Earnings Per Share [Abstract] Schedule of Earnings Per Share, Basic and Diluted [Table] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Liberty Property Limited Partnership [Member] Liberty Property Limited Partnership [Member] Limited Partnership. Earnings Per Unit, Basic and Diluted [Line Items] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Earnings Per Share [Text Block] Earnings Per Share [Text Block] Income Statement [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common shares [Member] Common Class A [Member] Common Units [Member] Common Class B [Member] Statement [Line Items] Statement [Line Items] OPERATING REVENUE Revenues [Abstract] Rental Operating Leases, Income Statement, Lease Revenue Operating expense reimbursement Tenant Reimbursements Development service fee income Fees and Commissions, Other Total operating revenue Revenues OPERATING EXPENSE Operating Expenses [Abstract] Rental property Direct Costs of Leased and Rented Property or Equipment Real estate taxes Real Estate Tax Expense General and administrative General and Administrative Expense Expensed pursuit costs Other General and Administrative Expense Systems implementation expense Technology Services Costs Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Development service fee expense Construction and Development Costs Total operating expenses Costs and Expenses Operating income Operating Income (Loss) OTHER INCOME (EXPENSE) Nonoperating Income (Expense) [Abstract] Interest and other income Other Income Interest expense Interest Expense Total other income (expense) Nonoperating Income (Expense) Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Gain on property dispositions Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Income taxes Income Tax Expense (Benefit) Equity in earnings of unconsolidated joint ventures Income (Loss) from Equity Method Investments Income from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Discontinued operations (including net gain on property dispositions of $90.0 million for the three months ended March 31, 2018) Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Noncontrolling interest – operating partnership Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable Noncontrolling interest - consolidated joint ventures Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Nonredeemable Preferred unit distributions Preferred Stock Dividends, Income Statement Impact Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Comprehensive income attributable to common shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Net income Other comprehensive income - foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other comprehensive income - derivative instruments Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to common shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Earnings per common share Basic: Earnings Per Share, Basic [Abstract] Income from continuing operations, per basic share Income (Loss) from Continuing Operations, Per Basic Share Income from discontinued operations, per basic share Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Income per common share - basic Earnings Per Share, Basic Diluted: Earnings Per Share, Diluted [Abstract] Income from continuing operations, per diluted share Income (Loss) from Continuing Operations, Per Diluted Share Income from discontinued operations, per diluted share Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Income per common share - diluted Earnings Per Share, Diluted Distributions per common share or unit Common Stock, Dividends, Per Share, Declared Weighted average number of common shares outstanding Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Net income allocated to general partners Net Income (Loss) Allocated to General Partners Net income allocated to limited partners Net Income (Loss) Allocated to Limited Partners Amounts attributable to common shareholders Income Amounts Attributable to Parent, Disclosures [Abstract] Income from continuing operations net of noncontrolling interest Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Income from discontinued operations net of noncontrolling interest Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Net income available to common shareholders Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Option Exercises [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock Option [Member] Employee Stock Option [Member] Stock Option Exercises [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Amount of Options Exercises in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Discontinued Operations and Disposal Groups [Abstract] Disposal Groups, Including Discontinued Operations [Table Text Block] Disposal Groups, Including Discontinued Operations [Table Text Block] Debt Instrument, Fair Value Disclosure [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Debt [Member] Unsecured Debt [Member] Mortgages [Member] Mortgages [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value by Liability Class [Axis] Liability Class [Axis] Fair