Mid-America Apartment Communities (MAA) 10-Q 3 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 29, 2019
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	MAA
Entity Registrant Name	MID AMERICA APARTMENT COMMUNITIES INC.,
Entity Central Index Key	0000912595
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		113,995,608
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Limited Partner [Member]
Document Information [Line Items]
Entity Registrant Name	MID-AMERICA APARTMENTS, L.P.
Entity Central Index Key	0001581776
Entity Filer Category	Non-accelerated Filer

MAA Condensed Consolidated Bala

MAA Condensed Consolidated Balance Sheets - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Land	$ 1,878,209	$ 1,868,828
Buildings, Improvements, and Other	11,730,705	11,670,216
Development and capital improvements in progress	57,396	59,506
Real Estate Investment Property, at Cost	13,666,310	13,598,550
Less accumulated depreciation	(2,668,708)	(2,549,287)
Real Estate Investment Property, Net	10,997,602	11,049,263
Undeveloped land	58,257	58,257
Investments in real estate joint ventures	44,138	44,181
Real estate assets, net	11,099,997	11,151,701
Cash and cash equivalents	44,623	34,259
Restricted Cash	14,764	17,414
Other assets	144,378	120,407
Total assets	11,303,762	11,323,781
Liabilities:
Unsecured notes payable	3,886,236	4,053,302
Secured notes payable	661,862	475,026
Accrued expenses and other liabilities	419,320	413,850
Total liabilities	4,967,418	4,942,178
Redeemable stock	11,045	9,414
Shareholders' equity:
Preferred Stock, Value, Outstanding	9	9
Common stock	1,137	1,136
Additional paid-in capital	7,141,544	7,138,170
Accumulated distributions in excess of net income	(1,037,268)	(989,263)
Accumulated other comprehensive income (losses)	(3,300)	(212)
Total MAA shareholders' equity	6,102,122	6,149,840
Noncontrolling interest	218,011	220,043
Total equity	6,320,133	6,369,883
Noncontrolling Interest in Joint Ventures	5,166	2,306
Permanent Equity Attributable to Parent and Noncontrolling Interest	6,325,299	6,372,189
Total liabilities and equity	$ 11,303,762	$ 11,323,781
Redeemable stock, shares issued and outstanding	101,025	98,371

MAALP Condensed Consolidated Ba

MAALP Condensed Consolidated Balance Sheets - Limited Partner [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Land	$ 1,878,209	$ 1,868,828
Buildings, Improvements, and Other	11,730,705	11,670,216
Development and capital improvements in progress	57,396	59,506
Real Estate Investment Property, at Cost	13,666,310	13,598,550
Less accumulated depreciation	(2,668,708)	(2,549,287)
Real Estate Investment Property, Net	10,997,602	11,049,263
Undeveloped land	58,257	58,257
Investments in real estate joint ventures	44,138	44,181
Real estate assets, net	11,099,997	11,151,701
Cash and cash equivalents	44,623	34,259
Restricted Cash	14,764	17,414
Other assets	144,378	120,407
Total assets	11,303,762	11,323,781
Liabilities:
Unsecured notes payable	3,886,236	4,053,302
Secured notes payable	661,862	475,026
Accrued expenses and other liabilities	419,320	413,850
Due to general partner	19	19
Total liabilities	4,967,437	4,942,197
Redeemable units	11,045	9,414
Capital [Abstract]
Preferred Units, Preferred Partners' Capital Accounts	66,840	66,840
General Partners' Capital Account	6,038,625	6,083,142
Limited Partners' Capital Account	218,011	220,043
Accumulated other comprehensive income (losses)	(3,362)	(161)
Capital	6,320,114	6,369,864
Noncontrolling Interest in Joint Ventures	5,166	2,306
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	6,325,280	6,372,170
Total Liabilities and Capital	$ 11,303,762	$ 11,323,781
Redeemable units, units issued and outstanding	101,025	98,371

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Common stock, shares outstanding	113,916,208
General Partners' Capital Account, Units Outstanding	113,916,208
Limited Partners' Capital Account, Units Outstanding	4,105,171
Preferred Stock, Liquidation Preference Per Share	$ 50
Limited Partner [Member]
General Partners' Capital Account, Units Outstanding	113,844,267	113,844,267
Limited Partners' Capital Account, Units Outstanding	4,111,301	4,111,301
Preferred Units, Issued	867,846	867,846
Preferred Units, Outstanding	867,846	867,846
Parent Company [Member]
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	113,916,208	113,844,267
Common stock, shares outstanding	113,916,208	113,844,267
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Shares Issued	867,846	867,846
Preferred Stock, Shares Outstanding	867,846	867,846
Preferred Stock, Liquidation Preference Per Share	$ 50	$ 50

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Limited Partner [Member]
Operating revenues:
Total operating revenues	$ 401,178	$ 386,017
Property operating expenses:
Total property operating expenses	89,793	89,148
Real estate taxes and insurance	59,584	55,256
Depreciation and amortization	122,789	120,744
Operating Expenses	272,166	265,148
Other Cost and Expense, Operating	13,842	12,880
General and administrative expenses	13,153	10,132
Business Combination, Merger and Integration Related Expenses	0	3,799
Interest expense	(45,700)	(40,905)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	13	0
Gain on sale of non-depreciable real estate assets	(8,963)	(150)
Other Nonoperating Income (Expense)	(935)	2,341
Income before income tax expense	66,202	50,962
Income tax expense	(641)	(640)
Income from continuing operations before joint venture activity	65,561	50,322
Gain (loss) from real estate joint ventures	397	498
Consolidated net income	65,958	50,820
Preferred Unit Dividends, Income Statement Impact	922	922
Net income available for Mid-America Apartments, L.P. common unitholders	$ 65,036	$ 49,898
Earnings per common share - basic:
Earnings per unit - basic	$ 0.55	$ 0.42
Earnings per common share - diluted:
Earnings per unit - diluted	$ 0.55	$ 0.42
Parent Company [Member]
Operating revenues:
Total operating revenues	$ 401,178	$ 386,017
Property operating expenses:
Total property operating expenses	89,793	89,148
Real estate taxes and insurance	59,584	55,256
Depreciation and amortization	122,789	120,744
Operating Expenses	272,166	265,148
Other Cost and Expense, Operating	13,842	12,880
General and administrative expenses	13,153	10,132
Business Combination, Merger and Integration Related Expenses	0	3,799
Interest expense	(45,700)	(40,905)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	13	0
Gain on sale of non-depreciable real estate assets	(8,963)	(150)
Other Nonoperating Income (Expense)	(935)	2,341
Income before income tax expense	66,202	50,962
Income tax expense	(641)	(640)
Income from continuing operations before joint venture activity	65,561	50,322
Gain (loss) from real estate joint ventures	397	498
Consolidated net income	65,958	50,820
Net income attributable to noncontrolling interests	2,298	1,801
Net income available for shareholders	63,660	49,019
Preferred Stock Dividends, Income Statement Impact	922	922
Net income available for MAA common shareholders	$ 62,738	$ 48,097
Earnings per common share - basic:
Earnings Per Share, Basic	$ 0.55	$ 0.42
Earnings per common share - diluted:
Earnings Per Share, Diluted	$ 0.55	$ 0.42

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Limited Partner [Member]
Consolidated net income	$ 65,958	$ 50,820
Unrealized (loss) gain from the effective portion of derivative instruments	(2,456)	832
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(745)	(193)
Comprehensive income attributable to Mid-America Apartments, L.P.	62,757	51,459
Parent Company [Member]
Consolidated net income	65,958	50,820
Unrealized (loss) gain from the effective portion of derivative instruments	(2,456)	832
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(745)	(193)
Total comprehensive income	62,757	51,459
Less: comprehensive income attributable to noncontrolling interests	(2,185)	(1,830)
Comprehensive income attributable to MAA	$ 60,572	$ 49,629

