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Organization and Basis (Details) | 12 Months Ended
--- | ---
Dec. 31, 2011 sqft
731 Lexington Avenue Property |
Operating Properties [Abstract] |
Total area of property | 1,307,000
731 Lexington Avenue Property | Office Space [Member] |
Operating Properties [Abstract] |
Total area of property | 885,000
731 Lexington Avenue Property | Office Space [Member] | Tenant Occupant [Member] | Bloomberg [Member] |
Operating Properties [Abstract] |
Total area of property | 885,000
731 Lexington Avenue Property | Retail Space [Member] |
Operating Properties [Abstract] |
Total area of property | 174,000
731 Lexington Avenue Property | Retail Space [Member] | Tenant Occupant [Member] | Container Store [Member] |
Operating Properties [Abstract] |
Total area of property | 34,000
731 Lexington Avenue Property | Retail Space [Member] | Tenant Occupant [Member] | Hennes Mauritz [Member] |
Operating Properties [Abstract] |
Total area of property | 27,000
731 Lexington Avenue Property | Retail Space [Member] | Tenant Occupant [Member] | Home Depot [Member] |
Operating Properties [Abstract] |
Total area of property | 83,000
731 Lexington Avenue Property | Residential Space [Member] |
Operating Properties [Abstract] |
Total area of property | 248,000
Number Of Residential Units Sold | 105
The Kings Plaza Regional Shopping Center |
Operating Properties [Abstract] |
Total area of property | 1,210,000
The Kings Plaza Regional Shopping Center | Owner Occupant [Member] | Macys [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 339,000
The Kings Plaza Regional Shopping Center | Tenant Occupant [Member] | Sears [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 289,000
The Kings Plaza Regional Shopping Center | Tenant Occupant [Member] | Lowes [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 114,000
Rego Park I Shopping Center |
Operating Properties [Abstract] |
Total area of property | 343,000
Rego Park I Shopping Center | Tenant Occupant [Member] | Burlington Coat Factory [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 50,000
Rego Park I Shopping Center | Tenant Occupant [Member] | Marshalls [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 36,000
Rego Park I Shopping Center | Tenant Occupant [Member] | Bed Bath Beyond [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 46,000
Rego Park I Shopping Center | Tenant Occupant [Member] | Sears [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 195,000
Rego Park II Property |
Operating Properties [Abstract] |
Total area of property | 610,000
Rego Park II Property | Tenant Occupant [Member] | Toys R Us [Member] |
Operating Properties [Abstract] |
Total area of property | 47,000
Related Party Ownership In Tenant | one-third
Rego Park II Property | Tenant Occupant [Member] | Kohls [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 133,000
Rego Park II Property | Tenant Occupant [Member] | Century 21 [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 135,000
Rego Park II Property | Tenant Occupant [Member] | Costco [Member] | Anchor [Member] |
Operating Properties [Abstract] |
Total area of property | 145,000
The Paramus Property | Tenant Occupant [Member] | Ikea [Member] |
Operating Properties [Abstract] |
Acres Of Real Estate Land | 30.3
The Flushing Property | Tenant Occupant [Member] | New World Mall Llc [Member] |
Operating Properties [Abstract] |
Total area of property | 167,000
The Rego Park III Property | Property To Be Developed [Member] |
Operating Properties [Abstract] |
Acres Of Real Estate Land | 3.4

X
- Definition The amount of acres related to land. + References No definition available. + Details
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Namespace Prefix: | alx_
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Balance Type: | na
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- Definition Number of residential units sold on the property + References No definition available. + Details
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Namespace Prefix: | alx_
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Period Type: | duration

X
- Details
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X
- Definition Vornado's Ownership interest in tenants occupying space at the company's properties + References No definition available. + Details
Name: | alx_RelatedPartyOwnershipInTenant
Namespace Prefix: | alx_
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X
- Definition The amount of square footage related to a real estate property. + References No definition available. + Details
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