Research Collaboration and License Agreements - Narrative (Details)				1 Months Ended		3 Months Ended				9 Months Ended		12 Months Ended		15 Months Ended	24 Months Ended	81 Months Ended
	Apr. 01, 2021	Mar. 31, 2021 USD ($)	Mar. 17, 2020 USD ($)	Mar. 31, 2019 USD ($)	Nov. 30, 2018 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2015 USD ($) option	Mar. 31, 2022 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	[1]
Collaborative Arrangement [Line Items]
Collaboration and license revenue							$ 18,575,000	$ 23,482,000		$ 56,923,000	$ 67,601,000
Related party contract asset		$ 4,600,000					0			0						$ 0	$ 6,100,000
Related party revenue							18,600,000
Contract liabilities							12,288,000			12,288,000						12,288,000	$ 0
Proof-Of-Concept Trial, CVM Research
Collaborative Arrangement [Line Items]
Milestone payment for potential achievement of certain clinical development events										10,000,000
Forecast
Collaborative Arrangement [Line Items]
Amount of additional fund received for research activities														$ 20,000,000
Merck Amended Agreement | Minimum
Collaborative Arrangement [Line Items]
Option exercise fee										40,000,000
Merck Amended Agreement | Maximum
Collaborative Arrangement [Line Items]
Option exercise fee										45,000,000
Merck Amended Agreement | Proof-Of-Concept Trial, CVM Research
Collaborative Arrangement [Line Items]
Option exercise fee										$ 6,000,000
Merck Sharp & Dohme Corp | Merck Original Agreement
Collaborative Arrangement [Line Items]
Performance of R&D services period									5 years				5 years
Number of options to extend performance of research program | option													2
Additional term		2 years	2 years	2 years						2 years			2 years
Research collaboration and license agreements extension fee													$ 20,000,000
Amount of fund received for research activities				$ 75,000,000
Upfront license fee					$ 20,000,000				$ 4,900,000
Funded percentage of global development costs													25.00%
Aggregate milestone payments													$ 449,000,000
Milestone payments													$ 125,000,000
R&D tail period													3 years
Upfront payment received													$ 94,000,000
Collaboration and license revenue																388,100,000
Transaction price for the two-year performance obligation			$ 170,000,000
Collaborative arrangement funding, amount			$ 75,000,000
Merck Sharp & Dohme Corp | Merck Original Agreement | Forecast
Collaborative Arrangement [Line Items]
Milestone payments						$ 20,000,000
Merck Sharp & Dohme Corp | Merck Amended Agreement
Collaborative Arrangement [Line Items]
Additional term	3 years
Research collaboration and license agreements extension fee										$ 20,000,000
Funded percentage of global development costs										50.00%
Transaction price for the two-year performance obligation							$ 126,100,000			$ 126,100,000						$ 126,100,000
Remaining extension fee										16,000,000
Required amount to expend										$ 35,000,000
Remaining extension term										2 years
Research and development performance obligation period										3 years
Merck Sharp & Dohme Corp | Merck Amended Agreement | Minimum
Collaborative Arrangement [Line Items]
Reinvestment amount from option fee										$ 5,000,000
Merck Sharp & Dohme Corp | Merck Amended Agreement | Maximum
Collaborative Arrangement [Line Items]
Reinvestment amount from option fee										$ 15,000,000
Merck Sharp & Dohme Corp | Merck Amended Agreement | Forecast
Collaborative Arrangement [Line Items]
Amount of fund received for research activities												$ 86,000,000
Amount of additional fund received for research activities												$ 20,000,000
Reimbursable expense															$ 20,100,000

[1] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited financial statements as of that date.