Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Debt Disclosure [Abstract] Senior Notes, Convertible Notes and Trust Preferred Securities Long-term Debt [Text Block] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Measurement Basis [Axis] Fair Value, Disclosure Item Amounts [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Amount [Member] Reported Value Measurement [Member] Fair Value [Member] Estimate of Fair Value Measurement [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value Measurements Using Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Liabilities Liabilities [Abstract] Debt, Carrying Amount Debt, Long-term and Short-term, Combined Amount Debt, Fair Value Debt Instrument, Fair Value Disclosure Real Estate [Abstract] Real Estate [Table] Real Estate [Table] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Etna GL 66 LLC [Member] Etna GL 66 LLC [Member] Etna GL 66 LLC [Member] Real Estate [Line Items] Real Estate [Line Items] Below-market leases, net of accretion Below Market Lease, Net Future accretion, year 1 Below Market Lease, Amortization Income, Next Twelve Months Future accretion, year 2 Below Market Lease, Amortization Income, Year Two Future accretion, year 3 Below Market Lease, Amortization Income, Year Three Future accretion, year 4 Below Market Lease, Amortization Income, Year Four Future accretion, year 5 Below Market Lease, Amortization Income, Year Five Area of land (in acres) Area of Land Change in amount of contingent consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Income Statement [Abstract] Preferred dividend rate Preferred Stock, Dividend Rate, Percentage Real Estate Investments, Net [Abstract] Investments in Real Estate Real Estate Disclosure [Text Block] Discontinued Operations and Disposal Groups [Abstract] Dispositions and Impairment Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Officer [Member] Officer [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of retirement agreements Number of Retirement Agreements Number of Retirement Agreements Maximum retirement agreement amount Other Commitments, Maximum Retirement Agreement Amount Other Commitments, Maximum Retirement Agreement Amount Retirement obligation earned Other Commitment Equity [Abstract] Equity [Table] Equity [Table] Equity [Table] Subsidiary, Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock, Name of Transaction [Domain] Sale of Stock [Domain] Public Offering And Direct Share Purchase Plan Proceeds [Member] Public Offering And Direct Share Purchase Plan Proceeds [Member] Public Offering And Direct Share Purchase Plan Proceeds [Member] At The Market [Member] At The Market [Member] At The Market [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series C [Member] Series C Preferred Stock [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Shares [Member] Common Stock [Member] Equity [Line Items] Equity [Line Items] Common shares issued through public offering and direct share purchase plan during period (in shares) Stock Issued During Period, Shares, New Issues Proceeds from issuance of common shares Proceeds from Issuance of Common Stock Value authorized Stockholders' Equity, Share Issuance Plan, Value Authorized Stockholders' Equity, Share Issuance Plan, Value Authorized Value, new issues Stock Issued During Period, Value, New Issues Preferred shares outstanding (in shares) Preferred Stock, Shares Outstanding Dividend rate (usd per share) Preferred Stock, Dividend Rate, Per-Dollar-Amount Preferred shares, liquidation preference Preferred Stock Aggregate Liquidation Preference Value Preferred Stock Aggregate Liquidation Preference Value Preferred shares to common shares conversion ratio Preferred Shares to Common Shares Conversion Ratio Preferred Shares to Common Shares Conversion Ratio Common share closing price percent of conversion price Common Share Closing Price Percent of Conversion Price Common Share Closing Price Percent of Conversion Price Shares issued, net of forfeitures (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Number of shares authorized to be repurchased (in shares) Stock Repurchase Program, Number of Shares Authorized to be Repurchased Repurchase of common shares (in shares) Stock Repurchased and Retired During Period, Shares Average cost per share (usd per share) Treasury Stock Acquired, Average Cost Per Share Unsettled repurchases Stock Repurchase Program, Unsettled Repurchases Stock Repurchase Program, Unsettled Repurchases OP unit equivalent in common shares (in unit per share) Partners Capital Equivalent In Common Shares Partners Capital Equivalent In Common Shares Shares issued for units redeemed (in shares) Partners Capital Account, Shares Issued For Units Redeemed Partners Capital Account, Shares Issued For Units Redeemed Partners' capital account, exchanges and conversions Partners' Capital Account, Exchanges and Conversions OP units outstanding (in units) Partners' Capital Account, Units Employee Benefits and Share-based Compensation, Noncash [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [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] Share Options [Member] Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Number of shares outstanding, beginning (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of shares exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Number of shares outstanding, ending (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Price per share outstanding, beginning (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Price per share exercised (usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Price per share outstanding, ending (usd per share) Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Notes [Member] Senior Notes [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Senior Notes Due 2024 [Member] Senior Notes Due 2024 [Member] Senior Notes Due 2024 [Member] Senior Notes Due 2023 [Member] Senior Notes Due 2023 [Member] Senior Notes Due 2023 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Principal amount of debt component Debt Instrument, Face Amount Unamortized debt discounts Debt Instrument, Unamortized Discount Unamortized debt issuance costs Debt Issuance Costs, Net Long-term debt Long-term Debt Debt interest rate percentage Debt Instrument, Interest Rate, Stated Percentage Issue Price Debt Instrument, Percentage of Issuance Price Debt Instrument, Percentage of Issuance Price Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivatives and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Two [Member] Index Performance Shares [Member] Index Performance Shares [Member] Index Performance Shares [Member] Peer Performance Shares [Member] Peer Performance Shares [Member] Peer Performance Shares [Member] Non-vested Shares [Member] Non-vested Shares [Member] Non-vested Shares [Member] Performance Shares [Member] Performance Shares [Member] Shares issued for services (in shares) Stock Issued During Period, Shares, Issued for Services Value per share granted (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Shares issued for services, value Stock Issued During Period, Value, Issued for Services Measurement period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Measurement Period Share-based Compensation Arrangement by Share-based Payment Award, Measurement Period Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Number of shares vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number of shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Real estate, at cost Disposal Group, Including Discontinued Operation, Real Estate At Cost Disposal Group, Including Discontinued Operation, Real Estate At Cost Real estate, intangible assets Disposal Group, Including Discontinued Operation, Intangible Assets Accumulated depreciation and amortization Disposal Group, Including Discontinued Operation, Accumulated Depreciation and Amortization Disposal Group, Including Discontinued Operation, Accumulated Depreciation and Amortization Rent receivable - deferred Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net Other Disposal Group, Including Discontinued Operation, Other Assets Assets held for sale Disposal Group, Including Discontinued Operation, Assets Other Disposal Group, Including Discontinued Operation, Mortgage Payable Disposal Group, Including Discontinued Operation, Mortgage Payable Liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities Mortgages and Notes Payable Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Leases, Acquired-in-Place [Member] Leases, Acquired-in-Place [Member] Customer Relationships [Member] Customer Relationships [Member] Above Market Leases [Member] Above Market Leases [Member] Buildings and building improvements Investment Building and Building Improvements Land, land estates and land improvements Land and Land Improvements Fixtures and equipment Fixtures and Equipment, Gross Construction in progress Development in Process Real estate - intangible assets Finite-Lived Intangible Assets, Gross Real estate, gross Real Estate Investment Property, Finite-Lived Intangible Assets and Construction in Progress, Gross Real Estate Investment Property, Finite-Lived Intangible Assets and Construction in Progress, Gross Accumulated depreciation and amortization Real Estate Investment Property, Accumulated Depreciation Real estate, net Real Estate Investment Property, Net Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Amortization expense, next 12 months Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Amortization expense, year 2 Finite-Lived Intangible Assets, Amortization Expense, Year Two Amortization expense, year 3 Finite-Lived Intangible Assets, Amortization Expense, Year Three Amortization expense, year 4 Finite-Lived Intangible Assets, Amortization Expense, Year Four Amortization expense, year 5 Finite-Lived Intangible Assets, Amortization Expense, Year Five Supplemental Cash Flow Information [Abstract] Other Significant Noncash Transactions [Table] Other Significant Noncash Transactions [Table] Other Significant Noncash Transactions by Unique Description [Axis] Other Significant Noncash Transaction [Axis] Other Significant Noncash Transaction, Name [Domain] Other Significant Noncash Transaction, Name [Domain] Conveyed Interest [Member] Conveyed Interest [Member] Conveyed Interest [Member] Interests Sold [Member] Interests Sold [Member] Interests Sold [Member] Other Significant Noncash Transactions [Line Items] Other Significant Noncash Transactions [Line Items] Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Restricted cash at beginning of period Restricted Cash and Cash Equivalents Restricted cash at end of period Cash, cash equivalents and restricted cash, at beginning of year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash, at end of year Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes paid, net Income Taxes Paid, Net Mortgage loans on real estate, foreclosures SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Foreclosure Loans assumed Loans Assumed Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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 Gains on sales of properties Gain (Loss) on Sale of Properties Debt satisfaction (gains) charges, net Gain (Loss) on Extinguishment of Debt, Operating Activities Gain (Loss) on Extinguishment of Debt, Operating Activities Impairment charges and loan losses Impairment Charges and Loan Losses, Continuing Operations Impairment Charges and Loan Losses, Continuing Operations Straight-line rents Straight Line Rent Other non-cash (income) expense, net Other Noncash Income (Expense) Equity in (earnings) losses of non-consolidated entities Income (Loss) from Equity Method Investments Distributions of accumulated earnings from non-consolidated entities Proceeds from Equity Method Investment, Distribution Unearned contingent acquisition consideration Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset Deferred taxes, net Increase (Decrease) in Deferred Income Taxes Change in accounts payable and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Change in rent receivable and prepaid rent, net Increase (Decrease) in Leasing Receivables Change in accrued interest payable Increase (Decrease) in Interest Payable, Net Other adjustments, net Other Operating Activities, Cash Flow Statement Net cash provided by operating activities: Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Investment in real estate, including intangible assets Payments for Capital Improvements Investment in real estate under construction Payments to Acquire and Develop Real Estate Capital expenditures Payments to Acquire Productive Assets Net proceeds from sale of properties Proceeds from Sale of Real Estate Held-for-investment Net proceeds from sale of non-consolidated investment Proceeds from Sale of Equity Method Investments Principal payments received on loans receivable Proceeds from Collection of Notes Receivable Investments in and advances to non-consolidated entities, net Payments to Acquire Equity Method Investments Distributions from non-consolidated entities in excess of accumulated earnings Proceeds from Equity Method Investment, Distribution, Return of Capital Payments of deferred leasing costs Payments to Acquire Lease Receivables Change in real estate deposits Payments for (Proceeds from) Deposits on Real Estate Acquisitions Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Dividends to common and preferred shareholders Payments of Dividends Conversion of convertible notes Repayments of Convertible Debt Principal amortization payments Repayments of Secured Debt Principal payments on debt, excluding normal amortization Repayments of Long-term