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Parent Company [Member]
Cash flows from operating activities:
Consolidated net income	$ (65,958)	$ (50,820)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(123,082)	(121,361)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	13	0
Gain on sale of non-depreciable real estate assets	(8,963)	(150)
Stock compensation expense	4,785	4,024
Amortization of debt premium	1,747	(1,569)
Proceeds from Other Operating Activities	(31,944)	(21,782)
Net cash provided by operating activities	154,678	152,704
Cash flows from investing activities:
Purchases of real estate and other assets	(13,595)	0
Normal capital improvements	(53,214)	(51,775)
Proceeds from Equity Method Investment, Distribution, Return of Capital	43	0
Contributions to Real Estate Joint Ventures	0	(750)
Proceeds from disposition of real estate assets	13,882	5,860
Net cash (used in) provided by investing activities	(52,884)	(46,665)
Cash flows from financing activities:
Proceeds from Lines of Credit	145,000	150,000
Repayments of Lines of Credit	610,000	110,000
Proceeds from notes payable	490,435	0
Principal payments on notes payable	(1,847)	(41,042)
Payment of deferred financing costs	4,705	0
Proceeds from Stock Options Exercised	200	600
Distributions to noncontrolling interests	(3,947)	(3,865)
Dividends paid on common shares	(109,324)	(104,876)
Dividends, Preferred Stock, Cash	(922)	(922)
Proceeds from (Payments for) Other Financing Activities	1,230	(2,091)
Net cash used in financing activities	(94,080)	(112,796)
Net (decrease) increase in cash and cash equivalents	7,714	(6,757)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	51,673	88,867
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	59,387	82,110
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	44,623	59,706
Restricted Cash	14,764	22,404
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	59,387	82,110
Supplemental disclosure of cash flow information:
Interest paid	18,322	24,889
Income Taxes Paid	59	2,522
Supplemental disclosure of noncash investing and financing activities:
Conversion of units to shares of common stock	336	2,780
Accrued construction in progress	15,155	14,640
Interest capitalized	388	795
Marked To Market Adjustment On Derivative Instruments	3,633	(1,363)
Limited Partner [Member]
Cash flows from operating activities:
Consolidated net income	(65,958)	(50,820)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(123,082)	(121,361)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	13	0
Gain on sale of non-depreciable real estate assets	(8,963)	(150)
Stock compensation expense	4,785	4,024
Amortization of debt premium	1,747	(1,569)
Proceeds from Other Operating Activities	(31,944)	(21,782)
Net cash provided by operating activities	154,678	152,704
Cash flows from investing activities:
Purchases of real estate and other assets	(13,595)	0
Normal capital improvements	(53,214)	(51,775)
Proceeds from Equity Method Investment, Distribution, Return of Capital	43	0
Contributions to Real Estate Joint Ventures	0	(750)
Proceeds from disposition of real estate assets	13,882	5,860
Net cash (used in) provided by investing activities	(52,884)	(46,665)
Cash flows from financing activities:
Proceeds from Lines of Credit	145,000	150,000
Repayments of Lines of Credit	610,000	110,000
Proceeds from notes payable	490,435	0
Principal payments on notes payable	(1,847)	(41,042)
Payment of deferred financing costs	4,705	0
Distributions paid on common units	(113,271)	(108,741)
Dividends, Preferred Stock, Cash	(922)	(922)
Proceeds from (Payments for) Other Financing Activities	1,230	(2,091)
Net cash used in financing activities	(94,080)	(112,796)
Net (decrease) increase in cash and cash equivalents	7,714	(6,757)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	51,673	88,867
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	59,387	82,110
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	44,623	59,706
Restricted Cash	14,764	22,404
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	59,387	82,110
Supplemental disclosure of cash flow information:
Interest paid	18,322	24,889
Income Taxes Paid	59	2,522
Supplemental disclosure of noncash investing and financing activities:
Accrued construction in progress	15,155	14,640
Interest capitalized	388	795
Marked To Market Adjustment On Derivative Instruments	$ 3,633	$ (1,363)

