Investments in Unconsolidated Ventures - West End Alexandria (Details) $ in Millions	3 Months Ended
	Dec. 31, 2021 USD ($) a
West End Alexandria | Landmark Land Holdings
Schedule of Investments [Line Items]
Area of land	52
West End Alexandria | Alexandria
Schedule of Investments [Line Items]
Area of land	11
Foulger Pratt Development, LLC | Landmark Mall Property
Schedule of Investments [Line Items]
Area of land	33
Fair value of property contributed | $	$ 56.0
Fair value of property contributed, additional | $	$ 10.0
Seritage | Landmark Mall Property
Schedule of Investments [Line Items]
Area of land	19
Fair value of property contributed | $	$ 30.0
Development Plans | Central Plaza
Schedule of Investments [Line Items]
Area of land	41
Area of real estate property (in sqft)	4,000,000