Collaboration and license agreements - Narrative (Details)			1 Months Ended						12 Months Ended		40 Months Ended
	Dec. 11, 2023 USD ($) target	May 29, 2023 USD ($) $ / shares shares	Sep. 30, 2021 USD ($)	Aug. 31, 2021	Nov. 30, 2020 USD ($) target	Feb. 29, 2020 USD ($) protein	Dec. 31, 2018 USD ($) performanceObligation target	Mar. 31, 2017 USD ($)	Dec. 31, 2023 USD ($) performance_obligation target	Dec. 31, 2022 USD ($)	Jun. 30, 2020 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract with customer, liability									$ 37,285,000	$ 33,513,000
Number of performance obligations | performanceObligation							12
Revenue from collaboration agreements									20,756,000	31,096,000
Revenue recognized that was included in the contract liability at the beginning of the period									20,185,000	25,412,000
Transaction price allocated to performance obligation									67,906,000
Foreign Tax Authority
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments for tax withholdings									1,000,000
Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement		90 days
Merck Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 10,000,000
Option to include number of additional targets | target	3
Potential proceeds from collaboration	$ 2,500,000,000
Contract with customer, liability									10,000,000
Merck Agreement | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	$ 600,000,000
Betta Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 10,000,000							9,000,000
Contract with customer, liability									12,000,000
Stock repurchase program, number of shares authorized to be repurchased (in shares) | 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%
Regulatory milestone achieved									2,000,000
Revenue from collaboration agreements									$ 0	$ 0
Betta Agreement | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive		$ 357,000,000
Betta Agreement | Drug Application Approval
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive		$ 40,000,000
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					2				2
Annual research plan payments receivables					$ 1,000,000
Option exercise fees					8,000,000
Restated Roche Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement									90 days
Restated Roche Agreement | Maximum | Research, development and commercial milestone payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive					273,000,000
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
Biogen Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research agreement, period						54 months
Nonrefundable upfront payment						$ 45,000,000
Biogen Research and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targeted protein degradation | protein						5
Biogen Research and License Agreement | Maximum | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						$ 35,000,000
Biogen Research and License Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						$ 26,000,000
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets | target									5
Number of performance obligations | performance_obligation									1
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									$ 800,000
Biogen License Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement									90 days
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment											$ 5,000,000
Research term								5 years
Research extend term				1 year
Amount payable for extend research term option			$ 1,000,000
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
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated to performance obligation									$ 41,900,000