Document and Entity Information Document Information [Table] Document Information [Line Items] Entity Registrant Name Document Type Document Quarterly Report Document Transition Report Document Period End Date Securities Act File Number Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Title of 12(b) Security Trading Symbol Security Exchange Name Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Central Index Key Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Period Focus Amendment Flag CONSOLIDATED BALANCE SHEETS Statement [Table] Statement [Line Items] Statement Assets [Abstract] ASSETS Real Estate Investment Property, Net [Abstract] Real estate investments, at cost Land Land Investment Building and Building Improvements Buildings and improvements Real Estate Investment Property, at Cost Total real estate investments, at cost Real Estate Investment Property, Accumulated Depreciation Less accumulated depreciation Accumulated depreciation Real Estate Investment Property, Net Real estate investments, net Inventory, Real Estate, Held-for-Sale Property held-for-sale Cash and Cash Equivalent Cash and cash equivalents Deferred Rent Receivables, Net Unbilled rent receivable This element represents the identifiable intangible asset established upon acquisition based on a favorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date, less accumulated amortization. This element also includes intangible origination costs representing estimated costs to execute similar leases, less accumulated amortization. Unamortized Intangible Lease Assets Unamortized intangible lease assets, net Intangible Lease Asset This element represents the designation of funds that are furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. It also includes prepaid expenses and tenant improvement allowance. It further includes carrying amounts due as of the balance sheet date from parties or arising from transactions not otherwise specified in the taxonomy and other assets. Escrow Deposits and Other Assets and Receivables Escrow, deposits and other assets and receivables Assets Total assets Liabilities and Equity [Abstract] LIABILITIES AND EQUITY Liabilities [Abstract] Liabilities: Secured Debt Mortgages payable, net Mortgages payable, net Mortgage payable, net of unamortized deferred financing costs of $41 and $45, respectively Long-Term Line of Credit Line of credit Dividends Payable Dividends payable Accrued Liabilities Accrued expenses and other liabilities Off-Market Lease, Unfavorable Unamortized intangible lease liabilities, net Liabilities Total liabilities Commitments and Contingencies Commitments and contingencies Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Equity: Equity, Attributable to Parent [Abstract] One Liberty Properties, Inc. stockholders' equity: Preferred Stock, Value, Issued Preferred stock, $1 par value; 12,500 shares authorized; none issued Common Stock, Value, Issued Common stock, $1 par value; 50,000 shares authorized; 21,069 and 20,916 shares issued and outstanding Additional Paid in Capital, Common Stock Paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Accumulated other comprehensive income Accumulated Distributions in Excess of Net Income Distributions in excess of net income Equity, Attributable to Parent Total One Liberty Properties, Inc. stockholders' equity Equity, Attributable to Noncontrolling Interest Non-controlling interest Non-controlling interests in consolidated joint ventures Equity, Including Portion Attributable to Noncontrolling Interest Ending Balance Beginning Balance Total equity Liabilities and Equity Total liabilities and equity Consolidated Entities [Axis] Consolidated Entities [Domain] Variable Interest Entity, Primary Beneficiary [Member] Consolidated Joint Venture-VIE Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding Other Assets Other assets The amount of debt on real estate net of deferred financing costs. Real Estate Debt, Net Real estate debt, net Other Liabilities Other liabilities CONSOLIDATED STATEMENTS OF INCOME Product and Service [Axis] Product and Service [Domain] Represents rental income of property. Rental income, net Rental income, net Represents lease termination fee. Lease termination fees Revenues [Abstract] Revenues: Operating Lease, Lease Income Total revenues Operating Expenses [Abstract] Operating expenses: Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Amount of expenses related to real estate owned such as real estate taxes, insurance, repairs and maintenance. Real Estate Operating Expenses Real estate expenses General and Administrative Expense General and administrative Represents the amount of federal excise tax paid and/or accrued during the period on taxable income generated but not yet distributed and amount of state taxes paid/and or accrued during period. Federal Excise and State Tax Paid and or Accrued State tax expense (benefit) Operating Expenses Total operating expenses n/a Other Operating Income [Abstract] Other operating income Amount of difference between the carrying amount and the sales price of real estate properties sold. Gain Loss on Disposition of Real Estate Gain on sale of real estate, net (Loss) Gain on Sale of Real Estate, Net Operating Income (Loss) Operating income Nonoperating Income (Expense) [Abstract] Other income and expenses: Other Nonoperating Income Other income Interest Expense, Operating and Nonoperating [Abstract] Interest: Interest Expense, Nonoperating Expense Amortization of Debt Issuance Costs and Discounts Amortization and write-off of deferred financing costs Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income Net income Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to non-controlling interests Deduct net income loss attributable to non-controlling interests Net income attributable to One Liberty Properties, Inc. Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted average number of common shares outstanding: Weighted Average Number of Shares Outstanding, Basic Basic (in shares) Weighted average number of common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Diluted (in shares) Weighted average number of shares Earnings Per Share, Basic [Abstract] Earnings per common share attributable to common stockholders: Earnings Per Share, Basic Earnings per common share, basic (in dollars per share) Basic (in dollars per share) Earnings Per Share, Diluted Diluted (in dollars per share) Earnings per common share, diluted (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Cash distributions per share of common stock (in dollars per share) CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income Amount, after reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification Net unrealized loss on derivative instruments Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income attributable to One Liberty Properties, Inc. CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Common Stock Additional Paid-in Capital [Member] Paid-in Capital AOCI Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Other Comprehensive Income (Loss) Accumulated Distributions in Excess of Net Income [Member] Accumulated