Schedule III - Real Estate and Accumulated Depreciation (Details)		12 Months Ended
		Dec. 31, 2022 USD ($) ft²		Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Gross leasable area | ft²		2,863,000
Initial cost to the Company, Land		$ 74,960,000
Initial cost to the Company, Building and Improvements		302,680,000
Subsequent cost capitalized	[1]	(13,530,000)
Gross carrying amount of Land		69,111,000
Gross carrying amount of building and improvements		294,999,000
SEC Schedule III, Real Estate, Gross, Total		364,110,000	[2]	$ 369,827,000	$ 604,265,000	$ 1,515,206,000
Accumulated Depreciation		$ 157,468,000		$ 155,250,000	$ 197,119,000	$ 389,861,000
Brickyard Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2004
Percent Owned		100.00%
Gross leasable area | ft²		228,000
Initial cost to the Company, Land		$ 7,632,000
Initial cost to the Company, Building and Improvements		29,308,000
Subsequent cost capitalized	[1]	(779,000)
Gross carrying amount of Land		7,648,000
Gross carrying amount of building and improvements		28,513,000
SEC Schedule III, Real Estate, Gross, Total		36,161,000
Accumulated Depreciation		$ 13,850,000
Brickyard Plaza [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1990
Brickyard Plaza [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2012
Carll's Corner [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		129,000
Initial cost to the Company, Land		$ 3,034,000
Initial cost to the Company, Building and Improvements		15,293,000
Subsequent cost capitalized	[1]	(11,815,000)
Gross carrying amount of Land		246,000
Gross carrying amount of building and improvements		6,266,000
SEC Schedule III, Real Estate, Gross, Total		6,512,000
Accumulated Depreciation		$ 5,321,000
Carll's Corner [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1960
Carll's Corner [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1999
Coliseum Marketplace [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2005
Percent Owned		100.00%
Gross leasable area | ft²		107,000
Initial cost to the Company, Land		$ 2,924,000
Initial cost to the Company, Building and Improvements		14,416,000
Subsequent cost capitalized	[1]	(4,860,000)
Gross carrying amount of Land		3,586,000
Gross carrying amount of building and improvements		8,894,000
SEC Schedule III, Real Estate, Gross, Total		12,480,000
Accumulated Depreciation		$ 7,091,000
Coliseum Marketplace [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1987
Coliseum Marketplace [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2012
Fairview Commons [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		53,000
Initial cost to the Company, Land		$ 858,000
Initial cost to the Company, Building and Improvements		3,568,000
Subsequent cost capitalized	[1]	462,000
Gross carrying amount of Land		858,000
Gross carrying amount of building and improvements		4,030,000
SEC Schedule III, Real Estate, Gross, Total		4,888,000
Accumulated Depreciation		$ 1,801,000
Fairview Commons [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1976
Fairview Commons [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2003
Fieldstone Marketplace [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Percent Owned		100.00%
Gross leasable area | ft²		194,000
Initial cost to the Company, Land		$ 5,229,000
Initial cost to the Company, Building and Improvements		21,440,000
Subsequent cost capitalized	[1]	(3,219,000)
Gross carrying amount of Land		5,167,000
Gross carrying amount of building and improvements		18,283,000
SEC Schedule III, Real Estate, Gross, Total		23,450,000
Accumulated Depreciation		$ 12,069,000
Fieldstone Marketplace [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2005
Year built/Year last renovated		1988
Fieldstone Marketplace [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2012
Year built/Year last renovated		2003
Gold Star Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2006
Percent Owned		100.00%
Year built/Year last renovated		1988
Gross leasable area | ft²		72,000
Initial cost to the Company, Land		$ 1,644,000
Initial cost to the Company, Building and Improvements		6,519,000
Subsequent cost capitalized	[1]	(140,000)
Gross carrying amount of Land		1,644,000
Gross carrying amount of building and improvements		6,379,000
SEC Schedule III, Real Estate, Gross, Total		8,023,000
Accumulated Depreciation		$ 2,840,000
Golden Triangle [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2003
Percent Owned		100.00%
Gross leasable area | ft²		203,000
Initial cost to the Company, Land		$ 2,320,000
Initial cost to the Company, Building and Improvements		9,713,000
Subsequent cost capitalized	[1]	12,345,000
Gross carrying amount of Land		2,320,000
Gross carrying amount of building and improvements		22,058,000
SEC Schedule III, Real Estate, Gross, Total		24,378,000
Accumulated Depreciation		$ 11,429,000
Golden Triangle [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1960
Golden Triangle [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2005
Hamburg Square [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2004
Percent Owned		100.00%
Gross leasable area | ft²		102,000
Initial cost to the Company, Land		$ 1,153,000
Initial cost to the Company, Building and Improvements		4,678,000
Subsequent cost capitalized	[1]	6,573,000
Gross carrying amount of Land		1,153,000
Gross carrying amount of building and improvements		11,251,000
SEC Schedule III, Real Estate, Gross, Total		12,404,000
Accumulated Depreciation		$ 4,902,000
Hamburg Square [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1993
Hamburg Square [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2010
Kings Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		168,000
Initial cost to the Company, Land		$ 2,413,000
Initial cost to the Company, Building and Improvements		12,604,000
Subsequent cost capitalized	[1]	1,915,000
Gross carrying amount of Land		2,408,000
Gross carrying amount of building and improvements		14,524,000
SEC Schedule III, Real Estate, Gross, Total		16,932,000
Accumulated Depreciation		$ 5,460,000
Kings Plaza [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1970
Kings Plaza [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1994
Oakland Commons [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		90,000
Initial cost to the Company, Land		$ 2,504,000
Initial cost to the Company, Building and Improvements		15,662,000
Subsequent cost capitalized	[1]	(4,668,000)
Gross carrying amount of Land		2,504,000
