BUSINESS SEGMENT DATA - Summary of Operations in Different Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Business segment data
Total Revenues	$ 16,577	$ 14,572	$ 45,572	$ 40,420
Operating Income	26,760	1,485	22,050	12,547
Impairment charge			16,527	1,905
Gain on Disposition of Assets	22,666	289	28,106	7,365
Gain (Loss) on Extinguishment of Debt			(641)	1,141
Depreciation and Amortization	5,567	4,761	15,428	14,334
Capital Expenditures	1,773	48,193	115,890	193,201
Identifiable Assets	686,682		686,682		$ 666,700
Operating Segments
Business segment data
Impairment charge			(16,527)	(1,905)
Gain on Disposition of Assets	22,666	289	28,106	7,365
General and Corporate Expense
Business segment data
Operating Income	(8,247)	(8,102)	(23,905)	(22,938)
Depreciation and Amortization	5	10	15	20
Capital Expenditures	19	4	29	16
Identifiable Assets	78,427		78,427		35,804
Income Properties
Business segment data
Total Revenues	13,734	12,933	36,757	35,409
Capital Expenditures	1,754	48,189	115,861	186,431
Identifiable Assets	508,409		508,409		531,325
Income Properties | Operating Segments
Business segment data
Operating Income	9,750	9,341	27,069	27,136
Depreciation and Amortization	5,562	4,751	15,413	14,314
Management Fee Income
Business segment data
Total Revenues	940	683	2,361	2,080
Identifiable Assets	1,355		1,355		700
Management Fee Income | Operating Segments
Business segment data
Operating Income	940	683	2,361	2,080
Interest Income from Commercial Loan and Master Lease Investments
Business segment data
Total Revenues	726	413	2,136	2,300
Capital Expenditures				6,754
Identifiable Assets	38,994		38,994		38,321
Interest Income from Commercial Loan and Master Lease Investments | Operating Segments
Business segment data
Operating Income	726	413	2,136	2,300
Real Estate Operations
Business segment data
Total Revenues	1,177	543	4,318	631
Identifiable Assets	58,662		58,662		59,717
Real Estate Operations | Operating Segments
Business segment data
Operating Income	925	$ (1,139)	3,451	$ (2,632)
Land Operations
Business segment data
Identifiable Assets	$ 835		$ 835		$ 833