Collaboration and license agreements - Narrative (Details) $ / shares in Units, $ in Thousands					1 Months Ended								3 Months Ended		9 Months Ended		40 Months Ended
	Sep. 30, 2024 USD ($) performanceObligation target	Mar. 01, 2024 USD ($) target	Dec. 11, 2023 USD ($) performanceObligation target	May 29, 2023 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) performanceObligation target	Apr. 30, 2024 USD ($)	Dec. 31, 2023 USD ($) target	Aug. 31, 2021 USD ($)	Nov. 30, 2020 USD ($) target	Feb. 29, 2020 USD ($) protein	Dec. 31, 2018 USD ($) target performanceObligation	Mar. 31, 2017 USD ($)	Sep. 30, 2024 USD ($) performanceObligation target	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) performanceObligation target	Sep. 30, 2023 USD ($)	Jun. 30, 2020 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of performance obligations | performanceObligation											12
Transaction price allocated to performance obligation	$ 19,064				$ 19,064								$ 19,064		$ 19,064
Contract with customer, liability	$ 49,417				$ 49,417		$ 37,285						49,417		49,417
Revenue from collaboration agreements													15,362	$ 11,072	30,407	$ 17,495
Revenue recognized that was included in the contract liability at the beginning of the period													$ 4,994	2,664	$ 9,996	5,895
MKDG Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of potential research and development targets | target	2	2			2								2		2
Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement				90 days
MKDG Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 16,000
Number of performance obligations | performanceObligation	2				2								2		2
Transaction price allocated to performance obligation	$ 16,000				$ 16,000								$ 16,000		$ 16,000
Contract with customer, liability	14,422				14,422								14,422		14,422
Revenue from collaboration agreements													2,368	0	4,317	0
MKDG Agreement | Discovery, Regulatory, and Commercial Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	740,000				740,000								740,000		740,000
MKDG Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement		60 days
Merck Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment			$ 10,000
Number of performance obligations | performanceObligation			1
Contract with customer, liability	6,569				6,569		10,000						6,569		6,569
Option to include number of additional targets | target			3
Potential proceeds from collaboration			$ 2,500,000
Revenue from collaboration agreements													1,684	0	3,431	0
Merck Agreement | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive			$ 600,000
Merck Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement			60 days
Betta Agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	10,000			$ 10,000										1,000
Contract with customer, liability	15,310				15,310		12,000						15,310		15,310
Stock repurchase program, number of shares authorized to be repurchased (in shares) | shares				5,567,928
Stock repurchase program, authorized amount				$ 25,000
Share price (in dollars per share) | $ / shares				$ 4.49
Stock repurchase program, premium percentage				25.00%
Duration of trading day volume weighted average closing price				60 days
Trading days prior to the effective date of the Stock Purchase Agreement				2 days
Estimated transaction price	135,700				135,700								135,700		135,700
Transaction price from closing of the stock purchase agreement	5,000
Regulatory milestone achieved							$ 2,000
Expected consideration to be received from manufactured clinical supply	118,700				118,700								118,700		118,700
Revenue from collaboration agreements													2,896	$ 0	2,896	$ 0
Betta Agreements | Research and development milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				$ 357,000
Betta Agreements | Drug Application Approval
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				$ 40,000
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets | target							2		2
Additional upfront consideration received											$ 40,000
Number of potential targets | target									5		6
Annual research plan payments receivables									$ 1,000
Option exercise fees									$ 8,000
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
Restated Roche Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive									150,000
Restated Roche Agreement | Lead series identification achievement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees									$ 2,000
Biogen Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research agreement, period										54 months
Nonrefundable upfront payment										$ 45,000
Revenue recognized that was included in the contract liability at the beginning of the period					8,000	$ 8,000
Biogen Research and 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
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
Biogen Research and License Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received										$ 26,000
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment																	$ 5,000
Research term												5 years
Research extend term								1 year
Amount payable for extend research term option								$ 1,000
Annual payments																	$ 5,000
Calico License Agreement | Maximum | One-time sales-based payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received												$ 65,000
Calico License Agreement | Maximum | Potential research, development and commercial milestone payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received												$ 132,000
Restated Roche Agreement And Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated to performance obligation	$ 170,000				$ 170,000								$ 170,000		$ 170,000