Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation And Principles Of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared by the Company's management in accordance with United States generally accepted accounting principles, or GAAP, and applicable rules and regulations of the Securities and Exchange Commission, or the SEC. The consolidated financial statements of MAA presented herein include the accounts of MAA, the Operating Partnership and all other subsidiaries in which MAA has a controlling financial interest. MAA owns, directly or indirectly, approximately 80% to 100% of all consolidated subsidiaries, including the Operating Partnership. The consolidated financial statements of MAALP presented herein include the accounts of MAALP and all other subsidiaries in which MAALP has a controlling financial interest. MAALP owns, directly or indirectly, 80% to 100% of all consolidated subsidiaries. In management's opinion, all adjustments necessary for a fair presentation of the consolidated financial statements have been included, and all such adjustments were of a normal recurring nature. All significant intercompany accounts and transactions have been eliminated in consolidation. The Company invests in entities which may qualify as variable interest entities, or VIEs, and MAALP is considered a VIE. A VIE is a legal entity in which the equity investors lack sufficient equity at risk for the entity to finance its activities without additional subordinated financial support or, as a group, the holders of the equity investment at risk lack the power to direct the activities of a legal entity as well as the obligation to absorb its expected losses or the right to receive its expected residual returns. MAALP is classified as a VIE because the limited partners lack substantive kick-out rights and substantive participating rights. The Company consolidates all VIEs for which it is the primary beneficiary and uses the equity method to account for investments that qualify as VIEs but for which it is not the primary beneficiary. In determining whether the Company is the primary beneficiary of a VIE, management considers both qualitative and quantitative factors, including, but not limited to, those activities that most significantly impact the VIE's economic performance and which party controls such activities. The Company uses the equity method of accounting for its investments in entities for which the Company exercises significant influence, but does not have the ability to exercise control. The factors considered in determining whether the Company has the ability to exercise control include ownership of voting interests and participatory rights of investors (see “Investments in Unconsolidated Affiliates” below).
Changes in Presentation	Changes in Presentation In order to simplify the Company's presentation of cash flows from financing activities within the Consolidated Statements of Cash Flows, the Company combined “Repurchase of common stock / units”; “Debt prepayment and extinguishment costs”; “Proceeds from issuances of common shares / units”; and “Exercise of stock / unit options” into one line, “Net change in other financing activities” within the cash flows from financing activities section. No presentation changes were made to the cash flows from operating or investing activities sections of the Consolidated Statements of Cash Flows. Prior year amounts have been changed to conform to the Company's current year presentation. These changes in presentation had no effect on the Company's ending cash, cash equivalents and restricted cash balances and did not impact the classification of cash flows between operating, investing and financing activities.
Noncontrolling Interests	Noncontrolling Interests As of December 31, 2019, the Company had two types of noncontrolling interests with respect to its consolidated subsidiaries, (1) noncontrolling interests related to the common unitholders of its Operating Partnership and (2) noncontrolling interests related to its consolidated real estate entities. The noncontrolling interests relating to the limited partnership interests in the Operating Partnership are owned by the holders of the Class A OP Units. MAA is the sole general partner of the Operating Partnership and holds all of the outstanding Class B OP Units. Net income (after allocations to preferred ownership interests) is allocated to MAA and the noncontrolling interests based on their respective ownership percentages of the Operating Partnership. Issuance of additional Class A OP Units or Class B OP Units changes the ownership percentage of both the noncontrolling interests and MAA. The issuance of Class B OP Units generally occurs when MAA issues common stock and the issuance proceeds are contributed to the Operating Partnership in exchange for Class B OP Units equal to the number of shares of MAA's common stock issued. At each reporting period, the allocation between total MAA shareholders’ equity and noncontrolling interests is adjusted to account for the change in the respective percentage ownership of the underlying equity of the Operating Partnership. MAA’s Board of Directors established economic rights in respect to each Class A OP Unit that were equivalent to the economic rights in respect to each share of MAA common stock. See Note 9 for additional details. The noncontrolling interests relating to the Company’s consolidated real estate entities are owned by private real estate companies that are generally responsible for the development and construction of the apartment communities that are owned through the consolidated real estate entities with a noncontrolling interest. The entities were determined to be VIE’s with the Company designated as the primary beneficiary. As a result, the accounts of the entities are consolidated by the Company. During the year ended December 31, 2019, the Company acquired a partial ownership interest in two consolidated real estate entities and acquired the noncontrolling interest of one consolidated real estate entity for cash proceeds of $10.9 million. As of December 31, 2019, the consolidated assets and liabilities of the Company’s consolidated real estate entities with a noncontrolling interest were $46.0 million and $3.2 million, respectively. As of December 31, 2018, the consolidated assets and liabilities of the Company’s consolidated real estate entity with a noncontrolling interest were $85.7 million and $1.3 million, respectively.
Use of Estimates	Use of Estimates Management has made a number of estimates and assumptions relating to the reporting of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported amounts of revenues and expenses to prepare these financial statements and notes in conformity with GAAP. Actual results could differ from those estimates.
Rental Costs	Rental Costs Costs associated with rental activities are expensed as incurred and include advertising expenses, which were $20.8 million, $20.2 million, and $18.8 million for the years ended December 31, 2019, 2018 and 2017, respectively.
Real Estate Assets and Depreciation and Amortization	Real Estate Assets and Depreciation and Amortization Real estate assets are carried at depreciated cost and consist of land, buildings and improvements and other and development and capital improvements in progress (see “Development Costs” below). Repairs and maintenance costs are expensed as incurred, while significant improvements, renovations and recurring capital replacements are capitalized and depreciated over their estimated useful lives. Recurring capital replacements typically include scheduled carpet replacement, new roofs, HVAC units, plumbing, concrete, masonry and other paving, pools and various exterior building improvements. In addition to these costs, the Company also capitalizes salary costs directly identifiable with renovation work. These expenditures extend the useful life of the property and increase the property’s fair market value. The cost of interior painting and blinds are typically expensed as incurred. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, which range from five to 40 years. The Consolidated Balance Sheets line “Buildings and improvements and other” includes land improvements and buildings, which have a useful life ranging from eight to 40 years, as well as furniture, fixtures and equipment, which have a useful life of five years.
