Leases - Narrative (Details) ft² in Thousands, $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended		18 Months Ended
	Aug. 31, 2021 USD ($) ft² renewal_option	May 31, 2019 renewal_option	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	May 31, 2022 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2018 ft²
Lessee, Lease, Description [Line Items]
Operating lease sublease land agreement (square feet) | ft²	25
Number of renewal options | renewal_option	1
Renewal term	5 years
Operating lease liability	$ 3,600		$ 6,107		$ 6,107			$ 5,886
Remaining lease term			6 years 8 months 12 days		6 years 8 months 12 days
Discount rate			5.20%		5.20%
Operating lease payments			$ 100	$ 300	$ 100	$ 800
Forecast
Lessee, Lease, Description [Line Items]
Operating lease income							$ 600
Leasehold improvements							1,100
Incentive from landlord, rent abatement							200
Incentive from landlord, refurbishment allowance, maximum							$ 400
Office Space Sublease
Lessee, Lease, Description [Line Items]
Operating lease sublease land agreement (square feet) | ft²									45
Number of renewal options | renewal_option		1
Renewal term		5 years