Condensed Consolidated Financial Information [Abstract] Condensed Consolidated Financial Information [Abstract] Condensed consolidating financial information Condensed Financial Statements [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Secured notes payable Secured Debt [Member] Secured Notes Payable Maturing on 1/1/23 Secured Debt Maturing on January 2023 [Member] Secured Debt Maturing on January 2023 [Member] Secured Notes Payable Maturing on 3/10/23 Secured Notes Payable Maturing March 10, 2023 [Member] Secured Notes Payable Maturing March 10, 2023 [Member] Secured Notes Payable Maturing on 2/6/24 Secured Notes Payable Maturing February 6, 2024 [Member] Secured Notes Payable Maturing February 6, 2024 [Member] Secured Notes Payable Maturing on 7/1/26 Secured Notes Payable Maturing on 7/1/26 [Member] Secured Notes Payable Maturing on July 1, 2026 Secured Notes Payable Maturing on 7/1/36 Secured Notes Payable Maturing July 1, 2036 [Member] Secured Notes Payable Maturing July 1, 2036 [Member] Unsecured Debt Unsecured Debt [Member] $2.2 billion unsecured senior line of credit Line of Credit [Member] Unsecured Senior Bank Term Loan Unsecured Bank Term Loan 2021 [Member] Unsecured Bank Term Loan 2021 [Member] 2.75% Unsecured Senior Notes Payable Unsecured Senior Notes Due in January 2020 [Member] Unsecured Senior Notes Due in January 2020 [Member] 4.60% Unsecured Senior Notes Payable Unsecured Senior Notes Due in April 2022 [Member] Represents the unsecured senior notes payable which are due in April, 2022. 3.90% Unsecured Senior Notes Payable Unsecured Senior Notes Due in June 2023 [Member] Unsecured Senior Notes Due in June 2023 [Member] 4.00% Unsecured Senior Notes Payable 4.00% Unsecured Senior Note Payable [Member] 4.00% Unsecured Senior Note Payable [Member] 3.45% Unsecured Senior Notes Payable 3.45% unsecured senior notes payable due in 2025 [Member] 3.45% unsecured senior notes payable due in 2025 [Member] 4.30% Unsecured Senior Notes Payable 4.30% Unsecured Senior Notes Payable [Member] 4.30% Unsecured Senior Notes Payable [Member] 3.80% Unsecured Senior Notes Payable 3.80% Unsecured Senior Notes Payable [Member] 3.80% Unsecured Senior Notes Payable 3.95% Unsecured Senior Notes Payable Due in 2027 3.95% Unsecured Senior Notes Payable [Member] 3.95% Unsecured Senior Notes Payable [Member] 3.95% Unsecured Senior Notes Payable Due in 2028 3.95% Unsecured Senior Notes Payable Due in 2028 [Member] 3.95% Unsecured Senior Notes Payable Due in 2028 [Member] 4.50% Unsecured Senior Notes Payable Unsecured Senior Notes Due in July 2029 [Member] Unsecured Senior Notes Due in July 2029 [Member] 4.70% Unsecured Senior Notes Payable 4.70% Unsecured Senior Notes Payable [Member] 4.70% Unsecured Senior Notes Payable [Member] 4.85% Unsecured Senior Note Payable 4.85% Unsecured Senior Note Payable [Member] 4.85% Unsecured Senior Note Payable [Member] Debt Instrument Debt Instrument [Line Items] Stated interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Applicable margin (as a percent) Debt Instrument, Basis Spread on Variable Rate Effective rate (as a percent) Debt Instrument, Interest Rate, Effective Percentage Maturity Date Debt Instrument, Maturity Date Future principal payments due on secured and unsecured debt Long-term Debt, Fiscal Year Maturity [Abstract] 2019 Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 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 Outstanding Balance Long-term Debt, Gross Unamortized (Deferred Financing Cost), (Discount) Premium Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Total Consolidated Long-term Debt Organization, Consolidation and Presentation of Financial Statements [Abstract] Summary of significant accounting policies Basis of Presentation and Significant Accounting Policies [Text Block] Equity [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Interest Rate Hedge Agreements Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Foreign Currency Translation Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Increase (Decrease) Accumulated Other Comprehensive Income (Loss) Net of Tax [Roll Forward] Increase (Decrease) Accumulated Other Comprehensive Income (Loss) Net of Tax [Roll Forward] -- None. No documentation exists for this element. -- Balance as of December 31, 2018 Accumulated Other Comprehensive Income (Loss), Net of Tax Unrealized interest rate hedge gains (losses) arising during the period Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized foreign currency translation gains (losses) arising during the period Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification adjustment for amortization of interest income included in net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Reclassification adjustment for cumulative foreign currency translation losses included in net income upon sale or liquidation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax Amounts reclassified from other comprehensive income to net income Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Balance as of March 31, 2019 Summary of secured and unsecured debt Schedule of Debt [Table Text Block] Schedule of maturities of secured and unsecured debt Schedule of Maturities of Secured and Unsecured Debt [Table Text Block] Tabular disclosure of the amount of fixed rate/hedged and unhedged floating rate debt and their respective principal maturities for each of the five years and thereafter following the date of the latest balance sheet date presented. Schedule of Interest Incurred Schedule of Interest Incurred [Table Text Block] Tabular reconciliation of interest expense incurred for continuing and discontinued operations. Investments [Abstract] Summary of investments Investment [Table Text Block] Schedule of net investment income Investment Income [Table Text Block] Leases [Abstract] Leases Lessor, Operating Leases [Text Block] Leases Lessor, Direct Financing Leases [Text Block] Leases Lessee, Operating Leases [Text Block] Discontinued Operations and Disposal Groups [Abstract] Summary of net assets of discontinued operations and (loss) income from discontinued operations, net Disposal Groups, Including Discontinued Operations [Table Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Investments in real estate Real Estate Investment Property, Net Investments in unconsolidated real estate joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents, Current Tenant receivables Accounts Receivable, Net Deferred rent Deferred Rent Receivables, Net Deferred leasing costs Deferred Costs Leasing and Finance Net Represents the aggregate of deferred leasing and financing costs net of accumulated amortization. Investments Equity Securities, FV-NI and without Readily Determinable Fair Value Other assets Other Assets Total assets Assets Liabilities, Noncontrolling Interests, and Equity Liabilities and Equity [Abstract] Secured notes payable Secured Debt Unsecured senior notes payable Senior Notes, Noncurrent Unsecured senior line of credit Long-term Line of Credit Unsecured senior bank term loan Loans Payable to Bank Accounts payable, accrued expenses, and tenant security deposits Accounts Payable and Accrued Liabilities Dividends payable Dividends Payable Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Redeemable noncontrolling interests Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Alexandria Real Estate Equities, Inc.’s stockholders’ equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] 7.00% Series D cumulative convertible preferred stock Convertible Preferred