Development Costs	Development Costs Development projects and the related carrying costs, including interest, property taxes, insurance and allocated direct development salary costs during the construction period, are capitalized and reported in the accompanying Consolidated Balance Sheets as “Development and capital improvements in progress” during the construction period. Interest is capitalized in accordance with accounting standards governing the capitalization of interest. Upon completion and certification for occupancy of individual buildings or floors within a development, amounts representing the completed portion of total estimated development costs for the project are transferred to “Buildings and improvements and other” as real estate held for investment. Capitalization of interest, property taxes, insurance and allocated direct development salary costs cease upon the transfer. The assets are depreciated over their estimated useful lives. Total capitalized costs (including capitalized interest, salaries and real estate taxes) during the years ended December 31, 2019, 2018 and 2017 were $6.5 million, $4.2 million and $11.0 million, respectively. Certain costs associated with the lease-up of development projects, including cost of model units, furnishings and signs, are capitalized and amortized over their respective estimated useful lives. All other costs relating to renting development projects are expensed as incurred.
Acquisition of Real Estate Assets	Acquisition of Real Estate Assets In accordance with Accounting Standards Codification, or ASC, Topic 805, Business Combinations, most acquisitions of operating properties qualify as an asset acquisition. Accordingly, the cost of the real estate acquired, including acquisition costs, is allocated to the acquired tangible assets, consisting of land, buildings and improvements and other, and identified intangible assets, consisting of the value of in-place leases and other contracts, on a relative fair value basis. Acquisition costs include appraisal fees, title fees, broker fees and other legal costs to acquire the property. The purchase price of an acquired property is allocated based on the relative fair value of the individual components as a proportion of the total assets acquired. The Company allocates the cost of the tangible assets of an acquired property by valuing the building as if it were vacant, based on management’s determination of the relative fair values of these assets. Management determines the as-if-vacant fair value of a building using methods similar to those used by independent appraisers. These methods include using stabilized net operating income, or NOI, and market specific capitalization and discount rates. In allocating the cost of identified intangible assets of an acquired property, the in-place leases are valued based on current rent rates and time and cost to lease a unit. Management concluded that the residential leases acquired in connection with each of its property acquisitions approximate at-market rates since the residential lease terms generally do not extend beyond one year. For residential leases, the fair value of the in-place leases and resident relationships is amortized over six months, which represents the estimated remaining term of the tenant leases. For retail and commercial leases, the fair value of in-place leases and tenant relationships is amortized over the remaining term of the leases. The net amount of these lease intangibles included in “Other assets” totaled $2.6 million and $3.9 million as of December 31, 2019 and 2018, respectively.
Impairment of Long-lived Assets, including Goodwill	Impairment of Long-lived Assets The Company accounts for long-lived assets in accordance with the provisions of accounting standards for the impairment or disposal of long-lived assets. Management periodically evaluates long-lived assets, including investments in real estate, for indicators that would suggest that the carrying amount of the assets may not be recoverable. The judgments regarding the existence of such indicators are based on factors such as operating performance, market conditions and legal factors. Long-lived assets, such as real estate assets, equipment and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of are separately presented in the Consolidated Balance Sheets and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated. The assets and liabilities of a disposed group or a property classified as held for sale are presented separately in the appropriate asset and liability sections of the Consolidated Balance Sheets.
Undeveloped Land	Undeveloped Land Undeveloped land includes sites intended for future multifamily developments, sites for future commercial development and sites intended for residential use, which are carried at the lower of cost or fair value in accordance with GAAP. Any costs incurred prior to commencement of pre-development activities are expensed as incurred.
Investments in Unconsolidated Affiliates	Investments in Unconsolidated Affiliates The Company uses the equity method to account for its investments in a real estate joint venture and a limited partnership that both qualify as a VIE. Management determined the Company is not the primary beneficiary in either investment but does have the ability to exert significant influence over the operations and financial policies of the real estate joint venture and considers its investment in the limited partnership to be more than minor. As of December 31, 2019 and 2018, the Company's investment in the real estate joint venture was $43.7 million and $44.2 million, respectively. As of December 31, 2019 and 2018, the Company's investment in the limited partnership was $13.1 million and $3.8 million, respectively, and is included in “Other assets” in the accompanying Consolidated Balance Sheets. As of December 31, 2019, the Company was committed until September 2022 to make additional capital contributions totaling $8.2 million if and when called by the general partner of the limited partnership.
Cash and Cash Equivalents	Cash and Cash Equivalents Investments in money market accounts and certificates of deposit with original maturities of three months or less are considered to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash consists of security deposits required to be held separately, escrow deposits held by lenders for property taxes, insurance, debt service and replacement reserves, and exchanges under Section 1031(b) of the Internal Revenue Code of 1986, as amended, or the Code. Section 1031(b) exchanges are presented within cash, cash equivalents and restricted cash reported in the Consolidated Statements of Cash Flows.
Other Assets	Other Assets Other assets consist primarily of receivables and deposits from residents, the value of derivative contracts, right-of-use lease assets, investment in a limited partnership, deferred rental concessions, deferred financing costs relating to a revolving credit facility and other prepaid expenses. Also included in other assets are the fair market value of in-place leases and resident relationships, net of accumulated amortization.
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses consist of accrued dividends payable, accrued real estate taxes, accrued interest payable, accrued loss contingencies (see Note 11), accounts payable, right-of-use lease liabilities, security deposits not related to restricted cash, other accrued expenses, and unearned income. Significant accruals include accrued dividends payable of $118.3 million and $113.2 million as of December 31, 2019 and 2018, respectively; accrued real estate taxes of $131.9 million and $123.5 million as of December 31, 2019 and 2018, respectively; unearned income of $42.0 million and $41.1 million as of December 31, 2019 and 2018, respectively; accrued loss contingencies of $8.6 million and $8.7 million as of December 31, 2019 and 2018, respectively; security deposits of $19.4 million and $18.7 million as of December 31, 2019 and 2018, respectively; and accrued interest payable of $21.4 million and $15.1 million as of December 31, 2019 and 2018, respectively.
Income Taxes	Income Taxes MAA has elected to be taxed as a REIT under the Code and intends to continue to operate in such a manner. The current and continuing qualification as a REIT depends on MAA's ability to meet the various requirements imposed by the Code, which are related to organizational structure, distribution levels, diversity of stock ownership and certain requirements with respect to the nature and diversity of MAA’s assets and sources of MAA’s gross income. As long as MAA qualifies for taxation as a REIT, it will generally not be subject to United States federal corporate income tax on its taxable income that is currently distributed to shareholders. This treatment substantially eliminates the “double taxation” (i.e., income taxation at both the corporate and shareholder levels) that generally results from an investment in a corporation. Even if MAA qualifies as a REIT, MAA may be subject to United States federal income and excise taxes in certain situations, such as if MAA fails to distribute timely all of its taxable income with respect to a taxable year. MAA also will be required to pay a 100% tax on any net income on non-arm’s length transactions between MAA and one of its taxable REIT subsidiaries, or TRS. Furthermore, MAA and its shareholders may be subject to state or local taxation in various state or local jurisdictions, including those in which MAA transacts business or its shareholders reside, and the applicable state and local tax laws may not conform to the United States federal income tax treatment. Any taxes imposed on MAA would reduce its operating cash flows and net income. The Company has elected TRS status for certain of its corporate subsidiaries. As a result, the TRS incur both federal and state income taxes on any taxable income after consideration of any net operating losses. The TRS use the liability method of accounting for income taxes. Deferred income tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. A valuation allowance is provided when it is more likely than not that all or some portion of the deferred tax assets will not be realized. The Company recognizes liabilities for uncertain income tax positions based on a two-step process. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step requires the Company to estimate and measure the tax benefit as the largest amount that is more likely than not to be realized upon ultimate settlement. See Note 7 for additional disclosures regarding income taxes.
