Organization (Details) ft² in Thousands, $ in Millions			12 Months Ended
	Sep. 27, 2023 USD ($)	Dec. 03, 2022 USD ($) ft²	Dec. 31, 2023 ft² segment property unit extension
Operating Properties
Number of properties | property			5
Number of segments | segment			1
731 Lexington Avenue
Operating Properties
Area of property (in square feet)			1,079
731 Lexington Avenue | Office space
Operating Properties
Area of property (in square feet)			939
731 Lexington Avenue | Retail space
Operating Properties
Area of property (in square feet)			140
731 Lexington Avenue | Retail space | Tenant Occupant | Home Depot
Operating Properties
Area of property (in square feet)			83
Rego Park I
Operating Properties
Area of property (in square feet)			338
Rego Park I | IKEA
Operating Properties
Area of property (in square feet)		112
Payment for termination of lease | $	$ 10	$ 10
Rego Park I | Burlington Coat Factory
Operating Properties
Area of property (in square feet)			50
Rego Park I | Marshalls
Operating Properties
Area of property (in square feet)			36
Rego Park II
Operating Properties
Area of property (in square feet)			616
Rego Park II | Costco
Operating Properties
Area of property (in square feet)			145
Rego Park II | Kohl's
Operating Properties
Area of property (in square feet)			133
Flushing
Operating Properties
Area of property (in square feet)			167
Number of extensions | extension			1
Length of extension			10 years
The Alexander apartment tower
Operating Properties
Area of property (in square feet)			255
Number of property units | unit			312