Collaboration and License Agreements - Additional Information (Details)		1 Months Ended			3 Months Ended	6 Months Ended
	Dec. 22, 2018 USD ($) Target	Aug. 31, 2021 USD ($)	May 31, 2021 USD ($)	Dec. 31, 2018 USD ($) Target Protein	Mar. 31, 2021	Jun. 30, 2021 USD ($) Target Performanceobligation TargetProtein
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of potential targets | Target	6
Additional upfront consideration received	$ 40,000,000.0
Annual research plan payments receivables	$ 1,000,000.0
Annual research plan payments periods	3 years
Collaboration description						The Company has control over the committee and may terminate the Roche Agreement on a target-by-target or product-by-product basis under several scenarios, upon at least 90 days’ prior written notice.
Restated Roche Agreement | Lead Series Identification Achievement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees	$ 2,000,000.0
Restated Roche Agreement | Good Laboratory Practice (“GLP”) Toxicology (“Tox”) Study Phase
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees	3,000,000.0
Restated Roche Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees	20,000,000.0
Restated Roche Agreement | Maximum | Research, Development and Commercial Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	275,000,000.0
Restated Roche Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	150,000,000.0
Restated Roche Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees	$ 7,000,000.0
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Agreement date				2018-12
Research agreement, period				54 months
Additional payment on extension of contract				$ 62,500,000
Nonrefundable upfront payment						$ 45,000,000.0
Number of performance obligation | Performanceobligation						1
Number of targets | Target						5
Number of additional targets | Target						2
Lead fee achieved			$ 3,000,000.0
Biogen License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targeted protein degradation | Protein				5
Additional targets for development | Target				5
Biogen License Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						$ 26,000,000.0
Biogen License Agreement | Maximum | Research And Development Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						$ 35,000,000.0
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]
Number of performance obligation | Performanceobligation						1
Number of targets | Target						5
Research term					5 years
Upfront payment						$ 5,000,000.0
Annual Payments						$ 5,000,000.0
Contractual term						5 years
Milestone payment received			$ 1,000,000.0
Calico License Agreement | Scenario Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research extend term		1 year
Amount payable for extend research term option		$ 1,000,000.0
Calico License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of target proteins | TargetProtein						5
Calico License Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						$ 65,000,000.0
Calico License Agreement | Maximum | Potential Research, Development and Commercial Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received						132,000,000.0
Restated Roche Agreement, Biogen License Agreement and Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate amount of the transaction price allocated to the performance obligations that are partially unsatisfied as of the end of the reporting period						$ 84,100,000