Fair value of derivative financial instruments	Fair Value Measurements The Company applies the guidance in ASC Topic 820, Fair Value Measurements and Disclosures, to the valuation of real estate assets recorded at fair value, to its impairment valuation analysis of real estate assets, to its disclosure of the fair value of financial instruments, principally indebtedness and to its derivative financial instruments. Fair value disclosures required under ASC Topic 820 as well as the Company's derivative accounting policies are summarized in Note 6 utilizing the following hierarchy: Level 1 - Quoted prices in active markets for identical assets or liabilities that are accessible at the measurement date. Level 2 - Inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly. Level 3 - Unobservable inputs for the assets or liability.
Leases	Leases In 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, 2016-02, Leases (Topic 842), which established new principles, presentation and disclosure requirements for lease accounting for both the lessee and lessor. On January 1, 2019, management adopted ASU 2016-02 using the modified retrospective transition approach with an effective date as of the adoption date and elected certain practical expedients allowed by the new standard. Under the new standard, lessors are generally required to account for leases in a similar manner as previous lease accounting guidance; however, certain aspects of the new standard are aligned with the recently adopted revenue recognition standard. Lessees are required to record most leases on the balance sheet and recognize lease expense in the income statement in a manner similar to previous practice. The new standard requires a lessee to recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for all leases with terms of more than twelve months. Expenses related to leases determined to be operating leases are recognized on a straight-line basis, while expenses related to leases determined to be financing leases are recognized based on an effective interest method in which interest and amortization are presented separately in the income statement. Comparative periods presented in this Annual Report on Form 10-K continue to apply guidance in ASC Topic 840, Leases, and have not been recast as the Company adopted the new standard using the modified retrospective transition approach effective as of January 1, 2019. The adoption of the new lease standard has not resulted in a significant change in the accounting for the Company’s rental revenues as the Company's residential, retail and commercial leases, where it is the lessor, will continue to be accounted for as operating leases. Management has elected available practical expedients that provide lessors an option not to separate lease and non-lease components when certain criteria are met, and instead, allow for those components to be accounted for as a single lease component. Beginning with the effective date of the adoption of the new standard, rental revenues and non-lease reimbursable property revenues meet the criteria to be aggregated into a single lease component and are reported in the line item, “Rental revenues”, as presented in the disaggregation of the Company's revenues in Note 13. The Company is the lessee under certain ground, office, equipment and other operating leases. Based on its election of the package of practical expedients provided in ASU 2016-02, the Company did not reassess the classification of existing leases with its adoption of ASC Topic 842. The Company’s existing leases as of January 1, 2019 have continued to be accounted for as operating leases; however, if contracts are modified subsequent to the adoption of the new standard, the Company is required to reassess the contracts using guidance provided under ASC Topic 842. The Company recognized total right-of-use assets of $54.3 million within “Other assets” and related lease obligations of $33.6 million within “Accrued expenses and other liabilities” in its Consolidated Balance Sheets for leases in effect as of January 1, 2019. As of December 31, 2019, right-of-use assets and the related lease obligations totaled $53.8 million and $33.1 million, respectively. As most leases do not provide a readily determinable implicit rate to discount future minimum lease payments to present value, management estimated the Company's incremental borrowing rate based on information available as of the date of adoption and based on the remaining lease terms as of the date of initial application. Operating leases recognized upon adoption had a weighted-average remaining lease term of approximately 33 years and management estimated a weighted-average discount rate of approximately 4.4%. Operating leases as of December 31, 2019 have a weighted-average remaining lease term of approximately 32 years and a weighted-average discount rate of approximately 4.4%. Lease expense recognized for the years ended December 31, 2019, 2018 and 2017 was immaterial to the Company and was recognized in a similar manner for all years presented. Cash paid for amounts included in the measurement of operating lease liabilities during the year ended December 31, 2019 was also immaterial.
Revenue Recognition	Revenue Recognition The Company primarily leases multifamily residential apartments under operating leases generally due on a monthly basis with terms of approximately one year or less, which are recorded as operating leases. Rental revenues are recognized in accordance with ASC Topic 842 using a method that represents a straight-line basis over the term of the lease. In addition, in circumstances where a lease incentive is provided to tenants, the incentive is recognized as a reduction of rental revenues on a straight-line basis over the reasonably assured lease term. Rental revenues represent approximately 93% of the Company's total revenues and include gross rents charged less adjustments for concessions and bad debt. Approximately 6% of the Company's total revenues represents reimbursable property revenues from its tenants for utility reimbursements, which are generally recognized and due on a monthly basis as tenants obtain control of the service over the term of the lease. The remaining 1% of the Company's total revenues represents other non-lease revenues primarily driven by nonrefundable fees and commissions. With the adoption of ASC Topic 842, rental revenues and non-lease reimbursable property revenues meet the criteria to be aggregated into a single lease component and are reported on a combined basis, while non-lease reimbursable property revenues recognized prior to January 1, 2019 is reported as non-lease revenues and recognized in accordance with ASC Topic 606, Revenue Recognition. ASC Topic 606 requires revenue recognized outside of the scope of ASC Topic 842 to be recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services.
Recently Issued Accounting Pronouncement	Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments, which amends the current approach to estimate credit losses on certain financial assets, including trade and other receivables, available-for-sale securities and other financial instruments. The ASU requires entities to estimate a lifetime expected credit loss for most financial instruments, including trade receivables. Subsequent changes in the valuation allowance are recorded in current earnings and reversal of previous losses is permitted. In November 2018, the FASB issued an amendment excluding operating lease receivables accounted for under ASU 2016-02 from the scope of the new credit losses standard. The Company has completed its analysis regarding the measurement of estimated credit losses and the impact this ASU will have on the Company. Management elected to adopt this standard on January 1, 2020. The adoption of ASU No. 2016-13 has not resulted in significant changes in the accounting for the Company’s approach to estimate credit losses on financial assets, as substantially all of the Company’s financial assets are operating lease receivables.

