Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessee Lease Description [Line Items]
Lease expense			$ 100,000	$ 700,000	$ 200,000	$ 2,000,000.0
Operating lease, cash payments			$ 33,000	$ 800,000	$ 100,000	$ 2,800,000
Operating lease weighted-average remaining lease term			2 years 1 month 6 days		2 years 1 month 6 days
Operating lease weighted-average discount rate			3.40%		3.40%
Waltham Sublease
Lessee Lease Description [Line Items]
Expiration date	Nov. 30, 2023
Sublease rent per month	$ 15,000
San Diego Sublease
Lessee Lease Description [Line Items]
Sublease rent per month		$ 12,000
Sublease term		7 years
Sublease cancellable written notice period		30 days
Payments of sublease			$ 42,000		$ 100,000