Revenue Recognition (Schedule of Revenues by Segment ) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Total revenues	Total revenues	Total revenues
Lease income	$ 1,492,684	$ 1,508,044	$ 1,544,671
Total revenues	1,810,425	1,787,686	1,811,163
Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,558,241	1,568,806	1,607,486
Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	1,492,684	1,508,044	1,544,671
Property rentals
Disaggregation of Revenue [Line Items]
Lease income	1,464,053	1,486,503	1,523,890
Trade shows
Disaggregation of Revenue [Line Items]
Lease income	21,997	21,541	20,781
Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	6,634
Tenant services
Disaggregation of Revenue [Line Items]
Revenues	45,237	41,549	42,460
Parking revenues
Disaggregation of Revenue [Line Items]
Revenues	20,320	19,213	20,355
Fee and other income
Disaggregation of Revenue [Line Items]
Revenues	252,184	218,880	203,677
Total revenues	252,184	218,880	203,677
BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenues	157,686	149,225	141,937
Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenues	11,564	14,680	13,040
Other income
Disaggregation of Revenue [Line Items]
Revenues	82,934	54,975	48,700
New York
Disaggregation of Revenue [Line Items]
Total revenues	1,476,522	1,471,997	1,452,158
New York | Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,243,310	1,260,426	1,269,817
New York | Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	1,195,526	1,215,854	1,222,229
New York | Property rentals
Disaggregation of Revenue [Line Items]
Lease income	1,188,892	1,215,854	1,222,229
New York | Trade shows
Disaggregation of Revenue [Line Items]
Lease income	0	0	0
New York | Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	6,634
New York | Tenant services
Disaggregation of Revenue [Line Items]
Revenues	31,839	29,344	31,086
New York | Parking revenues
Disaggregation of Revenue [Line Items]
Revenues	15,945	15,228	16,502
New York | Fee and other income
Disaggregation of Revenue [Line Items]
Revenues	233,212	211,571	182,341
New York | BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenues	166,526	159,903	151,608
New York | Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenues	12,157	15,443	13,619
New York | Other income
Disaggregation of Revenue [Line Items]
Revenues	54,529	36,225	17,114
Other
Disaggregation of Revenue [Line Items]
Total revenues	333,903	315,689	359,005
Other | Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	314,931	308,380	337,669
Other | Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	297,158	292,190	322,442
Other | Property rentals
Disaggregation of Revenue [Line Items]
Lease income	275,161	270,649	301,661
Other | Trade shows
Disaggregation of Revenue [Line Items]
Lease income	21,997	21,541	20,781
Other | Sales-type lease income
Disaggregation of Revenue [Line Items]
Lease income	0
Other | Tenant services
Disaggregation of Revenue [Line Items]
Revenues	13,398	12,205	11,374
Other | Parking revenues
Disaggregation of Revenue [Line Items]
Revenues	4,375	3,985	3,853
Other | Fee and other income
Disaggregation of Revenue [Line Items]
Revenues	18,972	7,309	21,336
Other | BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenues	(8,840)	(10,678)	(9,671)
Other | Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenues	(593)	(763)	(579)
Other | Other income
Disaggregation of Revenue [Line Items]
Revenues	$ 28,405	$ 18,750	$ 31,586