Commitments and Contingencies - Additional Information (Details)	1 Months Ended
	Dec. 31, 2017 ft² Phase $ / ft²	Nov. 30, 2017 USD ($) ft²	Sep. 30, 2016	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)	[1],[2]
Commitment And Contingencies [Line Items]
Sublease aggregate base rent obligation				$ 2,700,000
Security deposit				2,000,000.0	$ 1,300
Right-of-use assets				15,607,000	$ 5,897,000	$ 6,835,000
Maximum
Commitment And Contingencies [Line Items]
Tenant improvement allowance				10,900,000
Bedford, Massachusetts
Commitment And Contingencies [Line Items]
Operating lease beginning year and month			2016-11
Operating lease expiration year and month	2027-02	2027-02	2021-10
Operating lease agreements additional term			3 years
Sublease aggregate base rent obligation		$ 1,400,000		$ 4,700,000
Office space leased | ft²	67,000	23,011
Lessee, operating lease, lease not yet commenced, renewal term	5 years
Number of phases | Phase	2
Initial annual base rent per square foot | $ / ft²	39.50
Percentage increase in initial annual base rent per square foot.	3.00%	3.00%
Tenant improvement allowance		$ 5,300,000
Bedford, Massachusetts | Phase One
Commitment And Contingencies [Line Items]
Office space leased | ft²	46,000
Rent due date	2018-09
Bedford, Massachusetts | Phase Two
Commitment And Contingencies [Line Items]
Office space leased | ft²	21,000
Rent due date	2019-03

[1] Represents capitalization of operating right-of-use assets

[2] Represents reclassification of deferred rent and incentives as a reduction to operating right-of-use assets