Investor Notes Payable (Schedule of Investor Notes Payable) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Amount	$ 75,317	$ 73,101
Weighted Average Interest Rate	3.50%	4.06%
Public Offerings [Member]
Debt Instrument [Line Items]
Amount	$ 57,474	$ 55,317
Weighted Average Interest Rate	3.23%	3.82%
Public Offerings [Member] | Class A [Member]
Debt Instrument [Line Items]
Amount	$ 306	$ 487
Weighted Average Interest Rate	2.12%	3.97%
Public Offerings [Member] | Class 1 [Member]
Debt Instrument [Line Items]
Amount	$ 14,388	$ 22,098
Weighted Average Interest Rate	3.75%	4.01%
Public Offerings [Member] | Class 1A [Member]
Debt Instrument [Line Items]
Amount	$ 42,780	$ 32,732
Weighted Average Interest Rate	3.07%	3.70%
Private Offerings [Member]
Debt Instrument [Line Items]
Amount	$ 17,843	$ 17,784
Weighted Average Interest Rate	4.37%	4.78%
Private Offerings [Member] | Subordinated Notes [Member]
Debt Instrument [Line Items]
Amount	$ 11,328	$ 11,317
Weighted Average Interest Rate	4.59%	5.24%
Private Offerings [Member] | Secured Notes [Member]
Debt Instrument [Line Items]
Amount	$ 6,515	$ 6,467
Weighted Average Interest Rate	3.99%	3.98%
Unsecured [Member]
Debt Instrument [Line Items]
Amount	$ 68,802	$ 66,634
Weighted Average Interest Rate	3.46%	4.06%
Secured [Member]
Debt Instrument [Line Items]
Amount	$ 6,515	$ 6,467
Weighted Average Interest Rate	3.99%	3.98%