Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 180,166	$ 219,408
Restricted cash	47,745	53,726
Notes receivable, net	440,854	439,167
Lines-of-credit, notes payable, and receivable-backed notes payable	574,932	592,322
Junior subordinated debentures	71,691	71,323
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	180,166	219,408
Restricted cash	47,745	53,726
Notes receivable, net	575,000	537,000
Lines-of-credit, notes payable, and receivable-backed notes payable	598,700	596,900
Junior subordinated debentures	$ 90,500	$ 87,000