Basis of Presentation and Princ

Basis of Presentation and Principles of Consolidation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Consolidation and Basis of Presentation and Significant Accounting Policies [Abstract]
Consolidation and Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Principles of Consolidation and Significant Accounting Policies Unless the context otherwise requires, all references to the "Company" refer collectively to Mid-America Apartment Communities, Inc., together with its consolidated subsidiaries, including Mid-America Apartments, L.P. Unless the context otherwise requires, all references to "MAA" refer only to Mid-America Apartment Communities, Inc., and not any of its consolidated subsidiaries. Unless the context otherwise requires, the references to the "Operating Partnership" or "MAALP" refer to Mid-America Apartments, L.P. together with its consolidated subsidiaries. "Common stock" refers to the common stock of MAA and, unless the context otherwise requires, "shareholders" refers to the holders of shares of MAA’s common stock. The common units of limited partnership interests in the Operating Partnership are referred to as "OP Units," and the holders of the OP Units are referred to as "common unitholders". As of March 31, 2019 , MAA owned 113,916,208 OP Units (or 96.5% of the total number of OP Units). MAA conducts substantially all of its business and holds substantially all of its assets, directly or indirectly, through the Operating Partnership, and by virtue of its ownership of the OP Units and being the Operating Partnership's sole general partner, MAA has the ability to control all of the day-to-day operations of the Operating Partnership. Management believes combining the notes to the condensed consolidated financial statements of MAA and the Operating Partnership results in the following benefits: • enhances readers' understanding of MAA and the Operating Partnership by enabling the reader to view the business as a whole in the same manner that management views and operates the business; • eliminates duplicative disclosure and provides a more streamlined and readable presentation since a substantial portion of the disclosure applies to both MAA and the Operating Partnership; and • creates time and cost efficiencies through the preparation of one combined set of notes instead of two separate sets. MAA is a multifamily focused, self-administered and self-managed real estate investment trust, or REIT. Management operates MAA and the Operating Partnership as one business. The management of the Company is comprised of individuals who are officers of MAA and employees of the Operating Partnership. Management believes it is important to understand the few differences between MAA and the Operating Partnership in the context of how MAA and the Operating Partnership operate as a consolidated company. MAA and the Operating Partnership are structured as an umbrella partnership REIT, or UPREIT. MAA's interest in the Operating Partnership entitles MAA to share in cash distributions from, and in the profits and losses of, the Operating Partnership in proportion to MAA's percentage interest therein and entitles MAA to vote on substantially all matters requiring a vote of the partners. MAA's only material asset is its ownership of limited partnership interests in the Operating Partnership (other than cash held by MAA from time to time); therefore, MAA's primary function is acting as the sole general partner of the Operating Partnership, issuing public equity from time to time and guaranteeing certain debt of the Operating Partnership. The Operating Partnership holds, directly or indirectly, all of the Company's real estate assets. Except for net proceeds from public equity issuances by MAA, which are contributed to the Operating Partnership in exchange for limited partnership interests, the Operating Partnership generates the capital required by the business through the Operating Partnership's operations, direct or indirect incurrence of indebtedness and issuance of OP Units. The presentations of MAA's shareholders' equity and the Operating Partnership's capital are the principal areas of difference between the condensed consolidated financial statements of MAA and those of the Operating Partnership. MAA's shareholders' equity may include shares of preferred stock, shares of common stock, additional paid-in capital, cumulative earnings, cumulative distributions, noncontrolling interest, treasury shares, accumulated other comprehensive income and redeemable common stock. The Operating Partnership's capital may include common capital and preferred capital of the general partner (MAA), limited partners' common capital and preferred capital, noncontrolling interest, accumulated other comprehensive income and redeemable common units. Holders of OP Units (other than MAA and its subsidiaries) may require the Operating Partnership to redeem their OP Units from time to time, in which case the Operating Partnership may, at its option, pay the redemption price either in cash (in an amount per OP Unit equal, in general, to the average closing price of MAA's common stock on the New York Stock Exchange, or NYSE, over a specified period prior to the redemption date) or by delivering one share of MAA's common stock (subject to adjustment under specified circumstances) for each OP Unit so redeemed. Organization of Mid-America Apartment Communities, Inc. The Company owns, operates, acquires and selectively develops apartment communities primarily located in the Southeast, Southwest and Mid-Atlantic regions of the United States. As of March 31, 2019 , the Company owned and operated 303 apartment communities through the Operating Partnership and its subsidiaries and had an ownership interest in one apartment community through an unconsolidated real estate joint venture. As of March 31, 2019 , the Company had five development communities under construction totaling 1,090 apartment units. Total expected costs for these five development projects are $230.5 million , of which $59.5 million had been incurred through March 31, 2019 . The Company expects to complete two developments in the second half of 2019, one development in the first half of 2020, one development in the second half of 2020 and one development in the first half of 2021. Thirty of the Company's apartment communities include retail components with approximately 615,000 square feet of gross leasable space. The Company also has four commercial properties with approximately 260,000 square feet of combined gross leasable area. The Company’s apartment communities and commercial properties are located across 17 states and the District of Columbia. 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, since 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 an effort to simplify the Company's presentation of cash flows from financing activities within the condensed consolidated statements of cash flows, the Company combined "Repurchase of common stock"; "Debt prepayment and extinguishment costs"; "Proceeds from issuances of common shares"; and "Exercise of stock 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 condensed 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 March 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 (see below) and (2) noncontrolling interest related to its consolidated real estate entities (see "Investment in Consolidated Real Estate Entities" below). The noncontrolling interests in the accompanying condensed consolidated financial statements 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. Investments in Unconsolidated Affiliates Through its investment in a limited liability company, or the Apartment LLC, the Company together with an institutional investor indirectly owns one apartment community, Post Massachusetts Avenue, located in Washington, D.C. The Company owned a 35.0% equity interest in the unconsolidated real estate joint venture as of March 31, 2019 and provides property and asset management services to the Apartment LLC for which it earns fees. The joint venture was determined to be a VIE, but the Company is not designated as a primary beneficiary. As a result, the Company accounts for its investment in the Apartment LLC using the equity method of accounting as the Company is able to exert significant influence over the joint venture but does not have a controlling interest. As of March 31, 2019 , the Company's investment in the Apartment LLC totaled $44.1 million . In September 2017, a subsidiary of the Operating Partnership invested in a limited partnership, Real Estate Technology Ventures, L.P. As of March 31, 2019 , the Operating Partnership indirectly owned 20.7% of the limited partnership. The limited partnership was determined to be a VIE, but the Company is not designated as a primary beneficiary. As a result, the Company accounts for its investment in the limited partnership using the equity method of accounting as the investment is considered more than minor. As of March 31, 2019 , the Company's investment in the limited partnership totaled $3.7 million and is included in "Other assets" in the accompanying Condensed Consolidated Balance Sheet. As of March 31, 2019 , the Company was committed to make additional capital contributions totaling $13.6 million if and when called by the general partner of the limited partnership and until September 2022. Investments in Consolidated Real Estate Entities The Company owns a 92.5% equity interest in a consolidated real estate entity that developed, constructed and operates a 359 -unit apartment community in Denver, Colorado. The owner of the remaining 7.5% equity interest, a private real estate company, was generally responsible for the development and construction of the community, which was completed during the year ended December 31, 2018 . The Company will continue to operate and manage the community. The entity was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the entity are consolidated by the Company. As of March 31, 2019 , the consolidated assets and liabilities included buildings and improvements and other, net of accumulated depreciation of $69.8 million ; land of $14.9 million ; and accrued expenses and other liabilities of $1.0 million . During the first quarter of 2019, the Company acquired an 80.0% equity interest in a consolidated real estate entity that will develop, construct and operate an apartment community in Phoenix, Arizona. The joint venture acquired the land site and initiated development of the apartment community in the first quarter of 2019. The owner of the remaining 20.0% equity interest, a private real estate company, is responsible for the development and construction of the community, and the Company will operate and manage the community upon its completion. The entity was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the entity are consolidated by the Company. As of March 31, 2019 , the consolidated assets and liabilities included development and capital improvements in process of $4.7 million ; land of $9.4 million ; and accrued expenses and other liabilities of $0.7 million . Fair Value Measurements The Company applies the guidance in Accounting Standards Codification, or ASC, Topic 820, Fair Value Measurements and Disclosures , to the valuation of real estate assets recorded at fair value, if any; 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 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. Leases In 2016, the Financial Accounting Standard 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 required to account for leases in a similar manner as previous lease accounting guidance but aligned with the newly 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 Quarterly Report on Form 10-Q 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. Thus, beginning with the effective date of the adoption of the new standard, January 1, 2019, 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 11. 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 will continue to be accounted for as operating leases; however, if contracts are modified subsequent to the adoption of ASC Topic 842, the Company will be 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" on its Condensed Consolidated Balance Sheets for leases in effect as of January 1, 2019. 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 have a weighted-average remaining lease term of approximately 33 years and a weighted-average discount rate of approximately 4.4% . Lease expense for the three months ended March 31, 2019 , recognized under ASC Topic 842, continued to be immaterial for the Company and was recognized in a similar manner as compared to the three months ended March 31, 2018 . Cash paid for amounts included in the measurement of operating lease liabilities during the three months ended March 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 market rent less adjustments for concessions, vacancy loss 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 to be reported in a single line, while non-lease reimbursable property revenues recognized prior to January 1, 2019 will continue to be reported as non-lease revenues and recognized in accordance with ASC Topic 606, Revenue Recognition. The guidance requires that revenue recognized outside of the scope of ASC Topic 842 is 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.

Earnings Per Common Share of MA

Earnings Per Common Share of MAA	3 Months Ended
	Mar. 31, 2019
Earnings Per Common Share of MAA [Abstract]
Earnings Per Share [Text Block]	Earnings per Common Share of MAA Basic earnings per share is computed using the two-class method by dividing net income available to MAA common shareholders by the weighted average number of common shares outstanding during the period. All outstanding unvested restricted share awards contain rights to non-forfeitable dividends and participate in undistributed earnings with shareholders and, accordingly, are considered participating securities that are included in the two-class method of computing basic earnings per share. Both the unvested restricted shares and other potentially dilutive common shares, and the related impact to earnings, are considered when calculating earnings per share on a diluted basis with diluted earnings per share being the more dilutive of the treasury stock or two-class methods. OP Units are included in dilutive earnings per share calculations when the units are dilutive to earnings per share. For the three months ended March 31, 2019 and 2018 , MAA's diluted earnings per share was computed using the treasury stock method and the two-class method, respectively, as presented below (dollars and shares in thousands, except per share amounts): Three months ended March 31, 2019 2018 Calculation of Earnings per Common Share - basic Net income $ 65,958 $ 50,820 Net income attributable to noncontrolling interests (2,298 ) (1,801 ) Unvested restricted stock (allocation of earnings) (87 ) (79 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 62,651 $ 48,018 Weighted average common shares - basic 113,726 113,507 Earnings per common share - basic $ 0.55 $ 0.42 Calculation of Earnings per Common Share - diluted Net income $ 65,958 $ 50,820 Net income attributable to noncontrolling interests (1) (2,298 ) (1,801 ) Unvested restricted stock (allocation of earnings) (2) — (79 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 62,738 $ 48,018 Weighted average common shares - basic 113,726 113,507 Effect of dilutive securities (2) 207 — Weighted average common shares - diluted 113,933 113,507 Earnings per common share - diluted $ 0.55 $ 0.42 (1) For the three months ended March 31, 2019 and March 31, 2018 , 4.1 million OP Units and 4.2 million OP Units, respectively, and their related income are not included in the diluted earnings per share calculations as they are not dilutive. (2) For the three months ended March 31, 2018 , 0.2 million potentially dilutive securities and their related income are not included in the diluted earnings per share calculation as they are not dilutive.