Stock, Nonredeemable or Redeemable, Issuer Option, Value Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Alexandria Real Estate Equities, Inc.’s stockholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities, noncontrolling interests, and equity Liabilities and Equity Organization and basis of presentation Nature of Operations [Text Block] Fair Value Disclosures [Abstract] Fair value measurements Fair Value Disclosures [Text Block] Document and Entity Information -- None. No documentation exists for this element. -- Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Emerging Growth Company Entity Emerging Growth Company Small Business Entity Small Business Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Cash, cash equivalents, and restricted cash [Abstract] Cash, cash equivalents, and restricted cash [Abstract] Cash, cash equivalents, and restricted cash summary Restrictions on Cash and Cash Equivalents [Table Text Block] Accounts payable, accrued expenses, and tenant security deposits [Abstract] Accounts payable, accrued expenses, and tenant security deposits [Abstract] Accounts payable, accrued expenses, and tenant security deposits Other Liabilities Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Real Estate [Abstract] Real Estate [Table] Real Estate [Table] Additional Paid-In Capital Additional Paid-in Capital [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] 75/125 Binney Street 75/125 Binney Street [Member] 75/125 Binney Street [Member] Real Estate Real Estate [Line Items] Noncontrolling Interest Share (in percentage) Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Area of Real Estate Property Area of Real Estate Property Proceeds from sale of real estate Proceeds from Sale of Real Estate Proceeds from Sale of Real Estate (Per RSF) Proceeds from Sale of Real Estate (Per RSF) Proceeds from Sale of Real Estate (Per RSF) Contributions from noncontrolling interests Noncontrolling Interest, Increase from Sale of Parent Equity Interest Schedule of Cash and Cash Equivalents [Table] Schedule of Cash and Cash Equivalents [Table] Restricted Cash and Cash Equivalents [Axis] Restricted Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Funds held in trust under the terms of certain secured notes payable Funds held in trust under the terms of certain secured notes payable [Member] Funds held in trust under the terms of certain secured notes payable [Member] Funds held in escrow related to construction projects and investing activities Funds held in escrow related to construction projects and investing activities [Member] Funds held in escrow related to construction projects and investing activities [Member] Other restricted cash Other restricted cash [Member] Other restricted cash [Member] Cash and Cash Equivalents Cash and Cash Equivalents [Line Items] Cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Schedule of accounts payable and accrued liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Income from rentals Income from rentals [Member] Income from rentals [Member] Other income Product and Service, Other [Member] Statement [Line Items] Statement [Line Items] Revenue Revenue from Contract with Customer, Including Assessed Tax Expenses: Costs and Expenses [Abstract] Rental operations Direct Costs of Leased and Rented Property or Equipment General and administrative General and Administrative Expense Interest Interest Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Loss on early extinguishment of debt Gain (Loss) on Extinguishment of Debt Total expenses Costs and Expenses Equity in earnings of unconsolidated real estate joint ventures Income (Loss) from Equity Method Investments Investment income Equity Securities, FV-NI, Gain (Loss) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Alexandria Real Estate Equities, Inc.’s stockholders Net Income (Loss) Attributable to Parent Dividends on preferred stock Dividends, Preferred Stock Preferred stock redemption charge Preferred Stock, Accretion of Redemption Discount Net income attributable to unvested restricted stock awards Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted Net income attributable to Alexandria Real Estate Equities, Inc.’s common stockholders Net Income (Loss) Available to Common Stockholders, Basic Earnings per share attributable to Alexandria’s common stockholders – basic and diluted: Earnings Per Share, Basic and Diluted [Abstract] Earnings per share – basic (USD per share) Earnings Per Share, Basic Earnings per shares - diluted (USD per share) Earnings Per Share, Diluted Unconsolidated real estate joint ventures [Abstract] Unconsolidated real estate joint ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Secured debt maturing on 5/17/20 $25M Secured debt maturing on 7/1/20 [Member] $25M Secured debt maturing on 7/1/20 [Member] Secured debt maturing on 6/29/21 Secured debt maturing on 6/29/24 [Member] Secured debt maturing on 6/29/24 [Member] Secured debt maturing on 3/16/23 Secured debt maturing on 3/16/23 [Member] Secured debt maturing on 3/16/23 [Member] Secured debt maturing on 5/1/35 Secured debt maturing on 5/1/35 [Member] Secured debt maturing on 5/1/35 [Member] Secured debt maturing on 8/10/35 Secured debt maturing on 8/10/35 [Member] Secured debt maturing on 8/10/35 Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Initial ownership interest Initial ownership interest [Member] Initial ownership interest [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity Method Investee Equity Method Investee [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Menlo Gateway Menlo Gateway [Member] Menlo Gateway [Member] 1401/1413 Research Boulevard 1401/1413 Research Boulevard [Member] 1401/1413 Research Boulevard [Member] 704 Quince Orchard Road 704 Quince Orchard Road [Member] 704 Quince Orchard Road [Member] 1655 and 1725 Third Street 1655 and 1715 Third Street [Member] 1655 and 1715 Third Street [Member] Other unconsolidated real estate joint ventures Other unconsolidated real estate joint ventures [Member] Other unconsolidated real estate joint ventures [Member] Schedule of Equity Method Investments Schedule of Equity Method Investments [Line Items] Equity interest percentage (in percent) Equity Method Investment, Ownership Percentage Unconsolidated Real Estate Joint Ventures Debt Unconsolidated Real Estate Joint Venture Debt [Abstract] Unconsolidated Real Estate Joint Venture Debt [Abstract] Weighted-Average Interest Rate at End of Period Long-term Debt Long-term Debt, Percentage Bearing Variable Interest, Remaining Commitments Long-term Debt, Percentage Bearing Variable Interest, Remaining Commitments Long-term Debt, Percentage Bearing Variable Interest, Remaining Commitments Long-term Debt, Percentage Bearing Fixed Interest, Remaining Commitments Long-term Debt, Percentage Bearing Fixed Interest, Remaining Commitments Long-term Debt, Percentage Bearing Fixed Interest, Remaining Commitments Long-term Debt, Remaining Commitments Long-term debt, remaining commitments Long-term debt, remaining commitments Derivative Instruments and Hedging Activities Disclosure [Abstract] Outstanding interest rate hedge agreements designated as cash flow hedges of interest rate risk Schedule of Derivative Instruments [Table Text Block] Lessee, Lease, Description [Table] Lessee, Lease, Description [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] Ground and Operating Leases Ground and Operating Leases [Member] Ground and Operating Leases [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Ground and Operating