Notes Payable [Abstract] Summary Of Indebtedness Schedule of Long-term Debt Instruments [Table Text Block] Scheduled Repayments On Outstanding Debt Schedule of Maturities of Long-term Debt [Table 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 from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Distributions of income from joint ventures Proceeds from Equity Method Investment, Distribution Equity in income of joint ventures Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Share-based compensation Share-based Payment Arrangement, Noncash Expense Settlement of forward interest rate swaps Derivative, Cash Paid on Hedge Derivative, Cash Paid on Hedge Net change in operating accounts and other Other Operating Activities, Cash Flow Statement Net cash from operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Development and capital improvements, including land Payments to Develop Real Estate Assets Acquisition of operating properties Payments to Acquire Real Estate Proceeds from sale of land Proceeds from sale of operating properties, including land Proceeds from sale of operating properties, including land. Includes properties which are not designated as discontinued operations, and all land parcels not designated as held for sale. Increase in non-real estate assets Payments to Acquire Other Property, Plant, and Equipment Decrease (increase) in Notes Receivables Increase (Decrease) in Notes Receivables Other Payments for (Proceeds from) Other Investing Activities Net cash from investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings on unsecured credit facility and other short-term borrowings Proceeds from Lines of Credit Repayments on unsecured credit facility and other short-term borrowings Repayments of Lines of Credit Repayment of notes payable Repayments of Notes Payable Proceeds from notes payable Proceeds from Notes Payable Distributions to common shareholders and non-controlling interests Payments of Dividends Proceeds from issuance of common shares Proceeds from Issuance of Common Stock Payment of deferred financing costs Payments of Financing Costs Payments to Noncontrolling Interests Payments to Noncontrolling Interests Other Proceeds from (Payments for) Other Financing Activities Net cash from financing activities Net Cash Provided by (Used in) Financing Activities 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 year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash, end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents Total cash, cash equivalents, and restricted cash Supplemental information Supplemental Cash Flow Information [Abstract] Cash paid for interest, net of interest capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid for income taxes Income Taxes Paid Supplemental schedule of noncash investing and financing activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Distributions declared but not paid Dividends Value of shares issued under benefit plans, net of cancellations Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised Accrual associated with construction and capital expenditures Accrual associated with construction and capital expenditures Non-cash accrual associated with construction and capital expenditures and additions to retainage. Right-of-use assets obtained in exchange for the use of new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Accounting Policies [Abstract] Principles of Consolidation Consolidation, Policy [Policy Text Block] Interim Financial Reporting Interim Financial Reporting, Policy [Text Block] Describes an entity's accounting policy for interim financial reporting. Acquisitions of Real Estate Acquisitions of Real Estate [Policy Text Block] Acquisitions of Real Estate [Policy Text Block] Asset Impairment Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Cost Capitalization Property, Plant and Equipment, Policy [Policy Text Block] Derivatives Financial Instruments Derivatives, Policy [Policy Text Block] Fair Value Fair Value of Financial Instruments, Policy [Policy Text Block] Notes Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Anticipated Property Revenues [Abstract] Anticipated Property Revenues [Abstract] Lessor, Lease, Description [Table] Lessor, Lease, Description [Table] Property Revenue [Axis] Property Revenue [Axis] Property Revenue [Axis] Property Revenue [Domain] Property Revenue [Domain] [Domain] for Property Revenue [Axis] Residential Leases [Member] Residential Leases [Member] Residential Leases [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Lessor, Lease, Description [Line Items] Lessor, Lease, Description [Line Items] Lessor, Operating Lease, Payments to be Received, Next Twelve Months Lessor, Operating Lease, Payments to be Received, Next Twelve Months Lessor, Operating Lease, Payments to be Received, in Two Years Lessor, Operating Lease, Payments to be Received, Two Years Lessor, Operating Lease, Payments to be Received, in Three Years Lessor, Operating Lease, Payments to be Received, Three Years Lessor, Operating Lease, Payments to be Received, in Four Years Lessor, Operating Lease, Payments to be Received, Four Years Lessor, Operating Lease, Payments to be Received, in Five Years Lessor, Operating Lease, Payments to be Received, Five Years Lessor, Operating Lease, Payments to be Received, Thereafter Lessor, Operating Lease, Payments to be Received, Thereafter Lessor, Operating Lease, Payments to be Received, Total Lessor, Operating Lease, Payments to be Received Lessor, Operating Lease, Term of Contract Lessor, Operating