Collaboration and license agreements - Narrative (Details)		1 Months Ended						3 Months Ended		6 Months Ended		40 Months Ended
	Jun. 30, 2023 USD ($) performanceObligation target	Sep. 30, 2021 USD ($)	Aug. 31, 2021	Nov. 30, 2020 USD ($) target	Feb. 29, 2020 USD ($) protein	Dec. 31, 2018 USD ($) target	Mar. 31, 2017 USD ($)	Jun. 30, 2023 USD ($) performanceObligation target	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) performanceObligation target	Jun. 30, 2022 USD ($)	Jun. 30, 2020 USD ($)	May 29, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price	$ 38,618,000							$ 38,618,000		$ 38,618,000				$ 33,513,000
Revenue from collaboration agreements								2,664,000	$ 13,834,000	6,423,000	$ 21,488,000
Revenue recognized that was included in the contract liability at the beginning of the period								2,664,000	$ 12,122,000	5,895,000	$ 18,488,000
Transaction price allocated to performance obligation	$ 67,822,000							$ 67,822,000		$ 67,822,000
Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement					90 days
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additional upfront consideration received						$ 40,000,000
Number of potential targets | target				5		6
Number of targets | target	3							3		3
Annual research plan payments receivables				$ 1,000,000
Annual research plan payments periods				3 years
Restated Roche Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees				$ 7,000,000
Written notice period for termination of agreement										90 days
Restated Roche Agreement | Minimum | Research, development and commercial milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				260,000,000
Restated Roche Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees				12,000,000
Option exercise fees, through Phase 1 trials				20,000,000
Restated Roche Agreement | Maximum | Research, development and commercial milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				275,000,000
Restated Roche Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				150,000,000
Restated Roche Agreement | Lead Series Identification Achievement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees				2,000,000
Restated Roche Agreement | Good Laboratory Practice (“GLP”) Toxicology (“Tox”) Study Phase
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees				$ 3,000,000
Betta Agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares authorized to be repurchased | shares													5,567,928
Stock repurchase program, authorized amount													$ 25,000,000
Share price (in dollars per share) | $ / shares													$ 4.49
Stock Repurchase Program, Premium Percentage													25.00%
Transaction price	$ 10,000,000							$ 10,000,000		$ 10,000,000
Revenue from collaboration agreements								$ 0		$ 0
Upfront payment	$ 10,000,000
Betta Agreements | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive													$ 357,000,000
Betta Agreements | Drug Application Approval
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive													$ 40,000,000
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets | performanceObligation	5							5		5
Research agreement, period					54 months
Nonrefundable upfront payment					$ 45,000,000
Number of performance obligation | performanceObligation	1							1		1
Number of additional targets | target										2
Biogen License Agreement | Research and development services
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized that was included in the contract liability at the beginning of the period										$ 55,000,000
Transaction price allocated to performance obligation	$ 6,600,000							$ 6,600,000		6,600,000
Biogen License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targeted protein degradation | protein					5
Biogen License Agreement | Maximum | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received					$ 35,000,000
Biogen License Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received					$ 26,000,000
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research term							5 years
Amount payable for extend research term option		$ 1,000,000
Research extend term			1 year
Upfront payment												$ 5,000,000
Annual payments												$ 5,000,000
Calico License Agreement | Research and development services
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized that was included in the contract liability at the beginning of the period										13,000,000
Calico License Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							$ 65,000,000
Calico License Agreement | Maximum | Potential research, development and commercial milestone payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							$ 132,000,000
Restated Roche Agreement And Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated to performance obligation	$ 44,100,000							$ 44,100,000		$ 44,100,000