Organization and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Basis of Presentation And Principles Of Consolidation

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements have been prepared by the Company's management in accordance with United States generally accepted accounting principles, or GAAP, and applicable rules and regulations of the Securities and Exchange Commission, or the SEC. The consolidated financial statements of MAA presented herein include the accounts of MAA, the Operating Partnership and all other subsidiaries in which MAA has a controlling financial interest. MAA owns, directly or indirectly, approximately 80% to 100% of all consolidated subsidiaries, including the Operating Partnership. The consolidated financial statements of MAALP presented herein include the accounts of MAALP and all other subsidiaries in which MAALP has a controlling financial interest. MAALP owns, directly or indirectly, 80% to 100% of all consolidated subsidiaries. In management's opinion, all adjustments necessary for a fair presentation of the consolidated financial statements have been included, and all such adjustments were of a normal recurring nature. All significant intercompany accounts and transactions have been eliminated in consolidation.

The Company invests in entities which may qualify as variable interest entities, or VIEs, and MAALP is considered a VIE. A VIE is a legal entity in which the equity investors lack sufficient equity at risk for the entity to finance its activities without additional subordinated financial support or, as a group, the holders of the equity investment at risk lack the power to direct the activities of a legal entity as well as the obligation to absorb its expected losses or the right to receive its expected residual returns. MAALP is classified as a VIE because the limited partners lack substantive kick-out rights and substantive participating rights. The Company consolidates all VIEs for which it is the primary beneficiary and uses the equity method to account for investments that qualify as VIEs but for which it is not the primary beneficiary. In determining whether the Company is the primary beneficiary of a VIE, management considers both qualitative and quantitative factors, including, but not limited to, those activities that most significantly impact the VIE's economic performance and which party controls such activities. The Company uses the equity method of accounting for its investments in entities for which the Company exercises significant influence, but does not have the ability to exercise control. The factors considered in determining whether the Company has the ability to exercise control include ownership of voting interests and participatory rights of investors (see “Investments in Unconsolidated Affiliates” below).

