Basis of Presentation and Principles of Consolidation and Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying condensed 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 condensed 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 condensed 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 condensed 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).
Reclassifications	Reclassifications In order to present comparative financial statements, certain reclassifications have been made to the Condensed Consolidated Statements of Operations. Prior year amounts have been changed to conform to the Company’s current year presentation. As a result of these reclassifications, $0.8 million of expenses previously reported as “General and administrative expenses” for the three months ended March 31, 2019 have been reclassified to the “Other non-operating expense (income)” line item of the Condensed Consolidated Statements of Operations in this report.
Noncontrolling Interests	Noncontrolling Interests As of March 31, 2020, 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 two 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. As of March 31, 2020, the consolidated assets and liabilities of the Company’s consolidated real estate entities with a noncontrolling interest were $53.1 million and $4.9 million, respectively. 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.
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 two technology-focused limited partnerships that qualify as a VIE. Management determined the Company is not the primary beneficiary in any of these investments 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 partnerships to be more than minor. The Company’s investment in the real estate joint venture was $43.7 million as of March 31, 2020 and December 31, 2019. As of March 31, 2020 and December 31, 2019, the Company’s investments in the technology-focused limited partnerships were $13.9 million and $13.1 million, respectively, and are included in “Other assets” in the accompanying Condensed Consolidated Balance Sheets. As of March 31, 2020, the Company was committed until February 2025 to make additional capital contributions totaling $23.8 million if and when called by the general partners of the limited partnerships.
Fair value of derivative financial instruments	Fair Value Measurements The Company applies the guidance in Accounting Standards Codification (“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 7 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.
Revenue Recognition	Revenue Recognition The Company primarily leases multifamily residential apartments to residents under operating leases generally due on a monthly basis with terms of approximately one year or less. Rental revenues are recognized in accordance with ASC Topic 842, Leases, 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 represent non-lease reimbursable property revenues from its residents for utility reimbursements, which are generally recognized and due on a monthly basis as residents obtain control of the service over the term of the lease. The remaining 1% of the Company’s total revenues represents other non-lease property revenues primarily driven by nonrefundable fees and commissions. In accordance with 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 in the line item “Rental revenues”, as presented in the disaggregation of the Company’s revenues in Note 11. Other non-lease property revenues are accounted for in accordance with ASC Topic 606, Revenue from Contracts with Customers, which 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. Other non-lease property revenues are reported in the line item “Other property revenues”, as presented in the disaggregation of the Company’s revenues in Note 11.
Leases	Leases The Company is the lessee under certain ground, office, equipment and other operational leases, all of which are accounted for as an operating lease in accordance with ASC Topic 842. The Company recognizes a right-of-use asset for the right to use the underlying asset for all leases where the Company is the lessee with terms of more than twelve months, and a related lease liability for the obligation to make lease payments. Expenses related to leases determined to be operating leases are recognized on a straight-line basis. As of March 31, 2020 and December 31, 2019, right-of-use assets recorded within “Other assets” totaled $53.4 million and $53.8 million, respectively, and related lease obligations recorded within “Accrued expenses and other liabilities” totaled $32.8 million and $33.1 million, respectively, in the Condensed Consolidated Balance Sheets. As of March 31, 2020, the Company’s operating leases had 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 three months ended March 31, 2020 and 2019 was immaterial to the Company. Cash paid for amounts included in the measurement of operating lease liabilities during the three months ended March 31, 2020 and 2019 was also immaterial.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“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 ASC Topic 842 from the scope of the new credit losses standard. The Company adopted the standard on January 1, 2020. The adoption of ASU No. 2016-13 did not result 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.

Basis of Presentation and Principles of Consolidation and Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2020

Basis of Presentation and Principles of Consolidation

The accompanying condensed 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 condensed 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 condensed 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 condensed 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).

Reclassifications

In order to present comparative financial statements, certain reclassifications have been made to the Condensed Consolidated Statements of Operations. Prior year amounts have been changed to conform to the Company’s current year presentation. As a result of these reclassifications, $0.8 million of expenses previously reported as “General and administrative expenses” for the three months ended March 31, 2019 have been reclassified to the “Other non-operating expense (income)” line item of the Condensed Consolidated Statements of Operations in this report.

Noncontrolling Interests

As of March 31, 2020, 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 two 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. As of March 31, 2020, the consolidated assets and liabilities of the Company’s consolidated real estate entities with a noncontrolling interest were $53.1 million and $4.9 million, respectively. 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.

Investments in Unconsolidated Affiliates

The Company uses the equity method to account for its investments in a real estate joint venture and two technology-focused limited partnerships that qualify as a VIE. Management determined the Company is not the primary beneficiary in any of these investments 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 partnerships to be more than minor. The Company’s investment in the real estate joint venture was $43.7 million as of March 31, 2020 and December 31, 2019.

As of March 31, 2020 and December 31, 2019, the Company’s investments in the technology-focused limited partnerships were $13.9 million and $13.1 million, respectively, and are included in “Other assets” in the accompanying Condensed Consolidated Balance Sheets. As of March 31, 2020, the Company was committed until February 2025 to make additional capital contributions totaling $23.8 million if and when called by the general partners of the limited partnerships.

Fair value of derivative financial instruments

Fair Value Measurements

The Company applies the guidance in Accounting Standards Codification (“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 7 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.

Revenue Recognition

The Company primarily leases multifamily residential apartments to residents under operating leases generally due on a monthly basis with terms of approximately one year or less. Rental revenues are recognized in accordance with ASC Topic 842, Leases, 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 represent non-lease reimbursable property revenues from its residents for utility reimbursements, which are generally recognized and due on a monthly basis as residents obtain control of the service over the term of the lease. The remaining 1% of the Company’s total revenues represents other non-lease property revenues primarily driven by nonrefundable fees and commissions.

In accordance with 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 in the line item “Rental revenues”, as presented in the disaggregation of the Company’s revenues in Note 11. Other non-lease property revenues are accounted for in accordance with ASC Topic 606, Revenue from Contracts with Customers, which 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. Other non-lease property revenues are reported in the line item “Other property revenues”, as presented in the disaggregation of the Company’s revenues in Note 11.

Leases

The Company is the lessee under certain ground, office, equipment and other operational leases, all of which are accounted for as an operating lease in accordance with ASC Topic 842. The Company recognizes a right-of-use asset for the right to use the underlying asset for all leases where the Company is the lessee with terms of more than twelve months, and a related lease liability for the obligation to make lease payments. Expenses related to leases determined to be operating leases are recognized on a straight-line basis. As of March 31, 2020 and December 31, 2019, right-of-use assets recorded within “Other assets” totaled $53.4 million and $53.8 million, respectively, and related lease obligations recorded within “Accrued expenses and other liabilities” totaled $32.8 million and $33.1 million, respectively, in the Condensed Consolidated Balance Sheets. As of March 31, 2020, the Company’s operating leases had 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 three months ended March 31, 2020 and 2019 was immaterial to the Company. Cash paid for amounts included in the measurement of operating lease liabilities during the three months ended March 31, 2020 and 2019 was also immaterial.

Recently Adopted Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“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 ASC Topic 842 from the scope of the new credit losses standard. The Company adopted the standard on January 1, 2020. The adoption of ASU No. 2016-13 did not result 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.