Segments - Reconciliation of Net Operating Income to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net operating income	$ 8,466	$ 5,999
Depreciation and amortization	(9,475)	(8,149)
General and administrative expenses	(2,986)	(2,484)
Acquisition, development and other pursuit costs	(47)	(704)
Impairment charges	(4)	(35)
Interest income	1,398	182
Interest expense	(4,535)	(3,791)
Gain on real estate dispositions	3,395	26,674
Change in fair value of interest rate derivatives	294	(2,389)
Other income	37	76
Income tax provision	(302)	(218)
Net income	8,753	26,533
Operating Segments
Net operating income	20,978	17,371
Segment Reconciling Items
Depreciation and amortization	(9,475)	(8,149)
General and administrative expenses	(2,986)	(2,484)
Acquisition, development and other pursuit costs	(47)	(704)
Impairment charges	(4)	(35)
Interest income	1,398	182
Interest expense	(4,535)	(3,791)
Gain on real estate dispositions	3,395	26,674
Change in fair value of interest rate derivatives	294	(2,389)
Other income	37	76
Income tax provision	$ (302)	$ (218)