Organization (Details) ft² in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2024 ft² unit extension property	Dec. 31, 2024 USD ($) ft² unit extension property	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Operating Properties
Number of properties | property	5	5
Rental revenues | $		$ 217,656	$ 216,468	$ 197,230
731 Lexington Avenue
Operating Properties
Area of property (in square feet)	1,080	1,080
731 Lexington Avenue | Office space
Operating Properties
Area of property (in square feet)	947	947
731 Lexington Avenue | Retail space
Operating Properties
Area of property (in square feet)	133	133
731 Lexington Avenue | Retail space | Tenant Occupant | Home Depot
Operating Properties
Area of property (in square feet)	83	83
Rental revenues | $		$ 15,150
Rego Park I
Operating Properties
Area of property (in square feet)	338	338
Rego Park I | Burlington Coat Factory
Operating Properties
Area of property (in square feet)	50	50
Rego Park I | Marshalls
Operating Properties
Area of property (in square feet)	36	36
Rego Park II
Operating Properties
Area of property (in square feet)	615	615
Leases term of real estate property	10 years
Rego Park II | Costco
Operating Properties
Area of property (in square feet)	145	145
Rego Park II | Kohl's
Operating Properties
Area of property (in square feet)	133	133
Flushing
Operating Properties
Area of property (in square feet)	167	167
Number of extensions | extension	1	1
Length of extension		10 years
The Alexander apartment tower
Operating Properties
Area of property (in square feet)	255	255
Number of property units | unit	312	312