Earnings Per OP Unit of MAALP

Earnings Per OP Unit of MAALP	3 Months Ended
	Mar. 31, 2019
Earnings Per OP Unit of MAALP [Abstract]
Earnings Per Unit [Text Block]	Earnings per OP Unit of MAALP Basic earnings per common unit is computed using the two-class method by dividing net income available for common unitholders by the weighted average number of OP Units outstanding during the period. All outstanding unvested restricted unit awards contain rights to non-forfeitable distributions and participate in undistributed earnings with common unitholders and, accordingly, are considered participating securities that are included in the two-class method of computing basic earnings per common unit. Diluted earnings per common unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units. Both the unvested restricted unit awards and other potentially dilutive common units, and the related impact to earnings, are considered when calculating earnings per common unit on a diluted basis with diluted earnings per common unit being the more dilutive of the treasury stock or two-class methods. For the three months ended March 31, 2019 and 2018 , MAA's diluted earnings per common unit was computed using the treasury stock method and the two-class method, respectively, as presented below (dollars and units in thousands, except per unit amounts): Three months ended March 31, 2019 2018 Calculation of Earnings per Common Unit - basic Net income $ 65,958 $ 50,820 Unvested restricted stock (allocation of earnings) (87 ) (79 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 64,949 $ 49,819 Weighted average common units - basic 117,837 117,689 Earnings per common unit - basic $ 0.55 $ 0.42 Calculation of Earnings per Common Unit - diluted Net income $ 65,958 $ 50,820 Unvested restricted stock (allocation of earnings) (1) — (79 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 65,036 $ 49,819 Weighted average common units - basic 117,837 117,689 Effect of dilutive securities (1) 207 — Weighted average common units - diluted 118,044 117,689 Earnings per common unit - diluted $ 0.55 $ 0.42 (1) For the three months ended March 31, 2018 , 0.2 million potentially dilutive securities and their related income are not included in the diluted earnings per share calculation as they are not dilutive.

MAA Equity

MAA Equity	3 Months Ended
	Mar. 31, 2019
MAA Equity [Abstract]
Consolidated Statements of Equity [Text Block]	MAA Equity Changes in total equity and its components for the three months ended March 31, 2019 and 2018 were as follows (dollars in thousands): Mid-America Apartment Communities, Inc. Shareholders' Equity Preferred Stock Common Stock Additional Paid-In Capital Accumulated Distributions in Excess of Net Income Accumulated Other Comprehensive Income Noncontrolling Interests - Operating Partnership Noncontrolling Interests - Consolidated Real Estate Entities Total Equity EQUITY BALANCE DECEMBER 31, 2018 $ 9 $ 1,136 $ 7,138,170 $ (989,263 ) $ (212 ) $ 220,043 $ 2,306 $ 6,372,189 Net income — — — 63,660 — 2,298 — 65,958 Other comprehensive income - derivative instruments — — — — (3,088 ) (113 ) — (3,201 ) Issuance and registration of common shares — 1 1,128 — — — — 1,129 Shares repurchased and retired — — (3,023 ) — — — — (3,023 ) Exercise of stock options — — 208 — — — — 208 Shares issued in exchange for common units — — 336 — — (336 ) — — Redeemable stock fair market value adjustment — — — (1,351 ) — — — (1,351 ) Adjustment for noncontrolling interests in Operating Partnership — — (60 ) — — 60 — — Amortization of unearned compensation — — 4,785 — — — — 4,785 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock ($0.9600 per share) — — — (109,392 ) — — — (109,392 ) Dividends on noncontrolling interests units ($0.9600 per unit) — — — — — (3,941 ) — (3,941 ) Contribution from noncontrolling interest — — — — — — 2,860 2,860 EQUITY BALANCE MARCH 31, 2019 $ 9 $ 1,137 $ 7,141,544 $ (1,037,268 ) $ (3,300 ) $ 218,011 $ 5,166 $ 6,325,299 Mid-America Apartment Communities, Inc. Shareholders' Equity Preferred Stock Common Stock Additional Paid-In Capital Accumulated Distributions in Excess of Net Income Accumulated Other Comprehensive Income Noncontrolling Noncontrolling Interests - Consolidated Real Estate Entities Total Equity EQUITY BALANCE DECEMBER 31, 2017 $ 9 $ 1,134 $ 7,121,112 $ (784,500 ) $ 2,157 $ 231,676 $ 2,306 $ 6,573,894 Net income — — — 49,019 — 1,801 — 50,820 Other comprehensive loss - derivative instruments — — — — 610 29 — 639 Issuance and registration of common shares — 1 104 — — — — 105 Shares repurchased and retired — — (2,912 ) — — — — (2,912 ) Exercise of stock options — — 625 — — — 625 Shares issued in exchange for common units — — 2,780 — — (2,780 ) — — Shares issued in exchange for redeemable stock — 1,915 — — — — 1,915 Redeemable stock fair market value adjustment — — — 965 — — — 965 Adjustment for noncontrolling interests in Operating Partnership — — 92 — — (92 ) — — Cumulative adjustment due to adoption of ASU 2017-12 — (233 ) 233 — — Amortization of unearned compensation — — 4,024 — — — — 4,024 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock ($0.9225 per share) — — — (104,971 ) — — — (104,971 ) Dividends on noncontrolling interests units ($0.9225 per unit) — — — — — (3,819 ) — (3,819 ) EQUITY BALANCE MARCH 31, 2018 $ 9 $ 1,135 $ 7,127,740 $ (840,642 ) $ 3,000 $ 226,815 $ 2,306 $ 6,520,363

MAALP Capital

MAALP Capital	3 Months Ended
	Mar. 31, 2019
MAALP Capital [Abstract]
Consolidated Statements of Changes in Capital [Text Block]	MAALP Capital Changes in total capital and its components for the three months ended March 31, 2019 and 2018 were as follows (dollars in thousands): Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interests- Consolidated Real Estate Entities Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2018 $ 220,043 $ 6,083,142 $ 66,840 $ (161 ) $ 2,306 $ 6,372,170 Net income 2,298 62,738 922 — — 65,958 Other comprehensive income - derivative instruments — — — (3,201 ) — (3,201 ) Issuance of units — 1,129 — — — 1,129 Units repurchased and retired — (3,023 ) — — — (3,023 ) Exercise of unit options — 208 — — — 208 General partner units issued in exchange for limited partner units (336 ) 336 — — — — Redeemable units fair market value adjustment — (1,351 ) — — — (1,351 ) Adjustment for limited partners' capital at redemption value (53 ) 53 — — — — Amortization of unearned compensation — 4,785 — — — 4,785 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders ($0.9600 per unit) (3,941 ) (109,392 ) — — — (113,333 ) Contribution from noncontrolling interest — — — — 2,860 2,860 CAPITAL BALANCE MARCH 31, 2019 $ 218,011 $ 6,038,625 $ 66,840 $ (3,362 ) $ 5,166 $ 6,325,280 Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interests - Consolidated Real Estate Entities Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2017 $ 231,676 $ 6,270,758 $ 66,840 $ 2,295 $ 2,306 $ 6,573,875 Net income 1,801 48,097 922 — — 50,820 Other comprehensive income - derivative instruments — — — 639 — 639 Issuance of units — 105 — — — 105 Units repurchased and retired — (2,912 ) — — — (2,912 ) Exercise of unit options — 625 — — — 625 General partner units issued in exchange for limited partner units (2,780 ) 2,780 — — — — Units issued in exchange for redeemable units — 1,915 — — — 1,915 Redeemable units fair market value adjustment — 965 — — — 965 Adjustment for limited partners' capital at redemption value (63 ) 63 — — — — Cumulative adjustment due to adoption of ASU 2017-12 — (233 ) — 233 — — Amortization of unearned compensation — 4,024 — — — 4,024 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders ($0.9225 per unit) (3,819 ) (104,971 ) — — — (108,790 ) CAPITAL BALANCE MARCH 31, 2018 $ 226,815 $ 6,221,216 $ 66,840 $ 3,167 $ 2,306 $ 6,520,344