Value, Liabilities, Measured on Recurring Basis, Unobservable Input Reconciliation, by Liability Class [Domain] Fair Value by Liability Class [Domain] Long-term Debt [Member] Long-term Debt [Member] Mortgage Loans Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Mortgage loans Secured Debt Fair value of debt Financial and Nonfinancial Liabilities, Fair Value Disclosure Unsecured Debt Unsecured Debt Temporary Equity Disclosure [Abstract] Temporary Equity, by Class of Stock [Table] Temporary Equity, by Class of Stock [Table] Temporary Equity [Line Items] Temporary Equity [Line Items] Stockholders' Equity Note Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Selling, General and Administrative Expenses, Policy [Policy Text Block] Selling, General and Administrative Expenses, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Systems Implementation Expense [Policy Text Block] Research, Development, and Computer Software, Policy [Policy Text Block] Revenue Recognition, Policy [Policy Text Block] Revenue Recognition, Policy [Policy Text Block] Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Joint venture, 2018 sales current quarter [Member] Joint venture, 2018 sales current quarter [Member] Sales in the Company's joint ventures for the current quarter in the fiscal year 2018 Joint venture, 2017 sales current quarter [Member] Joint venture, 2017 sales current quarter [Member] Any sales by the Company's unconsolidated joint ventures during the current quarter of the fiscal year 2017. Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Leaseholds and Leasehold Improvements [Member] Leaseholds and Leasehold Improvements [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Income [Member] Other Income [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Cambridge Medipark Ltd [Member] Cambridge Medipark Ltd [Member] Cambridge Medipark Ltd [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Not Discontinued Operations [Member] Disposal Group, Not Discontinued Operations [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Ownership percentage of equity method investment Equity Method Investment, Ownership Percentage Gain on sale of leasehold interests Gain (Loss) on Sale of Investments Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Philadelphia [Member] Philadelphia [Member] Philadelphia [Member] Construction in Progress [Member] Construction in Progress [Member] Building and Building Improvements [Member] Building and Building Improvements [Member] Liberty Property 18th & Arch [Member] Liberty Property 18th & Arch [Member] Liberty Property 18th & Arch includes both joint ventures that own the Comcast Innovation and Technology Center in Philadelphia Pennsylvania. Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Guarantee Obligations [Member] Guarantee Obligations [Member] Number of equity method investments Number of equity method investments Number of equity method investments Number of stories in a high-rise building Number of stories in a high-rise building Number of stories in a high-rise building Leaseable square feet Net Rentable Area Number of hotel rooms Number of hotel rooms Number of hotel rooms in a hotel Anticipated Aggregate Investment Anticipated Aggregate Investment Total anticipated cost of investment in assets including but not limited to assets under construction. Anticipated investment in joint ventures Anticipated investment in joint ventures Anticipated balance in investment in unconsolidated joint ventures after development is completed. Investments in and advances to unconsolidated joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Loss Contingency [Abstract] Loss Contingency [Abstract] Possible cost overruns Loss Contingency, Estimate of Possible Loss Fair Value, by Balance Sheet Grouping [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Supply Commitment [Table] Supply Commitment [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity Method Investments [Member] Equity Method Investments [Member] Supply Commitment [Axis] Supply Commitment [Axis] Supply Commitment Arrangement [Domain] Supply Commitment Arrangement [Domain] Supply Commitment [Member] Supply Commitment [Member] Buildings and land parcels [Member] Land, Buildings and Improvements [Member] Tenant Improvements [Member] Leasehold Improvements [Member] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] American Water Works, Inc [Member] American Water Works, Inc [Member] American Water Works, Inc [Member] Supply Commitment [Line Items] Supply Commitment [Line Items] Number of Real Estate Properties Number of Real Estate Properties Total anticipated development cost Development in progress Development in Process Deferred leasing costs in development Deferred Costs, Leasing, Gross Remaining amount committed or obligated to pay Supply Commitment, Remaining Minimum Amount Committed Tenant improvements not yet completed Supply Commitment, Remaining Maximum Amount Committed Supply Commitment, Remaining Maximum Amount Committed Fee development commitment Other Commitment Costs