Segment Reporting [Abstract] Revenues, net operating income and income before gain on dispositions of Real Estate segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Assets of reportable segments and consolidated assets not allocated to segments Reconciliation of Assets from Segment to Consolidated [Table Text Block] Business Combinations [Abstract] Summarized information regarding acquisitions Schedule of Business Acquisitions, by Acquisition [Table Text Block] Summarized information regarding apartment communities sold Disposal Groups, Including Discontinued Operations [Table Text Block] Statement of Comprehensive Income [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] AIMCO Properties, L.P. AIMCO Properties, LP [Member] AIMCO Properties, L.P. [Member] Statement [Line Items] Statement [Line Items] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive gain: Other Comprehensive Income (Loss), Net of Tax [Abstract] Realized and unrealized (losses) gains on interest rate swaps Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Losses on interest rate swaps reclassified into earnings from accumulated other comprehensive loss Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Unrealized (losses) gains on available for sale debt securities Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Other comprehensive gain Other Comprehensive Income (Loss), Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to Aimco/Operating Partnership Comprehensive Income (Loss), Net of Tax, Attributable to Parent Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] TSR Stock Awards TSR Stock Awards [Member] TSR Stock Awards [Member] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Grant date market value of a common share (dollars per share) Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Grant Date Closing Price of a Common Share Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Grant Date Closing Price of a Common Share Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Derived vesting period of TSR Restricted Stock and TSR LTIP I units Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Derived Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Derived Vesting Period Weighted average expected term of options Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] La Jolla Cove La Jolla Cove [Member] La Jolla Cove [Member] Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Wholly and Partially Owned and Consolidated Properties Wholly And Partially Owned Consolidated Properties [Member] Consolidated Properties including those that are wholly and partially owned Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposed of by Sale, Not Discontinued Operations Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Held-for-sale, Not Discontinued Operations Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Gross proceeds from the sale of real estate Proceeds from Sale of Real Estate Gain on dispositions of real estate and the Asset Management Business Gain (Loss) on Sale of Properties, before Applicable Income Taxes Gain on dispositions of real estate Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes Net proceeds to Aimco from the sale of real estate Net Proceeds from the Sale of Real Estate Net Proceeds from the Sale of Real Estate Stated value of seller financing provided Notes, Loans and Financing Receivable, Gross, Noncurrent Net cash proceeds received Net Cash Proceeds from the Sale of Real Estate with Seller Financing Provided Net Cash Proceeds from the Sale of Real Estate with Seller Financing Provided Number of apartment homes Number of Real Estate Properties Number of apartment communities Number of Units in Real Estate Property Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Unconsolidated Properties Unconsolidated Properties [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Real Estate Operating Segments [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Aimco Real Estate Aimco Real Estate [Member] Aimco Real Estate [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Capital additions related to segments Property, Plant and Equipment, Additions Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Weighted average ownership interest Noncontrolling Interest, Weighted Average Ownership Percentage by Noncontrolling Owners During Period Noncontrolling Interest, Weighted Average Ownership Percentage by Noncontrolling Owners During Period Income Tax Disclosure [Abstract] Amount Dividends, Common Stock [Abstract] Ordinary income (dollars per share) Ordinary Income Dividends Per Share Declared Ordinary income dividends per share declared. Capital gains (dollars per share) Capital Gains Dividends Per Share Declared Capital gains dividends per share declared. Qualified dividends (dollars per share) Qualified Dividends Per Share Declared Qualified Dividends Per Share Declared Unrecaptured Section 1250 gain (dollars per share) Unrecaptured Gain Dividends Per Share Declared Unrecaptured gain dividends per share declared. Total (dollars per share) Common Stock, Dividends, Per Share, Declared Percentage Dividends, Common Stock, Percentage [Abstract] Dividends, Common Stock, Percentage [Abstract] Ordinary income Ordinary Income Dividends Declared Percentage Ordinary Income Dividends Declared Percentage Capital gains Capital Gains Dividends Declared Percentage Capital Gains Dividends Declared Percentage Qualified dividends Qualified Dividends Declared Percentage Qualified Dividends Declared Percentage Unrecaptured Section 1250 gain Unrecaptured Gain Dividends Declared Percentage Unrecaptured Gain Dividends Declared Percentage Total Common Stock Dividends Declared Percentage Common Stock Dividends Declared Percentage Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Real Estate Portfolio Consolidated Partnerships Served by the Asset Management Business Asset Management [Member] Asset Management [Member] 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 [Line Items] Variable Interest Entity [Line Items] VIEs with interests in apartment communities Number Of Variable Interest Entities Number of variable interest entities in which the company holds variable interests. Apartment communities owned by VIEs Apartment homes in communities owned by VIEs Term over which tax credits are generally realized Period Of Time Over Which Low Income Housing Tax Credits Realized By Investors Period of time over which low income housing tax credits realized by investors. Compliance period for low income housing tax credit syndication agreements Compliance Period Related To Low Income Housing Tax Credit Arrangements, Syndication Period Typical compliance period related to low income housing tax credit arrangements. Economic Interest in Low Income Housing Tax Credit Partnerships Economic Interest in Low Income Housing Tax Credit Partnerships Economic Interest in Low Income Housing