Debt Proceeds of mortgages and notes payable Proceeds from Notes Payable Term loan payments Repayments of Unsecured Debt Proceeds from term loans Proceeds from Issuance of Long-term Debt Revolving credit facility borrowings Line of Credit Facility, Increase (Decrease), Net Revolving credit facility payments Repayments of Lines of Credit Payment of early extinguishment of debt charges Payment for Debt Extinguishment or Debt Prepayment Cost Payment of developer liabilities Payment of Developer Liabilities Payment of Developer Liabilities Payments of deferred financing costs Payments of Financing Costs Cash distributions to noncontrolling interests Distributions To Noncontrolling Interests The cash outflow for distributions to noncontrolling interests. Redemption of a noncontrolling interest Payments to Acquire Interest in Joint Venture Repurchase of common shares Payments for Repurchase of Preferred Stock and Preference Stock Issuance of common shares, net of costs and repurchases to settle tax obligations Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Change in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Accounting Policies [Abstract] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Options 2010 [Member] 2010 Options [Member] Options 2009 [Member] 2009 Options [Member] Options 2008 [Member] 2008 Options [Member] Weighted-average fair value of options granted (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Weighted-average expected option lives (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Weighted-average expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate Weighted-average expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Mortgages, Notes Payable, Credit Facility Borrowings, and Term Loans [Member] Mortgages, Notes Payable, Credit Facility Borrowings, and Term Loans [Member] Mortgages, Notes Payable, Credit Facility Borrowings, and Term Loans [Member] 2019 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2020 Long-term Debt, Maturities, Repayments of Principal in Year Two 2021 Long-term Debt, Maturities, Repayments of Principal in Year Three 2022 Long-term Debt, Maturities, Repayments of Principal in Year Four 2023 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Long-term debt, gross Long-term Debt, Gross BASIC Earnings Per Share, Basic [Abstract] Net income attributable to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Weighted-average common shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Net income attributable to common shareholders - basic (usd per share) Earnings Per Share, Basic DILUTED: Earnings Per Share, Diluted [Abstract] Net income attributable to common shareholders - basic Income Loss From Continuing Operations Attributable To Common Shareholders Income Loss From Continuing Operations Attributable To Common Shareholders Impact of assumed conversions Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Net income attributable to common shareholders Loss From Continuing Operations Attributable to Common Shareholders Net of Deductions Loss From Continuing Operations Attributable to Common Shareholders Net of Deductions Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Unvested share-based payment awards and options (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Operating Partnership Units (in units) Incremental Common Shares Attributable to Operating Partnership Units Incremental Common Shares Attributable to Operating Partnership Units Weighted-average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Net income (loss) attributable to common shareholders - per common share diluted (usd per share) Earnings Per Share, Diluted Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Preferred Shares [Member] Preferred Stock [Member] Additional Paid-in-Capital [Member] Additional Paid-in Capital [Member] Accumulated Distributions in Excess of Net Income [Member] Accumulated Distributions in Excess of Net Income [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Noncontrolling Interests [Member] Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance at beginning of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning balance (in shares) Shares, Outstanding Redemption of noncontrolling OP units for common shares Stock Issued During Period, Value, Conversion of Units Redemption of noncontrolling OP units for common shares (in shares) Stock Issued During Period, Shares, Conversion of Units Repurchase of common shares Stock Repurchased During Period, Value Repurchase of common shares (in shares) Stock Repurchased During Period, Shares Issuance of common shares upon conversion of convertible notes Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments Issuance of common shares upon conversion of convertible notes (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Exercise of employee common share options Stock Issued During Period, Value, Stock Options Exercised Exercise of employee common share options, net (in shares) Issuance of common shares and deferred compensation amortization, net Common Shares Issuance And Deferred Compensation Costs Amortization The cost of issuing common shares and the amortization of deferred compensation costs, net Issuance of common shares and deferred compensation amortization, net (in shares) Common Shares Issuance And Deferred Compensation Costs Amortization, Shares Common Shares Issuance And Deferred Compensation Costs Amortization, Shares Repurchase of common shares to settle tax obligations Adjustments to Additional Paid in Capital, Repurchase of Common Shares to Settle Tax Obligations Adjustments to Additional Paid in Capital, Repurchase of Common Shares to Settle Tax Obligations Repurchase of common shares to settle tax obligations (in shares) Adjustments to Additional Paid in Capital, Repurchase of Common Shares to Settle Tax Obligations, Shares Adjustments to Additional Paid in Capital, Repurchase of Common Shares to Settle Tax Obligations, Shares Forfeiture of employee common shares Stock Issued During Period, Value, Share-based Compensation, Forfeited Forfeiture of employee common shares (in shares) Stock Issued During Period, Shares, Share-based Compensation, Forfeited Acquisition of consolidated joint venture partner's equity interest Adjustments to Additional Paid In Capital, Acquisition of Equity Interest Adjustments to Additional Paid In Capital, Acquisition of Equity Interest Dividends/distributions Stockholders' Equity, Dividends and Distributions Stockholders' Equity, Dividends and Distributions Net Income Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Balance at end of period Ending balance (in shares) Net income (loss) attributable to common shareholders Net Income (Loss) Attributable to Parent Increase in additional paid-in-capital for redemption of noncontrolling OP units Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Net Change from net income attributable to shareholders and transfers from noncontrolling interests Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net Maximum [Member] Mortgages and Notes Payable [Member] Mortgages and Notes Payable [Member] Mortgages and Notes Payable [Member] Effective interest percentage Debt Instrument, Interest Rate, Effective Percentage Weighted-average interest rate Debt, Weighted Average Interest Rate Debt satisfaction gains (charges), net Gain (Loss) on Extinguishment of Debt Interest paid, capitalized Interest Costs Capitalized Adjustment Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] 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] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Changes in Accumulated Other Comprehensive Income AOCI Attributable to Parent, Net of Tax [Roll Forward] Other comprehensive income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts of (income) loss reclassified from accumulated other comprehensive income (loss) to interest expense Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance Derivative Instruments, Gain (Loss) [Table Text Block] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Industrial Property [Member] Industrial Property [Member] Office Property [Member] Office Building [Member] Investment Geographic Region [Axis] Investment Geographic Region [Axis] Investment Geographic Region [Domain] Investment Geographic Region [Domain] Olive Branch, Mississippi [Member] Olive Branch, Mississippi [Member] Olive Branch, Mississippi [Member] Edwardsville, Illinois [Member] Edwardsville, Illinois [Member] Edwardsville, Illinois [Member] Spartanburg, South Carolina [Member] Spartanburg, South Carolina [Member] Spartanburg, South Carolina [Member] Pasadena, Texas [Member] Pasadena, Texas [Member] Pasadena, Texas [Member] Carrollton, Texas [Member] Carrollton, Texas [Member] Carrollton, Texas [Member] Goodyear, Arizona [Member] Goodyear, Arizona [Member] Goodyear, Arizona [Member] Chester, South Carolina [Member] Chester, South Carolina [Member] Chester, South Carolina [Member] Lake Jackson, Texas [Member] Lake Jackson, Texas [Member] Lake Jackson, Texas [Member] New Century, Kansas [Member] New Century, Kansas [Member] New Century, Kansas [Member] Lebanon, Indiana [Member] Lebanon, Indiana [Member] Lebanon, Indiana [Member] Charlotte, North Carolina [Member] Charlotte, North Carolina [Member] Charlotte, North Carolina [Member] Cleveland, Tennessee [Member] Cleveland, Tennessee [Member] Cleveland, Tennessee [Member] Grand Prairie, Texas [Member] Grand Prairie, Texas [Member] Grand Prairie, Texas [Member] San Antonio, Texas [Member] San Antonio, Texas [Member] San Antonio, Texas [Member] Opelika, Alabama [Member] Opelika, Alabama [Member] Opelika, Alabama [Member] McDonough, Georgia [Member] McDonough, Georgia [Member] McDonough, Georgia [Member] Byhalia, Mississippi [Member] Byhalia, Mississippi [Member] Byhalia, Mississippi [Member] Jackson, Tennessee [Member] Jackson, Tennessee [Member] Jackson, Tennessee [Member] Smyrna, Tennessee [Member] Smyrna, Tennessee [Member] Smyrna, Tennessee [Member] Lafayette, Indiana [Member] Lafayette, Indiana [Member] Lafayette, Indiana [Member] Romulus, Michigan [Member] Romulus, Michigan [Member] Romulus, Michigan [Member] Warren, Michigan [Member] Warren, Michigan [Member] Warren, Michigan [Member] Winchester, Virginia [Member] Winchester, Virginia [Member] Winchester, Virginia [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Olive Branch, Mississippi, Industrial Property Expiring 2029 [Member] Olive Branch, Mississippi, Industrial Property Expiring 2029 [Member] Olive Branch, Mississippi, Industrial Property Expiring 2029 [Member] Olive Branch, Mississippi, Industrial Property Expiring 2021 [Member] Olive Branch, Mississippi, Industrial Property Expiring 2021 [Member] Olive Branch, Mississippi, Industrial Property Expiring 2021 [Member] Leases, Acquired-in-Place, Market Adjustment [Member] Leases, Acquired-in-Place, Market Adjustment [Member] Initial Cost Basis Business Combination, Consideration Transferred Land and Land Estate Land Building and Improvements Investment Building and Building Improvements Acquired During Period Investment Building and Building Improvements Acquired During Period Lease in-place Value Finite-Lived Intangible Asset, Acquired-in-Place Leases Below Market Lease Below Market Lease, Gross Weighted-average life of intangible assets (years) Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Number of buildings completed Construction in Progress, Number of Buildings Completed Construction in Progress, Number of Buildings Completed Redemption of noncontrolling interests Payments for Repurchase of Redeemable Noncontrolling Interest Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Equity Method Investments and Joint Ventures [Abstract] Investments in and Advances to Affiliates [Table] Investments in and Advances to Affiliates [Table] Office Building [Member] Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Axis] Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Axis] Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Axis] Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Domain] Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Domain] [Domain] for Accounts, Notes, Loans and Financing Receivable by Location of Counterparty [Axis] Oklahoma City, Oklahoma [Member] Oklahoma City, Oklahoma [Member] Oklahoma City, Oklahoma [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Tenant-in-Common [Member] Tenant-in-Common [Member] Tenant-in-Common [Member] Russellville, Arkansas [Member] Russellville, Arkansas [Member] Russellville, Arkansas [Member] Palm Beach Gardens, Florida [Member] Palm Beach Gardens, Florida [Member] Palm Beach Gardens, Florida [Member] Legal Entity [Axis] Entity [Domain] Lexington Reality Advisors Inc [Member] Lexington Reality Advisors Inc [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Investment Advice [Member] Investment Advice [Member] Investments in and Advances to Affiliates [Line Items] Investments in and Advances to Affiliates [Line Items] Proceeds from divestiture of interest in joint venture Proceeds from Divestiture of Interest in Joint Venture Co-venture equity ownership percentage Equity Method Investment, Ownership Percentage Number of properties sold Real Estate, Number of Properties Sold Real Estate, Number of Properties Sold Aggregate gain on sale of properties Impairment charges on real estate Impairment of Real Estate Investment advisory fees Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Vorando Realty Trust [Member] Vorando Realty Trust [Member] Affiliated Entity [Member] Affiliated Entity [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Expense Reimbursement [Member] Expense Reimbursement [Member] Expense