Lease Obligation Due Ground and Operating Lease Obligation Due Represents the aggregate amount of ground and operating lease obligation due. Operating Lease Liability Operating Lease, Liability Operating lease right-of-use asset Operating Lease, Right-of-Use Asset Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term Operating lease discount rate Operating Lease, Weighted Average Discount Rate, Percent Number of Properties Subject to Ground Leases Number of Properties Subject to Ground Leases Net book value for the exclusion of one ground lease related to one operating property Ground Lease Related to Operating Property, Net Book Value Represents the net book value of ground leases related to operating property. Remaining lease term for ground lease obligation Ground Lease Obligation Remaining Lease Term Represents the term of ground lease obligation. Operating lease costs - cash rents Operating Lease, Payments Operating Lease Liabilities, Payments Due Operating Lease Liabilities, Payments Due [Abstract] 2019 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total future payments under our operating leases for which we are a lessee Lessee, Operating Lease, Liability, Payments, Due Effect of discounting Lessee, Operating Lease, Liability, Undiscounted Excess Amount Leasee operating costs Lease, Cost [Abstract] Gross operating lease costs Gross Operating Lease Costs Gross Operating Lease Costs Capitalized lease costs Capitalized Lease Costs Capitalized Lease Costs Expenses for operating leases in which we are the lessee Lease, Cost Investment Income [Table] Investment Income [Table] Investment [Axis] Investment [Axis] Investment [Domain] Investment [Domain] Investments in publicly traded companies Investments in publicly traded companies [Member] Investments in publicly traded companies [Member] Investments in privately held entities that report NAV Limited partnerships [Member] Limited partnerships [Member] Investments in privately held entities that do not report NAV Investments in privately held entities that do not report NAV [Member] Investments in privately held entities that do not report NAV [Member] Total investments at fair value, held at period end Total investments at fair value, held at period end [Member] Total investments at fair value, held at period end [Member] Investment disposed and recognized during the period Investment disposed and recognized during the period [Member] Investment disposed and recognized during the period [Member] Investment disposed and previously recognized Investment disposed and previously recognized [Member] Investment disposed and previously recognized [Member] Total investment disposition during the period Total investment disposition during the period [Member] Total investment disposition during the period [Member] Net Investment Income Net Investment Income [Line Items] Investment income, unrealized gains (losses) Equity Securities, FV-NI, Unrealized Gain (Loss) Investment income, realized gains (losses) Equity Securities, FV-NI, Realized Gain (Loss) Investment income Stockholders' Equity Note [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] 7.00% Series D Cumulative Convertible Preferred Stock Series D Preferred Stock [Member] Issuances of common stock Class of Stock [Line Items] Preferred stock Class of Stock Disclosures [Abstract] Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Number of shares repurchased/redeemed Stock Redeemed or Called During Period, Shares Aggregate price on repurchase of Series D preferred stock Treasury Stock, Value, Acquired, Cost Method Aggregate price on repurchase of Series D preferred stock, per share Treasury Stock Acquired, Average Cost Per Share Preferred stock redemption charge Write-off of stock issuance costs Write off of Stock Issuance Costs Write off of Stock Issuance Costs Payment of quarterly dividends in arrears at an annual rate (in dollars per share) Preferred Stock, Per Share Amounts of Preferred Dividends in Arrears Percentage of the closing sale price per share of the entity's common stock that the then-applicable conversion price must exceed in order for the shares to be automatically converted Preferred Stock Conversion, Common Stock Closing, Sale Price as Percentage of Conversion Price Represents the percentage of the closing sale price of the entity's common stock for at least 20 days within 30 consecutive trading days that the closing sale price of the entity's common stock must exceed the then-applicable conversion price so as to trigger the automatic conversion. Minimum number of trading days within 30 consecutive trading days during which the closing sale price per share of entity's common stock equals or exceeds the then-applicable conversion price for the shares to be automatically converted Preferred Stock Conversion, Common Stock Closing, Sale Price Number of Trading Days Minimum Represents the minimum number of trading days within a period of 30 consecutive trading days during which the closing sale price per share of the entity's common stock equals or exceeds the then-applicable conversion price so as to trigger the automatic conversion. Number of consecutive trading day period within which the closing sale price per share of entity's common stock equals or exceeds the then-applicable conversion price for at least 20 trading days for the shares to be automatically converted Preferred Stock Conversion, Number of Consecutive Trading Days Represents the number of consecutive trading day period within which the closing sale price per share of the entity's common stock equals or exceeds the then-applicable conversion price for a specified number of days to trigger the automatic conversion. Conversion rate at option of holder (in shares) Preferred Stock Conversion Rate at Option of Holder Represents the conversion rate of common stock at which the holders may at any time and from time to time convert some or all of their outstanding shares. Redemption price per share Preferred Stock, Redemption Price Per Share Conversion rate which is equivalent to an initial conversion price per share of common stock (in dollars per share) Preferred Stock Conversion Rate Per Share at Option of Holder Represents the conversion rate which is equivalent to an initial conversion price per share of common stock. Conversion rate dividend adjustment per quarter (in dollars per share) Preferred Stock Conversion Rate, Dividend Adjustment Per Share Per Quarter Represents the conversion rate of preferred stock subject to certain dividend adjustments per share per quarter. Conversion rate (in shares) Preferred Stock Conversion Rate Represents the conversion rate at which preferred stock can be converted into common stock. Conversion rate (in dollars per share) Preferred Stock Conversion Rate Per Share Represents the conversion price at which preferred stock can be converted into common stock. Dividends declared on common stock Dividends, Common Stock, Cash Dividends declared on common stock (USD per share) Common Stock, Dividends, Per Share, Declared Dividends declared on preferred stock Dividends, Preferred Stock, Cash Dividends declared on preferred stock (USD per share) Preferred Stock, Dividends Per Share, Declared Shares of common stock authorized Common Stock, Shares Authorized Shares of common stock issued and outstanding Common Stock, Shares, Issued Shares of preferred stock authorized Preferred Stock, Shares Authorized Shares of preferred stock issued and outstanding Preferred Stock, Shares Issued Number of "excess