Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2019
Leases
Operating lease liabilities	$ 168
Operating lease liability, Statement of Financial Position	us-gaap:OtherLiabilitiesNoncurrent
King of Prussia
Leases
Operating Lease, Increase (Decrease) In Right Of Use Asset	$ 1,100
Operating Lease, Increase (Decrease) In Lease Liability	$ 1,100
ASU 2016-02
Leases
Election of practical expedients package	true
ASU 2016-02 | Adjustment
Leases
ROU assets		$ 2,000
Operating lease, ROU assets, Statement of Financial Position		us-gaap:PropertyPlantAndEquipmentNet
Operating lease liabilities		$ 2,000
Operating lease liability, Statement of Financial Position		us-gaap:OtherLiabilitiesNoncurrent
Estimated incremental borrowing rate		9.80%