Real Estate Activities - Impairment of Assets (Details) - USD ($)			12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Impairment Of Assets [Line Items]
Total Impairment of Assets			$ 9,938,000	$ 0
Exton Square Mall
Impairment Of Assets [Line Items]
Total Impairment of Assets			8,374,000
Valley View Center
Impairment Of Assets [Line Items]
Total Impairment of Assets		$ 1,300,000	1,302,000
Monroe Marketplace
Impairment Of Assets [Line Items]
Total Impairment of Assets	$ 300,000		$ 262,000