Tax Credit Partnerships Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Fixed Rate Property Debt Fixed Rate [Member] Fixed rate Variable Rate Property Debt Variable Rate [Member] Variable rate Pledged as Collateral Pledged as collateral [Member] Pledged as collateral [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Interest rate Debt Instrument, Interest Rate, Stated Percentage Weighted average interest rate Debt, Weighted Average Interest Rate Aggregate gross book value Debt Instrument, Collateral Amount Significant Transactions Other Significant Transactions [Text Block] Other Significant Transactions [Text Block] Summary of non-recourse property loans payable related to properties classified as held for use Schedule of Long-term Debt Instruments [Table Text Block] Scheduled principal amortization and maturity payments for non-recourse debt related to apartment communities classified as held for use Schedule of Maturities of Long-term Debt [Table Text Block] 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] Office Lease Obligations Office and Equipment Leases [Member] Office and Equipment Leases [Member] Ground Lease Obligations Ground Leases [Member] Ground Leases [Member] Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Property, Plant and Equipment [Table] Property, Plant and Equipment [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] Building and Building Improvements Building and Building Improvements [Member] Furniture and Fixtures Furniture and Fixtures [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Estimated useful life Property, Plant and Equipment, Useful Life Interest costs capitalized Interest Costs Capitalized Other direct and indirect costs capitalized Other Direct And Indirect Costs Capitalized Other direct and indirect costs capitalized. Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Equipment Equipment [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Estimated useful life of software Finite-Lived Intangible Asset, Useful Life Estimated useful life of acquired equipment Equity [Abstract] Pro forma earnings per share Schedule Of Earnings Per Share, Basic And Diluted, Pro Forma [Table Text Block] Schedule Of Earnings Per Share, Basic And Diluted, Pro Forma [Table Text Block] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2015 Plan 2015 Plan [Member] 2015 Plan [Member] Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Domain] Option Indexed to Issuer's Equity, Type [Domain] NAREIT Apartment Index NAREIT Apartment Index [Member] NAREIT Apartment Index [Member] MSCI US REIT Index MSCI US REIT Index [Member] MSCI US REIT Index [Member] TSR Award Vesting [Axis] TSR Award Vesting [Axis] TSR Award Vesting [Axis] TSR Award Vesting [Domain] TSR Award Vesting [Domain] TSR Award Vesting [Domain] 36 Months After Grant Date 36 Months After Grant Date [Member] 36 Months After Grant Date [Member] 48 Months After Grant Date 48 Months After Grant Date [Member] 48 Months After Grant Date [Member] Index for TSR Restricted Shares [Axis] Index for TSR Restricted Shares [Axis] Index for TSR Restricted Shares [Axis] Index for TSR Restricted Shares [Domain] Index for TSR Restricted Shares [Domain] [Domain] for Index for TSR Restricted Shares [Axis] Equity Award [Domain] Employee Stock Option Employee Stock Option [Member] Restricted Stock Restricted Stock [Member] Shares available to be granted under plan (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Additional shares authorized under plan (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Total compensation cost recognized for stock options and restricted stock awards Allocated Share-based Compensation Expense Total compensation cost capitalized for options and restricted stock awards Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Total unvested compensation cost not yet recognized for options and restricted stock awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period over which unvested compensation cost expected to be recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Vest period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Weighted percentage of index used to compare to TSR Weighted Percentage of Index Used to Compare to TSR Weighted Percentage of Index Used to Compare to TSR TSR restricted shares performance measurement period TSR Restricted Shares Performance Measurement Period TSR Restricted Shares Performance Measurement Period Vesting percentage, TSR restricted stock Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Term of stock options Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Requisite service period Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period Options outstanding, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options outstanding, weighted average remaining contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options exercisable, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Options exercisable, weighted average remaining contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Intrinsic value of stock options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Options granted, weighted average grant-date fair value (dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value Aggregate fair value of shares that vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Investment Type [Axis] Investment Type [Axis] Summary of Investments, by Type [Domain] Investments [Domain] Available-for-sale Securities Available-for-sale Securities [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Expected Term Measurement Input, Expected Term [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Face amount of investment in available-for-sale debt securities Investment Owned, Face Amount Expected remaining term of available for sale securities Debt Securities, Available-for-sale, Term Amortized cost of the investment in available-for-sale debt securities Debt Securities, Available-for-sale, Amortized Cost Mortgage-backed securities available-for-sale, fair value disclosure Mortgage-backed Securities Available-for-sale, Fair Value Disclosure Document and Entity Information [Abstract] Document and Entity Information Abstract. Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] AIMCO PROPERTIES, L.P. Subsidiaries [Member] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Public Float Entity Public Float Loss Contingencies [Table] Loss Contingencies [Table] Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Commitments related to development, redevelopment and capital improvement activities Commitments related to development, redevelopment and capital improvement activities [Member] Commitments related to development, redevelopment and capital improvement activities [Member] Commitments related to operations Commitments related to operations [Member] Commitments related to operations [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Commitments and Contingencies [Abstract] Commitments and Contingencies (Textual) [Abstract] Commitments and contingencies. Commitments related to capital spending activities Long-term Purchase Commitment, Amount Long-term purchase commitment, period (or less) Long-term Purchase Commitment, Period Number of potentially-responsible parties Environmental Remediation, Number of Potentially Responsible Parties Environmental Remediation, Number of Potentially Responsible Parties Lessee leasing arrangements, operating leases, term of contract Lessee, Operating Lease, Term of Contract Rent expense Operating Leases, Rent Expense Business Segments Segment Reporting Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Total Aimco Equity Parent [Member] Preferred Stock Preferred Stock [Member] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Distributions in Excess of Earnings Accumulated Distributions in Excess of Net Income [Member] Noncontrolling Interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances (in shares) Shares, Issued Balances Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Redemption and repurchase of stock (in shares) Stock Repurchased During Period, Shares Redemption and repurchase of stock Stock Repurchased During Period, Value Issuance of Aimco Operating Partnership units Partners' Capital Account, Sale of Units Redemption of Aimco Operating Partnership units Redemption Of Operating Partnership Units In Exchange For Cash Or Shares Of Common Stock Operating partnership units redeemed in exchange for cash or shares of Aimco Common Stock. Amortization of share-based compensation cost (in shares) Amortization Of Stock Option And Restricted Stock Compensation Cost Amortization of stock option and restricted stock compensation cost. Amortization of share-based compensation cost Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Contributions from noncontrolling interests Noncontrolling Interest, Increase from Subsidiary Equity Issuance Effect of changes in ownership for consolidated entities Effect Of Changes In Ownership For Consolidated Entities Adjustment to additional paid-in capital resulting from acquisition of noncontrolling interests in consolidated entities. Cumulative effect of a change in accounting principle Cumulative Effect of New Accounting Principle in Period of Adoption Change in accumulated other comprehensive income Other Comprehensive Income Loss Other comprehensive income loss. Other, net (in shares) Stockholders' Equity, Other Shares Other, net Stockholders' Equity, Other Net income Net Income Loss Including Portion Attributable To Noncontrolling Interests Included In Permanent Equity Excluding Portion Attributable To Noncontrolling Interests Included In Temporary Equity Net income loss including portion attributable to noncontrolling interests included in permanent equity excluding portion attributable to noncontrolling interests included in temporary equity. Distributions to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Common Stock dividends Dividends, Common Stock, Cash Preferred Stock dividends Dividends, Preferred Stock, Cash Balances (in shares) Balances Time-Based Restricted Stock Awards TSR Restricted Stock Awards TSR Restricted Stock [Member] TSR Restricted Stock [Member] TSR LTIP I Units TSR LTIP I Units [Member] TSR LTIP I Units [Member] TSR LTIP II Units TSR LTIP II Units [Member] TSR LTIP II Units [Member] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Unvested (in shares) Weighted Average Grant-Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Unvested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Unvested (in dollars per share) Schedule of Significant Acquisitions and Disposals [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Philadelphia-Area Apartment Communities 2018 Philadelphia Acquisition Portfolio [Member] 2018 Philadelphia Acquisition Portfolio [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Purchase price Business Combination, Consideration Transferred Capitalized transaction costs Business Acquisition, Transaction Costs Total fair value allocated to land Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Land Total fair value allocated to building and improvements Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Buildings Total fair value allocated to intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Total fair value allocated to intangible liabilities Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Intangible Liabilities Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Intangible Liabilities Cash paid in acquisition Asset Acquisition, Cash paid Cash consideration paid in asset acquisition transaction. Property-level debt assumed in acquisition Asset Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Non-Recourse Property Debt Asset Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Non-Recourse Property Debt OP Units issued in acquisition (in shares) Partners' Capital Account, Units, Acquisitions Share price per unit (in dollars per share) Asset Acquisition, Share Price Asset Acquisition, Share Price SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, by Property [Table] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, by Property [Table] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Real Estate Segment: Real Estate Properties [Member] Real Estate Properties [Member] 100 Forest Place 100 Forest Place [Member] Forest Place 100. 118-122 West 23rd Street 118-122 West 23rd Street [Member] 118-122 West 23rd Street [Member] 173 E. 90th Street 173 E 90th Street [Member] Street E Ninetieth 173. 182-188 Columbus Avenue 182-188 Columbus Avenue [Member] Columbus Avenue 182 188. 1045 on the Park Apartments Homes 1045 on the Park Apartment Homes [Member] 1045 on the Park Apartment Homes [Member] 1582 First Avenue 1582 First Avenue [Member] First avenue 1582. 21 Fitzsimons 21 Fitzsimons [Member] 21 Fitzsimons [Member] 2200 Grace 2200 Grace [Member] 2200 Grace [Member] 234 East 88th Street 234 East 88th Street [Member] 234 East 88th Street [Member] 236-238 East 88th Street 236-238 East 88th Street [Member] East 88th Street 236 238. 237-239 Ninth Avenue 237-239 Ninth Avenue [Member] Ninth Avenue 237 239. 240 West 73rd Street, LLC 240 West 73rd Street, LLC [Member] West 73rd Street LLC 240. 2900 on First Apartments 2900 On First Apartments [Member] First Apartments on 2900. 306 East 89th Street 306 East 89th Street [Member] East 89th Street 306. 311 & 313 East 73rd Street 311 & 313 East 73rd Street [Member] East 73rd Street 311 and 313. 322-324 East 61st Street 322-324 East 61st Street [Member] East 61st Street 322 324. 3400 Avenue of the Arts 3400 Avenue Of The Arts [Member] Avenue of the Arts 3400. 452 East 78th Street 452 East 78th Street [Member] East 78th Street 452. 