Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 189,875	$ 219,408
Restricted cash	44,285	53,726
Notes receivable, net	435,629	439,167
Lines-of-credit, notes payable, and receivable-backed notes payable	563,363	592,322
Junior subordinated debentures	71,504	71,323
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	189,875	219,408
Restricted cash	44,285	53,726
Notes receivable, net	556,000	537,000
Lines-of-credit, notes payable, and receivable-backed notes payable	582,000	596,900
Junior subordinated debentures	$ 86,500	$ 87,000