stock" authorized (in shares) Preferred Stock Shares Additional Shares Authorized Represents the maximum number of an additional series of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter. Number of excess stock authorized issued and outstanding (in shares) Preferred Stock Shares Additional Shares Authorized Issued and Outstanding Represents the number of an additional series of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued and outstanding. Statement of Comprehensive Income [Abstract] Net income Other comprehensive income: Other Comprehensive Income (Loss), before Tax [Abstract] Unrealized (losses) gains on interest rate hedge agreements: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Unrealized interest rate hedge (losses) gains arising during the period Unrealized (losses) gains on interest rate hedge agreements, net Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Unrealized gains (losses) on foreign currency translation: Unrealized gains (losses) on foreign currency translation [Abstract] Unrealized gains (losses) on foreign currency translation [Abstract] Unrealized gains (losses) on foreign currency translation, net Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Total other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to Alexandria Real Estate Equities, Inc.’s stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Unsecured senior notes payable [Abstract] Unsecured senior notes payable [Abstract] 3.80%, 4.00%, and 4.85% Unsecured Senior Notes Payables 3.80%, 4.00%, and 4.85% Unsecured Senior Notes Payables [Member] 3.80%, 4.00%, and 4.85% Unsecured Senior Notes Payables [Member] Re-opening of 4.00% Unsecured Senior Note Payable Re-opening of 4.00% Unsecured Senior Note Payable [Member] Re-opening of 4.00% Unsecured Senior Note Payable [Member] Proceeds from issuance of unsecured senior notes payable Proceeds from Issuance of Senior Long-term Debt Yield to maturity rate (as a percent) Debt Securities, Held-to-maturity, Maturity, Rolling after Five Through Ten Years, Weighted Average Yield Statement of Stockholders' Equity [Abstract] Preferred Stock Preferred Stock [Member] Common Stock Common Stock [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Noncontrolling Interests Noncontrolling Interest [Member] Redeemable Noncontrolling Interests Redeemable Noncontrolling Interests [Member] This element represents that portion of equity (net assets) in a subsidiary attributable to redeemable noncontrolling interests. Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance (shares) Common Stock, Shares, Outstanding Beginning balance Net Income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Nonredeemable Noncontrolling Interest Other Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Nonredeemable Noncontrolling Interest Reclassification of cumulative net unrealized gains on non-real estate investments Reclassification Of Cumulative Net Unrealized Gains On Non-Real Estate Investments Reclassification Of Cumulative Net Unrealized Gains On Non-Real Estate Investments Distributions to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Issuances of common stock (in shares) Stock Issued During Period, Shares, New Issues Issuance of common stock Stock Issued During Period, Value, New Issues Issuances pursuant to stock plan (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Issuances pursuant to stock plan Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Taxes paid related to net settlement of equity awards (in shares) Shares Paid for Tax Withholding for Share Based Compensation Taxes paid related to net settlement of equity awards Adjustments Related to Tax Withholding for Share-based Compensation Repurchases of 7.00% Series D preferred stock Stock Redeemed or Called During Period, Value Dividends declared on common stock Dividends declared on preferred stock Cumulative effect of adjustment upon adoption of new ASU on lease accounting on January 1, 2019 New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets Distributions in excess of earnings Adjustments to Additional Paid in Capital, Dividends in Excess of Retained Earnings Ending balance (shares) Ending balance Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Beginning balance Net Income Temporary Equity, Net Income Redemption of noncontrolling interest Temporary equity, redemption of noncontrolling interest Temporary equity, redemption of noncontrolling interest Distributions to noncontrolling interests Temporary Equity, Decrease from Distributions to Noncontrolling Interest Temporary Equity, Decrease from Distributions to Noncontrolling Interest Contribution from noncontrolling interests Temporary equity, contribution from noncontrolling interests Temporary equity, contribution from noncontrolling interests Ending balance Secured and unsecured senior debt Debt Disclosure [Text Block] Lessor, Lease, Description [Table] Lessor, Lease, Description [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 - Revenue from Contract with Customers Accounting Standards Update 2014-09 [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] North America North America [Member] Land parcels subject to lease agreement that contains a purchase option Land parcels subject to lease agreement that contains a purchase option [Member] Land parcels subject to lease agreement that contains a purchase option [Member] Lessor, Lease, Description [Line Items] Lessor, Lease, Description [Line Items] Number of Real Estate Properties Number of Real Estate Properties Operating Lease Lessor, Operating Lease, Description [Abstract] Land parcel subject to lease agreement that contains a purchase option Land parcel subject to lease agreement that contains a purchase option Land parcel subject to lease agreement that contains a purchase option Rent Commence Date Rent Commence Date Rent Commence Date Remaining lease term Lessor, Operating Lease, Remaining Lease Term Lessor, Operating Lease, Remaining Lease Term Lessee Option to Purchase Underlying Asset Lessor, Operating Lease, Lessee Option to Purchase Underlying Asset Operating Leases, Future Minimum Payments Receivable Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract] 2019 Lessor, Operating Lease, Payments to be Received, Next Twelve Months 2020 Lessor, Operating Lease, Payments to be Received, Two Years 2021 Lessor, Operating Lease, Payments to be Received, Three Years 2022 Lessor, Operating Lease, Payments to be Received, Four Years 2023 Lessor, Operating Lease, Payments to be Received, Five Years Thereafter Lessor, Operating Lease, Payments to be Received, Thereafter Total Lessor, Operating Lease, Payments to be Received Direct Financing Lease Lessor, Direct Financing Lease, Description [Abstract] Remaining lease term Lessor, Finance Lease, Remaining Lease Term Lessor, Finance Lease, Remaining Lease Term Lessee Option to Purchase Underlying Asset Lessor, Direct Financing Lease, Lessee Option to Purchase Underlying Asset Direct Financing Lease, Net Investment in Leases Direct Financing Lease, Net Investment in Leases [Abstract] Gross investment in direct financing lease Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received Less: unearned income Direct Financing Lease, Unearned Income Direct Financing Lease, Unearned Income Net investment in direct financing lease Direct Financing Lease, Net Investment in Lease Direct Financing Leases, Future Minimum Payments Receivable Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] 2019 Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Next