Organization	12 Months Ended
Dec. 31, 2014
Organization and Basis of Presentation [Abstract]
Organization [Text Block]	1. ORGANIZATION Alexander's, Inc. (NYSE: ALX) is a real estate investment trust (“REIT”), incorporated in Delaware, engaged in leasing, managing, developing and redeveloping its properties. All references to “we,” “us,” “our,” “Company” and “Alexander's” refer to Alexander's, Inc. and its consolidated subsidiaries. We are managed by, and our properties are leased and developed by, Vornado Realty Trust (“Vornado”) (NYSE: VNO). We have six properties in the greater New York City metropolitan area consisting of: Operating properties 731 Lexington Avenue, a 1,307,000 square foot multi-use building, comprising the entire square block bounded by Lexington Avenue, East 59th Street, Third Avenue and East 58th Street in Manhattan. The building contains 885,000 and 174,000 of net rentable square feet of office and retail space, respectively, which we own, and 248,000 square feet of residential space consisting of 105 condominium units, which we sold. Bloomberg L.P. (“Bloomberg”) occupies all of the office space. The Home Depot (83,000 square feet), The Container Store (34,000 square feet) and Hennes & Mauritz (27,000 square feet) are the principal retail tenants; Rego Park I, a 343,000 square foot shopping center, located on Queens Boulevard and 63rd Road in Queens. The center is anchored by a 195,000 square foot Sears department store, a 50,000 square foot Burlington Coat Factory, a 46,000 square foot Bed Bath & Beyond and a 36,000 square foot Marshalls; Rego Park II, a 609,000 square foot shopping center, adjacent to the Rego Park I shopping center in Queens. The center is anchored by a 145,000 square foot Costco, a 135,000 square foot Century 21 and a 133,000 square foot Kohl's. In addition, 47,000 square feet is leased to Toys “R” Us/Babies “R” Us, a one-third owned affiliate of Vornado; Paramus, located at the intersection of Routes 4 and 17 in Paramus, New Jersey, consists of 30.3 acres of land that is leased to IKEA Property, Inc.; and Flushing, a 167,000 square foot building, located at Roosevelt Avenue and Main Street in Queens, that is sub-leased to New World Mall LLC for the remainder of our ground lease term. Property under development Rego Park II Apartment Tower; We are in the process of constructing an apartment tower above our Rego II shopping center, containing 312 units aggregating 255,000 square feet, which is expected to be completed in 2015. The estimated cost of this project is approximately $125,000,000, of which $73,327,000 has been incurred as of December 31, 2014. There can be no assurance that the project will be completed, or completed on schedule or within budget. Property to be developed Rego Park III, a 3.2 acre land parcel adjacent to the Rego Park II shopping center in Queens, at the intersection of Junction Boulevard and the Horace Harding Service Road. We have determined that our properties have similar economic characteristics and meet the criteria that permit the properties to be aggregated into one reportable segment (the leasing, management, development and redeveloping of properties in the greater New York City metropolitan area). Our chief operating decision-maker assesses and measures segment operating results based on a performance measure referred to as net operating income at the individual operating segment. Net operating income for each property represents net rental revenues less operating expenses.

Organization

12 Months Ended

Dec. 31, 2014

Organization and Basis of Presentation [Abstract]

1. ORGANIZATION

Alexander's, Inc. (NYSE: ALX) is a real estate investment trust (“REIT”), incorporated in Delaware, engaged in leasing, managing, developing and redeveloping its properties. All references to “we,” “us,” “our,” “Company” and “Alexander's” refer to Alexander's, Inc. and its consolidated subsidiaries. We are managed by, and our properties are leased and developed by, Vornado Realty Trust (“Vornado”) (NYSE: VNO).

We have six properties in the greater New York City metropolitan area consisting of:

Operating properties

731 Lexington Avenue, a 1,307,000 square foot multi-use building, comprising the entire square block bounded by Lexington Avenue, East 59th Street, Third Avenue and East 58th Street in Manhattan. The building contains 885,000 and 174,000 of net rentable square feet of office and retail space, respectively, which we own, and 248,000 square feet of residential space consisting of 105 condominium units, which we sold. Bloomberg L.P. (“Bloomberg”) occupies all of the office space. The Home Depot (83,000 square feet), The Container Store (34,000 square feet) and Hennes & Mauritz (27,000 square feet) are the principal retail tenants;
Rego Park I, a 343,000 square foot shopping center, located on Queens Boulevard and 63rd Road in Queens. The center is anchored by a 195,000 square foot Sears department store, a 50,000 square foot Burlington Coat Factory, a 46,000 square foot Bed Bath & Beyond and a 36,000 square foot Marshalls;
Rego Park II, a 609,000 square foot shopping center, adjacent to the Rego Park I shopping center in Queens. The center is anchored by a 145,000 square foot Costco, a 135,000 square foot Century 21 and a 133,000 square foot Kohl's. In addition, 47,000 square feet is leased to Toys “R” Us/Babies “R” Us, a one-third owned affiliate of Vornado;
Paramus, located at the intersection of Routes 4 and 17 in Paramus, New Jersey, consists of 30.3 acres of land that is leased to IKEA Property, Inc.; and
Flushing, a 167,000 square foot building, located at Roosevelt Avenue and Main Street in Queens, that is sub-leased to New World Mall LLC for the remainder of our ground lease term.

Property under development

Rego Park II Apartment Tower; We are in the process of constructing an apartment tower above our Rego II shopping center, containing 312 units aggregating 255,000 square feet, which is expected to be completed in 2015. The estimated cost of this project is approximately $125,000,000, of which $73,327,000 has been incurred as of December 31, 2014. There can be no assurance that the project will be completed, or completed on schedule or within budget.

Property to be developed

Rego Park III, a 3.2 acre land parcel adjacent to the Rego Park II shopping center in Queens, at the intersection of Junction Boulevard and the Horace Harding Service Road.

We have determined that our properties have similar economic characteristics and meet the criteria that permit the properties to be aggregated into one reportable segment (the leasing, management, development and redeveloping of properties in the greater New York City metropolitan area). Our chief operating decision-maker assesses and measures segment operating results based on a performance measure referred to as net operating income at the individual operating segment. Net operating income for each property represents net rental revenues less operating expenses.