Real Estate Activities - Dispositions (Details) - USD ($)			1 Months Ended	12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	May 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 10, 2021	Aug. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans payable, net				$ 851,283,000	$ 884,503,000
Gain on derecognition of property				0	8,127,000
Cash proceeds from sales of real estate				5,008,000	22,517,000
(Loss) gain on sales of real estate, net				(1,180,000)	11,444,000
Impairment of Real Estate				9,938,000	0
Land Parcel | Hotel Development
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration					2,500,000
Land Parcel | Multifamily Development
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration					87,200,000
Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of land					600,000
Gain on sale of land					200,000
Valley View Mall
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on derecognition of property					8,100,000
Valley View Mall | Mortgage Loan
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans payable, net					$ 27,200,000
Valley View Mall | Mortgage Loan | Commercial Real Estate
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans payable, net				27,200,000
Monroe Marketplace
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration	$ 1,000,000.0
Impairment of Real Estate	$ 300,000			262,000
Valley View Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration							$ 3,500,000
Impairment of Real Estate		$ 1,300,000		$ 1,302,000
Woodland Mall | Mortgage Loan | Commercial Real Estate
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans payable, net						$ 113,800,000
Moorestown Mall Parcel Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration			$ 10,100,000
Cash proceeds from sales of real estate			800,000
Lease termination fee			9,000,000.0
(Loss) gain on sales of real estate, net			$ 1,000,000.0