Commitments and Contingencies - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2019 lease	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Other Commitments [Line Items]
Restricted cash (included in other assets)		$ 1,000		$ 1,000		$ 1,000
Short-term lease cost		$ 0	$ 0	$ 64	$ 0
Commercial car fleet
Other Commitments [Line Items]
Lease term (in months)		36 months		36 months
Yardley Pennsylvania Office Space
Other Commitments [Line Items]
Lease agreement, term (in months)	88 months
Lease agreement, term including renewal options (in months)	148 months
Period from lease commencement to initial rent payment due	5 months
Number of operating leases | lease	2