464-466 Amsterdam & 200-210 W. 83rd Street 464-466 Amsterdam & 200-210 W 83rd Street [Member] 464-466 Amsterdam & 200-210 W. 83rd Street 510 East 88th Street 510 East 88th Street [Member] East 88th Street 510. 514-516 East 88th Street 514-516 East 88th Street [Member] 514-516 East 88th Street [Member] 518 East 88th Street 518 East 88th Street [Member] 518 East 88th Street [Member] 707 Leahy 707 Leahy [Member] Leahy 707. 777 South Broad Street 777 South Broad Street [Member] 777 South Broad Street [Member] 865 Bellevue 865 Bellevue [Member] Bellevue 865. Avery Row Avery Row [Member] Avery Row Apartments - Arlington, Virginia [Member] Axiom Axiom Apartment Homes - Cambridge MA [Member] Axiom Apartment Homes - Cambridge MA [Member] Bank Lofts Bank Lofts [Member] Bank Lofts. Bay Parc Plaza Bay Parc Plaza [Member] Bay Parc Plaza [Member] Bay Ridge at Nashua Bay Ridge At Nashua [Member] Bay Ridge at Nashua. Bayberry Hill Estates Bayberry Hill Estates [Member] Bayberry Hill Estates. Bent Tree Apartments Bent Tree Apartments - Fairfax County, Virginia [Member] Bent Tree Apartments - Fairfax County, Virginia [Member] Bluffs at Pacifica, The Bluffs at Pacifica [Member] Bluffs at pacifica. Boston Lofts Boston Lofts [Member] Boston Lofts. Boulder Creek Boulder Creek [Member] Boulder Creek. Broadcast Center Broadcast Center [Member] Broadcast Center. Broadway Lofts Broadway Lofts [Member] Broadway Lofts [Member] Burke Shire Commons Burke Shire Commons [Member] Burke Shire Commons. Calhoun Beach Club Calhoun Beach Club [Member] Calhoun Beach Club. Canyon Terrace Canyon Terrace [Member] Canyon Terrace. Cedar Rim Cedar Rim [Member] Cedar rim. Charlesbank Apartment Homes Charlesbank Apartment Homes [Member] Charlesbank Apartment Homes [Member] Chestnut Hall Chestnut Hall [Member] Chestnut hall. Chimneys of Cradle Rock Chimneys Of Cradle Rock [Member] Chimneys of Cradle Rock. Columbus Avenue Columbus Avenue [Member] Columbus Avenue. Creekside Creekside [Member] Creekside. Crescent at West Hollywood, The Crescent At West Hollywood [Member] Crescent at West Hollywood. Elm Creek Elm Creek [Member] Elm Creek. Evanston Place Evanston Place [Member] Evanston Place. Farmingdale Farmingdale [Member] Farmingdale. Flamingo Towers Flamingo Towers [Member] Flamingo towers. Four Quarters Habitat Four Quarters Habitat [Member] Four quarters habitat. Foxchase Foxchase [Member] Foxchase. Georgetown Georgetown [Member] Georgetown. Georgetown II Georgetown Two [Member] Georgetown Two. Heritage Park Escondido Heritage Park Escondido [Member] Heritage park escondido. Heritage Park Livermore Heritage Park Livermore [Member] Heritage park livermore. Heritage Village Anaheim Heritage Village Anaheim [Member] Heritage village anaheim. Hidden Cove Hidden Cove I [Member] Hidden cove one. Hidden Cove II Hidden Cove II [Member] Hidden cove two. Hillcreste Hillcreste [Member] Hillcreste. Hillmeade Hillmeade [Member] Hillmeade. Horizons West Apartments Horizons West Apartments [Member] Horizons west apartments. Hunt Club Hunt Club [Member] Hunt club Hyde Park Tower Hyde Park Tower [Member] Hyde park tower. Indian Oaks Indian Oaks [Member] Indian oaks. Indigo Indigo Apartment Homes - Redwood City CA [Member] [Domain] Indigo Apartment Homes - Redwood City CA [Member] [Domain] Island Club Island Club [Member] Island club two. Key Towers Key Towers [Member] Key towers. Lakeside Lakeside [Member] Lakeside. Latrobe Latrobe [Member] Latrobe. Laurel Crossing Laurel Crossing [Member] Laurel Crossing Lincoln Place (5) Lincoln Place Garden [Member] Lincoln place garden. Locust on the Park Locust On The Park [Member] Locust On The Park [Member] Lodge at Chattahoochee, The Lodge At Chattahoochee [Member] Lodge at chattahoochee. Malibu Canyon Malibu Canyon [Member] Malibu canyon. Mariners Cove Mariner's Cove [Member] Mariner's Meadow Creek Meadow Creek [Member] Meadow creek. Merrill House Merrill House [Member] Merrill house. Mezzo Mezzo [Member] Mezzo [Member] Monterey Grove Monterey Grove [Member] Monterey grove. Ocean House on Prospect Ocean House on Prospect [Member] Ocean House on Prospect [Member] One Canal One Canal [Member] One Canal [Member] Pacific Bay Vistas (5) Pacific Bay Vistas [Member] Pacific bay vistas. Pacifica Park Pacifica Park [Member] Pacifica park. Palazzo at Park La Brea, The Palazzo At Park La Brea [Member] Palazzo at park la brea. Palazzo East at Park La Brea, The Palazzo East At Park La Brea [Member] Palazzo east at park la brea. Parc Mosaic Parc Mosaic [Member] Parc Mosaic Park Towne Place Park Towne Place [Member] Park towne place. Pathfinder Village Pathfinder Village [Member] Pathfinder village. Peachtree Park Peachtree Park [Member] Peachtree park. Plantation Gardens Plantation Gardens [Member] Plantation gardens. Post Ridge Post Ridge [Member] Post ridge. Preserve at Marin Preserve at Marin [Member] Preserve at Marin [Member] Ravensworth Towers Ravensworth Towers [Member] Ravensworth towers. River Club,The River Club [Member] River club. Riverloft Riverloft [Member] Riverloft. Rosewood Rosewood [Member] Rosewood. Royal Crest Estates Royal Crest Estates [Member] Royal crest estates. Royal Crest Estates Royal Crest Estates Two [Member] Royal crest estates two. Royal Crest Estates Royal Crest Estates Three [Member] Royal crest estates. Royal Crest Estates Royal Crest Estates Four [Member] Royal crest estates. Saybrook Point Saybrook Pointe [Member] Saybrook Pointe [Member] Shenandoah Crossing Shenandoah Crossing [Member] Shenandoah crossing. SouthStar Lofts SouthStar Lofts [Member] SouthStar Lofts [Member] Springwoods at Lake Ridge Springwoods At Lake Ridge [Member] Springwoods at lake ridge. St. George Villas St. George Villas [Member] St. George Villas [Member] Sterling Apartment Homes, The Sterling Apartment Homes [Member] Sterling apartment homes. Stone Creek Club Stone Creek Club [Member] Stone creek club. The Left Bank The Left Bank [Member] The Left Bank [Member] Timbers at Long Reach Apartment Homes Timbers at Long Reach Apartment Homes [Member] Timbers at Long Reach Apartment Homes [Member] Towers Of Westchester Park, The Towers Of Westchester Park [Member] Towers of westchester park. Township At Highlands Township At Highlands [Member] Township at highlands. Tremont Tremont [Member] Tremont [Member] Twin Lake Towers Twin Lake Towers [Member] Twin lake towers. Vantage Pointe Vantage Pointe [Member] Vantage pointe. Villa Del Sol Villa Del Sol [Member] Villa del sol. Villas at Park La Brea, The Villas At Park La Brea [Member] Villas at park la brea. Villas of Pasadena Villas of Pasadena [Member] Villas of Pasadena [Member] Vivo Vivo - Cambridge MA [Member] Vivo - Cambridge MA [Member] Waterford Village Waterford Village [Member] Waterford village. Waterways Village Waterways Village [Member] Waterways village. Waverly Apartments Waverly Apartments [Member] Waverly apartments. Wexford Village Wexford Village [Member] Wexford village. Willow