Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended	9 Months Ended
	Aug. 04, 2020	Jun. 15, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Apr. 09, 2020
Loss Contingencies [Line Items]
Lease arrangement, contractual expiration period, beginning year				2021
Lease arrangement, contractual expiration period, ending year				2028
Lessee, operating lease, existence of option to extend [true false]				true
Lessee, operating lease, option to extend				These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain lease agreements also provide the Company with the option to renew for additional periods ranging from one to five years.
Cash paid for operating lease liabilities				$ 3.4
Rent expense			$ 1.2		$ 3.2
Samsung Biologics Co., Ltd
Loss Contingencies [Line Items]
Obligated to pay capacity reservation						$ 362.0
WuXi Biologics
Loss Contingencies [Line Items]
Obligated to pay capacity reservation		$ 130.0
GSKTSL | WuXi Biologics MSA and Samsung MSA | Antibody Program
Loss Contingencies [Line Items]
Percentage of development costs	72.50%
GSK | WuXi Biologics MSA and Samsung MSA | Antibody Program
Loss Contingencies [Line Items]
Percentage of development costs	27.50%
Maximum
Loss Contingencies [Line Items]
Lessee, operating lease, renewal term				5 years
Maximum | WuXi Biologics
Loss Contingencies [Line Items]
Percentage of estimated raw material costs		80.00%
Minimum [Member]
Loss Contingencies [Line Items]
Lessee, operating lease, renewal term				1 year
Minimum [Member] | WuXi Biologics
Loss Contingencies [Line Items]
Percentage of estimated raw material costs		70.00%