Investments in Partially Owned Entities (Schedule of Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 2,610,558	$ 2,665,073
Other Liabilities
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ (81,229)	(81,528)
Fifth Avenue and Times Square JV
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	51.50%
Carrying amount of investments in partially owned entities	$ 2,242,972	2,272,320
Partially Owned Office Buildings/Land
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 118,558	182,180
Alexander's
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	32.40%
Carrying amount of investments in partially owned entities	$ 87,510	87,796
Other investments
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 161,518	122,777
7 West 34th Street
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	53.00%
7 West 34th Street | Other Liabilities
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ (69,899)	(65,522)
85 Tenth Avenue
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	49.90%
85 Tenth Avenue | Other Liabilities
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ (11,330)	$ (16,006)