Leases - Additional Information (Details) $ in Thousands		9 Months Ended
	Jun. 30, 2020 USD ($) ft²	Sep. 30, 2021 USD ($) ft² option	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Tenant improvements (up to)		$ 9,500
Increase in right-of-use asset		0	$ 169
Increase in lease liability		(427)	313
Termination fee for lease termination	$ 500
Loss on termination of lease			300
Loss on disposal of property and equipment		0	$ 180
Operating lease right-of-use assets		11,008		$ 10,154
Finance lease right-of-use assets		$ 200		$ 300
Washington | Office space, principal executive offices and laboratory
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²		33,300
Number of option to extend leases | option		2
Lease agreement extended period		5 years
Washington | Office Space, additional offices and laboratory
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²		6,272
Lease agreement extended period		28 months
Increase in right-of-use asset		$ 1,600
Increase in lease liability		$ 1,600
Canada
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²	10,946