incurred to date Cost of Real Estate Sales Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Liberty Comcast 1701 JFK Boulevard, LP [Member] Liberty Comcast 1701 JFK Boulevard, LP [Member] Liberty Comcast 1701 JFK Boulevard, LP formerly known as Liberty Commerz 1701 JFK Boulevard, LP [Member] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity, Not Primary Beneficiary [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other Investments [Member] Other Investments [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Equity investment in joint venture Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net Ownership interest in operating partnership - Limited Partnership Noncontrolling Interest, Ownership Percentage by Parent Maximum exposure to loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Domain] Business Combination, Separately Recognized Transactions [Domain] 2018 acquisitions current quarter [Member] 2018 acquisitions current quarter [Member] Real estate acquisitions during the current quarter in the fiscal year 2018. Carolinas Richmond [Member] Carolinas Richmond [Member] Carolinas Richmond [Member] Chicago Minneapolis [Member] Chicago Minneapolis [Member] The Company's reportable segment of Chicago/Minneapolis. Southeastern PA [Member] Southeastern PA [Member] Southeastern PA United Kingdom [Member] United Kingdom [Member] United Kingdom Member. Other Segments [Member] Other Segments [Member] Southern California [Member] Southern California [Member] Operating segment of the company for the properties located in Southern California. Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] 2018 sales current quarter [Member] 2018 sales current quarter [Member] Real estate sales during the current quarter during the fiscal year 2018. Land, Buildings and Improvements [Member] Land and Land Improvements [Member] Land and Land Improvements [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Acres of Developable Land Area of Land Purchase Price Payments to Acquire Real Estate Gross Proceeds Proceeds from Sale of Real Estate Held-for-investment Stockholders' Equity Attributable to Noncontrolling Interest [Abstract] Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] 2018 (remaining) Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years 2023 and thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Other Expenses [Abstract] Other Expenses [Abstract] Operating ground lease expense Operating Ground Lease Expense Operating Ground Lease Expense Future Minimum Rental Payments Lessee, Operating Lease, Disclosure [Table Text Block] Limited Partners' Equity of the Operating Partnership [Abstract] Limited Partners' Equity of the Operating Partnership [Abstract] Schedule of Preferred Units [Table] Preferred Units [Line Items] Noncontrolling Interest Disclosure [Text Block] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment, Revenue and Net Operating Income [Table Text Block] Schedule of Segment Reporting Information, by Segment [Table Text Block] Assets by Segment and Reconciliation to Consolidated [Table Text Block] Reconciliation of Assets from Segment to Consolidated [Table Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] Equity Method Investments and Joint Ventures Disclosure [Text Block] Accumulated Other Comprehensive Income (Loss) Note [Text Block] Comprehensive Income (Loss) Note [Text Block] Schedule of Antidilutive Options Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Options Excluded from Computation of Earnings Per Share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Legal Matters [Abstract] Loss Contingency, Quantities [Abstract] Loss Contingency, Pending Claims, Number Loss Contingency, Pending Claims, Number Other [Abstract] Other Liabilities, Unclassified [Abstract] Letter of credit obligations Letters of Credit Outstanding, Amount Expensed Pursuit Costs [Abstract] Expensed Pursuit Costs [Abstract] Loss on Contracts Loss on Contracts Assets Held for Sale [Abstract] Assets Held for Sale [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Properties sold or classified as held for sale in the prior year and current year to date [Member] Properties sold or classified as held for sale in the prior year and current year to date [Member] Properties sold or classified as held for sale in the prior year and current year to date [Member] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Discontinued Operations, Held-for-sale [Member] Discontinued Operations, Held-for-sale [Member] Held for Sale, Includes Disposal Groups and Discontinued Operations [Member] Held for Sale, Includes Disposal Groups and Discontinued Operations [Member] Includes all assets held for sale as of the end of the period. This includes both discontinued operations and not discontinued operations. Discontinued Operations, Disposed of by Sale [Member] Discontinued Operations, Disposed of by Sale [Member] Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] Disposed of by Sale, Discontinued Operations and Not Discontinued Operations [Member] Disposed of by Sale, Discontinued