Investments in Partially Owned Entities (Summary of Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jun. 04, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Schedule Of Equity Method Investments
Our share of net income (loss)		$ 24,341	$ 26,269	$ 83,775	$ 86,768
Fifth Avenue and Times Square JV
Schedule Of Equity Method Investments
Equity method ownership percentage		51.50%		51.50%
Equity in net income		$ 11,941	12,671	$ 41,915	32,314
Return on preferred equity, net of our share of the expense		9,430	9,430	27,985	27,985
Our share of net income (loss)		$ 21,371	22,101	$ 69,900	60,299
Alexander’s
Schedule Of Equity Method Investments
Equity method ownership percentage		32.40%		32.40%
Equity in net income		$ 4,740	3,710	$ 14,235	17,764
Management, leasing and development fees		1,170	1,085	3,352	3,622
Our share of net income (loss)		5,910	4,795	17,587	21,386
Proceeds from sale of land held-for-investment	$ 10,000
Net gain on sale of real estate	2,956
Proceeds from commissions received	$ 300
Partially owned office buildings/land
Schedule Of Equity Method Investments
Our share of net income (loss)		(4,732)	418	(8,080)	8,395
Other investments
Schedule Of Equity Method Investments
Our share of net income (loss)		$ 1,792	$ (1,045)	$ 4,368	$ (3,312)