Segments - Reconciliation of Net Operating Income to Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information
Net operating income	$ 117,066	$ 106,367	$ 81,084
Amortization of right-of-use assets - finance leases	(586)	(377)	0
General and administrative expenses	(12,905)	(12,392)	(11,431)
Acquisition, development and other pursuit costs	(584)	(844)	(352)
Impairment charges	(666)	(252)	(1,619)
Gain on real estate dispositions	6,388	4,699	4,254
Interest income	19,841	23,215	10,729
Interest expense on indebtedness	(30,120)	(30,776)	(19,087)
Interest expense on finance leases	(915)	(568)	0
Equity in income of unconsolidated real estate entities	0	273	372
Change in fair value of derivatives and other	(1,130)	(3,599)	(951)
Provision for unrealized credit losses	(256)	0	0
Other income (expense), net	515	585	377
Income tax benefit	283	491	29
Net income	36,959	32,258	23,492
Operating Segments
Segment Reporting Information
Net operating income	117,066	106,367	81,084
Segment Reconciling Items
Segment Reporting Information
Depreciation and amortization	(59,972)	(54,564)	(39,913)
Amortization of right-of-use assets - finance leases	(586)	(377)	0
General and administrative expenses	(12,905)	(12,392)	(11,431)
Acquisition, development and other pursuit costs	(584)	(844)	(352)
Impairment charges	(666)	(252)	(1,619)
Gain on real estate dispositions	6,388	4,699	4,254
Interest income	19,841	23,215	10,729
Interest expense on indebtedness	(30,120)	(30,776)	(19,087)
Interest expense on finance leases	(915)	(568)	0
Equity in income of unconsolidated real estate entities	0	273	372
Change in fair value of derivatives and other	(1,130)	(3,599)	(951)
Provision for unrealized credit losses	(256)		0
Other income (expense), net	515	585	377
Income tax benefit	$ 283	$ 491	$ 29