Operations and Not Discontinued Operations [Member] Assets disposed of during the year including discontinued and not discontinued operations. Balance Sheet Disclosures by Disposal Groups [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract] Land and land improvements Disposal Group, Including Discontinued Operations, Land and Land Improvements Disposal Group, Including Discontinued Operations, Land and Land Improvements Buildings and improvements Disposal Group, Including Discontinued Operations, Building and Improvements Disposal Group, Including Discontinued Operations, Building and Improvements Development in progress Disposal Group, Including Discontinued Operation, Development in Progress Disposal Group, Including Discontinued Operation, Development in Progress Land held for development Disposal Group, Including Discontinued Operation, Land Available for Development Land available for development that is included in a disposal group or assets held for sale. Accumulated depreciation Disposal Group, Including Discontinued Operations, Accumulated Depreciation Disposal Group, Including Discontinued Operations, Accumulated Depreciation Deferred financing and leasing costs, net Disposal Group, Including Discontinued Operation, Intangible Assets Other assets Disposal Group, Including Discontinued Operation, Other Assets Assets held for sale Disposal Group, Including Discontinued Operation, Assets Liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities Impairment Charges [Abstract] Impairment Charges [Abstract] Impairment of Real Estate Impairment of Real Estate Valuation adjustment Real Estate Owned, Valuation Allowance Systems Implementation Expense [Abstract] Systems Implementation Expense [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Debt Repayment [Member] Debt Repayment [Member] Repayment of debt in full on the maturity date. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Interest Expense [Member] Interest Expense [Member] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Other Comprehensive Income (Loss) [Member] Other Comprehensive Income (Loss) [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Amount of gain related to the effective portion recognized in other comprehensive income (loss) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Amount of loss related to the effective portion subsequently reclassified to interest expense Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion Amount of (loss) gain related to the ineffective portion recognized in interest expense Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness Interest Rate Derivatives [Abstract] Interest Rate Derivatives [Abstract] Number of interest rate swaps Number of Interest Rate Derivatives Held Fair value Interest Rate Cash Flow Hedge Liability at Fair Value Aggregate notional amount Derivative, Notional Amount Reclassification during next 12 months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Termination value Assets Needed for Immediate Settlement, Aggregate Fair Value Segment Reporting, Policy [Policy Text Block] Segment Reporting, Policy [Policy Text Block] Equity Method Investee [Member] Equity Method Investee [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Repayments of mortgage loans Repayments of Secured Debt Basis of Presentation [Abstract] Basis of Presentation [Abstract] Prior Period Adjustment [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-18 [Member] Accounting Standards Update 2016-18 [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Previously Reported [Member] Scenario, Previously Reported [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Prior Period Adjustments [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Document and Entity Information [Abstract] Document And Entity Information. Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Discontinued Operations [Abstract] Discontinued Operations [Abstract] Arizona [Member] Arizona [Member] Arizona [Member] Discontinued Operations [Member] Discontinued Operations [Member] Discontined Operations Income Statement [Line Items] Capital expenditures Capital Expenditure, Discontinued Operations Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Revenues Disposal Group, Including Discontinued Operation, Revenue Operating expenses Disposal Group, Including Discontinued Operation, Operating Expense Depreciation and amortization Disposal Group, Including Discontinued Operation, Depreciation and Amortization Interest and other income Disposal Group, Including Discontinued Operation, Other Income Interest expense Disposal Group, Including Discontinued Operation, Interest Expense Net income before gain on property dispositions Disposal Group, Including Discontinued Operation, Operating Income (Loss) Gain on property dispositions Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Net income Noncontrolling interest - operating partnership Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest Income available to common shareholders Statement of Cash Flows [Abstract] OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Amortization of deferred financing costs Amortization of Debt Issuance Costs Equity in earnings of unconsolidated joint ventures Gain on property dispositions Gain (Loss) on Sale of Properties Share-based compensation/Non-cash compensation Share-based Compensation Other Other Operating Activities, Cash Flow Statement Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Deferred rent receivable Straight Line Rent Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued interest Increase (Decrease) in Interest Payable, Net Other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities [Abstract] Investment in properties - acquisitions Payments to Acquire Buildings Investment in properties - other Payments for Capital Improvements Investments in and advances to unconsolidated joint ventures Payments to Acquire Equity Method Investments Distributions from unconsolidated joint ventures Proceeds from Equity Method Investment, Distribution, Return of Capital Net proceeds from disposition of properties/land Investment in development in progress Payments to Develop Real Estate Assets Investment in land held for development Payments To Acquire And Develop Land The cash outflow associated with the purchase of or development of land held for investment. Payment of deferred leasing costs Payments for Leasing Costs Release of escrows and other Increase (Decrease) in Deposit Assets Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities [Abstract] Net proceeds from issuance of common shares Proceeds from Issuance of Common Stock Share repurchase including shares related to tax withholdings Payments for Repurchase of Common Stock Repayments of mortgage loans Proceeds from credit facility Proceeds from Long-term Lines of Credit Repayments on credit facility Repayments of Long-term Lines of Credit Distribution paid on common shares Payments of Ordinary Dividends, Common Stock Capital contributions Proceeds from Contributed Capital Distributions to partners/noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash, cash equivalents and restricted cash Cash and Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Increase in cash, cash equivalents and restricted cash related to foreign currency translation Effect of Exchange Rate on Cash and Cash Equivalents Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Disclosure of Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Revenue Recognition [Abstract] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Remaining performance obligation Revenue, Remaining Performance Obligation Remaining performance obligation through years Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Long-term Purchase Commitment [Table] Long-term Purchase Commitment [Table] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] Land Purchases [Member] Capital Addition Purchase Commitments [Member] Long-term Purchase Commitment [Line Items] Long-term Purchase Commitment [Line Items] Remaining amount committed to future acquisitions Purchase Commitment, Remaining Minimum Amount Committed Assets by Segment [Abstract] Assets by Segment [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] North America [Member] North America [Member] UNITED KINGDOM UNITED KINGDOM Corporate, Non-Segment [Member] Corporate, Non-Segment [Member] Florida [Member] Florida [Member] Area in the state of Florida which formally included the segments Tampa, Orlando and South Florida. Houston [Member] Houston [Member] Houston Reportable Segment Lehigh Central PA [Member] Lehigh Central PA [Member] Lehigh Central PA [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Assets Assets Schedule of Temporary Equity [Table Text Block] Temporary Equity [Table Text Block] Supplemental Cash Flow Information [Abstract] Supplemental Disclosure to Statements of Cash Flows Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Common shares [Member] Statement of Financial Position [Abstract] Series I 2 [Member] Redeemable Preferred Stock [Member] Deferred financing and leasing costs, accumulated amortization Deferred Costs, Leasing, Accumulated Amortization Limited Partners' common units outstanding Limited Partners' Capital Account, Units Outstanding Noncontrolling interest - operating partnership, preferred units outstanding Temporary Equity, Shares Outstanding Common shares of beneficial interest, par value per share Common Stock, Par or Stated Value Per Share Common shares of beneficial interest, shares authorized Common Stock, Shares Authorized Common shares of beneficial interest, shares issued Common Stock, Shares, Issued Common shares of beneficial interest, shares outstanding Common Stock, Shares, Outstanding Other Significant Noncash Transactions [Table] Other Significant Noncash Transactions [Table] Operating Activities [Axis] Operating Activities [Axis] Operating Activities [Domain] Operating Activities [Domain] Continuing Operations [Member] Continuing Operations [Member] Other Significant Noncash Transaction [Axis] Other Significant Noncash Transaction [Axis] Other Significant