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Notes Payable	Borrowings The following table summarizes the Company's outstanding debt as of March 31, 2019 (dollars in thousands): Balance Weighted Average Effective Rate Weighted Average Contract Maturity Unsecured debt Variable rate revolving credit facility $ 75,000 3.4 % 4/15/2020 Fixed rate senior notes 2,942,000 4.0 % 11/26/2025 Term loans fixed with swaps 300,000 2.3 % 3/1/2022 Variable rate term loans 600,000 3.4 % 1/22/2020 Debt issuance costs, discounts and fair market value adjustments (30,764 ) Total unsecured debt $ 3,886,236 3.8 % Fixed rate secured debt Individual property mortgages $ 665,588 4.5 % 5/2/2036 Debt issuance costs and fair market value adjustments (3,726 ) Total secured debt $ 661,862 4.5 % Total outstanding debt $ 4,548,098 3.9 % Unsecured Revolving Credit Facility MAALP maintains a $1.0 billion unsecured revolving credit facility with a syndicate of banks led by KeyBank National Association, or the Credit Facility. The Credit Facility includes an expansion option up to $1.5 billion . The Credit Facility bears an interest rate of the London Interbank Offered Rate, or LIBOR, plus a spread of 0.85% to 1.55% based on an investment grade pricing grid and, as of March 31, 2019 , the interest rate was 3.40% . The Credit Facility expires in April 2020 with an option to extend for an additional six months. As of March 31, 2019 , MAALP had $75.0 million outstanding under the Credit Facility with another $2.5 million of additional capacity used to support outstanding letters of credit. Senior Unsecured Notes As of March 31, 2019 , MAALP had approximately $2.7 billion in principal amount of publicly issued senior unsecured notes and $242.0 million of privately placed senior unsecured notes. The senior unsecured notes had maturities at issuance ranging from seven to twelve years , with an average of 6.7 years remaining until maturity as of March 31, 2019 . In March 2019, MAALP publicly issued $300.0 million in aggregate principal amount of senior unsecured notes, maturing March 2029 with an interest rate of 3.950% per annum, or the 2029 Notes. The purchase price paid by the initial purchasers was 99.720% of the principal amount. The 2029 Notes are general unsecured senior obligations of MAALP and rank equally in right of payment with all other senior unsecured indebtedness of MAALP. Interest on the 2029 Notes is payable on March 15 and September 15 of each year, beginning on September 15, 2019. The net proceeds of the offering, after deducting the original issue discount, underwriting commissions and expenses of approximately $2.8 million , were $297.2 million . The 2029 Notes have been reflected net of discount and debt issuance costs in the Condensed Consolidated Balance Sheet as of March 31, 2019 . In connection with the issuance of the 2029 Notes, MAALP cash settled $300.0 million in forward interest rate swap agreements, entered into during the second half of 2018 to effectively lock the interest rate on the planned transaction, resulting in an effective interest rate of 4.24% over the ten year life of the 2029 Notes. Unsecured Term Loans The Company maintains four term loans with a syndicate of banks, one led by KeyBank National Association, or KeyBank, two by Wells Fargo Bank, N.A., or Wells Fargo, and one by U.S. Bank National Association, or U.S. Bank. The KeyBank term loan has a balance of $150.0 million , matures in 2021, and has a variable interest rate of LIBOR plus a spread of 0.90% to 1.75% based on the Company's credit ratings. Both Wells Fargo term loans have balances of $300.0 million , mature in 2022 and 2019, respectively, and have variable interest rates of LIBOR plus spreads of 0.90% to 1.75% and 0.75% to 1.65% , respectively, based on the Company's credit ratings. The interest rate of the Wells Fargo term loan due in 2022 is fixed at 2.32% with a forward swap through the swap's maturity date, January 2020. The Wells Fargo term loan due in 2019 was entered into by the Company in December 2018. The U.S. Bank term loan has a balance of $150.0 million , matures in 2020, and has a variable interest rate of LIBOR plus a spread of 0.90% to 1.90% based on the Company's credit ratings. Secured Property Mortgages As of March 31, 2019 , the Company had $665.6 million of fixed rate conventional property mortgages with a weighted average interest rate of 4.5% and a weighted average maturity in 2036, which includes a $191.3 million mortgage with a fixed rate of 4.43% associated with seven apartment communities entered into in February 2019. The mortgage is scheduled to mature in February 2049. Guarantees As of March 31, 2019 , MAA fully and unconditionally guaranteed $242.0 million of the privately placed senior unsecured notes issued by MAALP.

