Investments in Partially Owned Entities (Schedule of Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]
Mortgage loans on real estate, face amount of mortgages	$ 303,000
Partially Owned Properties
Schedule of Equity Method Investments [Line Items]
Equity method investment pro rata share debt of partially owned entities	2,478,544	$ 2,477,701
7 West 34th Street
Schedule of Equity Method Investments [Line Items]
Mortgage loans on real estate, face amount of mortgages	$ 300,000
Partially owned office buildings
Schedule of Equity Method Investments [Line Items]
Weighted average interest rate	5.15%
Equity method investment debt of partially owned entities	$ 2,221,500	3,146,918
Alexander's
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	32.40%
Weighted average interest rate	4.82%
Equity method investment debt of partially owned entities	$ 836,691	996,544
Fifth Avenue and Times Square JV
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	51.50%
Weighted average interest rate	6.73%
Equity method investment debt of partially owned entities	$ 1,195,708	753,194
Other
Schedule of Equity Method Investments [Line Items]
Weighted average interest rate	6.31%
Equity method investment debt of partially owned entities	$ 1,417,019	$ 1,311,662