BUSINESS SEGMENT DATA - Summary of Operations in Different Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business segment data
Total Revenues	$ 70,272	$ 56,381	$ 44,941
Operating Income	23,345	12,280	34,199
Impairment charge	17,599	9,147
Gain on Disposition of Assets	28,316	9,746	21,978
Gain (Loss) on Extinguishment of Debt	(3,431)	1,141
Depreciation and Amortization	20,581	19,063	15,797
Capital Expenditures	256,854	196,029	187,526
Identifiable Assets	733,139	666,700
Operating Segments
Business segment data
Impairment charge	(17,599)	(9,147)
Gain on Disposition of Assets	28,316	9,746	21,978
General and Corporate Expense
Business segment data
Operating Income	(31,783)	(30,630)	(25,615)
Depreciation and Amortization	20	27	23
Capital Expenditures	34	30	4
Identifiable Assets	35,132	35,804
Income Properties
Business segment data
Total Revenues	50,679	49,953	41,956
Capital Expenditures	256,456	188,849	166,684
Identifiable Assets	630,747	531,325
Income Properties | Operating Segments
Business segment data
Operating Income	36,864	37,965	34,955
Depreciation and Amortization	20,561	19,036	15,774
Management Fee Income
Business segment data
Total Revenues	3,305	2,744	304
Capital Expenditures	0	0	0
Identifiable Assets	1,653	700
Management Fee Income | Operating Segments
Business segment data
Operating Income	3,305	2,744	304
Interest Income from Commercial Loan and Master Lease Investments
Business segment data
Total Revenues	2,861	3,034	1,829
Capital Expenditures	364	7,150	18,047
Identifiable Assets	39,095	38,321
Interest Income from Commercial Loan and Master Lease Investments | Operating Segments
Business segment data
Operating Income	2,861	3,034	1,829
Real Estate Operations
Business segment data
Total Revenues	13,427	650	852
Identifiable Assets	26,512	59,717
Real Estate Operations | Operating Segments
Business segment data
Operating Income	$ 4,812	(2,573)	748
Discontinued Real Estate Operations
Business segment data
Capital Expenditures			$ 2,791
Identifiable Assets		$ 833