Organization and Basis of Presentation - Schedule of Interests in Investment Properties (Details)	Dec. 31, 2024 ft² building
Manhattan
Real estate properties
Number of Buildings | building	30
Approximate Square Feet	24,072,287
Weighted Average Occupancy (as a percent)	92.50%
Commercial Property
Real estate properties
Number of Buildings | building	37
Approximate Square Feet	24,935,087
Weighted Average Occupancy (as a percent)	91.80%
Office | Manhattan
Real estate properties
Number of Buildings | building	24
Approximate Square Feet	21,762,590
Weighted Average Occupancy (as a percent)	92.50%
Office | Suburban
Real estate properties
Number of Buildings | building	7
Approximate Square Feet	862,800
Weighted Average Occupancy (as a percent)	73.50%
Retail | Manhattan
Real estate properties
Number of Buildings | building	3
Approximate Square Feet	43,442
Weighted Average Occupancy (as a percent)	100.00%
Development/Redevelopment | Manhattan
Real estate properties
Number of Buildings | building	3
Approximate Square Feet	2,266,255
Residential | Manhattan
Real estate properties
Number of Buildings | building	2
Approximate Square Feet	362,266
Weighted Average Occupancy (as a percent)	99.10%
Core Portfolio
Real estate properties
Number of Buildings | building	39
Approximate Square Feet	25,297,353
Core Portfolio | Manhattan
Real estate properties
Weighted Average Occupancy (as a percent)	91.90%
Alternative strategy portfolio | Manhattan
Real estate properties
Number of Buildings | building	7
Approximate Square Feet	2,567,025
Weighted Average Occupancy (as a percent)	63.00%
Consolidated | Manhattan
Real estate properties
Number of Buildings | building	19
Approximate Square Feet	10,498,708
Consolidated | Commercial Property
Real estate properties
Number of Buildings | building	26
Approximate Square Feet	11,361,508
Consolidated | Office | Manhattan
Real estate properties
Number of Buildings | building	15
Approximate Square Feet	9,587,441
Consolidated | Office | Suburban
Real estate properties
Number of Buildings | building	7
Approximate Square Feet	862,800
Consolidated | Retail | Manhattan
Real estate properties
Number of Buildings | building	2
Approximate Square Feet	30,496
Consolidated | Retail | Manhattan | 7 Dey/185 Broadway
Real estate properties
Approximate Square Feet	140,382
Consolidated | Development/Redevelopment | Manhattan
Real estate properties
Number of Buildings | building	2
Approximate Square Feet	880,771
Consolidated | Residential | Manhattan
Real estate properties
Number of Buildings | building	1
Approximate Square Feet	140,382
Consolidated | Residential | Manhattan | 7 Dey/185 Broadway
Real estate properties
Approximate Square Feet	50,206
Consolidated | Core Portfolio
Real estate properties
Number of Buildings | building	27
Approximate Square Feet	11,501,890
Consolidated | Alternative strategy portfolio | Manhattan
Real estate properties
Number of Buildings | building	0
Approximate Square Feet	0
Unconsolidated | Manhattan
Real estate properties
Number of Buildings | building	11
Approximate Square Feet	13,573,579
Unconsolidated | Commercial Property
Real estate properties
Number of Buildings | building	11
Approximate Square Feet	13,573,579
Unconsolidated | Office | Manhattan
Real estate properties
Number of Buildings | building	9
Approximate Square Feet	12,175,149
Unconsolidated | Office | Suburban
Real estate properties
Number of Buildings | building	0
Approximate Square Feet	0
Unconsolidated | Retail | Manhattan
Real estate properties
Number of Buildings | building	1
Approximate Square Feet	12,946
Unconsolidated | Development/Redevelopment | Manhattan
Real estate properties
Number of Buildings | building	1
Approximate Square Feet	1,385,484
Unconsolidated | Residential | Manhattan
Real estate properties
Number of Buildings | building	1
Approximate Square Feet	221,884
Unconsolidated | Core Portfolio
Real estate properties
Number of Buildings | building	12
Approximate Square Feet	13,795,463
Unconsolidated | Alternative strategy portfolio | Manhattan
Real estate properties
Number of Buildings | building	7
Approximate Square Feet	2,567,025