Investments in Partially Owned Entities (Summary of Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 2,665,073	$ 3,297,389
Other Liabilities
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ (81,528)	(78,985)
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	$ 2,272,320	2,770,633
Partially Owned Office Buildings/Land
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 182,180	299,101
Alexander's
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage	32.40%
Carrying amount of investments in partially owned entities	$ 87,796	91,405
Other investments
Schedule of Equity Method Investments [Line Items]
Carrying amount of investments in partially owned entities	$ 122,777	136,250
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	$ (65,522)	(60,918)
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	$ (16,006)	$ (18,067)