Dividends per common share (in usd per share) Common Stock, Dividends, Per Share, Cash Paid Statistical Measurement [Domain] Statistical Measurement [Domain] Incentive asset from lessor Incentive Asset From Lessor Incentive Asset From Lessor Property held for sale Disposal Group, Including Discontinued Operation, Property, Plant and Equipment Award Timing Predetermined Award Timing Predetermined [Flag] Related Party Transaction [Axis] Related Party Transaction [Axis] Self insured responsibility (in percentage) Self Insured Responsibility The percentage of the covered portion of a loss above the deductible for which our wholly owned insurance subsidiary is responsible for covered losses. Real Estate [Domain] Real Estate [Domain] Entity File Number Entity File Number Additional Capital Additional Paid-in Capital [Member] Interest rate swap Interest Rate Swap [Member] The Alexander apartment tower Alexander Apartment Tower [Member] Alexander apartment tower. Tabular List, Table Tabular List [Table Text Block] Recently Issued Accounting Literature New Accounting Pronouncements, Policy [Policy Text Block] Rent abatement amount Rent Abatement Amount Rent Abatement Amount Schedule of Fees to Vornado Schedule of Related Party Transactions [Table Text Block] Deferred leasing costs, net, including unamortized leasing fees to Vornado of $20,069 and $20,649, respectively Deferred Costs, Leasing, Net Schedule of Carrying Amount and Fair Value of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] All Risk Property and Rental Value All Risk Property And Rental Value [Member] All risk property and rental value. Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Measurement Basis [Axis] Measurement Basis [Axis] Net income per common share - basic (in usd per share) Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] Property management, cleaning, engineering, parking and security fees Property Management Fees [Member] Property management fees and payments for cleaning, engineering and security services. Related Party Transactions Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Schedule of Interest Rate Derivatives Schedule of Derivative Assets at Fair Value [Table Text Block] Revenue Recognition Revenue from Contract with Customer [Text Block] Schedule of Financial Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Debt Covenant Axis [Axis] Debt Covenant Axis [Axis] Debt Covenant Axis Common Area Common Area [Member] Common area. Area of property (in sqft.) Area of Real Estate Property Schedule Of Insurance Type And Tier Identifier [Axis] Schedule Of Insurance Type And Tier Identifier [Axis] Schedule Of Insurance Type And Tier Identifier [Axis] Adjustment to Compensation, Amount Adjustment to Compensation Amount Vornado Affiliated Entity [Member] Percentage rent contributed by tenant Concentration Risk, Percentage Office and Retail Space Office And Retail Space [Member] Office And Retail Space [Member] Other assets Increase (Decrease) in Other Operating Assets Notional Amount Derivative Asset, Notional Amount Employee Stock Option Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Dividends paid ($4.50 per common share) Dividends, Common Stock, Cash Total equity Beginning balance Ending balance Equity, Attributable to Parent Measurement Frequency [Axis] Measurement Frequency [Axis] Insider Trading Policies and Procedures [Line Items] Common stock: authorized shares (in shares) Common Stock, Shares Authorized Hedging Designation [Domain] Hedging Designation [Domain] Mortgages payable (excluding deferred debt issuance costs, net) Notes Payable, Fair Value Disclosure Amortization of deferred lease incentives Deferred Lease Incentives, Amortization Deferred Lease Incentives, Amortization Total liabilities and equity Liabilities and Equity Recurring Fair Value, Recurring [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Cover [Abstract] Cover [Abstract] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Property Held for Sale Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Maximum Maximum [Member] Percentage commissions on sale of assets under fifty million Percentage Commissions On Sale Of Assets Under Fifty Million Percentage of gross proceeds under $50,000,000 from the sale of any assets, payable to related party. Concentration Risk Type [Domain] Concentration Risk Type [Domain] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Insurance maximum coverage per incident Insurance Maximum Coverage Per Incident Insurance maximum coverage limit per incident. Treasury Stock Treasury Stock, Common [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Liabilities: Liabilities [Abstract] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Depreciation and amortization Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Entity Shell Company Entity Shell Company Insurance Type and Tier Identifier [Axis] Insurance Type and Tier Identifier [Axis] Proceeds from sale of investment Proceeds from Sale, Land, Held-for-Investment Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Disposal Group Name [Domain] Disposal Group Name [Domain] Name Measure Name Tenant services Direct Services [Member] Direct Services [Member] Document Fiscal Period Focus Document Fiscal Period Focus Real estate tax expense Real Estate Tax Expense Terrorism Coverage Including NBCR Terrorism