Fair Value of Instruments and D

Fair Value of Instruments and Derivatives Fair Value of Instruments and Derivatives (Notes)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Financial Instruments and Derivatives Financial Instruments Not Carried at Fair Value Cash and cash equivalents, restricted cash, and accrued expenses and other liabilities are carried at amounts that reasonably approximate their fair value due to their short term nature. Fixed rate notes payable as of March 31, 2019 and December 31, 2018 , totaled $3.6 billion and $3.1 billion , respectively, and had estimated fair values of $3.7 billion and $3.1 billion (excluding prepayment penalties) as of March 31, 2019 and December 31, 2018 , respectively. The carrying values of variable rate notes payable (excluding the impact of interest rate swap agreements) as of March 31, 2019 and December 31, 2018 , totaled $1.0 billion and $1.1 billion , respectively, and had estimated fair values of $1.0 billion and $1.1 billion (excluding prepayment penalties) as of March 31, 2019 and December 31, 2018 , respectively. The fair values of fixed rate debt are determined by using the present value of future cash outflows discounted with the applicable current market rate plus a credit spread. The fair values of variable rate debt are determined using the stated variable rate plus the current market credit spread. The variable rates reset every 30 to 90 days , and management concluded that these rates reasonably estimate current market rates. Financial Instruments Measured at Fair Value on a Recurring Basis As of March 31, 2019 , the Company had four outstanding interest rate derivatives with a total notional balance of $300.0 million that were designated as cash flow hedges of interest rate risk. The Company uses interest rate swaps to add stability to interest expense and to manage, or hedge, its exposure to interest rate movements associated with its variable rate debt or as hedges in anticipation of future debt transactions. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. The fair value of interest rate derivative contracts designated as hedging instruments recorded in "Other assets" in the accompanying Condensed Consolidated Balance Sheets was $2.5 million and $3.7 million as of March 31, 2019 and December 31, 2018 , respectively. The fair value of interest rate derivative contract liabilities recorded in "Accrued expenses and other liabilities" in the accompanying Condensed Consolidated Balance Sheet was $5.3 million as of December 31, 2018 . There were no interest rate derivative contract liabilities as of March 31, 2019 . To comply with the provisions of ASC Topic 820, management incorporates credit valuation adjustments to appropriately reflect both its nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of the derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. Based on guidance issued by the FASB, the Company made an accounting policy election to measure the credit risk of its derivative financial instruments that are subject to master netting agreements on a net basis by counterparty portfolio. The derivative asset related to the redemption feature embedded in the MAA Series I preferred stock is valued using widely accepted valuation techniques, including a discounted cash flow analysis in which the perpetual value of the preferred shares is compared to the value of the preferred shares assuming the call option is exercised, with the value of the bifurcated call option as the difference between the two values. This analysis reflects the contractual terms of the redeemable preferred shares, which are redeemable at the Company's option beginning on October 1, 2026 and at the redemption price of $50 per share (see Note 8). The analysis uses observable market-based inputs, including trading data available on the preferred shares, coupon yields on preferred stock issuances from REITs with similar credit ratings as MAA and treasury rates to determine the fair value of the bifurcated call option. The redemption feature embedded in the MAA Series I preferred stock is reported as a derivative asset in "Other assets" in the accompanying Condensed Consolidated Balance Sheets and is adjusted to its fair value at each reporting date, with a corresponding non-cash adjustment to "Other non-operating (expense) income" in the accompanying Condensed Consolidated Statements of Operations. As a result of adjustments of non-cash expense recorded to reflect the change in fair value of the derivative asset during the three months ended March 31, 2019 , the fair value of the embedded derivative decreased to $18.1 million as of March 31, 2019 as compared to $18.6 million as of December 31, 2018 . The Company has determined the majority of the inputs used to value its outstanding debt and derivatives, including its embedded derivative, fall within Level 2 of the fair value hierarchy, and as a result, the fair value valuation of its debt and all of its derivatives held as of March 31, 2019 and December 31, 2018 were classified as Level 2 in the fair value hierarchy. The Company's derivative financial instruments and their related gains and losses are reported in "Net change in operating accounts and other" in the accompanying Condensed Consolidated Statements of Cash Flows. Cash Flow Hedges of Interest Rate Risk The changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in "Accumulated other comprehensive loss" and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. As long as a hedging instrument is designated and the results of the effectiveness testing support that the instrument qualifies for hedge accounting treatment, there is no periodic measurement or recognition of ineffectiveness. Rather, the full impact of hedge gains and losses will be recognized in the period in which hedged transactions impact earnings, regardless of whether or not economic mismatches exist in the hedging relationship. Amounts reported in "Accumulated other comprehensive loss" related to derivatives designated as qualifying cash flow hedges will be reclassified to interest expense as interest payments are made on the Company's variable rate or fixed rate debt. During the next twelve months, the Company estimates that an additional $1.6 million will be reclassified to earnings as a decrease to "Interest expense", which primarily represents the difference between the fixed interest rate swap payments and the projected variable interest rate swap receipts. Tabular Disclosure of the Effect of Derivative Instruments on the Condensed Consolidated Statements of Operations The tables below present the effect of the Company's derivative financial instruments on the Condensed Consolidated Statements of Operations for the three months ended March 31, 2019 and 2018 (dollars in thousands): Derivatives in Cash Flow Hedging Relationships (Loss) Gain Recognized in OCI on Derivative Location of Gain Reclassified from Accumulated OCL into Income Gain Reclassified from Accumulated OCL into Interest Expense (1) Three months ended March 31, 2019 2018 2019 2018 Interest rate contracts $ (2,456 ) $ 832 Interest Expense $ 745 $ 193 (1) See the Condensed Consolidated Statements of Comprehensive Income for changes in accumulated other comprehensive loss as these changes are presented net of the allocation to noncontrolling interests. Derivatives Not Designated as Hedging Instruments Location of Loss Recognized in Income on Derivative Loss Recognized in Earnings on Derivative For the three months ended March 31, 2019 2018 Preferred stock embedded derivative Other non-operating (income) expense $ (524 ) $ (2,644 ) Credit-Risk-Related Contingent Features Certain of the Company's derivative contracts contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company's default on the indebtedness. As of March 31, 2019 , the Company had not breached the provisions of these agreements. If the provisions had been breached, the Company could have been required to settle its obligations under the agreements although there was no termination value liability as of March 31, 2019 . Although the Company's derivative contracts are subject to master netting arrangements, which serve as credit mitigants to both the Company and its counterparties under certain situations, the Company does not net its derivative fair values or any existing rights or obligations to cash collateral in the Condensed Consolidated Balance Sheets.

Shareholders' Equity of MAA

Shareholders' Equity of MAA	3 Months Ended
	Mar. 31, 2019
Shareholders' Equity of MAA [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Shareholders' Equity of MAA As of March 31, 2019 , 113,916,208 shares of common stock of MAA and 4,105,171 OP Units (excluding the OP Units held by MAA) were issued and outstanding, representing a total of 118,021,379 shares and units. As of March 31, 2018 , 113,745,207 shares of common stock of MAA and 4,141,780 OP Units (excluding the OP Units held by MAA) were outstanding, representing a total of 117,886,987 shares and units. Options to purchase 87,788 shares of MAA's common stock were outstanding as of March 31, 2019 , compared to 95,838 outstanding options as of March 31, 2018 . During the three months ended March 31, 2019 and 2018 , MAA issued 2,827 shares and 12,600 shares, respectively, related to the exercise of stock options. These exercises resulted in proceeds of $0.2 million and $0.6 million , respectively. Preferred Stock As of March 31, 2019 , MAA had one outstanding series of cumulative redeemable preferred stock, which has the following characteristics: Description Outstanding Shares Liquidation Preference (1) Optional Redemption Date Redemption Price (2) Stated Dividend Yield Approximate Dividend Rate Series I 867,846 $50.00 10/1/2026 $50.00 8.50% $4.25 (1) The total liquidation preference for the outstanding preferred stock is $43.4 million . (2) The redemption price is the price at which the preferred stock is redeemable, at MAA's option, for cash.