Bend Willow Bend [Member] Willow bend. Windrift Windrift [Member] Windrift. Windsor Park Windsor Park [Member] Windsor park. Yacht Club at Brickell Yacht Club At Brickell [Member] Yacht club at brickell. Yorktown Apartments Yorktown Apartments [Member] Yorktown apartments. Other Other Property [Member] Operating Activities [Axis] Operating Activities [Axis] Operating Activities [Domain] Operating Activities [Domain] Continuing Operations Continuing Operations [Member] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items] Apartment Type Real Estate And Accumulated Depreciation Property Type Real Estate And Accumulated Depreciation Property Type. Date Consolidated Real Estate And Accumulated Depreciation Date Consolidated Real Estate And Accumulated Depreciation Date Consolidated. Location Property Location Property location. Initial Cost, Land SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land Initial Cost, Buildings and Improvements SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements Costs Capitalized Subsequent to Consolidation SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Improvements Land SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount Buildings and Improvements SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount Total SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross Accumulated Depreciation (AD) SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation Total Cost Net of Accumulated Depreciation Real Estate and Accumulated Depreciation Net Value of Land and Buildings and Improvements Real estate and accumulated depreciation net value of land and buildings and improvements. Encumbrances SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances Real Estate and Accumulated Depreciation (Textual) [Abstract] Real Estate And Accumulated Depreciation (Textual) [Abstract] Real estate and accumulated depreciation. Aggregate cost of land and depreciable property for federal income tax purposes SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis SEC Schedule III, Real Estate and Accumulated Depreciation [Table] SEC Schedule III, Real Estate and Accumulated Depreciation [Table] SEC Schedule III, Real Estate and Accumulated Depreciation [Table] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Asset Management Real Estate and Accumulated Depreciation SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward] Real Estate Real Estates [Abstract] Real estate. Balance at beginning of year Additions during the year: Additions Of Real Estate During Period [Abstract] Additions of real estate during period abstract. Acquisitions SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Acquisition Capital additions SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Improvements Deductions during the year: Deductions Of Real Estate Abstract Deductions of real estate. Casualty and other write-offs SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Deduction Provision for real estate impairment loss SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Write-down or Reserve, Amount Amounts related to assets held for sale SEC Schedule III, Real Estate, Held For Sale SEC Schedule III, Real Estate, Held For Sale Sales SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Cost of Investment in Real Estate Sold Balance at end of year Accumulated Depreciation Accumulated Depreciation [Abstract] Accumulated depreciation. Balance at beginning of year Additions during the year Additions Of Real Estate Accumulated Depreciation During Period [Abstract] Additions of real estate accumulated depreciation during period. Depreciation SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense Deductions during the year: Deductions Of Real Estate Accumulated Depreciation During Period Abstract Deductions of real estate accumulated depreciation during period. Casualty and other write-offs SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Other Deduction Amounts related to assets held for sale SEC Schedule III, Accumulated Depreciation, Held For Sale SEC Schedule III, Accumulated Depreciation, Held For Sale Sales SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Investment in Real Estate Sold Balance at end of year Write-off of fully depreciated assets Write Off Of Fully Depreciated Assets Write-off of fully depreciated assets. Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Valuation Allowance by Deferred Tax Asset [Axis] Valuation Allowance by Deferred Tax Asset [Axis] Deferred Tax Asset [Domain] Deferred Tax Asset [Domain] Low-Income Housing and Rehabilitation Tax Credit Carryforward Low-Income Housing and Rehabilitation Tax Credit Carryforward [Member] Low-Income Housing and Rehabilitation Tax Credit Carryforward [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Income Taxes (Textual) [Abstract] Income Taxes (Textual) [Abstract] Income taxes. Net tax benefit due to the tax effects of the 2017 Act Tax Cuts And Jobs Act Of 2017, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Income Tax Expense (Benefit) Operating loss carryforwards Operating Loss Carryforwards Valuation allowance Operating Loss Carryforwards, Valuation Allowance Expiration years of net operating loss carryforwards Operating Loss Carryforwards, Expiration Date Net deferred tax asset related to tax credit carryforwards Tax Credit Carryforward, Amount Tax credit carryforward, expiration date Tax Credit Carryforward, Expiration Date Valuation allowance Deferred Tax Assets, Valuation Allowance Consolidated income (loss) subject to tax Consolidated Income Loss Subject to Tax The portion of consolidated income (loss) related to the net income (loss) generated by taxable REIT subsidiaries and gains or losses on sale of certain properties by those subsidiaries. Cash paid for income taxes Income Taxes Paid Term Loan Term Loan [Member] Term Loan [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Revolving loan commitments Line of Credit Facility, Maximum Borrowing Capacity Outstanding borrowings under the revolving credit facility Long-term Line of Credit Credit facility interest rate at period end Line of Credit Facility, Interest Rate at Period End Amount outstanding for undrawn letters of credit issued under revolving credit facility Letters of Credit Outstanding, Amount Remaining borrowing capacity under credit facility Line of Credit Facility, Remaining Borrowing Capacity Repayment of term loan Proceeds from (Repayments of) Short-term Debt, Maturing in More than Three Months Initial interest rate for credit facility Line of Credit Facility, Interest Rate Description Spread on variable interest rate Debt Instrument, Basis Spread on Variable Rate Credit facility maturity date Line of Credit Facility, Expiration Date Credit facility, dividend restrictions Line of Credit Facility, Dividend Restrictions Components of deferred tax liabilities and assets