Noncash Transaction, Name [Domain] Other Significant Noncash Transaction, Name [Domain] Other Significant Noncash Transactions [Line Items] Other Significant Noncash Transactions [Line Items] Write off of fully depreciated property and deferred costs Write off of fully depreciated property and deferred costs Write off of fully depreciated property and deferred costs Write Off Of Depreciated Property And Deferred Costs Due To Sale Write Off Of Depreciated Property And Deferred Costs Due To Sale Write Off Of Depreciated Property And Deferred Costs Due To Sale Change in accrued development capital expenditures Change in accrued development capital expenditures The change in accrued expenses from prior period for development capital expenditures. Unrealized gain (loss) on cash flow hedge, non cash transaction Unrealized gain (loss) on cash flow hedge, non cash transaction Unrealized gain (loss) on cash flow hedge, non cash transaction Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Conversion of Stock, Amount Converted Conversion of Stock, Amount Converted Supplemental Disclosure to Statements of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Redeemable Noncontrolling Interest, by Legal Entity [Table] Redeemable Noncontrolling Interest, by Legal Entity [Table] Redeemable Noncontrolling Interest [Line Items] Redeemable Noncontrolling Interest [Line Items] Market value of common units based on closing price Redeemable Noncontrolling Interest, Equity, Common, Fair Value Interest rate swaps [Text Block] Derivative Instruments and Hedging Activities Disclosure [Text Block] Cash and Cash Equivalents [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Cash and cash equivalents and restricted cash Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Accumulated Distributions in Excess of Net Income [Member] Accumulated Distributions in Excess of Net Income [Member] Parent [Member] Parent [Member] Noncontrolling interest operating partnership Common [Member] Noncontrolling interest operating partnership Common [Member] Noncontrolling Interest Operating Partnership. Noncontrolling interest-consolidated joint ventures [Member] Noncontrolling interest-consolidated joint ventures [Member] Noncontrolling Interest Consolidated Joint Ventures. Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] General Partner [Member] General Partner [Member] Limited Partner [Member] Limited Partner [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common shares outstanding - Beginning Balance (shares) Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest General Partner's units outstanding - Beginning Balance (units) General Partners' Capital Account, Units Outstanding Limited Partners' units outstanding - Beginning Balance (units) Net proceeds from the issuance of common shares Stock Issued During Period, Value, New Issues Net proceeds from issuance of common shares (shares) Stock Issued During Period, Shares, New Issues Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Contributions from partners Partners' Capital Account, Contributions Contributions from partners (units) Partners' Capital Account, Units, Sale of Units Distributions Dividends, Common Stock Distributions to partners Partners' Capital Account, Distributions Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Other comprehensive income - foreign currency translation activity Other comprehensive income - derivative instruments activity Redemption of noncontrolling interests Stock Issued During Period, Value, Conversion of Units Redemption of limited partners common units for common shares - common units (shares) Stock Issued During Period, Shares, Conversion of Units Redemption of limited partners common units for common shares - common units Partners' Capital Account, Exchanges and Conversions Partners' Capital Account, Units, Converted Partners' Capital Account, Units, Converted Common shares outstanding - Ending Balance (shares) General Partner's units outstanding - Ending Balance (units) Limited Partners' units outstanding - Ending Balance (units) Ending Balance Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Noncontrolling Interest - Operating Partnership (Mezzanine) - Beginning Balance Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Net income (Mezzanine) Temporary Equity, Net Income Distributions (Mezzanine) Temporary Equity, Other Changes Noncontrolling Interest - Operating Partnership (Mezzanine) - Ending Balance Unit Repurchase [Abstract] Unit Repurchase [Abstract] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] 2017 Share Repurchase Program [Member] 2017 Share Repurchase Program [Member] 2017 Share Repurchase Program [Member] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Authorized Amount Stock Repurchased During Period, Shares Stock Repurchased During Period, Shares Gain on property dispositions in discontinued operations Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of March 31, 2018 and December 31, 2017 Units Liquidation Preference Temporary Equity, Redemption Price Per Share Dividend Rate