Investor Notes Payable (Schedule of Investor Notes Payable) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Amount	$ 73,101	$ 68,392
Weighted Average Interest Rate	4.12%	3.96%
Public Offerings [Member]
Debt Instrument [Line Items]
Amount	$ 55,317	$ 51,689
Weighted Average Interest Rate	3.92%	3.88%
Public Offerings [Member] | Class A [Member]
Debt Instrument [Line Items]
Amount	$ 487	$ 8,758
Weighted Average Interest Rate	4.20%	4.14%
Public Offerings [Member] | Class 1 [Member]
Debt Instrument [Line Items]
Amount	$ 22,098	$ 29,114
Weighted Average Interest Rate	4.02%	3.88%
Public Offerings [Member] | Class 1A [Member]
Debt Instrument [Line Items]
Amount	$ 32,732	$ 13,817
Weighted Average Interest Rate	3.85%	3.71%
Private Offerings [Member]
Debt Instrument [Line Items]
Amount	$ 17,784	$ 16,703
Weighted Average Interest Rate	4.74%	4.21%
Private Offerings [Member] | Subordinated Notes [Member]
Debt Instrument [Line Items]
Amount	$ 11,317	$ 7,533
Weighted Average Interest Rate	5.21%	4.68%
Private Offerings [Member] | Secured Notes [Member]
Debt Instrument [Line Items]
Amount	$ 6,467	$ 9,170
Weighted Average Interest Rate	3.92%	3.83%
Unsecured [Member]
Debt Instrument [Line Items]
Amount	$ 66,634	$ 59,222
Weighted Average Interest Rate	4.14%	3.98%
Secured [Member]
Debt Instrument [Line Items]
Amount	$ 6,467	$ 9,170
Weighted Average Interest Rate	3.92%	3.83%