Changes in Presentation

In order to simplify the Company's presentation of cash flows from financing activities within the Consolidated Statements of Cash Flows, the Company combined “Repurchase of common stock / units”; “Debt prepayment and extinguishment costs”; “Proceeds from issuances of common shares / units”; and “Exercise of stock / unit options” into one line, “Net change in other financing activities” within the cash flows from financing activities section. No presentation changes were made to the cash flows from operating or investing activities sections of the Consolidated Statements of Cash Flows. Prior year amounts have been changed to conform to the Company's current year presentation. These changes in presentation had no effect on the Company's ending cash, cash equivalents and restricted cash balances and did not impact the classification of cash flows between operating, investing and financing activities.

Noncontrolling Interests

As of December 31, 2019, the Company had two types of noncontrolling interests with respect to its consolidated subsidiaries, (1) noncontrolling interests related to the common unitholders of its Operating Partnership and (2) noncontrolling interests related to its consolidated real estate entities. The noncontrolling interests relating to the limited partnership interests in the Operating Partnership are owned by the holders of the Class A OP Units. MAA is the sole general partner of the Operating Partnership and holds all of the outstanding Class B OP Units. Net income (after allocations to preferred ownership interests) is allocated to MAA and the noncontrolling interests based on their respective ownership percentages of the Operating Partnership. Issuance of additional Class A OP Units or Class B OP Units changes the ownership percentage of both the noncontrolling interests and MAA. The issuance of Class B OP Units generally occurs when MAA issues common stock and the issuance proceeds are contributed to the Operating Partnership in exchange for Class B OP Units equal to the number of shares of MAA's common stock issued. At each reporting period, the allocation between total MAA shareholders’ equity and noncontrolling interests is adjusted to account for the change in the respective percentage ownership of the underlying equity of the Operating Partnership. MAA’s Board of Directors established economic rights in respect to each Class A OP Unit that were equivalent to the economic rights in respect to each share of MAA common stock. See Note 9 for additional details.

The noncontrolling interests relating to the Company’s consolidated real estate entities are owned by private real estate companies that are generally responsible for the development and construction of the apartment communities that are owned through the consolidated real estate entities with a noncontrolling interest. The entities were determined to be VIE’s with the Company designated as the primary beneficiary. As a result, the accounts of the entities are consolidated by the Company. During the year ended December 31,

2019, the Company acquired a partial ownership interest in two consolidated real estate entities and acquired the noncontrolling interest of one consolidated real estate entity for cash proceeds of $10.9 million. As of December 31, 2019, the consolidated assets and liabilities of the Company’s consolidated real estate entities with a noncontrolling interest were $46.0 million and $3.2 million, respectively. As of December 31, 2018, the consolidated assets and liabilities of the Company’s consolidated real estate entity with a noncontrolling interest were $85.7 million and $1.3 million, respectively.

Use of Estimates

Management has made a number of estimates and assumptions relating to the reporting of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported amounts of revenues and expenses to prepare these financial statements and notes in conformity with GAAP. Actual results could differ from those estimates.