Partners' Capital of Mid-Americ

Partners' Capital of Mid-America Apartments, L.P.	3 Months Ended
	Mar. 31, 2019
Partners' Capital of Mid-America Apartments, L.P. [Abstract]
Partners' Capital Notes Disclosure [Text Block]	Partners' Capital of MAALP Common units of limited partnership interests in MAALP are represented by OP Units. As of March 31, 2019 , there were 118,021,379 OP Units outstanding, 113,916,208 , or 96.5% , of which represent Class B OP Units (common units issued to or held by MAALP's general partner or any of its subsidiaries), which were owned by MAA, MAALP's general partner. The remaining 4,105,171 OP Units were Class A OP Units owned by Class A limited partners. As of March 31, 2018 , there were 117,886,987 OP Units outstanding, 113,745,207 , or 96.5% , of which were owned by MAA and 4,141,780 of which were owned by the Class A limited partners. MAA, as the sole general partner of MAALP, has full, complete and exclusive discretion to manage and control the business of MAALP subject to the restrictions specifically contained within MAALP's agreement of limited partnership, or the Partnership Agreement. Unless otherwise stated in the Partnership Agreement, this power includes, but is not limited to, acquiring, leasing, or disposing of any real property; constructing buildings and making other improvements to properties owned; borrowing money, modifying or extinguishing current borrowings, issuing evidence of indebtedness, and securing such indebtedness by mortgage, deed of trust, pledge or other lien on MAALP's assets; and distribution of MAALP's cash or other assets in accordance with the Partnership Agreement. MAA can generally, at its sole discretion, issue and redeem OP Units and determine the consideration to be received or the redemption price to be paid, as applicable. The general partner may delegate these and other powers granted if the general partner remains in supervision of the designee. Under the Partnership Agreement, MAALP may issue Class A OP Units and Class B OP Units. Class A OP Units are any OP Units other than Class B OP Units, while Class B OP Units are those issued to or held by MAALP's general partner or any of its subsidiaries. In general, the limited partners do not have the power to participate in the management or control of MAALP's business except in limited circumstances including changes in the general partner and protective rights if the general partner acts outside of the provisions provided in the Partnership Agreement. The transferability of Class A OP Units is also limited by the Partnership Agreement. Net income (after allocations to preferred ownership interests) is allocated to the general partner and limited partners based on their respective ownership percentages of MAALP. Issuance or redemption of additional Class A OP Units or Class B OP Units changes the relative ownership percentage of the partners. The issuance of Class B OP Units generally occurs when MAA issues common stock and the proceeds from that issuance are contributed to MAALP in exchange for the issuance to MAA of a number of OP Units equal to the number of shares of common stock issued. Likewise, if MAA repurchases or redeems outstanding shares of common stock, MAALP generally redeems an equal number of Class B OP Units with similar terms held by MAA for a redemption price equal to the purchase price of those shares of common stock. At each reporting period, the allocation between general partner capital and limited partner capital is adjusted to account for the change in the respective percentage ownership of the underlying capital of MAALP. Holders of the Class A OP Units may require MAA to redeem their Class A OP Units, in which case MAA may, at its option, pay the redemption price either in cash (in an amount per Class A OP Unit equal, in general, to the average closing price of MAA's common stock on the NYSE over a specified period prior to the redemption date) or by delivering one share of MAA common stock (subject to adjustment under specified circumstances) for each Class A OP Unit so redeemed. At March 31, 2019 , a total of 4,105,171 Class A OP Units were outstanding and redeemable for 4,105,171 shares of MAA common stock, with an approximate value of $448.8 million , based on the closing price of MAA’s common stock on March 29, 2019 of $109.33 per share. At March 31, 2018 , a total of 4,141,780 Class A OP Units were outstanding and redeemable for 4,141,780 shares of MAA common stock, with an approximate value of $377.9 million , based on the closing price of MAA’s common stock on March 29, 2018 of $91.24 per share. MAALP pays the same per unit distributions in respect to the OP Units as the per share dividends MAA pays in respect to its common stock. As of March 31, 2019 , MAALP had one outstanding series of cumulative redeemable preferred units, or the MAALP Series I Preferred Units. The MAALP Series I Preferred Units have the same characteristics as the MAA Series I preferred stock described in Note 8. As of March 31, 2019 , 867,846 units of the MAALP Series I Preferred Units were outstanding.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Loss Contingency [Abstract]
Legal Matters and Contingencies [Text Block]	Commitments and Contingencies Leases The Company's leases include a ground lease expiring in 2074 related to one of its apartment communities and an office lease expiring in 2028 related to its corporate headquarters. Both leases contain stated rent increases that generally compensate for the impact of inflation. The Company also has other immaterial office and equipment operating leases. The table below reconciles undiscounted cash flows for each of the first five years and total of the remaining years to the operating lease obligations recorded on the Condensed Consolidated Balance Sheet as of March 31, 2019 (in thousands): Operating Leases 2019 $ 2,054 2020 2,744 2021 2,771 2022 2,767 2023 2,761 Thereafter 68,516 Total minimum lease payments 81,613 Net present value adjustments (48,056 ) Operating lease obligations $ 33,557 Legal Proceedings In June 2016, plaintiffs Cathi Cleven and Tara Cleven, on behalf of a purported class of plaintiffs, filed a complaint against MAA and the Operating Partnership in the United States District Court for the Western District of Texas, Austin Division. In January 2017, Areli Arellano and Joe L. Martinez joined the lawsuit as additional plaintiffs. The lawsuit alleges that the Company (but not Post Properties) charged late fees at its Texas properties that violate Section 92.019 of the Texas Property Code, or Section 92.019, which provides that a landlord may not charge a tenant a late fee for failing to pay rent unless, among other things, the fee is a reasonable estimate of uncertain damages to the landlord that are incapable of precise calculation and result from the late payment of rent. The plaintiffs are seeking monetary damages and attorneys' fees and costs. In September 2018, the District Court certified a class proposed by the plaintiffs. Additionally, in September 2018, the District Court denied the Company’s motion for summary judgment and granted the plaintiffs’ motion for partial summary judgment. Because the District Court certified a class prior to granting the plaintiffs’ motion for partial summary judgment, the District Court’s ruling applies to the entire class. In October 2018, the Fifth Circuit Court of Appeals accepted the Company’s petition to review the District Court’s order granting class certification. The Company also intends to appeal the District Court’s order granting plaintiff's motion for summary judgment to the Fifth Circuit Court of Appeals if permission to appeal is granted. The Company will continue to vigorously defend the action and pursue such appeals. Management estimates that the Company's maximum exposure in the lawsuit, given the class certification and summary judgment ruling, is $54.6 million , which includes both potential damages and attorneys' fees but excludes any prejudgment interest that may be awarded. In April 2017, plaintiff Nathaniel Brown, on behalf of a purported class of plaintiffs, filed a complaint against the Operating Partnership, as the successor by merger to Post Properties' primary operating partnership, and MAA in the United States District Court for the Western District of Texas, Austin Division. The lawsuit alleges that Post Properties, Inc. (and, following the Post Properties merger in December 2016, the Operating Partnership) charged late fees at its Texas properties that violate Section 92.019. The plaintiffs are seeking monetary damages and attorney's fees and costs. In September 2018, the District Court certified a class proposed by the plaintiff. Additionally, in September 2018, the District Court denied the Company’s motion for summary judgment and granted the plaintiff’s motion for partial summary judgment. Because the District Court certified a class prior to granting the plaintiff’s motion for partial summary judgment, the District Court’s ruling applies to the entire class. In October 2018, the Fifth Circuit Court of Appeals accepted the Company's petition to review the District Court's order granting class certification. The Company also intends to appeal the District Court’s order granting plaintiff’s motion for summary judgment to the Fifth Circuit Court of Appeals if permission to appeal is granted. The Company will continue to vigorously defend the action and pursue such appeals. Management estimates that the Company's maximum exposure in the lawsuit, given the class certification and summary judgment ruling, is $8.4 million , which includes both potential damages and attorneys' fees but excludes any prejudgment interest that may be awarded. The Company is subject to various other legal proceedings and claims that arise in the ordinary course of its business operations. Matters which arise out of allegations of bodily injury, property damage and employment practices are generally covered by insurance. While the resolution of these other matters cannot be predicted with certainty, management does not currently believe that such matters, either individually or in the aggregate, will have a material adverse effect on the Company's financial condition, results of operations or cash flows in the event of a negative outcome. Loss Contingencies The outcomes of claims, disputes and legal proceedings are subject to significant uncertainty. The Company records an accrual for loss contingencies when a loss is probable and the amount of the loss can be reasonably estimated. The Company also accrues an estimate of defense costs expected to be incurred in connection with legal matters. Management reviews these accruals quarterly and makes revisions based on changes in facts and circumstances. When a loss contingency is not both probable and reasonably estimable, management does not accrue the loss. However, if the loss (or an additional loss in excess of the accrual) is at least a reasonable possibility and material, then management discloses a reasonable estimate of the possible loss, or range of loss, if such reasonable estimate can be made. If the Company cannot make a reasonable estimate of the possible loss, or range of loss, then a statement to that effect is disclosed. The assessment of whether a loss is probable or a reasonable possibility, and whether the loss or range of loss is reasonably estimable, often involves a series of complex judgments about future events. Among the factors considered in this assessment, are the nature of existing legal proceedings and claims, the asserted or possible damages or loss contingency (if reasonably estimable), the progress of the matter, existing law and precedent, the opinions or views of legal counsel and other advisers, management's experience in similar matters, the facts available to management at the time of assessment, and how the Company intends to respond, or has responded, to the proceeding or claim. Management's assessment of these factors may change over time as individual proceedings or claims progress. For matters where management is not currently able to reasonably estimate a range of reasonably possible loss, the factors that have contributed to this determination include the following: (i) the damages sought are indeterminate; (ii) the proceedings are in the early stages; (iii) the matters involve novel or unsettled legal theories or a large or uncertain number of actual or potential cases or parties; and/or (iv) discussions with the parties in matters that are ultimately expected to be resolved through negotiation and settlement have not reached the point where management believes a reasonable estimate of loss, or range of loss, can be made. The Company believes that there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss or business impact, if any. As of March 31, 2019 and December 31, 2018 , the Company's accrual for loss contingencies relating to unresolved legal matters was $8.8 million and $8.7 million in the aggregate, respectively. The loss contingencies are presented in "Accrued expenses and other liabilities" in the accompanying Condensed Consolidated Balance Sheets.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Segment Information	Segment Information As of March 31, 2019 , the Company owned and operated 303 multifamily apartment communities in 17 different states from which it derived all significant sources of earnings and operating cash flows. The Company views each consolidated apartment community as an operating segment. The Company's chief operating decision maker, which is the Company’s Chief Executive Officer, evaluates performance and determines resource allocations of each of the apartment communities on a Same Store and Non-Same Store and Other basis, as well as an individual apartment community basis. This is consistent with the aggregation criteria under GAAP as each of the apartment communities generally has similar economic characteristics, facilities, services, and tenants. The following reflects the two reportable segments for the Company: • Same Store communities are communities that the Company has owned and have been stabilized for at least a full 12 months. • Non-Same Store and Other includes recent acquisitions, communities in development or lease-up, communities that have been identified for disposition and communities that have incurred a significant casualty loss. Also included in Non-Same Store and Other are non-multifamily activities. On the first day of each calendar year, the Company determines the composition of its Same Store and Non-Same Store and Other reportable segments for that year as well as adjusts the previous year, which allows the Company to evaluate full period-over-period operating comparisons. Properties in development or lease-up are added to the Same Store portfolio on the first day of the calendar year after it has been owned and stabilized for at least a full 12 months. Communities are considered stabilized after achieving 90% occupancy for 90 days . Communities that have been identified for disposition are excluded from the Same Store portfolio. The chief operating decision maker utilizes net operating income, or NOI, in evaluating the performance of its operating segments. Total NOI represents total property revenues less total property operating expenses, excluding depreciation and amortization, for all properties held during the period regardless of their status as held for sale. Management believes that NOI is a helpful tool in evaluating the operating performance of the segments because it measures the core operations of property performance by excluding corporate level expenses and other items not related to property operating performance. Revenues and NOI for each reportable segment for the three months ended March 31, 2019 and 2018 were as follows (in thousands): Three months ended March 31, 2019 2018 Revenues: Same Store Rental revenues $ 372,441 $ 341,095 Reimbursable property revenues (1) — 23,002 Other property revenues 3,099 2,874 Total Same Store revenues $ 375,540 $ 366,971 Non-Same Store and Other Rental revenues $ 25,499 $ 17,945 Reimbursable property revenues (1) — 685 Other property revenues 139 416 Total Non-Same Store and Other revenues $ 25,638 $ 19,046 Total rental and other property revenues $ 401,178 $ 386,017 Net Operating Income: Same Store NOI $ 237,439 $ 231,655 Non-Same Store and Other NOI 14,362 9,958 Total NOI 251,801 241,613 Depreciation and amortization (122,789 ) (120,744 ) Property management expenses (13,842 ) (12,880 ) General and administrative expenses (13,153 ) (10,132 ) Merger and integration expenses — (3,799 ) Interest expense (45,700 ) (40,905 ) Loss on sale of depreciable real estate assets (13 ) — Gain on sale of non-depreciable real estate assets 8,963 150 Other non-operating income (expense) 935 (2,341 ) Income tax expense (641 ) (640 ) Income from real estate joint venture 397 498 Net income attributable to noncontrolling interests (2,298 ) (1,801 ) Dividends to MAA Series I preferred shareholders (922 ) (922 ) Net income available for MAA common shareholders $ 62,738 $ 48,097 (1) As a result of the adoption of ASC Topic 842 referenced in Note 1, for the three months ended March 31, 2019 , Same Store and Non-Same Store reimbursable property revenues of $23.0 million and $0.8 million , respectively, are reflected as rental revenues. Assets for each reportable segment as of March 31, 2019 and December 31, 2018 were as follows (in thousands): March 31, 2019 December 31, 2018 Assets: Same Store $ 9,935,157 $ 9,991,538 Non-Same Store and Other 1,178,083 1,163,083 Corporate assets 190,522 169,160 Total assets $ 11,303,762 $ 11,323,781