Twelve Months 2020 Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years 2021 Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years 2022 Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years 2023 Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years Thereafter Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter Income from rentals Income from rentals [Abstract] Income from rentals [Abstract] Operating lease income Operating Lease, Lease Income Direct financing lease income Direct Financing Lease, Lease Income Revenues subject to the new lease accounting standard Lease Income Revenue subject to the revenue recognition ASU Revenue Subject To The ASU On Recognition Of Revenue Arising From Contracts With Customers Revenue subject to the ASU on recognition of revenue arising from contracts with customers Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] 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] Book Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Summary of investments in privately held entities that report NAV, secured notes payable, unsecured senior line of credit, and unsecured term loans Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Investments in privately held entities that report NAV Equity Securities, FV-NI Secured notes payable Notes Payable, Fair Value Disclosure Unsecured senior notes payable Senior Notes Fair Value Disclosure Including the current and noncurrent portions, fair value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders. Unsecured senior line of credit Lines of Credit, Fair Value Disclosure Unsecured senior bank term loans Unsecured Bank Term Loans Fair Value Disclosure The fair value of unsecured senior bank term loans as of balance sheet date. Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Acquired below-market ground leases Finite-Lived Intangible Asset, Off-market Lease, Favorable, Gross Acquired in-place leases Finite-Lived Intangible Asset, Acquired-in-Place Leases Deferred compensation plan Deferred Compensation Plan Assets Deferred financing costs – $2.2 billion unsecured senior line of credit Debt Issuance Costs, Net Deposits Deposits Assets Furniture, fixtures, and equipment Property, Plant and Equipment, Net Interest rate hedge assets Interest Rate Derivative Assets, at Fair Value Net investment in direct financing lease Capital Leases, Net Investment in Direct Financing Leases Notes receivable Financing Receivable, Net Other assets Other Assets, Miscellaneous Prepaid expenses Prepaid Expense Property, plant, and equipment Real Estate - Corporate Operations Real Estate - Corporate Operations Total Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures Disclosure Equity Method Investments and Joint Ventures Disclosure [Text Block] Consolidated and unconsolidated real estate joint venture properties Consolidated And Unconsolidated Real Estate Joint Venture Properties [Table Text Block] Consolidated And Unconsolidated Real Estate Joint Venture Properties [Table Text Block] Consolidated VIE's balance sheet information Schedule of Variable Interest Entities [Table Text Block] Investment in unconsolidated real estate joint ventures Equity Method Investments [Table Text Block] Summary of unconsolidated real estate joint ventures loans Summary of secured construction loans [Table Text Block] Summary of secured construction loans [Table Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Revenues subject to other accounting guidance Revenues subject to other accounting guidance [Member] Revenues subject to other accounting guidance [Member] Rental revenues Rental revenues [Member] Rental revenues [Member] Tenant recoveries Tenant recoveries [Member] Tenant recoveries [Member] Canada CANADA China CHINA Land improvements Land Improvements [Member] Buildings and building improvements Building and Building Improvements [Member] Property, plant and equipment depreciated on a straight-line basis using an estimated life Property, Plant and Equipment [Line Items] Estimated useful life Property, Plant and Equipment, Useful Life Maximum expected period of sale of property (in years) Maximum Expected Period of Sale of Property Represents the maximum period within which sale of property is expected to be completed. Cost method investment ownership percentage Cost Method Investment Ownership Percentage The percentage of ownership of common stock, less than ten percent in the investee accounted for under the cost method of accounting. Percentage of total revenues Percentage of total revenues Percentage of total revenues Write-off of lease origination costs that were capitalized in connection with leases executed prior to 1/1/19 Sales-type Lease, Initial Direct Cost Expense, Commencement Minimum percentage of taxable income to be distributed Minimum Percentage of Taxable Income to be Distributed Represents the percentage of annual taxable income which must be distributed to stockholders in order to comply with requirements of the federal tax law for treatment as a real estate investment trust. Percent of Taxable Income, Generally Distributed as Dividend Percent of Taxable Income, Generally Distributed as Dividend The entity generally distributes this percentage or more of its taxable income. Net investment in direct financing lease Income from rentals Revenues [Abstract] Revenues subject to the new lease accounting standard Investments in real estate Real Estate Investments, Net [Abstract] Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Asia Asia [Member] Real Estate Properties Real Estate Properties [Line Items] Land (related to rental properties) Land Buildings and building improvements Investment Building and Building Improvements Other improvements Improvements Others Carrying amount as of the balance sheet date of improvements not otherwise specified in the existing taxonomy. Rental properties Rental Properties Development and redevelopment projects (under construction, marketing, or pre-construction) Development in Process Future development projects Land Available for Development Gross investments in real estate Real Estate Investment Property, at Cost Less: accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Investments in real estate Lessor Lessor Disclosure [Abstract] Operating Lease - Schedule of Future Minimum Lease Receivable Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block] Net investment in direct financing lease Direct Financing Lease, Lease Income [Table Text Block] Direct Financing Leases - Schedule of Future Minimum Payment Receivable Sales-type and Direct Financing Leases, Lease Receivable, Maturity [Table Text Block] Income from rentals Income from rentals [Table Text Block] [Table Text Block] for Income from rentals [Table] Lessee Lessee Disclosure [Abstract] Operating Lease - Schedule of Future Minimum Lease Payable Lessee, Operating Lease, Liability, Maturity [Table Text Block] Lessee Operating Costs Lease, Cost [Table Text Block] ATM Common Stock Offering Program Summary, Established August 2018 At-the-Market Common Stock Offering Program Summary, Established August 2018 [Table Text Block] At-the-Market Common Stock Offering Program Summary, Established August 2018 [Table Text Block] Accumulated other comprehensive loss attributable to Alexandria Real Estate Equities, Inc. Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Alexandria Real Estate Equities, Inc. (Issuer) Parent Company [Member] Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary) Guarantor Subsidiaries [Member] Combined Non- Guarantor Subsidiaries Non-Guarantor Subsidiaries [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Eliminations Consolidation, Eliminations [Member] Condensed Income Statements Condensed Income Statements, Captions [Line Items] Equity in earnings of affiliates Income (Loss) from Subsidiaries, before Tax Cash, cash equivalents, and restricted cash Cash and Cash Equivalents Disclosure [Text Block] Interest rate hedge agreements Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Investments [Table] Schedule of Investments [Table] Entities with observable price change Entities with observable price change [Member] Entities with observable price change [Member] Entities without observable price changes Entities without observable price changes [Member] Entities without observable price changes [Member] Schedule of Investments Schedule of Investments [Line Items] Investments in privately held entities that do not report NAV, cumulative upward price adjustment Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount Investments in privately held entities that do not report NAV, cumulative downward price adjustment Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Cumulative Amount Annual adjustments recognized on investments in privately held entities that do not report NAV Annual adjustments recognized on investments in privately held entities that do not report NAV Annual adjustments recognized on investments in privately held entities that do not report NAV Investments in privately held entities that do not report NAV, annual upward price adjustment Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Investments in privately held entities that do not report NAV, annual downward price adjustment Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount Investment commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Limited partnership maximum expiration terms Limited Partnership Maximum Expiration Terms Limited Partnership Maximum Expiration Terms Weighted-average remaining liquidation term (in years) Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period Limited partnership liquidation, expected initial term (in years) Limited Partnership Liquidation, Expected Initial Term (In Years) Limited Partnership Liquidation, Expected Initial Term (In Years) Summary of Investment [Abstract] Summary of Investment [Abstract] Summary of Investment [Abstract] Investment at fair value, cost Equity Securities, FV-NI, Cost Cumulative unrealized gains (losses) on investments Cumulative Effect of New Accounting Principle in Period of Adoption Investments at fair value, book value Investments in privately held entities that do not report fair value, book value Equity Securities without Readily Determinable Fair Value, Amount Total investments Earnings Per Share [Abstract] Forward Contract Indexed to Issuer's Equity, Type [Axis] Forward Contract Indexed to Issuer's Equity, Type [Axis] Forward Contract Indexed to Issuer's Equity, Type [Domain] Forward Contract Indexed to Issuer's Equity, Type [Domain] January 2018 forward equity sales agreement Forward contract 2 [Member] Forward contract 2 [Member] Shares of Common Stock Authorized [Axis] Shares of Common Stock Authorized [Axis] Shares of common stock authorized Shares of Common Stock Authorized [Domain] Shares of Common Stock Authorized [Domain] [Domain] for Shares of common stock authorized Total Shares Total Shares [Member] Total Shares [Member] Series D Convertible Preferred Stock Cumulative Preferred Stock [Member] Class of Stock Average issue price per share Sale of Stock, Price Per Share Preferred stock, dividend rate (as a percent) Preferred Stock, Dividend Rate, Percentage Earnings Per Share Reconciliation Earnings Per Share Reconciliation [Abstract] Net income (loss) Net income attributable to noncontrolling interests Dividends on preferred stock Net income attributable to unvested restricted stock awards Numerator for basic and diluted EPS – net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders Net Income (Loss) Available to Common Stockholders, Diluted Denominator for basic EPS – weighted-average shares of common stock outstanding Weighted Average Number of Shares Outstanding, Basic Dilutive effect of forward equity sales agreements Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements Denominator for diluted EPS – weighted-average shares of common stock outstanding Weighted Average Number of Shares Outstanding, Diluted Earnings per share attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted: Earnings Per Share, Basic [Abstract] Noncontrolling Interest [Abstract] Noncontrolling interests Noncontrolling Interest Disclosure [Text Block] Assets held for sale - area of real estate Disposal Group Including Assets Held for Sale, Not Qualifying as Discontinued Operations, Area of Real Estate Disposal Group Including Assets Held for Sale, Not Qualifying as Discontinued Operations, Area of Real Estate Net assets held for sale [Abstract] Real Estate Held for Development and Sale [Abstract] Total assets Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Assets Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Assets Total liabilities Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Liabilities Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Liabilities Total accumulated other comprehensive income Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Accumulated Other Comprehensive Income (Loss) Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Accumulated Other Comprehensive Income (Loss) Net assets classified as held for sale Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Net Assets Disposal Group, Including Assets Held for Sale Not Qualifying as Discontinued Operations, Net Assets Condensed consolidating balance sheet Condensed Balance Sheet [Table Text Block] Condensed consolidating statements of income Condensed Income Statement [Table Text Block] Condensed consolidating statement comprehensive income Condensed Statement of Comprehensive Income [Table Text Block] Condensed consolidating statement cash flows Condensed Cash Flow Statement [Table Text Block] 10260 Campus Point Drive and 4161 Campus Point Court 10260 Campus Point Drive and 4161 Campus Point Court [Member] 10260 Campus Point Drive and 4161 Campus Point Court [Member] Installment Payment [Axis] Installment Payment [Axis] Installment Payment [Axis] Installment Payment [Domain] Installment Payment [Domain] [Domain] for Installment Payment [Axis] First Installment Payment First Installment Payment [Member] First Installment Payment [Member] Final Installment Payment Second Installment Payment [Member] Second Installment Payment Property Type [Axis] Property Type [Axis] Represents whether a property is currently operating or under going construction (development or redevelopment). Property Type [Domain] Property Type [Domain] [Domain] for Represents whether a property is currently operating or under going construction (development or redevelopment). Future development Future development projects [Member] Future development projects [Member] Operating with future development/redevelopment Operating with future development and redevelopment [Member] Operating with future development and redevelopment [Member] Operating property Operating properties [Member] Operating properties [Member] Greater Boston Greater Boston [Member] Greater Boston [Member] San Francisco San Francisco [Member] San Francisco [Member] San Diego San Diego [Member] San Diego [Member] Other markets Other markets [Member] Other markets [Member] Number of Real Estate Properties Acquired Number Of Real Estate Properties Acquired Number of real estate properties acquired Purchase price Payments to Acquire Real Estate Reconciliation of the numerators and denominators of the basic and diluted earnings per share computations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Other Assets Schedule of Other Assets [Table Text Block] 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] Equity in earnings of unconsolidated real estate joint ventures Distributions of earnings from unconsolidated real estate joint ventures Proceeds from Equity Method Investment, Distribution Amortization of loan fees Amortization of Debt Issuance Costs Amortization of debt discounts (premiums) Amortization of Debt Discount (Premium) Amortization of acquired below-market leases Amortization of above and below Market Leases Deferred rent Straight Line Rent Stock compensation expense Share-based Compensation Investment income Gain (Loss) on Investments Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Tenant receivables Increase (Decrease) in Leasing Receivables Deferred leasing costs Increase (Decrease) in Deferred Leasing Fees Other assets Increase (Decrease) in Other Operating Assets Accounts payable, accrued expenses, and tenant security deposits Increase (Decrease) in Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to real estate Payments to Develop Real Estate Assets Purchases of real estate Returns of deposits/(deposits) for investing activities Payments for (Proceeds from) Deposits on Real Estate Acquisitions Acquisition of interest in unconsolidated joint venture Acquisition Of Interest In Unconsolidated Joint Venture Acquisition of interest in unconsolidated joint venture Investments in unconsolidated real estate joint ventures Payments to Acquire Equity Method Investments Additions to investments Payments to Acquire Investments Sales of investments Proceeds from Sale, Maturity and Collection of Investments Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings from secured notes payable Proceeds from Issuance of Secured Debt Repayments of borrowings from secured notes payable Repayments of Secured Debt Borrowings from unsecured senior line of credit Proceeds from Long-term Lines of Credit Repayments of borrowings from unsecured senior line of credit Repayments of Long-term Lines of Credit Payment of loan fees Payments of Financing Costs Taxes paid related to net settlement of equity awards Payments Related to Tax Withholding for Share-based Compensation Repurchase of Series D preferred stock Payments for Repurchase of Convertible Preferred Stock Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Dividends on common stock Payments of Ordinary Dividends, Common Stock Dividends on preferred stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Contributions from and sales of noncontrolling interests Proceeds from Noncontrolling Interests Distributions to noncontrolling interests Payments to Noncontrolling Interests Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of foreign exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents, and restricted cash, beginning of period Cash, cash equivalents, and restricted cash, end of period Supplemental Disclosures and Non-Cash Investing and Financing Activities: Supplemental Cash Flow Information [Abstract] Cash paid during the period for interest, net of interest capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities Change in accrued construction Increase (Decrease) in Construction Payables Accrued construction for current period additions to real estate Capital Expenditures Incurred but Not yet Paid Assumption of secured notes payable in connection with purchase of properties Notes Assumed Right-of-use asset Noncash, right-of-use asset Noncash, right-of-use asset Lease liability Noncash, lease liability Noncash, lease liability 225 Binney Street 225 Binney Street [Member] 225 Binney Street [Member] 409/499 Illinois Street 409/499 Illinois Street [Member] 409/499 Illinois Street [Member] 1500 Owens Street 1500 Owens Street [Member] 1500 Owens Street [Member] Campus Pointe by Alexandria 10290, 10300 Campus Point Drive and 4110 Campus Point Court [Member] 10290, 10300 Campus Point Drive and 4110 Campus Point Court [Member] 9625 Towne Centre Drive 9625 Towne Centre Drive [Member] 9625 Towne Centre Drive [Member] Accounts payable and accrued expenses Accounts Payable and Other Accrued Liabilities Accrued construction Accrued Construction Accrued Construction Acquired below market leases Below Market Lease, Net Conditional Asset Retirement Obligation Asset Retirement Obligation Deferred Rent Liability Deferred Rent Liability Represents the amount of deferred rent liability as of the balance sheet date. Interest rate hedge liabilities Interest Rate Derivative Liabilities, at Fair Value Unearned Rent and Tenant Security Deposits Prepaid Rent and Tenant Security Deposits Carrying value as of the balance sheet date of obligations pertaining to prepaid rent and tenant security deposits. Other Accounts Payable and Accrued Liabilities Other Accounts Payable and Accrued Liabilities Accounts Payable and Accrued Liabilities Interest expense incurred Interest Costs Incurred [Abstract] Gross interest Interest Costs Incurred Capitalized interest Interest Costs Capitalized Interest expense Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair value measured on recurring basis Fair Value, Measurements, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy Transfers in Fair Value Hierarchy Transfers In Fair Value Hierarchy Transfers in Fair Value Hierarchy Description Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract] Assets: Assets, Fair Value Disclosure [Abstract] Investments in publicly traded companies Liabilities: Liabilities, Fair Value Disclosure [Abstract] Summary of investments in real estate Schedule of Real Estate Properties [Table Text Block] Real estate assets acquisitions Real estate assets acquisitions [Table Text Block] Real estate assets acquisitions [Table Text Block] Revenues subject to new revenue recognition and lease ASUs Revenues subject to new accounting standards [Table Text Block] Revenues subject to new accounting standards [Table Text Block] Reconciliation of prior period presentation of income statement line items Reconciliation of prior period presentation of income statement line items [Table Text Block] Reconciliation of prior period presentation of income statement line items [Table Text Block] Reclassifications Reclassification, Policy [Policy Text Block] Consolidation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Use of estimates Use of Estimates, Policy [Policy Text Block] Investments in real estate and properties classified as held for sale Rental Properties Net Land Held for Future Development Construction in Progress and Discontinued Operations [Policy Text Block] Disclosure of accounting policy for assets acquired and noncontrolling interest in an acquired entity at their fair value as of the acquisition date, values allocated to land improvements, values of acquired above and below market lease amortization, construction in progress and discontinued operations. Impairment of long-lived assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] International operations Foreign Currency Transactions and Translations Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Revenues Revenue Recognition, Leases [Policy Text Block] Leases Summary Leases