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Commitments and Contingencies (Details) $ in Thousands		1 Months Ended		12 Months Ended
	Oct. 05, 2020 USD ($)	Nov. 30, 2019 USD ($)	Feb. 28, 2018 USD ($) ft²	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2015
Leased assets
Rent for facility lease				$ 3,200	$ 1,400
Letter of credit				2,500
Lease Cost:
Operating lease cost				3,229
Variable lease cost				1,027
Total lease cost				4,256
Operating cash flows used for operating leases				$ 2,111
Weighted average remaining lease term				4 years 4 months 24 days
Weighted average incremental borrowing rate				7.50%
620 Memorial Drive, Cambridge MA
Leased assets
Term of lease						5 years
Option to extend the term			true
Area of lease space | ft²			20,751
Renewal term			5 years
Sublease annual base rent	$ 1,900
620 Memorial Drive, Cambridge MA | Minimum
Leased assets
Rent for facility lease			$ 1,400
620 Memorial Drive, Cambridge MA | Maximum
Leased assets
Rent for facility lease			$ 1,700
301 Binney St, Cambridge MA
Leased assets
Option to extend the term		true
Renewal term		2 years
Base rent		$ 6,900
Annual upward adjustment (as a percent)		3.50%
Incentive to lease		$ 14,100
Letter of credit		$ 2,300

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