Commitments and Contingencies (Details) $ in Thousands		3 Months Ended		5 Months Ended	9 Months Ended
	Jan. 15, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Feb. 28, 2019 agreement	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Sublease income		$ 87	$ 86		$ 300	$ 200
Number of non-cancelable operating lease | agreement				2
Right-of-use assets		2,360			2,360		$ 3,331
Operating Lease, Liability		$ 2,685			$ 2,685
Operating lease discount rate		7.00%			7.00%
Noncancelable operating leases term		3 years 5 months 4 days			3 years 5 months 4 days
Operating lease expense		$ 200	200		$ 700	400
Cash paid for amount included in lease liabilities		$ 500	$ 500		1,400	$ 1,000
Waltham Massachusetts
Lessee, Lease, Description [Line Items]
Sublease income	$ 600				$ 58
Minimum
Lessee, Lease, Description [Line Items]
Operating lease term		2 months			2 months
Operating lease renewal term		5 years			5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease term		4 years			4 years
Operating lease renewal term		10 years			10 years