Lease, Term of Contract Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Statement [Line Items] Statement [Line Items] Property revenues Real Estate [Abstract] Property revenues Operating Lease, Lease Income Property expenses Real Estate Investment Property, at Cost [Abstract] Property operating and maintenance Direct Costs of Leased and Rented Property or Equipment Real estate taxes Real Estate Tax Expense Total property expenses Costs and Expenses Non-property income Nonoperating Income (Expense) [Abstract] Fee and asset management Revenue from Contract with Customer, Excluding Assessed Tax Interest and other income Interest and Other Income Income on deferred compensation plans Income (Loss) On Deferred Compensation Plans This item represents the income (loss) on our deferred compensation plans included in earnings for the period as a result of holding marketable securities categorized as trading. Gross presentation is based on principal vs. agent accounting for revenues as the company is the principal and gains control of the assets from the deferred compensation plan before transferring the assets to the employees and the company's performance obligation is to provide the assets to the employees. Total non-property income Total Non Property Income Loss Total non-property income (loss). Includes fee and asset management income, interest and other income, net and income (loss) on deferred compensation plans. Other expenses Other Expenses [Abstract] Property management Cost of Property Repairs and Maintenance Fee and asset management Cost of Fee and Asset Management Cost of Fee and Asset Management General and administrative General and Administrative Expense Interest Interest Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Expense on deferred compensation plans Expense (Benefit) On Deferred Compensation Plans This item represents the expense (benefit) on our deferred compensation plans included in earnings for the period as a result of holding marketable securities categorized as trading. Gross presentation is based on principal vs. agent accounting for revenues as the company is the principal and gains control of the assets from the deferred compensation plan before transferring the assets to the employees and the company's performance obligation is to provide the assets to the employees. Total other expenses Total Other Expenses This element represents a sum total of property management, fee and asset management, general and administrative, interest, depreciation and amortization, amortization of deferred financing costs, and expense (benefit) on deferred compensation plans. Equity in income of joint ventures Income from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Domestic Income tax expense Current Income Tax Expense (Benefit) Less income allocated to non-controlling interests from continuing operations Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to common shareholders Net Income (Loss) Attributable to Parent Earnings per share – basic Earnings Per Share, Basic Earnings per share – diluted Earnings Per Share, Diluted Weighted average number of common shares outstanding – basic Weighted Average Number of Shares Outstanding, Basic Weighted average number of common shares outstanding – diluted Weighted Average Number of Shares Outstanding, Diluted Condensed Consolidated Statements of Comprehensive Income Statement of Comprehensive Income [Abstract] Other comprehensive income Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized (loss) gain on cash flow hedging activities Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification of net loss (gain) on cash flow hedging activities, prior service cost and net loss on post-retirement obligation Reclassification of net loss on cash flow hedging activities, prior service cost and net loss on post retirement obligation The amount after tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss), combined with the net loss (gain) previously recognized as a component of net periodic benefit costs for the period and the amount of the prior service cost or (credit) recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or plan initiation. Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to common shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Stockholders' Equity Note [Abstract] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] April 2007 Repurchase Plan [Member] April 2007 Repurchase Plan [Member] April 2007 Repurchase Plan [Member] Share Offering Program [Axis] Share Offering Program [Axis] Share Offering Program [Axis] Share Offering Program [Domain] Share Offering Program [Domain] Share Offering Program [Domain] 2017 ATM program [Member] 2017 ATM program [Member] 2017 ATM program [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Credit Facility [Member] Line of Credit [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Maximum aggregate offering price of remaining common shares available for sale Maximum aggregate offering price of remaining common shares available for sale Maximum aggregate offering price of common shares under the at-the-market share offering program available for sale. Maximum aggregate offering price of common shares Maximum aggregate offering price of common shares Maximum aggregate offering price of common shares under the at-the-market share offering program. Maximum borrowing capacity under unsecured credit facility Line of Credit Facility, Maximum Borrowing Capacity Treasury stock allowed for repurchase Stock Repurchase Program, Authorized