Investments in Partially Owned Entities (Schedule of Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule Of Equity Method Investments
Equity in net income			$ 82,457	$ 72,207
Return on preferred equity, net of our share of the expense			101,826	131,308
Our share of net income (loss)	$ 18,229	$ 18,269	$ 82,457	72,207
Fifth Avenue and Times Square JV
Schedule Of Equity Method Investments
Interest	51.50%		51.50%
Equity in net income	$ 9,253	10,917	$ 28,971	27,057
Return on preferred equity, net of our share of the expense	10,541	9,430	30,127	27,985
Our share of net income (loss)	$ 19,794	20,347	$ 59,098	55,042
Default accrual interest amount				5,120
Alexander's
Schedule Of Equity Method Investments
Interest	32.40%		32.40%
Equity in net income	$ 2,099	3,341	$ 9,902	10,230
Management, leasing and development fees	1,530	1,184	3,895	4,056
Net gain on sale of land	0	0	0	16,396
Our share of net income (loss)	3,629	4,525	13,797	30,682
Partially owned office buildings
Schedule Of Equity Method Investments
Our share of net income (loss)	(7,633)	(7,647)	3,261	(16,864)
Gain on extinguishment of debt			31,215
Other investments
Schedule Of Equity Method Investments
Our share of net income (loss)	$ 2,439	$ 1,044	$ 6,301	$ 3,347