CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income:
Rental income	$ 118,957,000	$ 115,527,000	$ 128,654,000
Other property income	183,000	162,000	254,000
Total income	119,140,000	115,689,000	128,908,000
Cost and Expenses:
Property operating expenses	21,649,000	19,416,000	23,083,000
Real estate tax expense	14,388,000	14,505,000	15,869,000
General and administrative expenses	4,784,000	5,206,000	5,040,000
Business management fee	8,950,000	8,924,000	9,342,000
Provision for asset impairment	0	0	4,420,000
Depreciation and amortization	48,906,000	52,834,000	57,691,000
Total expenses	98,677,000	100,885,000	115,445,000
Other Income (Expense):
Interest expense	(23,240,000)	(25,349,000)	(28,305,000)
Gain on sale of investment properties			3,279,000
Interest and other income	274,000	157,000	143,000
Net loss	$ (2,503,000)	$ (10,388,000)	$ (11,420,000)
Net loss per common share, basic and diluted	$ (0.07)	$ (0.29)	$ (0.32)
Weighted average number of common shares outstanding, basic and diluted	36,031,088	36,021,040	35,748,672
Comprehensive income (loss):
Net loss	$ (2,503,000)	$ (10,388,000)	$ (11,420,000)
Unrealized gain (loss) on derivatives	2,445,000	(16,497,000)	(11,513,000)
Reclassification adjustment for amounts included in net loss	7,654,000	5,837,000	(888,000)
Comprehensive income (loss)	$ 7,596,000	$ (21,048,000)	$ (23,821,000)