Amount Share Repurchase Program, Remaining Authorized Repurchase Amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Number of common and preferred stock authorized to issue Shares Authorized The maximum number of common shares and nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. Common shares, authorized Common Stock, Shares Authorized Preferred shares, authorized Preferred Stock, Shares Authorized Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Stock Issued During Period, Shares, New Issues Stock Issued During Period, Shares, New Issues Share-based Payment Arrangement, Noncash Expense [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] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] 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] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Nonvested share awards outstanding at December 31, 2018, Share Awards Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted, Share Awards Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Exercised/Vested, Share Awards Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited, Share Awards Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Nonvested share awards outstanding at September 30, 2019, Share Awards Outstanding Nonvested share awards outstanding at December 31, 2018, Weighted Average Exercise/Grant Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted, Weighted Average Exercise/Grant Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Exercised/Vested, Weighted Average Exercise/Grant Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited, Weighted Average Exercise/Grant Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Nonvested share awards outstanding at September 30, 2019, Weighted Average Exercise/Grant Price Income Tax Disclosure [Abstract] Annual dividends distribution percentage to shareholders to qualify as a REIT Annual Dividend Distribution Percentage To Shareholders To Qualify As Real Estate Investment Trust As a Real Estate Investment Trust (REIT), we are required to distribute annual dividends to shareholders to qualify as a REIT equal to a minimum percentage of 90% of REIT taxable income, computed without regard to the dividends paid deduction and net capital gains. Significant temporary differences or tax credits associated with our taxable REIT subsidiaries Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability, Undistributed Earnings of Domestic Subsidiaries Uncertain tax positions or unrecognized tax benefits Unrecognized Tax Benefits Leases [Abstract] Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] Rent expense related to operating lease liabilities Operating Lease, Cost Operating Lease, Right-of-Use Asset Operating Lease, Right-of-Use Asset Operating lease liabilities Operating Lease, Liability Variable lease expense Variable Lease, Cost Cash flows from operating leases Operating Lease, Payments Weighted average remaining lease term (years) Operating Lease, Weighted Average Remaining Lease Term Weighted average discount rate - operating leases (1) Operating Lease, Weighted Average Discount Rate, Percent Fair Value Disclosures [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap [Member] Interest Rate Swap [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] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Deferred compensation plan investments (1) Deferred Compensation Plan Assets Participant Withdrawals From Deferred Compensation Plan Investments Participant Withdrawals From Deferred Compensation Plan Investments Participant withdrawals from deferred compensation plan investments Interest Rate Derivative Assets, at Fair Value Interest Rate Derivative Assets, at Fair Value Interest Rate Derivative Liabilities, at Fair Value Interest Rate Derivative Liabilities, at Fair Value Number of Operating properties Acquired Number of Operating properties Acquired Number of operating properties acquired which are now fully consolidated during the period. Two Thousand Eighteen Share Incentive Plan [Member] Two Thousand Eighteen Share Incentive Plan [Member] Two Thousand Eighteen Share Incentive Plan [Member] Award Type [Domain] Share Awards and Vesting [Member] Share Awards And Vesting [Member] Share Awards and Vesting [Member] Total common shares available Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Common shares To Full Value Award Conversion Ratio Fungible Units To Full Value Award Conversion Ratio The award conversion ratio regarding the shares from the 2002 share incentive plan transferred into the 2011 share incentive plan. Value Of Option Right Or Other Award In The Fungible Unit Conversion Value Of Option Right Or Other Award In The Fungible Unit Conversion An option, right, or other award which does not deliver the full value at date of grant and expires five years or less from the date of grant counts against the Fungible Pool Limit as this portion of a fungible pool unit Full Value award in the common share conversion ratio Full Value award in the fungible unit conversion ratio The full value award in the fungible unit to full value award conversion ratio regarding the shares from the 2002 share incentive plan transferred into the 2011 share incentive plan. Common shares which could be granted pursuant to full value awards Common Shares Which Could Be Granted Pursuant To Full Value Awards Common shares which could be granted pursuant to full value awards based on the 3.45 to 1.0 fungible unit-to-full value award conversion ratio. Vesting