XML 40 R44.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Commitments and Contingencies (Details) (USD $) | 12 Months Ended | 0 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2021 | Jun. 24, 2014 Fires | Dec. 31, 2001 acre | Jan. 01, 2016
Rego Park 2 Property [Abstract] |  |  |  |  |  |  |
Development and construction in progress | $ 75,289,000 us-gaap_DevelopmentInProcess | $ 4,924,000 us-gaap_DevelopmentInProcess |  |  |  |  |
Paramus Property [Abstract] |  |  |  |  |  |  |
Mortgages payable | 1,032,780,000 us-gaap_NotesPayable | 1,049,959,000 us-gaap_NotesPayable |  |  |  |  |
Purchase option excercised, gain on sale of land | 0 us-gaap_GainLossOnDispositionOfRealEstateDiscontinuedOperations | 0 us-gaap_GainLossOnDispositionOfRealEstateDiscontinuedOperations | 599,628,000 us-gaap_GainLossOnDispositionOfRealEstateDiscontinuedOperations |  |  |  |
Letters Of Credit [Abstract] |  |  |  |  |  |  |
Standby letters of credit, issued and outstanding | 3,308,000 us-gaap_LettersOfCreditOutstandingAmount |  |  |  |  |  |
Lexington Avenue Property [Member] | Retail Space [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Mortgage loans, recourse | 75,000,000 alx_MortgageLoanConvertedToRecourse / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |  |  |  |  |
Paramus Property [Abstract] |  |  |  |  |  |  |
Mortgages payable | 320,000,000 us-gaap_NotesPayable / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = us-gaap_RetailSiteMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_LexingtonAvenuePropertyMember |  |  |  |  |  |
Paramus Property [Member] | Tenant Occupant [Member] |  |  |  |  |  |  |
Paramus Property [Abstract] |  |  |  |  |  |  |
Debt Instrument Maturity Date String | October 2018 |  |  |  |  |  |
Paramus Property [Member] | Tenant Occupant [Member] | Ikea [Member] |  |  |  |  |  |  |
Paramus Property [Abstract] |  |  |  |  |  |  |
Area Of Land (in acre) |  |  |  |  |  | 30.3 us-gaap_AreaOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember |
Mortgages payable | 68,000,000 us-gaap_NotesPayable / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember |  |  |  |  |  |
Fixed interest rate on the debt (in percentage) | 2.90%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember |  |  |  |  |  |
Triple-net rent, annual amount | 700,000 alx_TripleNetRentAnnualAmount / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember |  |  |  |  |  |
Paramus Property [Member] | Tenant Occupant [Member] | Ikea [Member] | Scenario Forecast [Member] |  |  |  |  |  |  |
Paramus Property [Abstract] |  |  |  |  |  |  |
Property purchase option exercisable be leasee with purchase option in 2021 |  |  |  | 75,000,000 alx_PropertyPurchaseOptionExcercisableByLessee / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |  |  |
Purchase option exercised, net cash proceeds from sale of land |  |  |  | 7,000,000 alx_PurchaseOptionExercisedProceedsFromSaleOfLandHeldForUse / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |  |  |
Purchase option excercised, gain on sale of land |  |  |  | 60,000,000 us-gaap_GainLossOnDispositionOfRealEstateDiscontinuedOperations / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |  |  |
Purchase option not excercised amount included in triple net rent over remainder of lease |  |  |  | 68,000,000 alx_PurchaseOptionNotExcercisedAmountIncludedInTripleNetRentOverRemainderOfLease / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_ParamusPropertyMember / alx_RealEstateOccupantPossessionTypeAxis = alx_TenantOccupantMember / alx_RealEstatePropertyOccupantAxis = alx_IkeaMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |  |  |
Loan Amortization Period |  |  |  | 20 years |  |  |
Rego Park I [Member] | Sears [Member] |  |  |  |  |  |  |
Loss Contingency [Abstract] |  |  |  |  |  |  |
Number Of Fires |  |  |  |  | 2 alx_NumberOfFires / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstatePropertyOccupantAxis = alx_SearsMember |  |
Rego Park I [Member] | Sears [Member] | Minimum [Member] |  |  |  |  |  |  |
Loss Contingency [Abstract] |  |  |  |  |  |  |
Loss Contingency, Damages Sought, Value |  |  |  |  | 4,000,000 us-gaap_LossContingencyDamagesSoughtValue / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstatePropertyOccupantAxis = alx_SearsMember |  |
Rego Park I [Member] | Sears [Member] | Minimum [Member] | Estimated Future Damages [Member] |  |  |  |  |  |  |
Loss Contingency [Abstract] |  |  |  |  |  |  |
Loss Contingency, Damages Sought, Value |  |  |  |  | 25,000,000 us-gaap_LossContingencyDamagesSoughtValue / us-gaap_LossContingenciesByNatureOfContingencyAxis = alx_EstimatedFutureDamagesMember / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = alx_RegoPark1ShoppingMember / alx_RealEstatePropertyOccupantAxis = alx_SearsMember |  |
Rego Park 2 Property [Member] | Apartment Tower [Member] | Property Under Development [Member] |  |  |  |  |  |  |
Rego Park 2 Property [Abstract] |  |  |  |  |  |  |
Number of units in apartment tower (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 2 Property [Member] | Maximum [Member] | Apartment Tower [Member] | Property Under Development [Member] |  |  |  |  |  |  |
Rego Park 2 Property [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 |  |  |  |  |  |
General Liability [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Insurance Maximum Coverage Per Incident | 300,000,000 alx_InsuranceMaximumCoveragePerIncident / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = us-gaap_GeneralLiabilityMember |  |  |  |  |  |
All Risk Property And Rental Value [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Insurance Maximum Coverage Per Incident | 1,700,000,000 alx_InsuranceMaximumCoveragePerIncident / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_AllRiskPropertyAndRentalValueMember |  |  |  |  |  |
Terrorism Coverage Including Nbcr [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Insurance Maximum Coverage Per Incident | 1,700,000,000 alx_InsuranceMaximumCoveragePerIncident / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_TerrorismCoverageIncludingNbcrMember |  |  |  |  |  |
Reinsurance For Terrorism Coverage Excluding Nbcr [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Insurance Maximum Coverage Per Incident | 1,700,000,000 alx_InsuranceMaximumCoveragePerIncident / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_ReinsuranceForTerrorismCoverageExcludingNbcrMember |  |  |  |  |  |
NBCR [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Deductible | $ 275,000 alx_Deductible / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_NbcrMember |  |  |  |  |  |
Self Insured Responsibility (in percentage) | 15.00%alx_SelfInsuredResponsibility / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_NbcrMember |  |  |  |  |  |
Federal Government Responsibility (in percentage) | 85.00%alx_FederalGovernmentResponsibility / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_NbcrMember |  |  |  |  |  |
NBCR [Member] | Scenario Forecast [Member] |  |  |  |  |  |  |
Insurance [Abstract] |  |  |  |  |  |  |
Self Insured Responsibility (in percentage) |  |  |  |  |  |  | 16.00%alx_SelfInsuredResponsibility / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_NbcrMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember
Federal Government Responsibility (in percentage) |  |  |  |  |  |  | 84.00%alx_FederalGovernmentResponsibility / alx_ScheduleOfInsuranceTypeAndTierIdentifierAxis = alx_NbcrMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember

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