Leases (Details) $ in Thousands		3 Months Ended
	Apr. 01, 2019 USD ($) item ft²	Mar. 31, 2020 USD ($)
Operating Lease, Right-of-Use Asset		$ 12,221
Operating Lease, Liability, Noncurrent		22,741
Lease for facilities in Billerica, Massachusetts
Term of operating lease	137 months
Square footage of office and laboratory space | ft²	92,000
Drawing capacity	$ 1,000
Landlord Contribution Towards Tenant Improvements	$ 8,200
Lease Agreement Number Of Options To Extend | item	2
Lease Agreement Lease Extension Term	5 years
Deferred rent expense		3,000
Lease Obligation Incentive		7,600
Tristeyagen Umea Lease [Member]
Operating Lease, Right-of-Use Asset		100
Operating Lease, Liability, Noncurrent		$ 100