Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Interest on notes and mortgages receivable	$ 792	$ 752	$ 2,314	$ 2,259
Total revenues	34,694	29,464	101,052	86,150
Operating expenses:
Property costs	5,592	5,307	16,955	15,368
Impairments	729	2,167	3,987	6,549
Environmental	1,208	1,045	3,898	931
General and administrative	3,556	3,395	10,998	10,562
Allowance for uncollectible accounts	357	139	364	200
Depreciation and amortization	6,068	4,678	17,569	13,465
Total operating expenses	17,510	16,731	53,771	47,075
Operating income	17,184	12,733	47,281	39,075
Gain (loss) on dispositions of real estate	(29)	163	3,636	339
Other income (expense), net	(78)	881	510	4,992
Interest expense	(6,060)	(4,319)	(16,425)	(12,678)
Earnings from continuing operations	11,017	9,458	35,002	31,728
Discontinued operations:
Earnings (loss) from discontinued operations	(73)	(118)	(486)	2,422
Net earnings	$ 10,944	$ 9,340	$ 34,516	$ 34,150
Basic earnings per common share:
Earnings from continuing operations	$ 0.27	$ 0.24	$ 0.86	$ 0.87
Earnings (loss) from discontinued operations			(0.01)	0.07
Net earnings	0.27	0.24	0.85	0.94
Diluted earnings per common share:
Earnings from continuing operations	0.27	0.24	0.86	0.87
Earnings (loss) from discontinued operations			(0.01)	0.07
Net earnings	$ 0.27	$ 0.24	$ 0.85	$ 0.94
Weighted average common shares outstanding:
Basic	40,430	38,702	40,016	35,979
Diluted	40,455	38,702	40,031	35,979
Dividends declared per common share	$ 0.32	$ 0.28	$ 0.96	$ 0.84
Real Estate [Member]
Revenues:
Revenues	$ 29,570	$ 24,913	$ 86,877	$ 73,174
Tenant Reimbursements [Member]
Revenues:
Revenues	$ 4,332	$ 3,799	$ 11,861	$ 10,717