Other Assets - Schedule of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Retained interest investments	$ 11,147	$ 10,635
Accounts receivable, net	8,460	4,625
Notes receivable	9,522	1,926
Prepaid expenses	6,625	5,685
Straight line rent	3,804	3,812
Other assets	4,637	8,789
Accrued interest receivable for Senior Notes held by SPE	2,938	2,938
Total other assets	$ 47,133	$ 38,410