Reimbursement [Member] Structuring Fee [Member] Structuring Fee [Member] Structuring Fee [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Rent revenue Operating Leases, Income Statement, Lease Revenue Rent expense for corporate headquarters Operating Leases, Rent Expense, Net Notes payable, related parties Notes Payable, Related Parties Expenses from transactions with related party Related Party Transaction, Expenses from Transactions with Related Party Related party transaction, rate Related Party Transaction, Rate Statement of Financial Position [Abstract] Assets: Assets [Abstract] Accumulated amortization on deferred expenses Deferred Costs, Leasing, Accumulated Amortization Liabilities: Accumulated accretion on deferred revenue Below Market Lease, Accumulated Amortization Equity: Preferred shares, par value (usd per share) Preferred Stock, Par or Stated Value Per Share Preferred shares, authorized shares (in shares) Preferred Stock, Shares Authorized Preferred shares, liquidation preference Preferred Stock, Liquidation Preference, Value Preferred shares, convertible preferred, shares issued (in shares) Preferred Stock, Shares Issued Preferred shares, redeemable preferred, shares outstanding (in shares) Common shares, par value (usd per share) Common Stock, Par or Stated Value Per Share Common shares, authorized shares (in shares) Common Stock, Shares Authorized Common shares, shares issued (in shares) Common Stock, Shares, Issued Common shares, shares outstanding (in shares) Common Stock, Shares, Outstanding Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Convertible Debt [Member] Convertible Debt [Member] 6.804% Trust Preferred Securities [Member] Six Point Eight Zero Four Percent Trust Preferred Securities [Member] Six Point Eight Zero Four Percent Trust Preferred Securities [Member] Six Percent Convertible Guaranteed Note [Member] Six Percent Convertible Guaranteed Note [Member] 6.00% Convertible Guaranteed Note [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Face amount Original debt, amount Debt Conversion, Original Debt, Amount Shares issued (in shares) Debt Conversion, Converted Instrument, Shares Issued Cash payments Debt Conversion, Converted Instrument, Cash Payments Debt Conversion, Converted Instrument, Cash Payments Debt satisfaction (gains) charges, net Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Principal amount outstanding on Trust Preferred Securities Principal Amount Outstanding on Loans Securitized or Asset-backed Financing Arrangement Debt issuance costs, gross Debt Issuance Costs, Gross Organization, Consolidation and Presentation of Financial Statements [Abstract] The Company Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Quarterly Financial Information Disclosure [Abstract] Unaudited Quarterly Financial Data Quarterly Financial Information [Text Block] Real estate, at cost Real Estate Investment Property, at Cost Less: accumulated depreciation and amortization Assets held for sale Cash and cash equivalents Restricted cash Investment in and advances to non-consolidated entities Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Deferred expenses (net of accumulated amortization of $27,397 in 2018 and $35,072 in 2017) Deferred Costs, Noncurrent Rent receivable - current Accounts Receivable, Net, Current Rent receivable – deferred Deferred Rent Receivables, Net Other assets Other Assets Total assets Assets Liabilities and Equity: Liabilities and Equity [Abstract] Mortgages and notes payable, net Notes Payable Revolving credit facility borrowings Long-term Line of Credit Term loans payable, net Loans Payable Senior notes payable, net Senior Notes Trust preferred securities, net Unsecured Debt Dividends payable Dividends Payable Liabilities held for sale Accounts payable and other liabilities Accounts Payable and Accrued Liabilities Accrued interest payable Interest Payable Deferred revenue - including below market leases (net of accumulated accretion of $17,606 in 2018 and $26,081 in 2017) Deferred Revenue, Leases, Net Prepaid rent Advance Rent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Preferred shares, par value $0.0001 per share; authorized 100,000,000 shares, Series C Cumulative Convertible Preferred, liquidation preference $96,770 and 1,935,400 shares issued and outstanding Preferred Stock, Value, Issued Common shares, par value $0.0001 per share; authorized 400,000,000 shares, 235,008,554 and 240,689,081 shares issued and outstanding in 2018 and 2017, respectively Common Stock, Value, Issued Additional paid-in-capital Additional Paid in Capital Accumulated distributions in excess of net income Accumulated Distributions in Excess of Net Income Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total liabilities and equity Liabilities and Equity Statement of Comprehensive Income [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Change in unrealized gain (loss) on interest rate swaps, net Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Other comprehensive income (loss) Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Comprehensive income attributable to Lexington Realty Trust shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State and Local Jurisdiction [Member] State and Local Jurisdiction [Member] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] State taxes paid State Taxes Paid State Taxes Paid Document and Entity Information [Abstract] Document and Entity Information [Abstract] 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 Well-known Seasoned User Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Document Type Document Type Amendment Flag Amendment Flag Document Period Ended Date Document Period End Date Leases [Abstract] Property Subject to or Available for Operating Lease, by Major Property Class [Table] Property Subject to or Available for Operating Lease, by Major Property Class [Table] 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 Interests [Member] Leaseholds and Leasehold Improvements [Member] Corporate HQ and Office Space [Member] Building [Member] Property Subject to or Available for Operating Lease [Line Items] Property Subject to or Available for Operating Lease [Line Items] Minimum Future Rental Receipts [Abstract] Operating Leases, Future Minimum Payments Receivable [Abstract] 2019 Operating Leases, Future Minimum Payments Receivable, Current 2020 Operating Leases, Future Minimum Payments Receivable, in Two Years 2021 Operating Leases, Future Minimum Payments Receivable, in Three Years 2022 Operating Leases, Future Minimum Payments Receivable, in Four Years 2023 Operating Leases, Future Minimum Payments Receivable, in Five Years Thereafter Operating Leases, Future Minimum Payments Receivable, Thereafter Future Minimum Payments Receivable Operating Leases, Future Minimum Payments Receivable Future Rental Payments [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Future Minimum Payments Due Operating Leases, Future Minimum Payments Due Rent expense for leasehold interests Schedule of Future Minimum Rental Payments Receivable for Operating Leases Schedule of Future Minimum Rental Payments Receivable for Operating Leases [Table Text Block] Schedule of Future Minimum Rental Payments Receivable for Operating Leases [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Earnings Per Share Reconciliation Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Senior Notes, Convertible Notes, and Trust Preferred Securities [Member] Senior Notes, Convertible Notes, and Trust Preferred Securities [Member] Senior Notes, Convertible Notes, and Trust Preferred Securities [Member] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity, Primary Beneficiary [Member] Building and Building Improvements [Member] Building and Building Improvements [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-15 [Member] Accounting Standards Update 2016-15 [Member] Accounting Standards Update 2016-02 [Member] Accounting Standards Update 2016-02 [Member] NNN Office Joint Venture [Member] NNN Office Joint Venture [Member] NNN Office Joint Venture [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Maximum [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] VIE, ownership percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Acquisition expense Acquisition Costs Expensed Acquisition Costs Expensed Maximum useful life of PPE (in years) Property, Plant and Equipment, Useful Life Expiration period of options (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Number of operating segments Number of Operating Segments Increase (decrease) in cash from operating activities Increase (decrease) in cash from investing activities Increase (decrease) in cash from financing activities Right-of-use asset Operating Lease, Right-of-Use Asset Lease, liability Operating Lease, Liability Income Tax Contingency [Table] Income Tax Contingency [Table] Common [Member] Series C Cumulative Redeemable Preferred Shares [Member] Tax on Dividends, by Nature [Axis] Tax on Dividends, by Nature [Axis] Tax on Dividends, by Nature [Domain] Tax on Dividends, by Nature [Domain] Ordinary Income [Member] Ordinary Income [Member] Ordinary Income [Member] 15% Rate, Qualifying Dividend [Member] Fifteen Percent Rate, Qualifying Dividend [Member] Fifteen Percent Rate, Qualifying Dividend [Member] 15% Rate Gain [Member] Fifteen Percent Rate Gain [Member] Fifteen Percent Rate Gain [Member] Return of Capital [Member] Return of Capital [Member] Return of Capital [Member] Income Tax Contingency [Line Items] Income Tax Contingency [Line Items] Total dividends per share, common (usd per share) Common Stock, Dividends, Per Share, Declared Total dividends per share, preferred (usd per share) Preferred Stock, Dividends Per Share, Declared Taxable percentage allocation on dividends Taxable Percentage Allocation on Dividends Taxable Percentage Allocation on Dividends SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract] Real Estate and Accumulated Depreciation, by Property [Table] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, by Property [Table] Legal Entity [Axis] Entity [Domain] Real Estate and Accumulated Depreciation [Line Items] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] Total cost basis for federal income tax purposes SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis Reconciliation of real estate owned: SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward] Balance at the beginning of year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross Additions during year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Acquisition Properties sold and impaired during the year Real Estate, Properties Sold Real Estate, Properties Sold Other reclassifications SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Deduction Balance at end of year Reconciliation of accumulated depreciation and amortization: SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward] Balance at the beginning of year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation Depreciation and amortization expense SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense Accumulated depreciation and amortization of properties sold, impaired and held for sale during year SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Other Deduction Other reclassifications Real Estate Accumulated Depreciation, Other Reclassifications Real Estate Accumulated Depreciation, Other Reclassifications Balance at end of year Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements Using Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value Measurements Using Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Nonrecurring [Member] Fair Value, Measurements, Nonrecurring [Member] 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] Interest rate swap assets Interest Rate Derivative Assets, at Fair Value Impaired real estate assets Impaired Real Estate Assets, Fair Value Disclosure Impaired Real Estate Assets Fair Value Disclosure Supplemental Disclosure of Statement of Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Line of Credit Facility [Table] Line of Credit Facility [Table] Unsecured Revolving Credit Facility, Expiring August 2019 [Member] Unsecured Revolving Credit Facility, Expiring August 2019 [Member] Unsecured Revolving Credit Facility, Expiring August 2019 [Member] Unsecured Term Loan, Expiring January 2021 [Member] Unsecured Term Loan, Expiring January 2021 [Member] Unsecured Term Loan, Expiring January 2021 [Member] Unsecured Term Loan, Expiring January 2019 [Member] Unsecured Term Loan, Expiring January 2019 [Member] Unsecured Term Loan, Expiring January 2019 [Member] Revolving Credit Facility [Member] Revolving Credit Facility [Member] Interest Rate Swap [Member] Interest Rate Swap [Member] Unsecured Term Loan [Member] Unsecured Term Loan [Member] Unsecured Term Loan [Member] Interest rate stated percentage rate range minimum excluding LIBOR Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Options 2010 [Member] Options 2009 [Member] Options 2008 [Member] Non-Management Award Grant [Member] Non-Management Award Grant [Member] Non-Management Award Grant [Member] Shares Subject to Time [Member] Shares Subject to Time [Member] Shares Subject to Time [Member] Shares Subject to Performance [Member] Shares Subject to Performance [Member] Shares Subject to Performance [Member] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Four [Member] Share-based Compensation Award, Tranche Five [Member] Share-based Compensation Award, Tranche Five [Member] Share-based Compensation Award, Tranche Five [Member] Schedule of Share-based Compensation Arrangement By Share Based Payment Award Vesting [Axis] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Vesting [Axis] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Vesting [Axis] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Vesting [Domain] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Vesting [Domain] Share Based Compensation Arrangement By Share Based Payment Award Vesting Rate First Vesting Trigger [Member] Share Based Compensation Arrangement By Share Based Payment Award Vesting Rate First Vesting Trigger [Member] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Common share options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Common share options exercise price (usd per share) Award vesting rights, percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Expiration period after termination (in months) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period After Termination Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period After Termination Number of trading period days (in days) Number Of Trading Period Days Where Entity's Average Closing Price Per Common Share Is Greater Than The Stated Lower Amount Triggering Vesting Number Of Trading Period Days Where Entity's Average Closing Price Per Common Share Is Greater Than The Stated Lower Amount Triggering Vesting Average closing price, lower limit (usd per share) Stated Lower Amount Where Entity's Average Closing Price Per Common Share Is Greater Than The Stated Amount Triggering Stated Lower Amount Where Entity's Average Closing Price Per Common Share Is Greater Than The Stated Amount Triggering Vesting Options convertible to common shares Share Based Compensation Arrangement by Share Based Payment Award Options Convertible To Common Shares Share Based Compensation Arrangement by Share Based Payment Award Options Convertible To Common Shares Options converted to common shares exercise price (usd per share) Options Converted To Common Shares Exercise Price Options Converted To Common Shares Exercise Price Deferred compensation equity Deferred Compensation Equity Recognized compensation expense average period (in years) Share Based Compensation Expense Average Period Share Based Compensation Expense Average Period Exercises in period, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Options, exercisable, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Non-options, nonvested, number (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number of shares available for grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Compensation cost not yet recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Total compensation cost not yet recognized, period for recognition (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Shares held in employee trust (in shares) Common Stock, Shares Held in Employee Trust, Shares Initial vesting percentage Initial Vesting Percentage Initial Vesting Percentage Vesting percentage Vesting Percentage Vesting Percentage Vesting period (in years) Defined Contribution Plan, Vesting Period Defined Contribution Plan, Vesting Period Cost recognized Defined Contribution Plan, Cost Allocated share-based compensation expense Allocated Share-based Compensation Expense Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Benefit Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Leases Leases of Lessor and Lessee Disclosure [Text Block] Leases of Lessor and Lessee Disclosure [Text Block] Number of consolidated properties Number of Real Estate Properties Number of states in which entity has interests Number of States in which Entity Operates Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] NNN Office Joint Venture Properties [Member] NNN Office Joint Venture Properties [Member] NNN Office Joint Venture Properties [Member] Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Transferred Property [Member] Transferred Property [Member] Transferred Property [Member] Land [Member] Land [Member] New York, New York [Member] New York, New York [Member] New York, New York [Member] 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] Proceeds from sale of property Proceeds from Sale of Property Held-for-sale Gain (loss) on debt extinguishment on sale of properties Discontinued Operations, Gain (Loss) on Debt Extinguishment on Sale of Properties, Net Discontinued Operations, Gain (Loss) on Debt Extinguishment on Sale of Properties, Net Properties classified as held-for-sale (in number of properties) Number of Real Estate Properties, Held For Sale Number of Real Estate Properties, Held For Sale Other asset impairment charges Other Asset Impairment Charges Asset impairment charges Asset Impairment Charges Impairment losses related to real estate partnerships Impairment Losses Related to Real Estate Partnerships Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Real estate, net Total assets Total liabilities Investment in and Advances to Non-Consolidated Entities Equity Method Investments and Joint Ventures Disclosure [Text Block] Accumulated Other Comprehensive Income Loss Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Effects of Changes in the Company's Ownership Interests in Noncontrolling Interests Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Etna Park 70 [Member] Etna Park 70 [Member] Etna Park 70 [Member] Other Joint Ventures [Member] Other Joint Ventures [Member] Other Joint Ventures [Member] 2 of 21 Transferred Properties [Member] 2 of 21 Transferred Properties [Member] 2 of 21 Transferred Properties [Member] Mortgages [Member] Mortgages [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Ownership percentage Equity method investments Equity Method Investments Contribution of property Contribution of Property Payments to acquire interest in joint venture Gain (loss) on disposition of assets Gain (Loss) on Disposition of Assets Transfer mortgage payable Transfer Mortgage Payable Non-recourse debt Non-Recourse Debt Long-term debt, term Long-term Debt, Term Number of additional extensions available Long-term Debt, Number of Additional Extensions Available Long-term Debt, Number of Additional Extensions Available Term of additional extensions Long-term Debt, Term of Additional Extensions Long-term Debt, Term of Additional Extensions Basis spread rate increase per extension Debt Instrument, Basis Spread Rate Increase Per Extension Debt Instrument, Basis Spread Rate Increase Per Extension Cap interest rate Derivative, Cap Interest Rate Term of contract Derivative, Term of Contract Equity method investments, assets Equity Method Investment, Summarized Financial Information, Assets Equity method investments, liabilities Equity Method Investment, Summarized Financial Information, Liabilities Number of joint venture interests Number of Joint Venture Interests Number of Joint Venture Interests Proceeds from collection of loans receivable Proceeds from Collection of Loans Receivable Derivative [Table] Derivative [Table] Hedging Relationship [Axis] Hedging Relationship [Domain] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Derivative Instrument [Axis] Derivative Contract [Domain] Hedging Designation [Axis] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Other Assets [Member] Other Assets [Member] Income Statement Location [Axis] Income Statement Location [Domain] Interest Expense [Member] Interest Expense [Member] Derivative [Line Items] Derivative [Line Items] Expected amount of derivative related interest to be reclassified to interest expense over the next 12 months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Number of derivative instruments held Derivative, Number of Instruments Held Notional amount of derivatives Derivative, Notional Amount Derivative asset Derivative Asset Amount of Income Recognized in OCI on Derivative (Effective Portion) December 31, Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Amount of (Income) Loss Reclassified from Accumulated OCI into Income (Effective Portion) December 31, Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Risks and Uncertainties [Abstract] Concentration of Risk Concentration Risk Disclosure [Text Block] Investments in and Advances to Affiliates Investments in and Advances to Affiliates [Table Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Number of shares outstanding, beginning (in shares) Number of shares vested (in shares) Number of shares forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number of shares outstanding, ending (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Value per share outstanding, beginning (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Value per share vested (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Value per share forfeited (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Value per share outstanding, ending (usd per share) Equity Stockholders' Equity Note Disclosure [Text Block] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State and local Current State and Local Tax Expense (Benefit) NOL utilized Current Net Operating Loss Utilized Current Net Operating Loss Utilized Deferred: Deferred Income Taxes and Other Assets [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State and local Deferred State and Local Income Tax Expense (Benefit) Benefit (provision) for income taxes Income Tax Expense (Benefit) Basis of Presentation and Consolidation Basis of Accounting, Policy [Policy Text Block] Variable Interest Entity Consolidation, Variable Interest Entity, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Fair Value Measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Acquisition of Real Estate Real Estate, Policy [Policy Text Block] Impairment of Real Estate Property, Plant and Equipment, Impairment [Policy Text Block] Investments in Non-Consolidated Entities Equity Method Investments [Policy Text Block] Impairment of Equity Method Investments Impairment of Equity Method Investments [Policy Text Block] Impairment of Equity Method Investments, Policy [Policy Text Block] Acquisition, Development and Construction Arrangements Acquisition Development And Construction Arrangements [Policy Text Block] Acquisition Development And Construction Arrangements [Policy Text Block] Properties Held For Sale Real Estate Held for Development and Sale, Policy [Policy Text Block] Deferred Expenses Deferred Charges, Policy [Policy Text Block] Derivative Financial Instruments Derivatives, Policy [Policy Text Block] Stock Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Tax Status Income Tax, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Environmental Matters Environmental Costs, Policy [Policy Text Block] Segment Reporting Segment Reporting, Policy [Policy Text Block] Reclassification Reclassification, Policy [Policy Text Block] Recently Issued Accounting Guidance New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Compensation, Stock Options, Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of Nonvested Share Activity Schedule of Nonvested Share Activity [Table Text Block] Schedule of Share-based Compensation, Activity Share-based Compensation, Activity [Table Text Block] Mortgages and notes payable Revenues Revenues Federal provision at statutory tax rate (21% for 2018 and 34% for 2017 and 2016) Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Federal tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent State and local taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Other Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Subsequent Event [Table] Subsequent Event [Table] Richland, Washington [Member] Richland, Washington [Member] Richland, Washington [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Proceeds from sale of real estate Proceeds from Sale of Real Estate Number of real estate properties acquired Number of Real Estate Properties Acquired Number of Real Estate Properties Acquired Payments to acquire real estate Payments to Acquire Real Estate Repurchase of common shares (in shares) Common stock dividends declared (usd per share) Fair Value Measurements Fair Value Disclosures [Text Block] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Statutory Accounting Practices Disclosure Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Summary of Average Taxable Nature of Dividends Summary of Average Taxable Nature of Dividends [Table Text Block] Summary of Average Taxable Nature of Dividends [Table Text Block] Schedule of Assets and Liabilities of Held for Sale Properties Disposal Groups, Including Discontinued Operations [Table Text Block] Real Estate [Member] Real Estate [Member] Gross revenues: Revenues [Abstract] Rental Tenant reimbursements Total gross revenues Expense applicable to revenues: Operating Expenses [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Property operating Cost of Goods and Services Sold General and administrative General and Administrative Expense Litigation settlement Gain (Loss) Related to Litigation Settlement Non-operating income Nonoperating Income (Expense) Interest and amortization expense Interest Expense Debt satisfaction gains (charges), net Impairment charges and loan losses Impairment Charges and Loan Losses The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value and the allowance expensed for the period based on estimated losses to be realized from loan transactions. Gains on sales of properties Gain (Loss) on Sale of Properties, before Applicable Income Taxes Income (loss) before provision for income taxes and equity in earnings of non-consolidated entities Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Provision for income taxes Equity in earnings (losses) of non-consolidated entities Income (loss) from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Less net income attributable to noncontrolling interests