Organization and Basis of Presentation - Schedule of Commercial Office Properties (Details)	Mar. 31, 2024 ft² building
Commercial properties
Real estate properties
Number of Buildings | building	37
Approximate Square Feet unaudited (sqft)	25,501,181
Weighted Average Leased Occupancy	88.00%
Core portfolio
Real estate properties
Number of Buildings | building	39
Approximate Square Feet unaudited (sqft)	25,863,447
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	13
Approximate Square Feet unaudited (sqft)	14,981,521
Unconsolidated | Core portfolio
Real estate properties
Number of Buildings | building	14
Approximate Square Feet unaudited (sqft)	15,203,405
Manhattan
Real estate properties
Number of Buildings | building	30
Approximate Square Feet unaudited (sqft)	24,638,381
Weighted Average Leased Occupancy	88.60%
Manhattan | Office
Real estate properties
Number of Buildings | building	24
Approximate Square Feet unaudited (sqft)	21,762,590
Weighted Average Leased Occupancy	88.60%
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	4
Approximate Square Feet unaudited (sqft)	2,840,197
Manhattan | Residential
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft)	362,266
Weighted Average Leased Occupancy	99.60%
Manhattan | Core portfolio
Real estate properties
Weighted Average Leased Occupancy	88.20%
Manhattan | Alternative Strategy Portfolio
Real estate properties
Number of Buildings | building	10
Approximate Square Feet unaudited (sqft)	3,712,844
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
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft)	17,888
Manhattan | Unconsolidated
Real estate properties
Number of Buildings | building	13
Approximate Square Feet unaudited (sqft)	14,981,521
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	2
Approximate Square Feet unaudited (sqft)	1,959,426
Manhattan | Unconsolidated | Residential
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft)	221,884
Manhattan | Unconsolidated | Alternative Strategy Portfolio
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	73.80%
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