Investments in Partially Owned Entities (Schedule of Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ 1,965,901	$ 2,691,478
Other liabilities
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ (90,012)	(89,530)
Fifth Avenue and Times Square JV
Schedule Of Equity Method Investments
Interest	51.50%
Carrying amount of investments in partially owned entities	$ 1,549,488	2,235,546
Partially owned office buildings/land
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ 154,359	186,190
Alexander's
Schedule Of Equity Method Investments
Interest	32.40%
Carrying amount of investments in partially owned entities	$ 53,592	68,492
Other investments
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ 208,462	201,250
7 West 34th Street
Schedule Of Equity Method Investments
Interest	53.00%
7 West 34th Street | Other liabilities
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ (66,168)	(70,552)
85 Tenth Avenue
Schedule Of Equity Method Investments
Interest	49.90%
85 Tenth Avenue | Other liabilities
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities	$ (23,844)	$ (18,978)