Gross carrying amount of building and improvements		10,994,000
SEC Schedule III, Real Estate, Gross, Total		13,498,000
Accumulated Depreciation		$ 6,450,000
Oakland Commons [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1962
Oakland Commons [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2013
Patuxent Crossing [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2009
Percent Owned		100.00%
Gross leasable area | ft²		264,000
Initial cost to the Company, Land		$ 14,849,000
Initial cost to the Company, Building and Improvements		18,445,000
Subsequent cost capitalized	[1]	1,835,000
Gross carrying amount of Land		13,211,000
Gross carrying amount of building and improvements		21,918,000
SEC Schedule III, Real Estate, Gross, Total		35,129,000
Accumulated Depreciation		$ 10,679,000
Patuxent Crossing [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1985
Patuxent Crossing [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1997
Pine Grove Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2003
Percent Owned		100.00%
Gross leasable area | ft²		79,000
Initial cost to the Company, Land		$ 2,010,000
Initial cost to the Company, Building and Improvements		6,489,000
Subsequent cost capitalized	[1]	632,000
Gross carrying amount of Land		1,622,000
Gross carrying amount of building and improvements		7,509,000
SEC Schedule III, Real Estate, Gross, Total		9,131,000
Accumulated Depreciation		$ 3,849,000
Pine Grove Plaza [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2001
Pine Grove Plaza [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2002
Oregon Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2016
Percent Owned		100.00%
Year built/Year last renovated		2011
Gross leasable area | ft²		20,000
Initial cost to the Company, Land		$ 2,247,000
Initial cost to the Company, Building and Improvements		18,616,000
Subsequent cost capitalized	[1]	(16,980,000)
Gross carrying amount of Land		2,141,000
Gross carrying amount of building and improvements		1,742,000
SEC Schedule III, Real Estate, Gross, Total		3,883,000
Accumulated Depreciation		$ 358,000
South Philadelphia [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2003
Percent Owned		100.00%
Gross leasable area | ft²		222,000
Initial cost to the Company, Land		$ 8,222,000
Initial cost to the Company, Building and Improvements		36,314,000
Subsequent cost capitalized	[1]	(9,764,000)
Gross carrying amount of Land		8,222,000
Gross carrying amount of building and improvements		26,550,000
SEC Schedule III, Real Estate, Gross, Total		34,772,000
Accumulated Depreciation		$ 21,389,000
South Philadelphia [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1950
South Philadelphia [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2003
Southington Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2003
Percent Owned		100.00%
Gross leasable area | ft²		156,000
Initial cost to the Company, Building and Improvements		$ 11,834,000
Subsequent cost capitalized	[1]	1,464,000
Gross carrying amount of building and improvements		13,298,000
SEC Schedule III, Real Estate, Gross, Total		13,298,000
Accumulated Depreciation		$ 6,208,000
Southington Center [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1972
Southington Center [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2000
Timpany Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		183,000
Initial cost to the Company, Land		$ 3,412,000
Initial cost to the Company, Building and Improvements		19,240,000
Subsequent cost capitalized	[1]	(4,845,000)
Gross carrying amount of Land		3,368,000
Gross carrying amount of building and improvements		14,439,000
SEC Schedule III, Real Estate, Gross, Total		17,807,000
Accumulated Depreciation		$ 7,953,000
Timpany Plaza [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1970
Timpany Plaza [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1989
Trexler Mall [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2005
Percent Owned		100.00%
Gross leasable area | ft²		337,000
Initial cost to the Company, Land		$ 6,932,000
Initial cost to the Company, Building and Improvements		32,815,000
Subsequent cost capitalized	[1]	13,720,000
Gross carrying amount of Land		6,932,000
Gross carrying amount of building and improvements		46,535,000
SEC Schedule III, Real Estate, Gross, Total		53,467,000
Accumulated Depreciation		$ 19,962,000
Trexler Mall [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1973
Trexler Mall [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2013
Washington Centers Shoppes [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2001
Percent Owned		100.00%
Gross leasable area | ft²		157,000
Initial cost to the Company, Land		$ 2,061,000
Initial cost to the Company, Building and Improvements		7,314,000
Subsequent cost capitalized	[1]	7,513,000
Gross carrying amount of Land		2,000,000
Gross carrying amount of building and improvements		14,888,000
SEC Schedule III, Real Estate, Gross, Total		16,888,000
Accumulated Depreciation		$ 7,241,000
Washington Centers Shoppes [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1979
Washington Centers Shoppes [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1995
Webster Commons [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year acquired		2007
Percent Owned		100.00%
Gross leasable area | ft²		99,000
Initial cost to the Company, Land		$ 3,551,000
Initial cost to the Company, Building and Improvements		18,412,000
Subsequent cost capitalized	[1]	(1,518,000)
Gross carrying amount of Land		4,081,000
Gross carrying amount of building and improvements		16,364,000
SEC Schedule III, Real Estate, Gross, Total		20,445,000
Accumulated Depreciation		$ 8,447,000
Webster Commons [Member] | Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		1960
Webster Commons [Member] | Maximum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Year built/Year last renovated		2004
Other [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Percent Owned		100.00%
Initial cost to the Company, Land		$ 1,965,000
Subsequent cost capitalized	[1]	(1,401,000)
Gross carrying amount of building and improvements		564,000
SEC Schedule III, Real Estate, Gross, Total		564,000
Accumulated Depreciation		$ 169,000

[1] Negative amounts represent write-offs of fully depreciated assets and impairments.

[2] At December 31, 2022, the aggregate cost for federal income tax purposes was approximately $49.6 million greater than the Company's recorded values.