Leases - Operating Leases (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jan. 31, 2019 USD ($)	Sep. 30, 2020 USD ($) ft² lease agreement item	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number of real estate leases | lease		2
Right-of-use assets		$ 14,477		$ 15,587
Lease liabilities		$ 22,578
Unamortized lease incentive and straight-line lease liability balances	$ 9,700
Weighted-average discount rate		11.00%
Lease expense for operating lease payments		$ 3,000	$ 3,300
Cash paid against operating lease liabilities		$ 4,100	4,000
Weighted average remaining term of the operating leases		5 years 4 months 24 days
Sublease income		$ 1,600
Maximum
Lessee, Lease, Description [Line Items]
100 basis point change effect on ROU asset		$ 1,000
CRP/King 830 Winter L.L.C.
Lessee, Lease, Description [Line Items]
Area of space leased | ft²		120,000
Number of additional terms for which lease agreement can be extended | item		2
Operating lease term extension period		5 years
Number of executed sub-lease spaces | lease		4
Area of executed sublease space | ft²		65,000
PDM 930 Unit, LLC
Lessee, Lease, Description [Line Items]
Area of executed sublease space | ft²		10,281
Winter Street 930 Waltham MA
Lessee, Lease, Description [Line Items]
Number of executed sub-lease spaces | agreement		4
Area of executed sublease space | ft²		65,000
Leasehold impairment charge			$ 600
Minimum rental payments over the remaining term of the sublease		$ 16,600
Adjustment | ASU 2016-2
Lessee, Lease, Description [Line Items]
Right-of-use assets	17,600
Lease liabilities	$ 27,300