Components of Deferred Tax Assets and Liabilities [Abstract] Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Real estate and real estate partnership basis differences Deferred Tax Liabilities, Partnership Differences Deferred Tax Liabilities, Partnership Differences Deferred tax assets: Deferred Tax Assets, Net [Abstract] Net operating, capital and other loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Accruals and expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards Management contracts and other Deferred Tax Assets, Other Total deferred tax assets Deferred Tax Assets, Gross Valuation allowance Net deferred tax assets Deferred Tax Assets, Net Statement of Financial Position [Abstract] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Earnings Per Share [Abstract] Earnings per Share/Unit Earnings Per Share [Text Block] Approximate minimum annual rentals under operating lease obligations and sublease receivables Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Other Commitments [Table] Other Commitments [Table] Other Commitments [Line Items] Other Commitments [Line Items] Scheduled principal amortization and maturity payments Scheduled Principal Amortization And Maturity Payments [Abstract] Scheduled principal amortization and maturity payments. Amortization Amortization [Abstract] 2019 Long Term Debt Amortization Of Principal In Next Twelve Months Long term debt amortization of principal in next twelve months. 2020 Long Term Debt Amortization Of Principal In Year Two Long term debt amortization of principal in year two. 2021 Long Term Debt Amortization Of Principal In Next Year Three Long term debt amortization of principal in next year three. 2022 Long Term Debt Amortization Of Principal In Year Four Long term debt amortization of principal in year four. 2023 Long Term Debt Amortization Of Principal In Year Five Long term debt amortization of principal in year five. Maturities Maturities of Long-term Debt [Abstract] 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 Long-term Debt, Gross Loans maturing in 2021 that may be prepaid without penalty Long-Term Debt, Maturities, Potential Prepayments, Maturing In Year Four Long-Term Debt, Maturities, Potential Prepayments, Maturing In Year Four Components of deferred tax liabilities and assets Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Reconciliation of unrecognized tax benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Components of the provision (benefit) for income taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Reconciliation of income tax attributable to continuing and discontinued operations Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Dividends paid to holders of Common Stock Dividends Paid to Holders of Common Stock [Table Text Block] Dividends paid to holders of Common Stock. Non-Recourse Property Debt and Credit Agreement Debt Disclosure [Text Block] Summary of outstanding stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Number of Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Ending balance (in shares) Exercisable at end of year (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted Average Exercise Price, Stock Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Ending balance (in dollars per share) Exercisable (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Basis of Presentation and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Estimated aggregate amortization of below-market leases Below Market Lease, Future Amortization Income [Table Text Block] Other assets Schedule of Other Assets [Table Text Block] Accounting pronouncements adopted in the current year Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Quarterly Financial Information Disclosure [Abstract] Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Summarized unaudited consolidated quarterly information Quarterly Financial Data [Abstract] Total revenues Revenues Net income Net income attributable to Aimco common stockholders Net Income (Loss) Available to Common Stockholders, Basic Net income attributable to the company per common share/unit - basic (in dollars per share) Earnings Per Share, Basic Net income attributable to the company per common share/unit - diluted (in dollars per share) Earnings Per Share, Diluted Partners' Capital [Abstract] Partners' Capital Partners' Capital Notes Disclosure [Text Block] Corporate and other assets Corporate, Non-Segment [Member] Total assets Assets Statement of Cash Flows [Abstract] AIMCO PROPERTIES, L.P. CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Provision for real estate impairment loss Impairment of Real Estate Gain on dispositions of real estate and the Asset Management business Income tax benefit Income Tax Expense (Benefit) Share-based compensation expense Share-based Compensation Amortization of deferred loan costs and other Amortization of Debt Issuance Costs Other, net Other Noncash Income (Expense) Changes in operating assets and operating liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable and other assets Increase (Decrease) in Other Operating Assets Accounts payable, accrued liabilities and other Increase (Decrease) in Accounts Payable and Accrued Liabilities Total adjustments Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of real estate and deposits related to purchases of real estate Payments to Acquire Residential Real Estate Capital expenditures Payments for Capital Improvements Proceeds from dispositions of real estate Proceeds from Sale of Real Estate Held-for-investment Purchases of corporate assets Payments to Acquire Other Productive Assets Proceeds from repayments on notes receivable Proceeds from Collection of Loans Receivable Other investing activities Payments for (Proceeds from) Other Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from non-recourse property debt Proceeds from Issuance of Secured Debt Principal repayments on non-recourse property debt Repayments of Secured Debt (Repayment of) proceeds from term loan Net borrowings on (repayments of) revolving credit facility Proceeds from (Repayments of) Lines of Credit Payment of debt issue costs Payments of Debt Issuance Costs Payment of debt extinguishment costs Payment for Debt Extinguishment or Debt Prepayment Cost Repurchases of Common Stock Payments for Repurchase of Common Stock Redemptions of Preferred Stock Payments for Repurchase of Preferred Stock and Preference Stock Payment of dividends to holders of Preferred Stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Payment of dividends to holders of Common Stock Payments of Ordinary Dividends, Common Stock Payment of distributions to General Partner and Special Limited Partner Payment Of Distributions To General Partner And Special Limited Partner Payment of distributions to general partner and special limited partner. Payment of distributions to Limited Partners