period, years Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Total unrecognized compensation cost which is expected to be amortized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Expected amortized period of unrecognized compensation expected to be recognized for share-based compensation plans Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Fair value of shares vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Total compensation cost for option and share awards Share Based Compensation Arrangement By Share Based Payment Award Compensation Cost For Period Equity-based compensation cost during the period with respect to the award, which was recognized in income. Total capitalized compensation cost for option and share awards Share-based Payment Arrangement, Amount Capitalized Fair Value Measurements Fair Value Disclosures [Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fixed rate notes payable Fixed Rate Notes Payable [Member] Fixed Rate Notes Payable [Member] Floating rate notes payable (1) Floating Rate Notes Payable [Member] Floating Rate Notes Payable [Member] Carrying Value Notes Payable Estimated Fair Value Notes Payable, Fair Value Disclosure Earnings Per Share [Abstract] Per Share Data Earnings Per Share [Text Block] Summary of Operating Leases Lessee, Operating Lease, Disclosure [Table Text Block] Property, Plant and Equipment [Abstract] Acquisitions [Text Block] Acquisitions, Dispositions, Assets Held For Sale and Impairment [Text Block] The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, and assets held for sale. The tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregated would be included in this disclosure. Additionally, the entire disclosure for the facts and circumstances leading to the completed or expected disposal, manner and timing of disposal, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), the segment in which the disposal group was reported, and the classification (whether sold or classified as held for sale) and carrying value of the assets and liabilities comprising the disposal group. Includes all disposal groups, including those classified as components of the entity. Subsequent Events [Abstract] Commitments and Contingencies [Abstract] Commitments and Contingencies [Abstract] Summary of Maturities of Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Camden Summit Partnership L P [Member] Camden Summit Partnership L P [Member] Camden Summit Partnership LP [Member] Camden Operating L P [Member] Camden Operating L P [Member] Camden Operating LP [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Amortization of Intangible Assets Amortization of Intangible Assets Outstanding common limited partnership units, ownership interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest General Partner of Consolidated Operating Partnerships, Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Capitalized interest Interest Costs Capitalized Capitalized real estate taxes Capitalized Real Estate Taxes The amount of real estate or property taxes that were capitalized during the period. Outstanding notes receivable SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate Weighted average interest rate on outstanding notes receivable SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Interest Rate Amortization of Below Market Lease Amortization of Below Market Lease Maturities Due In 2019 [Member] Maturities Due In 2019 [Member] Maturities Due In 2019 [Member] Maturities Due In 2020 [Member] Maturities Due In 2020 [Member] Maturities Due In 2020 [Member] Maturities due in 2021 [Member] Maturities due in 2021 [Member] Maturities due in 2021 [Member] Maturities due in 2022 [Member] Maturities due in 2022 [Member] Maturities due in 2022 [Member] Maturities due in 2023 [Member] Maturities due in 2023 [Member] Maturities due in 2023 [Member] Maturities Due Thereafter [Member] Maturities Due Thereafter [Member] Maturities Due Thereafter [Member] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] 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 Total notes payable Long-term Debt Weighted Average Interest Rate Debt, Weighted Average Interest Rate Document And Entity Information [Abstract] Document and Entity Information. Title of 12(b) Security Title of 12(b) Security Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code City Area Code City Area Code Entity Address, State or Province Entity Address, State or Province Entity Tax Identification Number Entity Tax Identification Number Entity Registrant Name Entity Registrant Name Local Phone Number Local Phone Number Entity Interactive Data Current Entity Interactive Data Current Document Quarterly Report Document Quarterly Report Document Transition Report Document Transition Report Entity Central Index Key Entity Central Index Key Trading Symbol Trading Symbol Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Entity File Number Entity File Number Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity Current Reporting Status Security Exchange Name Security Exchange Name Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, Postal Zip Code Entity Address, Postal Zip Code Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Floating rate notes payable [Member] Secured Notes Fixed Rate Debt due 2019 [Member] Secured Notes Fixed Rate Debt due 2019 [Member] Secured Notes Fixed Rate Debt due 2019 [Member] 4.78% Notes Due 2021 [Member] Four Point Seven Eight Percentage Notes Due2021 [Member] Four Point Seven Eight Percentage Notes Due2021 4.38% Conventional Mortgage Notes, due 2045 [Member] Secured Notes 4.38% Fixed Rate Note Due 2045 [Member] Secured Notes 4.38% Fixed Rate Note Due 2045 [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Commercial Banks [Member] Commercial Banks [Member] Commercial Banks. Senior Unsecured Notes [Member] Senior Unsecured Notes [Member] Senior unsecured notes. Secured Debt [Member] Secured Debt [Member] Letter Of Credit [Member] Letter of Credit [Member] Repayments of Secured Debt Repayments of Secured Debt Notes Payable Unamortized debt discounts and debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Unsecured Credit Facility, Current Borrowing Capacity Line of Credit Facility, Current Borrowing Capacity Maximum term of bid rate loans (days) Terms Of Bid Rate Loans Maximum term of bid rate loans in days related to the line of credit. Advances under the line of credit may be priced at the scheduled rates, or we may enter into bid rate loans with participating banks at rates below the scheduled rates Lesser of amount stated or the amount available under the unsecured credit facility Value not exceeding the amount available under the line of credit Advances under the line of credit may be priced at the scheduled rates, or we may enter into bid rate loans with participating banks at rates below the scheduled rates. These bid rate loans have terms of 180 days or less and may not exceed the lesser of $250 million or the remaining amount available under the line of credit. Maximum Ability to Issue Letters of Credit Under Unsecured Credit Facility Maximum Ability to Issue Letters of Credit Under Unsecured Credit Facility Maximum Ability to Issue Letters of Credit Under Unsecured Credit Facility Unsecured Debt Unsecured Debt Outstanding balance under credit facility Long-term Line of Credit Available amount under unsecured credit facility Line of Credit Facility, Remaining Borrowing Capacity Weighted average maturity of indebtedness (including unsecured line of credit) (in years) Weighted Average Maturity Of Indebtedness Including Unsecured Line Of Credit Weighted Average Maturity Of Indebtedness Including Unsecured Line Of Credit Notes payable, effective interest rate Debt Instrument, Interest Rate, Effective Percentage Secured Debt Secured Debt Derivative, Notional Amount Derivative, Notional Amount Debt Instrument, Interest Rate During Period Debt Instrument, Interest Rate During Period Proceeds from Issuance of Debt Proceeds from Issuance of Debt Debt Instrument, Maturity Date Debt Instrument, Maturity Date Debt Instrument, Face Amount Debt Instrument, Face Amount Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Discounted notes payable face amount Discounted notes payable face amount The discount percentage applied to the new notes payable face amount for the public offering of the debt. Debt Instrument, Interest Rate Before June 2026 Debt Instrument, Interest Rate Before June 2026 Debt Instrument, Interest Rate On 2029 Notes Before June 2026. Debt Instrument, Interest Rate After June 2026 Debt Instrument, Interest Rate After June 2026 Debt Instrument, Interest Rate on 2029 Notes After June 2026. Payment for Debt Extinguishment or Debt Prepayment Cost Payment for Debt Extinguishment or Debt Prepayment Cost Related Party Transactions [Abstract] Common Shares [Text Block] Stockholders' Equity Note Disclosure [Text Block] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Buildings And Improvements [Member] Building and Building Improvements [Member] Furniture, Fixtures, Equipment, And Other [Member] Furniture and Fixtures [Member] Estimated Useful Life (in years) Property, Plant and Equipment, Useful Life Intangible assets/liabilities (in-place leases and above and below market leases) Expected useful lives Of Intangible assets Related to in place leases and above and below market leases Expected useful lives of intangible assets related to in-place leases and above and below market leases. Financial Assets And Liabilities Measured At Fair Value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Of Notes Payable Fair Value Of Notes Receivable And Notes Payable Table Text Block Fair Value Of Notes Receivable And Notes Payable. Increase (Decrease) in Operating Capital [Abstract] Other assets, net Increase (Decrease) in Other Operating Assets Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Accrued real estate taxes Increase (Decrease) in Property and Other Taxes Payable Other liabilities Increase (Decrease) in Other Operating Liabilities Other Other Noncash Income (Expense) Change in operating accounts and other Increase (Decrease) in Operating Capital Notes Payable Debt Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitment and Contingencies Commitment And Contingencies [Table] Commitment and contingencies [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Partnership Interest [Member] Partnership Interest [Member] Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Leases, Future Minimum Payments, Due in Two Years Operating Leases, Future Minimum Payments, Due in Two Years Operating Leases, Future Minimum Payments, Due in Three Years Operating Leases, Future Minimum Payments, Due in Three Years Operating Leases, Future Minimum Payments, Due in Four Years Operating Leases, Future Minimum Payments, Due in Four Years Operating Leases, Future Minimum Payments, Due in Five Years Operating Leases, Future Minimum Payments, Due in Five Years Operating Leases, Future Minimum Payments, Due Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Number of consolidated projects under construction