Distributions in Excess of Net Income Noncontrolling Interest [Member] Non-Controlling Interests in Consolidated Joint Ventures Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity Dividends, Common Stock, Cash Cash distributions - common stock Stock Issued During Period, Value, Dividend Reinvestment Plan Shares issued through dividend reinvestment plan Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Restricted stock vesting APIC, Share-Based Payment Arrangement, Restricted Stock Unit, Increase for Cost Recognition Compensation expense - restricted stock and RSUs Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Distributions to non-controlling interests Other Comprehensive Income (Loss), Net of Tax Other comprehensive loss CONSOLIDATED STATEMENTS OF CASH FLOWS Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Cash flows from operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Noncash Item [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Cash flow impact of gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group. Gain Loss On Sale of Property Cash Flow Impact Gain on sale of real estate, net Straight Line Rent Increase in net amortization and write-off of unbilled rental income Amortization of above and below Market Leases Amortization of acquired intangible lease assets/liabilities Amortization and write-off of intangibles relating to leases, net Share-Based Payment Arrangement, Noncash Expense Amortization of restricted stock and RSU compensation expense Depreciation, Depletion and Amortization Depreciation and amortization Amortization of Debt Issuance Costs Amortization and write-off of deferred financing costs Amount of cash payments to brokers for lease commissions, classified as operating activities. Payments to Brokers for Commissions, Classified as Operating Activities Payment of leasing commissions Amount of difference between the carrying amount and sales price of real estate properties sold relating to unconsolidated joint venture. Gain Loss On Disposition Of Real Estate, Unconsolidated Joint Venture Equity in (loss) earnings of unconsolidated joint ventures included in other income Increase (Decrease) in Operating Assets Decrease in escrow, deposits, other assets and receivables Increase (Decrease) in Operating Liabilities Decrease in accrued expenses and other liabilities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Net cash provided by operating activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Cash flows from investing activities: Payments to Acquire Real Estate Purchase of real estate Payments to Develop Real Estate Assets Improvements to real estate Proceeds from Sale, Real Estate, Held-for-Investment Net proceeds from sale of real estate Proceeds from Equity Method Investment, Distribution, Return of Capital Distributions of capital from unconsolidated joint venture included in other assets Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Net cash used in investing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Cash flows from financing activities: Proceeds from Issuance of Secured Debt Proceeds from mortgage financings Repayments of Secured Debt Repayments of mortgages financings This element represents the cash outflow for regular amortization payments of mortgages payable during the reporting period. Payments of Amortization of Mortgages Payable Scheduled amortization payments of mortgages payable Proceeds from Long-Term Lines of Credit Proceeds from bank line of credit Repayments of Long-Term Lines of Credit Repayments on bank line of credit Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan Issuance of shares through dividend reinvestment plan Payments of Financing Costs Payment of financing costs Payments to Noncontrolling Interests Distributions to non-controlling interests Payments of Ordinary Dividends, Common Stock Cash distributions to common stockholders Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Net cash provided by financing activities Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Cash, cash equivalents and restricted cash at end of period Cash, cash equivalents and restricted cash at beginning of year Total cash, cash equivalents and restricted cash shown in the consolidated statement of cash flows Supplemental Cash Flow Information [Abstract] Supplemental disclosure of cash flow information: Interest Paid, Excluding Capitalized Interest, Operating Activity Cash paid during the period for interest expense Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing activity: No definition available. Cash Flow, Noncash Investing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing activities: Amount of Non-cash activities related to intangible lease assets under Purchase accounting allocation. Non Cash Investing Activities Purchase Accounting Allocation, Intangible Lease Assets Purchase accounting allocation - intangible lease assets Amount of Non-cash activities related to intangible lease liabilities under Purchase accounting allocation. Non Cash Investing Activities Purchase Accounting Allocation, Intangible Lease Liabilities Purchase accounting allocation - intangible lease liabilities No definition available. Cash Flow, Noncash Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash financing activity: Amount of non-cash outflow in the form of ordinary dividends to common shareholders of the parent entity . Non-cash payment of Ordinary Dividends, Common Stock Distributions to common stockholders from other assets Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Reconciliation of cash, cash equivalents, and restricted cash This element represents the restricted cash included in escrow, deposits and other assets and receivables. Restricted cash included in escrow, deposits and other assets and receivables ORGANIZATION AND BACKGROUND Nature of Operations [Text Block] ORGANIZATION AND BACKGROUND SIGNIFICANT ACCOUNTING POLICIES Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] SIGNIFICANT ACCOUNTING POLICIES LEASES The entire disclosure of information about leases. Lease Disclosure [Text Block] LEASES REAL ESTATE ACQUISITIONS Asset Acquisition [Text Block] REAL ESTATE ACQUISITION SALES OF PROPERTIES AND PROPERTY HELD-FOR-SALE Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] SALES OF PROPERTIES AND PROPERTY HELD-FOR-SALE DEBT OBLIGATIONS Debt Disclosure [Text Block] Debt Obligations Variable Interest Entities, Contingent Liabilities and Consolidated Joint Ventures Disclosure CONSOLIDATED JOINT VENTURE AND VARIABLE INTEREST ENTITY Total disclosure of Variable Interest Entities, Contingent Liabilities and Consolidated Joint Ventures. Variable Interest Entities Contingent Liabilities And Consolidated Joint Ventures Disclosure [Text Block] CONSOLIDATED JOINT VENTURE AND VARIABLE INTEREST ENTITY STOCKHOLDERS' EQUITY Shareholders' Equity and Share-Based Payments [Text Block] STOCKHOLDERS' EQUITY EARNINGS PER COMMON SHARE Earnings Per Share [Text Block] EARNINGS PER COMMON SHARE FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] FAIR VALUE MEASUREMENTS RELATED PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Related Party Transactions