Payment Of Distributions To Limited Partners Payment of distributions to limited partners. Payment of distributions to noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Redemptions of noncontrolling interests in the Aimco Operating Partnership Payments for Repurchase of Redeemable Noncontrolling Interest Redemption of common and preferred units Payments For Redemption Of Common And Preferred Units Payments For Redemption Of Common And Preferred Units Redemptions of noncontrolling interests in the Aimco Operating Partnership Payments to Acquire Additional Interest in Subsidiaries Other financing activities Proceeds from (Payments for) Other Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT BEGINNING OF PERIOD Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD SUPPLEMENTAL CASH FLOW INFORMATION: Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid for income taxes Non-cash transactions associated with the acquisition or disposition of real estate: Non Cash Transactions Associated With Disposition Of Real Estate Abstract Non cash transactions associated with disposition of real estate. Non-recourse property debt assumed by buyer in connection with the disposition of the Asset Management business Notes Reduction Non-recourse property debt assumed in connection with the acquisition of real estate Noncash or Part Noncash Acquisition, Debt Assumed Issuance of preferred OP Units in connection with acquisition of real estate Operating Partnership Units Issued in Exchange for Acquisitions of Real Estate Operating Partnership Units Issued in Exchange for Acquisitions of Real Estate Issuance of common OP Units in connection with acquisition of real estate Noncash Or Part Noncash Acquisition, Noncash Financial Or Equity Instrument Consideration, Shares Issued, Value Noncash Or Part Noncash Acquisition, Noncash Financial Or Equity Instrument Consideration, Shares Issued, Value Other non-cash transactions: Other Noncash Investing and Financing Items [Abstract] Accrued capital expenditures (at end of period) Capital Expenditures Incurred but Not yet Paid Accrued dividends on TSR restricted stock and LTIP awards (at end of period) (Note 8) Dividends, Share-based Compensation, Accrued Amount of accrued cash dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares. Weighted average shares, basic (in shares) Weighted Average Basic Shares Outstanding, Pro Forma Weighted average shares, diluted (in shares) Pro Forma Weighted Average Shares Outstanding, Diluted Basic earnings per share (in dollars per share) Basic Earnings Per Share, Pro Forma Diluted earnings per share (in dollars per share) Diluted Earnings Per Share Pro Forma Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Forecast Scenario, Forecast [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Redeemable partnership preferred units redeemed for cash during period (in units) Temporary Equity, Units Redeemed During Period, Units Temporary Equity, Units Redeemed During Period, Units Common OP Units redeemed in exchange for cash during period (in units) Partners' Capital Account, Units, Redeemed Dividends declared per common share/unit (in dollars per share) Reverse stock split, conversion ratio Stockholders' Equity Note, Stock Split, Conversion Ratio Cash dividends on common stock declared Stock dividends on common stock declared (in shares) Common Stock Dividends, Shares Components of the provision (benefit) for income taxes Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Current Income Tax Expense [Abstract] Current Income Tax Expense [Abstract] Federal Total Current Federal Tax Expense (Benefit) Total Current Federal Tax Expense (Benefit) including continuing and discontinued operations and gains on sale of real estate State Total Current State and Local Tax Expense (Benefit) Total Current State and Local Tax Expense (Benefit) including both continuing and discontinued operations Total current Total Current Income Tax Expense (Benefit) Total Current Income Tax Expense (Benefit) including both continuing and discontinued operations Deferred: Deferred Income Tax Expense [Abstract] Deferred Income Tax Expense [Abstract] Federal Total Deferred Federal Income Tax Expense (Benefit) Total Deferred Federal Income Tax Expense (Benefit) including both continuing and discontinued operations State Total Deferred State and Local Income Tax Expense (Benefit) Total Deferred State and Local Income Tax Expense (Benefit) including both continuing and discontinued operations Revaluation of deferred taxes due to change in tax rate Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Total deferred Total Deferred Income Tax Expense (Benefit) Total Deferred Income Tax Expense (Benefit) including both continuing and discontinued operations Total income tax benefit Income Tax Expense Benefits Income Tax Expense Benefits. Number of apartment communities sold Number of apartment homes sold Gain on disposition Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Preferred Units by Name [Axis] Preferred Units by Name [Axis] Limited Partners' Capital Account, Class [Domain] Preferred Units, Class [Domain] Class One Class One [Member] Class One [Member] Class Two Class Two [Member] Class Two [Member] Class Three Class Three [Member] Class Three [Member] Class Four Class Four [Member] Class Four [Member] Class Six Class Six [Member] Class Six [Member] Class Seven Class Seven [Member] Class Seven [Member] Class Nine Class Nine [Member] Class Nine Preferred Stock [Member] Class Ten Class Ten [Member] Class Ten Preferred Stock [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Distributions per annum Temporary Equity, Distribution Made to Member or Limited Partner, Distributions Paid, Percentage Temporary Equity, Distribution Made to Member or Limited Partner, Distributions Paid, Percentage Distributions per annum (in dollars per share) Distribution Made to Limited Partner, Distributions Paid, Per Unit Units issued (in shares) Temporary Equity, Shares Issued Units outstanding (in shares) Temporary Equity, Shares Outstanding Redemption values Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Unaudited Summarized Consolidated Quarterly Information Quarterly Financial Information [Text Block] Statement of Partners' Capital [Abstract] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Preferred Units Preferred Units [Member] Preferred units. General Partner and Special Limited Partner General Partner and Special Limited Partner [Member] General partner and special limited partner. Limited Partners Limited Partner [Member] Partners’ Capital Attributable to the Partnership Partners Capital Attributable To The Partnership [Member] Partners' capital attributable to the partnership. Noncontrolling Interests Increase (Decrease) in Partners' Capital [Roll Forward] Increase (Decrease) in Partners' Capital [Roll Forward] Balances Partners' Capital, Including Portion Attributable to Noncontrolling Interest Redemption of preferred units held by Aimco Partners Capital Account Redemption Of Preferred Units from Parent Redemption of preferred units held by parent in connection with parent's redemption of corresponding class of equity held by third parties. Repurchases of common partnership units Partners' Capital Account, Treasury Units, Purchased Issuance of common partnership units Redemption of partnership units held by non-Aimco partners Partners' Capital Account, Redemptions Amortization of Aimco stock-based compensation Partners Capital Account Amortization Of Stock Based Compensation Partners capital account amortization of stock based compensation. Contributions from noncontrolling interests Effect of changes in ownership for consolidated entities Partners Capital Account Effect Of Changes In Ownership For Consolidated Adjustment to partner's capital balances resulting from acquisition of noncontrolling interests in consolidated partnerships. Change in accumulated other comprehensive income Other, net Partners' Capital, Other Net income Net Income Loss Including Portion Attributable To Preferred Units And Noncontrolling Interests Included In Permanent Equity Excluding Portion Attributable To Preferred Units Included In Temporary Equity The consolidated profit or loss for the period, net of income taxes, including the portion attributable to preferred units and noncontrolling interests classified within permanent equity and excluding the portion of net income attributable to redeemable preferred units classified within temporary equity. Distributions to noncontrolling interests Distributions to common unitholders Partners' Capital Account, Distributions Distributions to preferred unitholders Partners Capital Account Distributions To Preferred Unit holders Partners Capital Account Distributions To Preferred Unitholders. Balances Proportionate and Other Adjustments Segment Reconciling Items [Member] Corporate and Amounts Not Allocated to Reportable Segment Summary information for the reportable segments Segment Reporting Information, Profit (Loss) [Abstract] Rental and other property revenues Operating Leases Income Statement Lease Revenue And Other Real Estate Revenue The aggregate amount of revenue recognized for the period from operating leases (including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue) and other real estate revenue not otherwise specified in the taxonomy. Tax credit and transaction revenues Tax credit and asset management revenues Tax credit and asset management revenues. Total revenues Property operating expenses Direct Costs of Leased and Rented Property or Equipment Other operating expenses not allocated to reportable segment Other Operating Expenses Not Allocated to Reportable Segment Other Operating Expenses Not Allocated to Reportable Segment Total operating expenses Operating Expenses Proportionate property net operating income Operating Income (Loss), Property Operating Income (Loss), Property Other items included in income before income tax benefit Other Items Included in Continuing Operations Other items included in continuing operations, including but not limited to nonoperating income and expense, income from discontinued operations and the provision (benefit) for income taxes. Income before income tax benefit Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Schedule of Unaudited Quarterly Financial Information [Table] Schedule of Unaudited Quarterly Financial Information [Table] Schedule of Unaudited Quarterly Financial Information [Table] Schedule of Unaudited Quarterly Financial Information [Line Items] Schedule of Unaudited Quarterly Financial Information [Line Items] [Line Items] for Schedule of Unaudited Quarterly Financial Information [Table] Summarized unaudited consolidated quarterly information Quarterly Financial Information [Table Text Block] Summary of activity for outstanding stock options Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of activity for restricted stock awards Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Assumptions used in the determination of grant-date fair value of awards Schedule of Share Based Payment Award TSR Units Valuation Assumptions [Table Text Block] [Table Text Block] for Schedule of Share Based Payment Award Performance Share Units Valuation Assumptions [Table] Income Statement [Abstract] REVENUES: Revenues [Abstract] Rental and other property revenues OPERATING EXPENSES: Operating Expenses [Abstract] Property operating expenses Depreciation and amortization General and administrative expenses General and Administrative Expense Other expenses, net Other Cost and Expense, Operating Provision for real estate impairment loss Interest income Investment Income, Interest Interest expense Interest Expense Other, net Other Nonoperating Income (Expense) Income before income tax benefit Income tax benefit (Note 9) Net income Noncontrolling interests: Net Income (Loss) Attributable to Noncontrolling Interest [Abstract] Net income attributable to noncontrolling interests in consolidated real estate partnerships Noncontrolling Interest in Net Income (Loss) Limited Partnerships, Nonredeemable Net income attributable to preferred noncontrolling interests in Aimco Operating Partnership Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Nonredeemable Net income attributable to common noncontrolling interests in Aimco Operating Partnership Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Nonredeemable Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to the company Net Income (Loss) Attributable to Parent Net income attributable to the company's preferred equityholders Preferred Stock Dividends and Other Adjustments Net income attributable to participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Net income attributable to Aimco common stockholders Weighted average common shares/units outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average common shares/units outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Investments in securitization trust that holds Aimco property debt Debt Securities, Available-for-sale Deferred tax asset, net (Note 9) Intangible assets, net Intangible Assets, Net (Including Goodwill) Prepaid expenses, real estate taxes and insurance Other Assets, Miscellaneous Software, equipment and leasehold improvements Software, Equipment, and Leasehold Improvements Software, Equipment, and Leasehold Improvements Investments in unconsolidated real estate partnerships Equity Method Investments Accounts and notes receivable, net Accounts Receivable, Net Deferred costs, deposits and other Prepaid Expense and Other Assets, Current Total other assets Other Assets Aimco Equity Stockholders' Equity Note Disclosure [Text Block] Classes of preferred OP Units Schedule of Preferred Units [Table Text Block]