Rental Costs

Costs associated with rental activities are expensed as incurred and include advertising expenses, which were $20.8 million, $20.2 million, and $18.8 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Real Estate Assets and Depreciation and Amortization

Real estate assets are carried at depreciated cost and consist of land, buildings and improvements and other and development and capital improvements in progress (see “Development Costs” below). Repairs and maintenance costs are expensed as incurred, while significant improvements, renovations and recurring capital replacements are capitalized and depreciated over their estimated useful lives. Recurring capital replacements typically include scheduled carpet replacement, new roofs, HVAC units, plumbing, concrete, masonry and other paving, pools and various exterior building improvements. In addition to these costs, the Company also capitalizes salary costs directly identifiable with renovation work. These expenditures extend the useful life of the property and increase the property’s fair market value. The cost of interior painting and blinds are typically expensed as incurred.

Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, which range from five to 40 years. The Consolidated Balance Sheets line “Buildings and improvements and other” includes land improvements and buildings, which have a useful life ranging from eight to 40 years, as well as furniture, fixtures and equipment, which have a useful life of five years.

Development Costs

Development projects and the related carrying costs, including interest, property taxes, insurance and allocated direct development salary costs during the construction period, are capitalized and reported in the accompanying Consolidated Balance Sheets as “Development and capital improvements in progress” during the construction period. Interest is capitalized in accordance with accounting standards governing the capitalization of interest. Upon completion and certification for occupancy of individual buildings or floors within a development, amounts representing the completed portion of total estimated development costs for the project are transferred to “Buildings and improvements and other” as real estate held for investment. Capitalization of interest, property taxes, insurance and allocated direct development salary costs cease upon the transfer. The assets are depreciated over their estimated useful lives. Total capitalized costs (including capitalized interest, salaries and real estate taxes) during the years ended December 31, 2019, 2018 and 2017 were $6.5 million, $4.2 million and $11.0 million, respectively. Certain costs associated with the lease-up of development projects, including cost of model units, furnishings and signs, are capitalized and amortized over their respective estimated useful lives. All other costs relating to renting development projects are expensed as incurred.

Acquisition of Real Estate Assets

In accordance with Accounting Standards Codification, or ASC, Topic 805, Business Combinations, most acquisitions of operating properties qualify as an asset acquisition. Accordingly, the cost of the real estate acquired, including acquisition costs, is allocated to the acquired tangible assets, consisting of land, buildings and improvements and other, and identified intangible assets, consisting of the value of in-place leases and other contracts, on a relative fair value basis. Acquisition costs include appraisal fees, title fees, broker fees and other legal costs to acquire the property.

The purchase price of an acquired property is allocated based on the relative fair value of the individual components as a proportion of the total assets acquired. The Company allocates the cost of the tangible assets of an acquired property by valuing the building as if it were vacant, based on management’s determination of the relative fair values of these assets. Management determines the as-if-vacant fair value of a building using methods similar to those used by independent appraisers. These methods include using stabilized net operating income, or NOI, and market specific capitalization and discount rates. In allocating the cost of identified intangible assets of an acquired property, the in-place leases are valued based on current rent rates and time and cost to lease a unit. Management concluded that the residential leases acquired in connection with each of its property acquisitions approximate at-market rates since the residential lease terms generally do not extend beyond one year.

For residential leases, the fair value of the in-place leases and resident relationships is amortized over six months, which represents the estimated remaining term of the tenant leases. For retail and commercial leases, the fair value of in-place leases and tenant relationships is amortized over the remaining term of the leases. The net amount of these lease intangibles included in “Other assets” totaled $2.6 million and $3.9 million as of December 31, 2019 and 2018, respectively.

Impairment of Long-lived Assets, including Goodwill

Impairment of Long-lived Assets

The Company accounts for long-lived assets in accordance with the provisions of accounting standards for the impairment or disposal of long-lived assets. Management periodically evaluates long-lived assets, including investments in real estate, for indicators that would suggest that the carrying amount of the assets may not be recoverable. The judgments regarding the existence of such indicators are based on factors such as operating performance, market conditions and legal factors. Long-lived assets, such as real estate assets, equipment and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of are separately presented in the Consolidated Balance Sheets and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated. The assets and liabilities of a disposed group or a property classified as held for sale are presented separately in the appropriate asset and liability sections of the Consolidated Balance Sheets.

Undeveloped Land

Undeveloped land includes sites intended for future multifamily developments, sites for future commercial development and sites intended for residential use, which are carried at the lower of cost or fair value in accordance with GAAP. Any costs incurred prior to commencement of pre-development activities are expensed as incurred.