Number of consolidated projects under construction Number of consolidated projects under construction Anticipated expenditures relating to completion of construction type contracts Anticipated Expenditures Relating To Completion Of Construction Type Contracts General description of anticipated expenditures which may be required in performing under a construction-type contract at the balance sheet date. Earnest Money Deposits Earnest Money Deposits Operating Lease, Expense Operating Lease, Expense Rental expense Operating Leases, Rent Expense Minimum Rental Commitments, Remainder of 2019 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months Minimum Rental Commitments, 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two Minimum Rental Commitments, 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three Minimum Rental Commitments, 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four Minimum Rental Commitments, 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Minimum Rental Commitments, Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Less: interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Less than joint venture economic interest noted Economic Interest In Joint Ventures Economic interest in the community or land owned directly by the joint venture or partnership is less than this amount in order to qualify as a joint venture or partnership. Summary of Significant Accounting Policies and Recent Accounting Pronouncements Basis of Presentation and Significant Accounting Policies [Text Block] Calculation Of Basic And Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Investments in Joint Ventures [Abstract] Investments in Joint Ventures. Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Non-consolidated entity [Axis] nonconsolidated entity [Axis] nonconsolidated entity [Axis] nonconsolidated entity [Domain] nonconsolidated entity [Domain] [Domain] for nonconsolidated entity [Axis] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity method investment ownership percentage Equity Method Investment, Ownership Percentage Number of joint ventures accounted for under equity method investments Number of joint ventures accounted for under equity method investments Number of joint ventures accounted for under equity method investments. Maximum guaranteed amount of loans utilized for construction and development activities for joint ventures Guarantor Obligations, Maximum Exposure, Undiscounted Maximum Investments by Formed Unconsolidated Joint Venture Prior maximum Investments by Formed Unconsolidated Joint Venture Prior maximum investment by formed unconsolidated joint venture including leverage of approximately 70% of the estimated value of the underlying real estate prior to change in June 2019. Maximum Investments by Formed Unconsolidated Joint Venture Maximum Investments by Formed Unconsolidated Joint Venture Maximum investment by formed unconsolidated joint venture including leverage of approximately 50% of the estimated value of the underlying real estate after to change in June 2019. Fees earned for property and asset management, construction, development, and other services to joint ventures Fees Earned For Property And Asset Management Construction Development And Other Services To Joint Ventures Revenue earned by providing property management, construction, development, and other services to joint ventures. Statement of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component Equity Component [Domain] Common shares of beneficial interest Common Stock [Member] Additional paid-in capital Additional Paid-in Capital [Member] Distributions in excess of net income Accumulated Distributions in Excess of Net Income [Member] Treasury shares, at cost Treasury Stock [Member] Accumulated other comprehensive (loss)/income AOCI Attributable to Parent [Member] Non-controlling interests Noncontrolling Interest [Member] Cash distributions declared to equity holders per common share Common Stock, Dividends, Per Share, Declared Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net Income Net Income Attributable To Common Shareholders And Noncontrolling Interests Net income (loss) attributable to common shareholders and noncontrolling interests, excluding amounts allocated to perpetual preferred units. Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Common shares issued Net share awards Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Employee share purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Common share options exercised Stock Issued During Period, Value, Stock Options Exercised Change in classification of deferred compensation plan Change in classification of deferred compensation plan The value of share awards reclassed from additional paid in capital into temporary equity following amendment of the Non-Qualified Deferred Compensation plan permitting diversification of awards into other equity securities subject to a six month holding period and at the holders’ option. Change in classification of deferred compensation plan (See Note 11) Reclassifications of Temporary to Permanent Equity Change in redemption value of non-qualified share awards Temporary Equity, Carrying Amount, Period Increase (Decrease) Diversification of share awards within deferred compensation plan (Equity) Diversification of share awards within deferred compensation plan (Equity) Non-qualified share awards diversified into other equity securities during the period. Conversion of operating partnership units Stock Issued During Period, Value, Conversion of Units Common shares repurchased Treasury Stock, Value, Acquired, Par Value Method Cash distributions declared to equity holders Dividends, Common Stock, Cash Other Stockholders' Equity, Other Ending balance Derivatives [Abstract] Derivatives [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Text Block] Expected useful lives of depreciable property Expected Useful Lives Of Depreciable Property Text Block Expected useful lives of depreciable property including buildings and improvements, furniture, fixtures, equipment and other, and intangible assets such as in-place leases and above and below market leases. Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block] Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block] Effect Of Changes In The Operating And Other Accounts On Cash Flows From Operating Activities Cash Flow, Operating Capital [Table Text Block] Summary of Share Incentive Plans Share-based Payment Arrangement, Activity [Table Text Block] Revenues [Abstract] Scheduled Property Revenue from Leases Revenue Recognition Leases, Operating [Policy Text Block] Statement of Financial Position [Abstract] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Assets Assets [Abstract] Land Land Buildings and improvements Investment Building and Building Improvements Real estate assets, at cost, total Real estate assets, at cost, total The value of land and buildings and improvement before accumulated depreciation. Accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Net operating real estate assets Net operating real estate assets The net book value of land and buildings and improvement. Properties under development, including land Properties under development including land The current amount of expenditures for a real estate project that has not yet been completed including the carrying amount of land available for development. Investments in joint ventures Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Total real estate assets Real Estate Assets Total Total net real estate assets, including investments in joint ventures. Accounts receivable – affiliates Accounts Receivable, Related Parties Other assets, net Other Assets Cash and cash equivalents Total assets Assets Liabilities and equity Liabilities and Equity [Abstract] Liabilities Liabilities [Abstract] Unsecured notes payable Secured notes payable Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities Accrued real estate taxes Accrual for Taxes Other than Income Taxes Distributions payable Distributions payable Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding, in addition to distributions due to real estate partnerships. Other liabilities Other Liabilities Total liabilities Liabilities Commitments and contingencies (Note 13) Commitments and Contingencies Non-qualified deferred compensation share awards Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Equity Stockholders' Equity Attributable to Parent [Abstract] Common shares of beneficial interest; $0.01 par value per share; 175,000 shares authorized; 108,882 and 105,503 issued; 106,472 and 103,080 outstanding at September 30, 2019 and December 31, 2018, respectively Common Stocks Value Outstanding Value of all classes of common stock held by shareholders (excluding shares held in our deferred compensation arrangements); including treasury stock. May be all or a portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Additional paid-in capital Additional Paid in Capital, Common Stock Distributions in excess of net income attributable to common shareholders Accumulated Distributions in Excess of Net Income Treasury shares, at cost (9,640 and 9,841 common shares at September 30, 2019 and December 31, 2018, respectively) Treasury Stock, Value Accumulated other comprehensive (loss) income Accumulated Other Comprehensive Income (Loss), Net of Tax Total common equity Stockholders' Equity Attributable to Parent Non-controlling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total liabilities and equity Liabilities and Equity Equity Method Investments and Joint Ventures [Abstract] Aggregate Balance Sheet And Statement Of Income Data For Unconsolidated Joint Ventures Equity Method Investments [Table Text Block] Description of Business [Abstract] Description of Business [Abstract] Description of Business Nature of Operations [Text Block] Total assets Equity Method Investment, Summarized Financial Information, Assets Total third-party debt Equity Method Investment, Summarized Financial Information, Liabilities Total equity Equity Method Investment, Summarized Financial Information, Equity Excluding Noncontrolling Interests Total revenues Equity Method Investment, Summarized Financial Information, Revenue Net income Equity Method Investment, Summarized Financial Information, Net Income (Loss) Equity in income (1) Fair value measurements [Abstract] Fair value measurements [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Camden Rainey Street [Member] Camden Rainey Street [Member] Camden Rainey Street [Member] Camden Old Town Scottsdale [Member] Camden Old Town Scottsdale [Member] Camden Old Town Scottsdale [Member] Camden Thornton Park [Member] Camden Thornton Park [Member] Camden Thornton Park [Member] Camden Pier District [Member] Camden Pier District [Member] Camden Pier District [Member] Camden Hayden II [Member] Camden Hayden II [Member] Camden Hayden II Camden North Quarter [Member] Camden North Quarter [Member] Camden North Quarter [Member] Camden Chadbourne Mill [Member] Camden NoDa [Member] Camden NoDa [Member] Area of Land Area of Land Payments to Acquire Land Payments to Acquire Land Number of Units in Real Estate Property Number of Units in Real Estate Property Purchase Price of Operating Properties Acquired Proceeds from Sale of Land Held-for-investment Proceeds from Sale of Land Held-for-investment Number of common share equivalent securities excluded from the diluted earnings per share calculation Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Income from continuing operations attributable to common shareholders Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Amount allocated to participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Net income attributable to common shareholders – basic Net Income (Loss) Available to Common Stockholders, Basic Total earnings per common share – basic Net income attributable to common shareholders – diluted Net Income (Loss) Available to Common Stockholders, Diluted Total earnings per common share – diluted Common share options and share awards granted Common share options and share awards granted Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method and incremental common shares attributable to participating nonvested shares with non-forfeitable dividend rights using the two class method. Weighted average number of common shares outstanding – diluted Common shares, par value, per share Common Stock, Par or Stated Value Per Share Common shares, issued Common Stock, Shares, Issued Common shares, outstanding Common Shares Outstanding Including Treasury Shares Total number of shares of common stock held by shareholders (excluding shares held in our deferred compensation arrangements), including treasury stock. May be all or a portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Treasury shares, at cost Treasury Stock, Shares Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative, Cash Paid on Hedge Unrealized Gain (Loss) on Derivatives Unrealized Gain (Loss) on Derivatives Number of Interest Rate Derivatives Held Number of Interest Rate Derivatives Held Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Share-based Compensation and Non-Qualified Deferred Compensation Plan Share-based Payment Arrangement [Text Block] Net Change in Operating Accounts Effect Of Changes In The Operating Accounts On Cash Flows From Operating Activities [Text Block] Entire disclosure of the net increase (decrease) in operating capital in the operating section of the statement of cash flows, and represents the entire footnote disclosure that provides details regarding the net change during the reporting period of all assets and liabilities used in operating activities. Leases Leases of Lessee Disclosure [Text Block] Revenues Revenue Recognition, Leases [Policy Text Block] Investments in Joint Ventures Equity Method Investments and Joint Ventures Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] 3.11% Term loan, due 2022 [Member] Term loan, due 2022 [Member] Term loan, due 2022 [Member] 3.15% Notes Due 2022 [Member] Three Point One five Percentage Notes Due 2022 [Member] Three Point One five Percentage Notes Due 2022 5.07% Notes Due 2023 [Member] Five Point Zero Seven Percentage Notes Due 2023 [Member] Five Point Zero Seven Percentage Notes Due 2023 4.36% Notes Due 2024 [Member] Four Point Three Six Percentage Notes Due 2024 [Member] Four Point Three Six Percentage Notes Due 2024 3.68% Notes Due 2024 [Member] Three Point Six Eight Percentage Notes Due 2024 [Member] Three Point Six Eight Percentage Notes Due 2024 3.74% Notes Due 2028 [Member] Unsecured notes 3.74% due 2028 [Member] Unsecured notes 3.74% due 2028 [Member] 3.67% Notes due 2029 [Member] Unsecured notes 3.67% due 2029 [Member] Unsecured notes 3.67% due 2029 [Member] 5.19% Conventional Mortgage Notes, due 2019 [Member] Secured Notes 5.19% Fixed Rate Note Due 2019 [Member] Secured Notes 5.19% Fixed Rate Note Due 2019 [Member] 5.33% Conventional Mortgage Notes Due 2019 [Member] Secured Notes 5.33% Fixed Rate Mortgage Note Due 2019 [Member] Secured Notes 5.33% Fixed Rate Mortgage Note Due 2019 [Member] Unsecured 3.11% Floating Rate Debt [Member] Unsecured 3.33% Notes Floating Rate [Member] Unsecured 3.33% Notes Floating Rate [Member] Total notes payable (1) Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale by Asset Type [Axis] Long Lived Assets Held-for-sale, Name [Domain] Long Lived Assets Held-for-sale, Name [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Number of multifamily properties owned, operated, or under development Number Of Multifamily Communities The total number of real estate properties the company owned interests in, operated, or were developing as of the balance sheet date. Total number of apartment homes in multifamily properties Total Number Of Apartment Homes In Multifamily Communities The total number of units in real estate properties the company owned interests in, operated, or were developing as of the balance sheet date. Number of multifamily properties under development Number of Multifamily Properties Under Development The number of real estate properties under development the company owned interests in or fully owned as of the balance sheet date. Total Number of apartment homes in multifamily properties upon completion of development Total Number of Apartment Homes in Multifamily Properties Upon Completion Of Development The number of units in the real estate properties under development the company owned interests in or fully owned as of the balance sheet date which will be added upon completion of development.