CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Properties held-for-sale, accumulated depreciation	$ 1,916	$ 0
Mortgage loans receivable, loan loss reserve	2,255	2,315
Notes receivable, loan loss reserve	166	166
Straight-line rent receivable, allowance for doubtful accounts	$ 814	$ 960
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	60,000	60,000
Common stock, shares issued	39,570	39,221
Common stock, shares outstanding	39,570	39,221
Senior Unsecured Notes
Debt issue costs, net	$ 1,131	$ 1,009