssen Agreement
Collaboration agreement
Development, regulatory, and sales milestones		$ 898,000,000.0
Additional candidate milestone Payments		460,000,000.0
Additional Cancer Targets | Maximum | Janssen Agreement
Collaboration agreement
Development, regulatory, and sales milestones		706,000,000.0
Additional candidate milestone Payments		$ 340,000,000.0