Leases - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended						3 Months Ended		9 Months Ended
	Jul. 31, 2024	Jun. 30, 2024	Feb. 29, 2024	Dec. 31, 2023	Oct. 31, 2022	Sep. 30, 2021	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Leases [Line Items]
ROU asset				$ 2,187
Operating lease costs							$ 0	$ 2,600	$ 600	$ 7,700
Impairment loss to operating lease right-of-use assets				16,600			0	0	0	0
Cash paid for operating lease							7,000	800	17,000	3,900
Variable lease costs							$ 0	$ 200	$ 100	$ 900
Waltham Leases
Leases [Line Items]
Expiration date						Jul. 30, 2030
Lease commencement month and year						2021-09
New Lease Agreement with BP Bay Colony LLC
Leases [Line Items]
ROU asset						$ 6,000
Lease liability						6,000
Sublease Agreement with AMAG Pharmaceuticals Inc.
Leases [Line Items]
ROU asset						17,300
Lease liability						$ 17,300
Gain on termination of lease		$ 1,800
Lease, termination date		Jun. 30, 2024
Termination fee paid		$ 5,700
2022 SOW Under the DMS Agreement
Leases [Line Items]
Lease expiration month and year					2024-12
ROU asset					$ 14,700
Lease liability					14,700
Utilization fee					$ 16,300
Lessee operating lease, lease term including renewal option					2 years 3 months
Reduction to right-of-use asset and lease liability				$ 4,900
2024 SOW Under the DMS Agreement
Leases [Line Items]
Gain on termination of lease			$ 5,600
Termination Agreement with BP Bay Colony LLC
Leases [Line Items]
Gain on termination of lease	$ 1,500
Termination fee paid	$ 7,000