Coverage Including NBCR [Member] Terrorism coverage including NBCR. Award Timing Method Award Timing Method [Text Block] Award Type Award Type [Axis] Mortgage loans Long-Term Debt Legal Entity [Axis] Legal Entity [Axis] Assets Assets Trading Symbol Trading Symbol Debt Covenant Axis [Domain] Debt Covenant Axis [Domain] Debt Covenant Axis [Domain] 731 Lexington Avenue Property 731 Lexington Avenue Property [Member] 731 Lexington Avenue Property Entity Address, City or Town Entity Address, City or Town CASH FLOWS FROM OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other segment expenses Segment Reporting, Other Segment Item, Amount Concentration Risk Type [Axis] Concentration Risk Type [Axis] Total Real Estate Investment Property, at Cost Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Deferred debt issuance costs, net of accumulated amortization of $5,907 and $5,263, respectively Debt Issuance Costs, Net Restricted cash Restricted cash at beginning of period Cash and cash equivalents at end of period Restricted Cash and Cash Equivalent Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Basis of Presentation Basis of Accounting [Text Block] Related Party Vornado Related Party [Member] Common stock: outstanding shares (in shares) Common Stock, Shares, Outstanding PEO PEO [Member] Schedule of Revenue Disaggregation of Revenue [Table Text Block] NON-CASH TRANSACTIONS Noncash Investing and Financing Items [Abstract] Junior Subordinated Debt Junior Subordinated Debt [Member] Change in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Alexander's Inc. Alexander's Inc. [Member] Alexander's Inc. [Member] Retained Earnings Retained Earnings [Member] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Interest rate Debt Instrument, Interest Rate, Effective Percentage Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Restricted cash at beginning of period Restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Rate spread Debt Instrument, Basis Spread on Variable Rate Other assets Other Assets Property management fee agreement, price per square foot Property Management Fee Agreement, Price Per Square Foot Property Management Fee Agreement, Price Per Square Foot Preferred stock: issued shares (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Product and Service [Domain] Product and Service [Domain] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Customer Concentration Risk Customer Concentration Risk [Member] Change in fair value of interest rate derivatives Change in fair value of interest rate derivatives Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Property management, cleaning, engineering, parking and security fees Property Management, Cleaning, Engineering, Parking And Security Fees [Member] Property Management, Cleaning, Engineering, Parking And Security Fees Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations and Disposal Groups [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Mortgages Mortgages [Member] Company management fees Company Management Fees [Member] Company management fees. Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Buildings and leasehold improvements Buildings and Improvements, Gross CASH FLOWS FROM INVESTING ACTIVITIES Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] General and administrative, including management fees to Vornado of $610 in each period Management fees to Vornado General and administrative General and Administrative Expense Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Land Land Available for Development Related Party Transactions [Abstract] Related Party Transactions [Abstract] Preferred stock: par value per share (in usd per share) Preferred Stock, Par or Stated Value Per Share Other liabilities Other Liabilities Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Equity Components [Axis] Equity Components [Axis] Organization Nature of Operations [Text Block] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Gains on sales of investment Gains (Losses) on Sales of Investment Real Estate Leasing fees Leasing Fees [Member] Leasing fees. Interest and other income Interest and other income Interest and Other Income Other Performance Measure, Amount Other Performance Measure, Amount Entity Address, State or Province Entity Address, State or Province Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Derivative Instrument [Axis] Derivative Instrument [Axis] Other comprehensive income (loss): Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent [Abstract] Individual: Individual [Axis] Tenant fund by corresponding amount Tenant Fund By Corresponding Amount Tenant Fund By Corresponding Amount Dividends paid Payments of Ordinary Dividends, Common Stock Entity [Domain] Entity [Domain] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Cash payments for interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Debt repayments Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Insurance deductible Insurance Deductible The deductible owed by our wholly owned insurance subsidiary in the event of a covered loss. Carrying Amount Reported Value Measurement [Member] Segment Information Segment Reporting Disclosure [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Ownership [Domain] Ownership [Domain] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Depreciation and