Fair Value Measurements (Narrative) (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of fixed rate mortgage loans payable	$ 159,000,000.0	$ 47,000,000.0
Carrying value of fixed rate mortgage payable	156,800,000	45,400,000
Impairment charges	99,888,000	7,607,000	$ 8,938,000
Aggregate fair value of impairment charges	$ 194,500,000
Number of properties | property	50
Real estate held for sale	$ 73,251,000	$ 9,498,000
Level 2 [Member] | Assets [Member] | Retail Properties [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges	$ 18,500,000
Number of properties | property	4
Real estate held for sale	$ 73,300,000
Dual-track Strategic Alternatives Process [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges	$ 83,200,000