Summary [Policy Text Block] Leases Summary [Policy Text Block] Leases, lessor accounting Lessor, Leases [Policy Text Block] Leases, lessee accounting Lessee, Leases [Policy Text Block] Recognition of revenue arising from contracts with customers Revenue from Contract with Customer [Policy Text Block] Monitoring tenant credit quality Tenant Credit Quality [Policy Text Block] Tenant Credit Quality [Policy Text Block] Income taxes Income Tax, Policy [Policy Text Block] Employee share-based payments Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Hedge accounting Derivatives, Methods of Accounting, Hedge Effectiveness [Policy Text Block] Joint venture distribution Joint Venture Distribution [Policy Text Block] Joint Venture Distribution [Policy Text Block] Restricted cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Recent accounting pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements Condensed Cash Flow Statements, Captions [Line Items] Net income Equity in earnings of unconsolidated real estate JVs Equity in earnings of affiliates Investments in subsidiaries Payments to Acquire Interest in Subsidiaries and Affiliates Acquisition of interest in unconsolidated joint venture Borrowings from unsecured senior line of credit Transfers to/from parent company Transfers Due to (due from) Parent Entity Represents the transfers due to or due from it's parent entity. Non-Cash Investing Activities Noncash Investing and Financing Items [Abstract] Noncash, right-of-use asset Noncash, lease liability The percentage of effectiveness of interest rate swap agreements Percentage of Effective Portion of Interest Rate Hedge Agreements The percentage of effective notional amount of interest rate hedge agreements. Interest rate swap hedge ineffectiveness recognized in earnings Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Cash flow hedge loss to be reclassified within twelve month Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Collateral obligation requirements Derivative, Collateral, Obligation to Return Cash Assets Needed for Immediate Settlement, Aggregate Fair Value Assets Needed for Immediate Settlement, Aggregate Fair Value Noncontrolling Interest [Table] Noncontrolling Interest [Table] Noncontrolling interests Noncontrolling Interest [Line Items] Number of real estate properties subject to ownership from noncontrolling interest Number Of Real Estate Properties Subject To Ownership From Noncontrolling Interest Number of real estate properties subject to ownership from noncontrolling interest Payments to Noncontrolling Interests Investments in real estate Real Estate Disclosure [Text Block] Stockholders' equity Stockholders' Equity Note Disclosure [Text Block] Investments Cost and Equity Method Investments Disclosure [Text Block] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements Condensed Balance Sheet Statements, Captions [Line Items] Investments in and advances to affiliates Deferred rent Investments in and advances to affiliates Investments in and Advances to Affiliates, Balance, Principal Amount Liabilities, Noncontrolling Interests, and Equity Alexandria Real Estate Equities, Inc.’s stockholders’ equity Secured notes payable Unsecured senior notes payable Senior Notes [Member] Long-term Debt Long-term Debt, Percentage Bearing Fixed Interest, Amount, Net Long-term Debt, Percentage Bearing Fixed Interest, Amount, Net Long-term Debt, Percentage Bearing Variable Interest, Amount, Net Long-term Debt, Percentage Bearing Variable Interest, Amount, Net Long-term Debt, Percentage Bearing Variable Interest, Amount, Net Percentage of Total Debt Instrument, Percentage Of Outstanding Balance Represents the outstanding balance of debt as a percentage of aggregate debt outstanding. Weighted Average Remaining Terms (in years) Debt Instrument, Weighted Average Remaining Period Represents the weighted average remaining term of the debt instrument in years. Percentage of fixed rate/hedged total debt Fixed Interest Rate Debt as Percentage of Total Outstanding Balance Represents the outstanding balance of fixed interest rate debt as a percentage of aggregate debt outstanding. Percentage of unhedged floating rate total debt Variable Interest Rate Debt as Percentage of Total Outstanding Balance Represents the outstanding balance of variable interest rate debt as a percentage of aggregate debt outstanding. Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Earnings per share Earnings Per Share [Text Block] Consolidated VIE's balance sheet information [Abstract] Consolidated VIE's balance sheet information [Abstract] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Variable Interest Entity Variable Interest Entity [Line Items] Total assets Other Liabilities Other Liabilities Total liabilities Alexandria Real Estate Equities, Inc.'s share of equity Noncontrolling interests' share of equity Total liabilities, noncontrolling interests, and equity Derivative [Table] Derivative [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] 1.89% Interest rate swap, effective March 29, 2019 Interest Rate Hedge 2 [Member] Interest Rate Hedge 2 [Member] 2.84% Interest rate swap, effective March 29, 2019 Interest Rate Hedge 3 [Member] Interest Rate Hedge 3 [Member] Interest rate hedge agreements Derivative [Line Items] Number of Contracts Number of Interest Rate Derivatives Held Interest Pay Rate (as a percent) Derivative, Average Swaption Interest Rate Fair Values Interest Rate Cash Flow Hedge Derivative at Fair Value, Net Notional Amount in Effect as of 3/31/19 Effective Portion Of Interest Rate Cash Flow Hedge At Fiscal Year End Effective Portion of Interest Rate Cash Flow Hedge at Fiscal Year End Notional Amount in Effect as of 12/31/19 Effective Portion Of Interest Rate Cash Flow Hedge In The Next Twelve Months Effective Portion of Interest Rate Cash Flow Hedge in the Next Twelve Months Other assets Other Assets Disclosure [Text Block] Assets classified as held for sale Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Secured Notes Payable Maturing on 4/1/20 Secured Debt Other Maturing 1 April 2020 [Member] Secured Debt Other Maturing 1 April 2020 [Member] Secured Notes Payable Maturing on 1/28/20 Secured Debt Maturing January 28, 2019 [Member] Secured Debt Maturing January 28, 2019 [Member] Repayments of Secured Debt Loss on early extinguishment of debt ATM common stock offering program [Abstract] ATM common stock offering program [Abstract] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] ATM Common Stock Offering Program, Established August 2018 ATM Common Stock Offering Program, Established August 2018 [Member] ATM Common Stock Offering Program, Established August 2018 [Member] Gross proceeds from issuance of common stock Proceeds from Shares Sold Gross Represents the aggregate proceeds received from sale of common stock. Common stock value available for future issuance Common Stock Value Available for Future Issuance Represents the aggregate value of shares available for future issuance by the entity. Schedule of fair value of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of the book and fair values of our marketable securities, interest rate swap agreements, secured notes payable, unsecured senior notes payable, unsecured senior line of credit, and unsecured senior bank term loan Fair Value, by Balance Sheet Grouping [Table Text Block] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income Condensed Statement of Income Captions [Line Items] Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax [Abstract]