Other Assets - Schedule of Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other Assets
Retained interest investments	$ 11,285	$ 11,147
Accounts receivable, net	9,662	8,460
Notes receivable	4,903	9,522
Prepaid expenses	8,512	6,625
Straight line rent	3,779	3,804
Other assets	5,354	4,637
Accrued interest receivable for Senior Notes held by SPE	2,938	2,938
Total other assets	$ 46,433	$ 47,133