Investments in Unconsolidated Affiliates

The Company uses the equity method to account for its investments in a real estate joint venture and a limited partnership that both qualify as a VIE. Management determined the Company is not the primary beneficiary in either investment but does have the ability to exert significant influence over the operations and financial policies of the real estate joint venture and considers its investment in the limited partnership to be more than minor. As of December 31, 2019 and 2018, the Company's investment in the real estate joint venture was $43.7 million and $44.2 million, respectively. As of December 31, 2019 and 2018, the Company's investment in the limited partnership was $13.1 million and $3.8 million, respectively, and is included in “Other assets” in the accompanying Consolidated Balance Sheets. As of December 31, 2019, the Company was committed until September 2022 to make additional capital contributions totaling $8.2 million if and when called by the general partner of the limited partnership.

Cash and Cash Equivalents

Investments in money market accounts and certificates of deposit with original maturities of three months or less are considered to be cash equivalents.

Restricted Cash

Restricted cash consists of security deposits required to be held separately, escrow deposits held by lenders for property taxes, insurance, debt service and replacement reserves, and exchanges under Section 1031(b) of the Internal Revenue Code of 1986, as amended, or the Code. Section 1031(b) exchanges are presented within cash, cash equivalents and restricted cash reported in the Consolidated Statements of Cash Flows.

Other Assets

Other assets consist primarily of receivables and deposits from residents, the value of derivative contracts, right-of-use lease assets, investment in a limited partnership, deferred rental concessions, deferred financing costs relating to a revolving credit facility and other prepaid expenses. Also included in other assets are the fair market value of in-place leases and resident relationships, net of accumulated amortization.

Accrued Expenses and Other Liabilities

Accrued expenses consist of accrued dividends payable, accrued real estate taxes, accrued interest payable, accrued loss contingencies (see Note 11), accounts payable, right-of-use lease liabilities, security deposits not related to restricted cash, other accrued expenses, and unearned income. Significant accruals include accrued dividends payable of $118.3 million and $113.2 million as of December 31, 2019 and 2018, respectively; accrued real estate taxes of $131.9 million and $123.5 million as of December 31, 2019 and 2018, respectively; unearned income of $42.0 million and $41.1 million as of December 31, 2019 and 2018, respectively; accrued

loss contingencies of $8.6 million and $8.7 million as of December 31, 2019 and 2018, respectively; security deposits of $19.4 million and $18.7 million as of December 31, 2019 and 2018, respectively; and accrued interest payable of $21.4 million and $15.1 million as of December 31, 2019 and 2018, respectively.

Income Taxes

MAA has elected to be taxed as a REIT under the Code and intends to continue to operate in such a manner. The current and continuing qualification as a REIT depends on MAA's ability to meet the various requirements imposed by the Code, which are related to organizational structure, distribution levels, diversity of stock ownership and certain requirements with respect to the nature and diversity of MAA’s assets and sources of MAA’s gross income. As long as MAA qualifies for taxation as a REIT, it will generally not be subject to United States federal corporate income tax on its taxable income that is currently distributed to shareholders. This treatment substantially eliminates the “double taxation” (i.e., income taxation at both the corporate and shareholder levels) that generally results from an investment in a corporation. Even if MAA qualifies as a REIT, MAA may be subject to United States federal income and excise taxes in certain situations, such as if MAA fails to distribute timely all of its taxable income with respect to a taxable year. MAA also will be required to pay a 100% tax on any net income on non-arm’s length transactions between MAA and one of its taxable REIT subsidiaries, or TRS. Furthermore, MAA and its shareholders may be subject to state or local taxation in various state or local jurisdictions, including those in which MAA transacts business or its shareholders reside, and the applicable state and local tax laws may not conform to the United States federal income tax treatment. Any taxes imposed on MAA would reduce its operating cash flows and net income.

The Company has elected TRS status for certain of its corporate subsidiaries. As a result, the TRS incur both federal and state income taxes on any taxable income after consideration of any net operating losses. The TRS use the liability method of accounting for income taxes. Deferred income tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. A valuation allowance is provided when it is more likely than not that all or some portion of the deferred tax assets will not be realized.

The Company recognizes liabilities for uncertain income tax positions based on a two-step process. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step requires the Company to estimate and measure the tax benefit as the largest amount that is more likely than not to be realized upon ultimate settlement. See Note 7 for additional disclosures regarding income taxes.

Fair value of derivative financial instruments

Fair Value Measurements

The Company applies the guidance in ASC Topic 820, Fair Value Measurements and Disclosures, to the valuation of real estate assets recorded at fair value, to its impairment valuation analysis of real estate assets, to its disclosure of the fair value of financial instruments, principally indebtedness and to its derivative financial instruments. Fair value disclosures required under ASC Topic 820 as well as the Company's derivative accounting policies are summarized in Note 6 utilizing the following hierarchy:

Level 1 - Quoted prices in active markets for identical assets or liabilities that are accessible at the measurement date.

Level 2 - Inputs other than quoted prices that are observable for the asset or liability, either directly or indirectly.

Level 3 - Unobservable inputs for the assets or liability.