amortization, including amortization of debt issuance costs Depreciation, Depletion and Amortization Customer [Domain] Customer [Domain] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Rental revenues Rental revenues Rental revenues Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION Supplemental Cash Flow Elements [Abstract] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Office Space Office Building [Member] Segments [Axis] Segments [Axis] Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Proceeds from sale of real estate Disposal Group, Including Discontinued Operation, Consideration ASSETS Assets: Assets [Abstract] Nonrelated Party Nonrelated Party [Member] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Fair Value Measurements Fair Value Disclosures [Text Block] Building and leasehold improvements Investment Building and Building Improvements Management fee agreement value Management Fee Agreement Value The amount of management fee paid to related party to manage corporate activities. Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Accumulated  Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Fixed interest rate Debt Instrument, Interest Rate, Stated Percentage Ownership [Axis] Ownership [Axis] Rego Park II shopping center mortgage loan (included in other assets) Derivative Asset, Subject to Master Netting Arrangement, before Offset Land Land Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Name of Property [Domain] Name of Property [Domain] Fair Value as of Grant Date Award Grant Date Fair Value Tenant and other receivables Accounts Receivable, after Allowance for Credit Loss Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Disposal Group, Held-for-Sale, Not Discontinued Operations Disposal Group, Held-for-Sale, Not Discontinued Operations [Member] Schedule of Outstanding Mortgages Payable Schedule of Long-Term Debt Instruments [Table Text Block] Property management fee, percent fee Property Management Fee, Percent Fee Interest rate cap (included in other assets) Interest Rate Derivative Assets, at Fair Value Related Party Transaction [Line Items] Related Party Transaction [Line Items] Type and Tier Identifier [Domain] Type and Tier Identifier [Domain] Document Quarterly Report Document Quarterly Report Reclassification of property held for sale Reclassification Of Property Held For Sale Reclassification Of Property Held For Sale Mortgages Payable Mortgage Notes Payable Disclosure [Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Accounting Standards Update and Change in Accounting Principle [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Related Party [Axis] Related and Nonrelated Parties [Axis] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Senior Subordinated Notes Senior Subordinated Notes [Member] Interest and debt expense Interest and debt expense Interest and Debt Expense Restatement Determination Date: Restatement Determination Date [Axis] Non-PEO NEO Non-PEO NEO [Member] General Liability General Liability [Member] Asset sale commission threshold Asset Sale Commission Threshold Asset sale commission threshold. Name Trading Arrangement, Individual Name All Award Types Award Type [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Other non-cash adjustments Other Noncash Income (Expense) Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Vornado Vornado [Member] Vornado [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Face amount Debt Instrument, Face Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Straight-lining of rents Straight Line Rent Operating, including fees to Vornado of $1,411 and $1,592, respectively Operating, including fees to Vornado Total operating expenses Operating Costs and Expenses Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] FNSIC Fifty Ninth Street Insurance Company LLC [Member] Fifty ninth street insurance company LLC. MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Name Awards Close in Time to MNPI Disclosures, Individual Name Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] REVENUES Revenues [Abstract] Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Write-off of fully depreciated assets Write Off Of Fully Amortized And Depreciated Assets This element represents written off amount of fully amortized and depreciated assets. Segments [Domain] Segments [Domain] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Construction in progress and real estate additions Payments For Capital Improvements And Construction In Process and Other The cash outflow for acquisition of or capital improvements to properties held for investment (operating, managed, leased) or for use and the cash outflow from construction costs to date on capital projects that have not been completed and assets being constructed that are not ready to be placed into service. Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Minimum Minimum [Member] Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] Senior Notes Senior Notes [Member] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Weighted average shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Entity Small Business Entity Small Business Preferred stock: outstanding shares (in shares) Preferred Stock, Shares Outstanding Document Transition Report Document Transition Report Recently Issued Accounting Literature Accounting Standards Update and Change in Accounting Principle [Text Block] Preferred stock: $1.00 par value per share; authorized, 3,000,000 shares; issued and outstanding, none Preferred Stock, Value, Outstanding Underlying Securities Award Underlying Securities Amount Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Unamortized leasing fees to Vornado Unamortized Leasing Fees To Related Party Unamortized Leasing Fees To Related Party Scenario [Axis] Scenario [Axis] Loan Amounts Above $65M Loan Amounts Above $65M [Member] Loan Amounts Above $65M Document Type Document Type Level 3 Fair Value, Inputs, Level 3 [Member] Earnings Per Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Additional capital Additional Paid in Capital Product and Service [Axis] Product and Service [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Reportable Segment Reportable Segment [Member] Reportable Segment Mortgages payable, net of deferred debt issuance costs Notes Payable Notes Payable Revenue from contract with customer Revenue from Contract with Customer, Excluding Assessed Tax All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Statistical Measurement [Axis] Statistical Measurement [Axis] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Variable lease revenues Operating Lease, Variable Lease Income Disposal Group Classification [Axis] Disposal Group Classification [Axis] RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Development fee as percentage of development costs Development Fee Percentage Percentage of development costs that the related party will receive as per the Development agreement. Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Disposal Group Name [Axis] Disposal Group Name [Axis] Insurance maximum coverage per property Insurance Maximum Coverage Per Property Insurance Maximum Coverage Per Property. Rego Park II Rego Park 2 Property [Member] Rego park II. Lease incentive liability Tenant fund Incentive from Lessor Rego Park I shopping Center Rego Park I shopping Center [Member] Rego Park I shopping Center Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Lease fee percentage of rent one to ten years Lease Fee Percentage Of Rent One To Ten Years Percentage of rent payable to related party for leasing services for the first ten years of the lease. Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Total expenses Operating Expenses Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Level 1 Fair Value, Inputs, Level 1 [Member] Related Party Transaction [Table] Related Party Transaction [Table] Net income per common share - diluted (in usd per share) Earnings Per Share, Diluted Forecast Forecast [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Title of 12(b) Security Title of 12(b) Security SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Schedule [Table] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Schedule [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Treasury stock: shares (in shares) Treasury Stock, Common, Shares PIK interest expense Paid-in-Kind Interest Earnings Per Share [Abstract] Earnings Per Share [Abstract] Capped Rate Derivative, Cap Interest Rate Subsidiary, Ownership Percentage, Parent Subsidiary, Ownership Percentage, Parent 731 Lexington Avenue Lexington Avenue Property [Member] 731 Lexington avenue. Rego Park II shopping center mortgage loan (included in other assets) Rego Park II shopping center mortgage loan [Member] Rego Park II shopping center mortgage loan Award Timing Disclosures [Line Items] Measurement Frequency [Domain] Measurement Frequency [Domain] Real estate, at cost: Real Estate Investment Property, at Cost [Abstract] Carrying value Asset, Held-for-Sale, Not Part of Disposal Group Net income Net income Net Income (Loss) Attributable to Parent Schedule of Components of Lease Revenue Operating Lease, Lease Income [Table Text Block] Expiration Date Trading Arrangement Expiration Date Real estate, net Real Estate Investment Property, Net Fixed lease revenues Operating Lease, Lease Income, Lease Payments Other liabilities Increase (Decrease) in Other Operating Liabilities Fees to related party Related Party Transaction, Amounts of Transaction Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock: authorized shares (in shares) Preferred Stock, Shares Authorized Adoption Date Trading Arrangement Adoption Date Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Tenant and other receivables Increase (Decrease) in Accounts Receivable Notes payable, gross Notes Payable Gross Notes payable gross. Interest rate cap premium amortization Interest Rate Cap Premium Amortization Interest Rate Cap Premium Amortization Entity Current Reporting Status Entity Current Reporting Status Customer [Axis] Customer [Axis] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] NOI NOI Operating Income (Loss) Retained earnings Retained Earnings (Accumulated Deficit) Federal government responsibility (in percentage) Federal Government Responsibility The percentage of the covered portion of a loss above the deductible for which the Federal Government is responsible for covered losses. Name of Property [Axis] Name of Property [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Executive Category: Executive Category [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Amounts due to Vornado Increase (Decrease) in Due to Related Parties Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Statement [Table] Statement [Table] Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] CASH FLOWS FROM FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Revenue Revenue Benchmark [Member] Bloomberg Bloomberg L.P. [Member] Bloomberg L.P. Net proceeds from sale of real estate Proceeds from Debt, Net of Issuance Costs Potentially dilutive securities outstanding (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount All Adjustments to Compensation All Adjustments to Compensation [Member] Amendment Flag Amendment Flag NBCR NBCR [Member] NBCR. Treasury stock: 66,160 shares, at cost Treasury Stock, Common, Value Termination Date Trading Arrangement Termination Date Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Liability for real estate additions, including $419 in 2025 for development fees due to Vornado Development fees Non Cash Additions To Real Estate Non-cash additions to real estate included in accounts payable and accrued expenses. Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Measure: Measure [Axis] Schedule of Property Held For Sale Disclosure of Long-Lived Assets Held-for-Sale [Table Text Block] Schedule of Financial Assets Measured at Fair Value Fair Value, Assets Measured on Recurring Basis [Table Text Block] Weighted average shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Receivable arising from the straight-lining of rents Deferred Rent Receivables, Net Disposal Group Classification [Domain] Disposal Group Classification [Domain] Schedule of Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Lease fee percentage of rent twenty first to thirty years Lease Fee Percentage Of Rent Twenty First To Thirty Years Percentage of rent payable to related party for leasing services for the twenty-first through thirtieth years of the lease. Related Party Transaction [Domain] Related Party Transaction [Domain] Segment Reporting [Abstract] Payments related to property held for sale Payments Related To Property Held For Sale Payments Related To Property Held For Sale Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Entity Tax Identification Number Entity Tax Identification Number Scenario [Domain] Scenario [Domain] Insurance maximum coverage in aggregate Insurance Maximum Coverage In Aggregate Insurance maximum coverage limit in aggregate. Number of properties Number of Real Estate Properties Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Common stock: par value per share (in usd per share) Common Stock, Par or Stated Value Per Share Common stock: issued shares (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Issued Percentage of third-party lease commission Lease Commission, Percentage Lease Commission, Percentage Percentage commissions on sale of assets over fifty million Percentage Commissions On Sale Of Assets Over Fifty Million Percentage of gross proceeds over $50,000,000 from the sale of any assets, payable to related party. Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Lease revenues Lease revenues Operating Lease, Lease Income Loss Contingencies [Line Items] Loss Contingencies [Line Items] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Insider Trading Arrangements [Line Items] Parking revenue Parking [Member] Security Exchange Name Security Exchange Name Development fees Development Fees [Member] Development fees. Deferred debt issuance costs, accumulated amortization Accumulated Amortization, Debt Issuance Costs Management And Development Agreement, Base Management Fee Management And Development Agreement, Base Management Fee [Member] Management And Development Agreement, Base Management Fee Lease fee percentage of rent eleven to twenty years Lease Fee Percentage Of Rent Eleven To Twenty Years Percentage of rent payable to related party for leasing services for the eleventh through twentieth years of the lease. Total liabilities Liabilities SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] Retail Space Retail Site [Member] Common stock: $1.00 par value per share; authorized, 10,000,000 shares; issued, 5,173,450 shares; outstanding, 5,107,290 shares Common Stock, Value, Outstanding Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] EXPENSES Operating Expenses [Abstract] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Schedule Of Insurance Type And Tier Identifier [Domain] Schedule Of Insurance Type And Tier Identifier [Domain] Schedule Of Insurance Type And Tier Identifier [Domain] Loan Amounts below $65M Loan Amounts Below $65M [Member] Loan Amounts Below $65M Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Property management fee escalation percentage per annum Property Management Fee Escalation Percentage Per Annum Annual increase in the amount paid to related party as property management fees. Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and Cash Equivalent Cash and Cash Equivalent Development and construction in progress Development in Process Common Stock Common Stock [Member] Equity before treasury stock Stockholders' Equity before Treasury Stock Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Accumulated depreciation and amortization Real Estate Investment Property, Accumulated Depreciation Net decrease in cash and cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation