Organization and Basis of Presentation - Schedule of Commercial Office Properties (Details)	Jun. 30, 2024 ft² building
Commercial properties
Real estate properties
Number of Buildings | building	36
Approximate Square Feet unaudited (sqft)	24,927,239
Weighted Average Leased Occupancy	88.70%
Core portfolio
Real estate properties
Number of Buildings | building	38
Approximate Square Feet unaudited (sqft)	25,289,505
Consolidated | Commercial properties
Real estate properties
Number of Buildings | building	24
Approximate Square Feet unaudited (sqft)	10,519,660
Consolidated | Core portfolio
Real estate properties
Number of Buildings | building	25
Approximate Square Feet unaudited (sqft)	10,660,042
Unconsolidated | Commercial properties
Real estate properties
Number of Buildings | building	12
Approximate Square Feet unaudited (sqft)	14,407,579
Unconsolidated | Core portfolio
Real estate properties
Number of Buildings | building	13
Approximate Square Feet unaudited (sqft)	14,629,463
Manhattan
Real estate properties
Number of Buildings | building	29
Approximate Square Feet unaudited (sqft)	24,064,439
Weighted Average Leased Occupancy	89.30%
Manhattan | Office
Real estate properties
Number of Buildings | building	24
Approximate Square Feet unaudited (sqft)	21,762,590
Weighted Average Leased Occupancy	89.30%
Manhattan | Retail
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft)	35,594
Weighted Average Leased Occupancy	100.00%
Manhattan | Development/Redevelopment
Real estate properties
Number of Buildings | building	3
Approximate Square Feet unaudited (sqft)	2,266,255
Manhattan | Residential
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft)	362,266
Weighted Average Leased Occupancy	99.30%
Manhattan | Core portfolio
Real estate properties
Weighted Average Leased Occupancy	88.80%
Manhattan | Alternative Strategy Portfolio (3)
Real estate properties
Number of Buildings | building	9
Approximate Square Feet unaudited (sqft)	3,702,804
Weighted Average Leased Occupancy	66.10%
Manhattan | Consolidated
Real estate properties
Number of Buildings | building	17
Approximate Square Feet unaudited (sqft)	9,656,860
Manhattan | Consolidated | Office
Real estate properties
Number of Buildings | building	14
Approximate Square Feet unaudited (sqft)	8,753,441
Manhattan | Consolidated | Retail
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	22,648
Manhattan | Consolidated | Retail | 7 Dey / 185 Broadway
Real estate properties
Approximate Square Feet unaudited (sqft)	140,382
Manhattan | Consolidated | Development/Redevelopment
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft)	880,771
Manhattan | Consolidated | Residential
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	140,382
Manhattan | Consolidated | Residential | 7 Dey / 185 Broadway
Real estate properties
Approximate Square Feet unaudited (sqft)	50,206
Manhattan | Consolidated | Alternative Strategy Portfolio (3)
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	7,848
Manhattan | Unconsolidated
Real estate properties
Number of Buildings | building	12
Approximate Square Feet unaudited (sqft)	14,407,579
Manhattan | Unconsolidated | Office
Real estate properties
Number of Buildings | building	10
Approximate Square Feet unaudited (sqft)	13,009,149
Manhattan | Unconsolidated | Retail
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	12,946
Manhattan | Unconsolidated | Development/Redevelopment
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	1,385,484
Manhattan | Unconsolidated | Residential
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	221,884
Manhattan | Unconsolidated | Alternative Strategy Portfolio (3)
Real estate properties
Number of Buildings | building	8
Approximate Square Feet unaudited (sqft)	3,694,956
Suburban | Office
Real estate properties
Number of Buildings | building	7
Approximate Square Feet unaudited (sqft)	862,800
Weighted Average Leased Occupancy	72.40%
Suburban | Consolidated | Office
Real estate properties
Number of Buildings | building	7
Approximate Square Feet unaudited (sqft)	862,800
Suburban | Unconsolidated | Office
Real estate properties
Number of Buildings | building	0
Approximate Square Feet unaudited (sqft)	0