Leases

In 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, 2016-02, Leases (Topic 842), which established new principles, presentation and disclosure requirements for lease accounting for both the lessee and lessor. On January 1, 2019, management adopted ASU 2016-02 using the modified retrospective transition approach with an effective date as of the adoption date and elected certain practical expedients allowed by the new standard. Under the new standard, lessors are generally required to account for leases in a similar manner as previous lease accounting guidance; however, certain aspects of the new standard are aligned with the recently adopted revenue recognition standard. Lessees are required to record most leases on the balance sheet and recognize lease expense in the income statement in a manner similar to previous practice. The new standard requires a lessee to recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for all leases with terms of more than twelve months. Expenses related to leases determined to be operating leases are recognized on a straight-line basis, while expenses related to leases determined to be financing leases are recognized based on an effective interest method in which interest and amortization are presented separately in the income statement.

Comparative periods presented in this Annual Report on Form 10-K continue to apply guidance in ASC Topic 840, Leases, and have not been recast as the Company adopted the new standard using the modified retrospective transition approach effective as of January 1, 2019. The adoption of the new lease standard has not resulted in a significant change in the accounting for the Company’s rental

revenues as the Company's residential, retail and commercial leases, where it is the lessor, will continue to be accounted for as operating leases. Management has elected available practical expedients that provide lessors an option not to separate lease and non-lease components when certain criteria are met, and instead, allow for those components to be accounted for as a single lease component. Beginning with the effective date of the adoption of the new standard, rental revenues and non-lease reimbursable property revenues meet the criteria to be aggregated into a single lease component and are reported in the line item, “Rental revenues”, as presented in the disaggregation of the Company's revenues in Note 13.

The Company is the lessee under certain ground, office, equipment and other operating leases. Based on its election of the package of practical expedients provided in ASU 2016-02, the Company did not reassess the classification of existing leases with its adoption of ASC Topic 842. The Company’s existing leases as of January 1, 2019 have continued to be accounted for as operating leases; however, if contracts are modified subsequent to the adoption of the new standard, the Company is required to reassess the contracts using guidance provided under ASC Topic 842.

The Company recognized total right-of-use assets of $54.3 million within “Other assets” and related lease obligations of $33.6 million within “Accrued expenses and other liabilities” in its Consolidated Balance Sheets for leases in effect as of January 1, 2019. As of December 31, 2019, right-of-use assets and the related lease obligations totaled $53.8 million and $33.1 million, respectively. As most leases do not provide a readily determinable implicit rate to discount future minimum lease payments to present value, management estimated the Company's incremental borrowing rate based on information available as of the date of adoption and based on the remaining lease terms as of the date of initial application. Operating leases recognized upon adoption had a weighted-average remaining lease term of approximately 33 years and management estimated a weighted-average discount rate of approximately 4.4%. Operating leases as of December 31, 2019 have a weighted-average remaining lease term of approximately 32 years and a weighted-average discount rate of approximately 4.4%. Lease expense recognized for the years ended December 31, 2019, 2018 and 2017 was immaterial to the Company and was recognized in a similar manner for all years presented. Cash paid for amounts included in the measurement of operating lease liabilities during the year ended December 31, 2019 was also immaterial.

Revenue Recognition

The Company primarily leases multifamily residential apartments under operating leases generally due on a monthly basis with terms of approximately one year or less, which are recorded as operating leases. Rental revenues are recognized in accordance with ASC Topic 842 using a method that represents a straight-line basis over the term of the lease. In addition, in circumstances where a lease incentive is provided to tenants, the incentive is recognized as a reduction of rental revenues on a straight-line basis over the reasonably assured lease term. Rental revenues represent approximately 93% of the Company's total revenues and include gross rents charged less adjustments for concessions and bad debt. Approximately 6% of the Company's total revenues represents reimbursable property revenues from its tenants for utility reimbursements, which are generally recognized and due on a monthly basis as tenants obtain control of the service over the term of the lease. The remaining 1% of the Company's total revenues represents other non-lease revenues primarily driven by nonrefundable fees and commissions.

With the adoption of ASC Topic 842, rental revenues and non-lease reimbursable property revenues meet the criteria to be aggregated into a single lease component and are reported on a combined basis, while non-lease reimbursable property revenues recognized prior to January 1, 2019 is reported as non-lease revenues and recognized in accordance with ASC Topic 606, Revenue Recognition. ASC Topic 606 requires revenue recognized outside of the scope of ASC Topic 842 to be recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services.

Recently Issued Accounting Pronouncement

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments, which amends the current approach to estimate credit losses on certain financial assets, including trade and other receivables, available-for-sale securities and other financial instruments. The ASU requires entities to estimate a lifetime expected credit loss for most financial instruments, including trade receivables. Subsequent changes in the valuation allowance are recorded in current earnings and reversal of previous losses is permitted. In November 2018, the FASB issued an amendment excluding operating lease receivables accounted for under ASU 2016-02 from the scope of the new credit losses standard. The Company has completed its analysis regarding the measurement of estimated credit losses and the impact this ASU will have on the Company. Management elected to adopt this standard on January 1, 2020. The adoption of ASU No. 2016-13 has not resulted in significant changes in the accounting for the Company’s approach to estimate credit losses on financial assets, as substantially all of the Company’s financial assets are operating lease receivables.