Segments - Reconciliation of Net Operating Income to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Gross profit	$ 32,858			$ 26,761			$ 94,647	$ 86,489
Amortization of finance leases	(278)			(147)			(745)	(440)
General and administrative expenses	(3,449)			(2,601)			(10,957)	(9,382)
Acquisition, development and other pursuit costs	(8)			(26)			(111)	(555)
Impairment charges	0			(47)			(3,122)	(205)
Gain (loss) on real estate dispositions, net	(113)			3,612			3,604	6,388
Interest income	3,766			4,417			14,628	16,055
Interest expense	(8,827)			(7,523)			(25,220)	(22,938)
Change in fair value of derivatives and other	131			318			838	(1,424)
Unrealized credit loss release (provision)	617			33			284	(227)
Other income (expense), net	(105)			177			81	521
Income tax benefit	42			28			522	220
Net income	7,748	$ 8,455	$ 6,009	10,826	$ 12,309	$ 9,135	22,212	32,270
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Gross profit	32,858			26,761			94,647	86,489
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	(16,886)			(14,176)			(52,237)	(42,232)
Amortization of finance leases	(278)			(147)			(745)	(440)
General and administrative expenses	(3,449)			(2,601)			(10,957)	(9,382)
Acquisition, development and other pursuit costs	(8)			(26)			(111)	(555)
Impairment charges	0			(47)			(3,122)	(205)
Gain (loss) on real estate dispositions, net	(113)			3,612			3,604	6,388
Interest income	3,766			4,417			14,628	16,055
Interest expense	(8,827)			(7,523)			(25,220)	(22,938)
Change in fair value of derivatives and other	131			318			838	(1,424)
Unrealized credit loss release (provision)	617			33			284	(227)
Other income (expense), net	(105)			177			81	521
Income tax benefit	$ 42			$ 28			$ 522	$ 220