XML 50 R35.htm IDEA: XBRL DOCUMENT
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Organization (Details) (USD $) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2014 Segment property | Dec. 31, 2013 | Dec. 31, 2001 acre
Operating Properties [Abstract] |  |  |
Number of properties in greater New York City metropolitan area (in property) | 6 us-gaap_NumberOfRealEstateProperties |  |
Development and construction in progress | $ 75,289,000 us-gaap_DevelopmentInProcess | $ 4,924,000 us-gaap_DevelopmentInProcess |
Number Of Operating Segments | 1 us-gaap_NumberOfOperatingSegments |  |
731 Lexington Avenue [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 1,307,000 us-gaap_AreaOfRealEstateProperty / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |
731 Lexington Avenue [Member] | Office Space [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 885,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_OfficeBuildingMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |
731 Lexington Avenue [Member] | Office Space [Member] | Tenant Occupant [Member] | Bloomberg [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 885,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_OfficeBuildingMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_BloombergMember |  |
731 Lexington Avenue [Member] | Retail Space [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 174,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Container Store [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 34,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_ContainerStoreMember |  |
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Hennes Mauritz [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 27,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_HennesMauritzMember |  |
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Home Depot [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 83,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_HomeDepotMember |  |
731 Lexington Avenue [Member] | Residential Space [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Number of units in real estate property (in units) | 105 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = alx_ResidentialSpaceMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |
Area of property (in square feet) | 248,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = alx_ResidentialSpaceMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |
Rego Park I [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 343,000 us-gaap_AreaOfRealEstateProperty / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember |  |
Rego Park I [Member] | Tenant Occupant [Member] | Burlington Coat Factory [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 50,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_BurlingtonCoatFactoryMember |  |
Rego Park I [Member] | Tenant Occupant [Member] | Marshalls [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 36,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_MarshallsMember |  |
Rego Park I [Member] | Tenant Occupant [Member] | Bed Bath Beyond [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 46,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_BedBathBeyondMember |  |
Rego Park I [Member] | Tenant Occupant [Member] | Sears [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 195,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_SearsMember |  |
Rego Park II [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 609,000 us-gaap_AreaOfRealEstateProperty / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember |  |
Rego Park II [Member] | Tenant Occupant [Member] | Toys R Us/ Babys R Us [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 47,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_ToysRUsMember |  |
Rego Park II [Member] | Tenant Occupant [Member] | Kohls [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 133,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_KohlsMember |  |
Rego Park II [Member] | Tenant Occupant [Member] | Century 21 [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 135,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_Century21Member |  |
Rego Park II [Member] | Tenant Occupant [Member] | Costco [Member] | Anchor [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 145,000 us-gaap_AreaOfRealEstateProperty / alx_OccupantTypeAxis = alx_AnchorMember / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_CostcoMember |  |
Rego Park II [Member] | Apartment Tower [Member] | Property Under Development [Member] |  |  |
Operating Properties [Abstract] |  |  |
Number of units in real estate property (in units) | 312 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ApartmentBuildingMember / alx_PropertyOperatingStatusAxis = alx_PropertyUnderDevelopmentMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember |  |
Area of property (in square feet) | 255,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ApartmentBuildingMember / alx_PropertyOperatingStatusAxis = alx_PropertyUnderDevelopmentMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember |  |
Estimated Date Of Completion | 2015 |  |
Development and construction in progress | 73,327,000 us-gaap_DevelopmentInProcess / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ApartmentBuildingMember / alx_PropertyOperatingStatusAxis = alx_PropertyUnderDevelopmentMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember |  |
Rego Park II [Member] | Apartment Tower [Member] | Maximum [Member] | Property Under Development [Member] |  |  |
Operating Properties [Abstract] |  |  |
Estimated Budgeted Cost | $ 125,000,000 alx_EstimatedBudgetedCost / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_ApartmentBuildingMember / alx_PropertyOperatingStatusAxis = alx_PropertyUnderDevelopmentMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark2PropertyMember |  |
Paramus [Member] | Tenant Occupant [Member] | Ikea [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area Of Land (in acre) |  |  | 30.3 us-gaap_AreaOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember
Paramus [Member] | Tenant Occupant [Member] | Ikea [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area Of Land (in acre) | 30.3 us-gaap_AreaOfLand / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember |  |
Flushing [Member] | Tenant Occupant [Member] | New World Mall Llc [Member] | Operating Property [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area of property (in square feet) | 167,000 us-gaap_AreaOfRealEstateProperty / alx_PropertyOperatingStatusAxis = alx_OperatingPropertyMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_FlushingPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_NewWorldMallLlcMember |  |
Rego Park III [Member] | Property To Be Developed [Member] |  |  |
Operating Properties [Abstract] |  |  |
Area Of Land (in acre) | 3.2 us-gaap_AreaOfLand / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = alx_PropertyToBeDevelopedMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark3PropertyMember |  |

X
- Definition Estimated total cost for proposed development. + References No definition available. + Details
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- Definition Area of a real estate property. + References No definition available. + Details
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- Definition The current amount of expenditures for a real estate project that has not yet been completed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.10) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
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- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
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- Definition The number of units in a real estate property owned as of the balance sheet date. + References No definition available. + Details
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