Revenue Recognition (Schedule of Revenues by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Total revenues	Total revenues	Total revenues	Total revenues
Lease income	$ 369,879	$ 369,692	$ 1,127,005	$ 1,124,538
Total revenues	453,700	443,255	1,356,716	1,329,896
Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	389,097	387,470	1,176,104	1,170,343
Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	369,879	369,692	1,127,005	1,124,538
Property rentals
Disaggregation of Revenue [Line Items]
Lease income	360,416	362,903	1,103,097	1,104,972
Trade shows
Disaggregation of Revenue [Line Items]
Lease income	6,956	6,789	19,807	19,566
Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	2,507	0	4,101	0
Tenant services
Disaggregation of Revenue [Line Items]
Revenue	14,158	13,190	34,177	31,822
Parking revenues
Disaggregation of Revenue [Line Items]
Revenue	5,060	4,588	14,922	13,983
Fee and other income
Disaggregation of Revenue [Line Items]
Revenue	64,603	55,785	180,612	159,553
Total revenues	64,603	55,785	180,612	159,553
BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenue	42,530	37,772	116,437	112,017
Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenue	2,998	2,841	8,954	12,161
Other income
Disaggregation of Revenue [Line Items]
Revenue	19,075	15,172	55,221	35,375
New York
Disaggregation of Revenue [Line Items]
Total revenues	367,340	362,483	1,101,713	1,088,295
New York | Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	306,764	307,169	934,453	931,807
New York | Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	293,508	294,258	898,753	898,569
New York | Property rentals
Disaggregation of Revenue [Line Items]
Lease income	291,001	294,258	894,652	898,569
New York | Trade shows
Disaggregation of Revenue [Line Items]
Lease income	0	0	0	0
New York | Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	2,507	0	4,101	0
New York | Tenant services
Disaggregation of Revenue [Line Items]
Revenue	9,364	9,300	24,043	22,220
New York | Parking revenues
Disaggregation of Revenue [Line Items]
Revenue	3,892	3,611	11,657	11,018
New York | Fee and other income
Disaggregation of Revenue [Line Items]
Revenue	60,576	55,314	167,260	156,488
New York | BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenue	44,902	41,007	123,143	120,336
New York | Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenue	3,170	3,089	9,525	12,712
New York | Other income
Disaggregation of Revenue [Line Items]
Revenue	12,504	11,218	34,592	23,440
Other
Disaggregation of Revenue [Line Items]
Total revenues	86,360	80,772	255,003	241,601
Other | Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	82,333	80,301	241,651	238,536
Other | Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	76,371	75,434	228,252	225,969
Other | Property rentals
Disaggregation of Revenue [Line Items]
Lease income	69,415	68,645	208,445	206,403
Other | Trade shows
Disaggregation of Revenue [Line Items]
Lease income	6,956	6,789	19,807	19,566
Other | Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	0	0	0	0
Other | Tenant services
Disaggregation of Revenue [Line Items]
Revenue	4,794	3,890	10,134	9,602
Other | Parking revenues
Disaggregation of Revenue [Line Items]
Revenue	1,168	977	3,265	2,965
Other | Fee and other income
Disaggregation of Revenue [Line Items]
Revenue	4,027	471	13,352	3,065
Other | BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenue	(2,372)	(3,235)	(6,706)	(8,319)
Other | Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenue	(172)	(248)	(571)	(551)
Other | Other income
Disaggregation of Revenue [Line Items]
Revenue	$ 6,571	$ 3,954	$ 20,629	$ 11,935