Collaboration Agreements - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended			12 Months Ended	27 Months Ended	33 Months Ended
	Jan. 31, 2021	Dec. 31, 2019	Jun. 30, 2019	May 31, 2022	Feb. 28, 2022	Feb. 28, 2021	Nov. 30, 2021	Feb. 28, 2022	Feb. 28, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue					$ 9,621,000	$ 5,011,000
Deferred revenue, current					43,186,000		$ 41,212,000	$ 43,186,000	$ 43,186,000
Contract asset unbilled amount					$ 2,000,000			2,000,000	2,000,000
Gilead Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment			$ 45,000,000.0
Upfront payment of additional fees			3,000,000.0
Research milestones payments received									24,500,000
Variable consideration included in transaction price			$ 30,500,000
Collaboration agreement contract term					5 years
Collaboration revenue					$ 6,200,000	2,700,000
Collaboration revenue recognized from opening contract liability							3,300,000
Performance obligation satisfied					2,500,000	500,000
Recorded deferred revenue					40,900,000		41,100,000	40,900,000	40,900,000
Deferred revenue, current					19,800,000		19,900,000	19,800,000	19,800,000
Accounts receivable					6,000.0		6,000.0	6,000.0	6,000.0
Gilead Agreement | Scenario Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Recognized research milestone payments to be received				$ 6,000,000.0
Gilead Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total additional payments receivable					2,300,000,000			2,300,000,000	2,300,000,000
Development milestone payments, receivable					671,500,000			671,500,000	671,500,000
Sales milestone payments, receivable					1,500,000,000			1,500,000,000	1,500,000,000
Additional fees receivable related to target licensing, reservation and selection and research term extensions					139,800,000			139,800,000	139,800,000
Sanofi Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment		$ 55,000,000.0			55,000,000.0
Research milestones payments received								1,000,000.0
Variable consideration included in transaction price					3,000,000.0			3,000,000.0	3,000,000.0
Collaboration revenue recognized from opening contract liability							2,900,000
Performance obligation satisfied					400,000
Recorded deferred revenue					57,700,000		59,200,000	57,700,000	57,700,000
Deferred revenue, current					23,400,000		$ 21,300,000	23,400,000	23,400,000
Payment received to exercise option to expand number of targets	$ 22,000,000.0
Additional payment received to exercise option to expand number of targets	$ 22,000,000.0
Collaborative agreement expected transaction price					77,000,000.0			77,000,000.0	77,000,000.0
Collaborative agreement additional transaction price					$ 22,000,000.0			22,000,000.0	22,000,000.0
Contractual initial research period					4 years 3 months
Collaboration revenue					$ 3,400,000	$ 2,300,000
Contract asset unbilled amount					2,000,000.0			2,000,000.0	2,000,000.0
Sanofi Agreement | Scenario Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research milestones payments received				$ 2,000,000.0
Sanofi Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestone payments, receivable					497,000,000.0			497,000,000.0	497,000,000.0
Sales milestone payments, receivable					1,300,000,000			1,300,000,000	1,300,000,000
Milestone payments additional fees, total					2,500,000,000			2,500,000,000	2,500,000,000
Regulatory milestone payments, receivable					625,000,000.0			625,000,000.0	625,000,000.0
Additional fees receivable related to target licensing and reservation					$ 131,800,000			$ 131,800,000	$ 131,800,000