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Organization and Basis of Presentation - Schedule of Commercial Office Properties (Details)	Jun. 30, 2025 ft² building
Commercial properties
Real estate properties
Number of buildings | building	37
Approximate square feet unaudited (sqft)	25,087,626
Weighted average leased occupancy	89.80%
Core portfolio
Real estate properties
Number of buildings | building	39
Approximate square feet unaudited (sqft)	25,449,892
Consolidated | Commercial properties
Real estate properties
Number of buildings | building	27
Approximate square feet unaudited (sqft)	11,526,993
Consolidated | Core portfolio
Real estate properties
Number of buildings | building	28
Approximate square feet unaudited (sqft)	11,667,375
Unconsolidated | Commercial properties
Real estate properties
Number of buildings | building	10
Approximate square feet unaudited (sqft)	13,560,633
Unconsolidated | Core portfolio
Real estate properties
Number of buildings | building	11
Approximate square feet unaudited (sqft)	13,782,517
Manhattan
Real estate properties
Number of buildings | building	30
Approximate square feet unaudited (sqft)	24,224,826
Weighted average leased occupancy	90.40%
Manhattan | Office
Real estate properties
Number of buildings | building	26
Approximate square feet unaudited (sqft)	23,349,485
Weighted average leased occupancy	90.40%
Manhattan | Retail
Real estate properties
Number of buildings | building	2
Approximate square feet unaudited (sqft)	30,496
Weighted average leased occupancy	100.00%
Manhattan | Development/Redevelopment
Real estate properties
Number of buildings | building	2
Approximate square feet unaudited (sqft)	844,845
Manhattan | Residential
Real estate properties
Number of buildings | building	2
Approximate square feet unaudited (sqft)	362,266
Weighted average leased occupancy	99.80%
Manhattan | Core portfolio
Real estate properties
Weighted average leased occupancy	89.90%
Manhattan | Alternative Strategy Portfolio
Real estate properties
Number of buildings | building	7
Approximate square feet unaudited (sqft)	2,567,025
Weighted average leased occupancy	59.30%
Manhattan | Consolidated
Real estate properties
Number of buildings | building	20
Approximate square feet unaudited (sqft)	10,664,193
Manhattan | Consolidated | Office
Real estate properties
Number of buildings | building	16
Approximate square feet unaudited (sqft)	9,788,852
Manhattan | Consolidated | Retail
Real estate properties
Number of buildings | building	2
Approximate square feet unaudited (sqft)	30,496
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)	844,845
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	0
Approximate square feet unaudited (sqft)	0
Manhattan | Unconsolidated
Real estate properties
Number of buildings | building	10
Approximate square feet unaudited (sqft)	13,560,633
Manhattan | Unconsolidated | Office
Real estate properties
Number of buildings | building	10
Approximate square feet unaudited (sqft)	13,560,633
Manhattan | Unconsolidated | Retail
Real estate properties
Number of buildings | building	0
Approximate square feet unaudited (sqft)	0
Manhattan | Unconsolidated | Development/Redevelopment
Real estate properties
Number of buildings | building	0
Approximate square feet unaudited (sqft)	0
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	7
Approximate square feet unaudited (sqft)	2,567,025
Suburban | Office
Real estate properties
Number of buildings | building	7
Approximate square feet unaudited (sqft)	862,800
Weighted average leased occupancy	71.40%
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

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