Preferred Stock, Dividend Rate, Percentage ASSETS Assets [Abstract] Real Estate [Abstract] Real Estate [Abstract] Land and land improvements Land and Land Improvements Building and improvements Investment Building and Building Improvements Less accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Operating real estate Real Estate Investments, Other Development in progress Land held for development Land Available for Development Net real estate Real Estate Investment Property, Net Cash and cash equivalents Restricted cash Accounts receivable Accounts Receivable, Net Deferred rent receivable Deferred Rent Receivables, Net Deferred financing and leasing costs, net of accumulated amortization (March 31, 2018, $168,754; December 31, 2017, $164,755) Deferred Costs, Leasing, Net Investments in and advances to unconsolidated joint ventures Assets held for sale Prepaid expenses and other assets Prepaid Expense and Other Assets Total assets LIABILITIES Liabilities [Abstract] Unsecured notes Credit facility Long-term Line of Credit Accounts payable Accounts Payable Accrued interest Interest Payable Dividend and distributions payable Dividends Payable Other liabilities Other Liabilities Total liabilities Liabilities EQUITY Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 147,773,141 and 147,450,691 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively Common Stock, Value, Issued General partner’s equity - 147,773,141 and 147,450,691 common units outstanding as of March 31, 2018 and December 31, 2017, respectively General Partners' Capital Account Limited partners' equity Limited Partners' Capital Account Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Distributions in excess of net income Accumulated Distributions in Excess of Net Income Total Liberty Property Trust shareholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interest - operating partnership Noncontrolling interest - operating partnerships Noncontrolling Interest in Operating Partnerships Noncontrolling interest - consolidated joint ventures Noncontrolling Interest in Joint Ventures Total owners' equity Total liabilities, noncontrolling interest - operating partnership and equity Liabilities and Equity Share Repurchase [Abstract] Share Repurchase [Abstract] Income (Numerator) [Abstract] Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Income from continuing operations net of noncontrolling interest - consolidated joint ventures Less: Preferred unit distributions Income from continuing operations available to common unitholders Income from Continuing Operations available to Common Unitholders Income from Continuing Operations available to Common Unitholders Income from discontinued operations Weighted Average Units (Denominator) [Abstract] Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted Average Number of Shares Outstanding, Basic Dilutive units for long-term compensation plans Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted Average Number of Shares Outstanding, Diluted Earnings Per Unit, Basic [Abstract] Income from discontinued operations, per basic share Earnings Per Unit, Diluted [Abstract] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Discontinued operations Development Service Fee Income [Member] Development Service Fee Income [Member] Development Service Fee Income [Member] Segment Reconciling Items [Member] Segment Reconciling Items [Member] Intersegment Eliminations [Member] Intersegment Eliminations [Member] Operating revenue Net operating income Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Depreciation and amortization expense Gain on property dispositions General and administrative expense Expensed pursuit costs Discontinued operations excluding gain on property dispositions Other Other Nonoperating Income (Expense) Income from continuing operations Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Attributable to Noncontrolling Interest [Member] AOCI Attributable to Noncontrolling Interest [Member] AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Unrealized income (loss) Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification adjustment Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Total accumulated other comprehensive loss Total accumulated other comprehensive loss included in shareholders' equity/owners' equity Discontinued Operations, Policy [Policy Text Block] Discontinued Operations, Policy [Policy Text Block] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Market value of common units based on closing price Schedule of Adjustments to Previously Reported Financial Statements Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] Dispositions [Table Text Block] Earnings Per Share, Basic and Diluted [Line Items] Weighted Average Shares (Denominator) [Abstract] Dilutive shares for long-term compensation plans Weighted Average Number of Shares Outstanding, Diluted Derivative Instruments, Gain (Loss) [Table Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] Segment Information Segment Reporting Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]