Collaborations - Additional Information (Details)						3 Months Ended		12 Months Ended
	Aug. 20, 2020	Jul. 07, 2020 USD ($)	May 09, 2019 USD ($) $ / shares shares	Nov. 01, 2018	Oct. 31, 2017 shares	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($) shares
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized						$ 18,702,000	$ 3,428,000
Stock split, conversion ratio	1.5949
Research and development						25,962,000	12,116,000
Sanofi Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 150,000,000
Collaboration agreement transaction price		150,000,000
Revenue recognized recorded in deferred revenue						11,600,000
Unsatisfied performance obligation						122,000,000		$ 132,600,000
Cost reimbursement receivable						600,000
Milestone receivable						0
Royalty receivable						0
Unbilled accounts receivable						900,000
Billed accounts receivable						$ 900,000
Remaining research term of collaboration						3 years
Sanofi Agreement | Collaboration Target 1
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement transaction price		120,000,000
Revenue recognized recorded in deferred revenue						$ 9,500,000
Sanofi Agreement | Collaboration Target 2
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement transaction price		30,000,000
Revenue recognized recorded in deferred revenue						2,100,000
Sanofi Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestone payments		1,480,000,000
Commercial Milestone Payments		700,000,000
Sanofi Agreement | Minimum | IRAK4 Program
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestone payments		1,000,000,000
Commercial Milestone Payments		$ 400,000,000
Vertex Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized recorded in deferred revenue						7,100,000
Unsatisfied performance obligation						30,600,000		37,700,000
Initial research term of collaboration			4 years
Extended research term of collaboration			1 year
Revenue recognized						$ 7,100,000	3,400,000
Vertex Agreement | Series B-1 Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement transaction price			$ 55,900,000
Non refundable upfront payment received			$ 50,000,000
Number of shares issued | shares			3,059,695
Stock issued price per share | $ / shares			$ 6.54
Preferred stock premium			$ 5,900,000
Vertex Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Eligible to receive payments including development, regulatory and commercial milestones			$ 170,000,000
Revenue remaining research term						1 year 7 months 6 days
Compound Collaboration
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period to terminate collaboration agreement						60 days
Compound Collaboration | Series A Preferred Units
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares issued | shares					886,305
Stock split, conversion ratio				100
Share-based compensation vesting period				3 years
Research and development							$ 100,000	$ 100,000
Number of shares vested | shares							55,394	55,394