Consolidated Statements of Cash Flows	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
OPERATING ACTIVITIES
Net (loss) income	$ (520,000)	$ 1,566,000	$ 4,358,000
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Gain on sales	(4,396,000)	(2,942,000)	(4,864,000)
Impairment charges	7,607,000	8,938,000	20,689,000
Extinguishment of debt costs			4,829,000
Straight-line rents and expenses, net	1,279,000	(265,000)	(1,142,000)
Provision for doubtful accounts	1,478,000	412,000	2,273,000
Depreciation and amortization	48,412,000	45,861,000	40,053,000
Amortization of intangible lease liabilities, net	(1,373,000)	(2,827,000)	(4,361,000)
Expense relating to share-based compensation, net	3,723,000	4,117,000	3,763,000
Amortization of premium on mortgage loans payable			(80,000)
Amortization of deferred financing costs	1,331,000	1,286,000	1,224,000
Changes in operating assets and liabilities, net of effects of acquisitions and dispositions:
Rents and other receivables	(2,811,000)	(812,000)	(3,902,000)
Prepaid expenses and other	(9,216,000)	(3,037,000)	(6,591,000)
Accounts payable and accrued liabilities	(2,934,000)	1,378,000	1,651,000
Net cash provided by operating activities	42,580,000	53,675,000	57,900,000
INVESTING ACTIVITIES
Expenditures for real estate improvements	(39,551,000)	(31,910,000)	(30,377,000)
Net proceeds from sales of real estate	21,182,000	18,651,000	19,118,000
Acquisition of real estate		(9,083,000)	(179,000)
Issuance of mortgage note receivable			(3,500,000)
Net cash (used in) investing activities	(18,369,000)	(22,342,000)	(14,938,000)
FINANCING ACTIVITIES
Repayments under revolving credit facility	(104,000,000)	(21,000,000)	(123,500,000)
Advances under revolving credit facility	173,000,000	27,000,000	168,500,000
Repayment under term loan	(75,000,000)
Advance under term loan			75,000,000
Mortgage repayments	(1,067,000)	(1,027,000)	(80,330,000)
Payment of early extinguishment of debt costs			(5,159,000)
Payments of debt financing costs	(326,000)		(705,000)
Noncontrolling interests:
Distributions to limited partners	(42,000)	(111,000)	(90,000)
Redemption of OP Units		(43,000)	(7,000)
Redemption on preferred stock			(50,016,000)
Common stock sales less issuance expenses, net	13,000	22,000	9,000
Common stock repurchases		(6,844,000)	(2,329,000)
Preferred stock dividends	(10,752,000)	(10,752,000)	(11,276,000)
Distributions to common shareholders	(7,147,000)	(17,808,000)	(18,301,000)
Net cash (used in) financing activities	(25,321,000)	(30,563,000)	(48,204,000)
Net (decrease) increase in cash, cash equivalents and restricted cash	(1,110,000)	770,000	(5,242,000)
Cash, cash equivalents and restricted cash at beginning of year	2,747,000	1,977,000	7,219,000
Cash, cash equivalents and restricted cash at end of year	1,637,000	2,747,000	1,977,000
Reconciliation to consolidated balance sheets:
Cash and cash equivalents	1,637,000	2,747,000	1,977,000
Cash, cash equivalents and restricted cash at end of year	$ 1,637,000	$ 2,747,000	$ 1,977,000