Real Estate Acquisitions and Di

Real Estate Acquisitions and Dispositions	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Real Estate Acquisitions and Dispositions	Real Estate Acquisitions and Dispositions The following table reflects the Company's acquisition activity for the three months ended March 31, 2019 : Multifamily Acquisition (1) Market Units Date Acquired Novel Midtown Phoenix, AZ 345 February 2019 (1) This pre-purchase multifamily community development is being developed through a joint venture with a local developer. The Company holds an 80% interest in the joint venture. The following table reflects the Company's disposition activity for the three months ended March 31, 2019 : Land Disposition Market Acres Date Sold Peachtree Road - Outparcel Atlanta, GA 1 February 2019 Commercial Disposition Market Sq Ft Date Sold Poplar Avenue Office Memphis, TN 42,000 March 2019

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On April 5, 2019, the Company acquired approximately two acres of development land located in the Orlando, Florida market.

Basis of Presentation and Pri_2

Basis of Presentation and Principles of Consolidation (Policies)	3 Months Ended
	Mar. 31, 2019
Basis of Presentation and Principles of Consolidation [Abstract]
Basis Of Presentation And Principles Of Consolidation Policy [Policy Text Block]	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, since 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 an effort to simplify the Company's presentation of cash flows from financing activities within the condensed consolidated statements of cash flows, the Company combined "Repurchase of common stock"; "Debt prepayment and extinguishment costs"; "Proceeds from issuances of common shares"; and "Exercise of stock 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 condensed 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 March 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 (see below) and (2) noncontrolling interest related to its consolidated real estate entities (see "Investment in Consolidated Real Estate Entities" below). The noncontrolling interests in the accompanying condensed consolidated financial statements 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. Investments in Unconsolidated Affiliates Through its investment in a limited liability company, or the Apartment LLC, the Company together with an institutional investor indirectly owns one apartment community, Post Massachusetts Avenue, located in Washington, D.C. The Company owned a 35.0% equity interest in the unconsolidated real estate joint venture as of March 31, 2019 and provides property and asset management services to the Apartment LLC for which it earns fees. The joint venture was determined to be a VIE, but the Company is not designated as a primary beneficiary. As a result, the Company accounts for its investment in the Apartment LLC using the equity method of accounting as the Company is able to exert significant influence over the joint venture but does not have a controlling interest. As of March 31, 2019 , the Company's investment in the Apartment LLC totaled $44.1 million . In September 2017, a subsidiary of the Operating Partnership invested in a limited partnership, Real Estate Technology Ventures, L.P. As of March 31, 2019 , the Operating Partnership indirectly owned 20.7% of the limited partnership. The limited partnership was determined to be a VIE, but the Company is not designated as a primary beneficiary. As a result, the Company accounts for its investment in the limited partnership using the equity method of accounting as the investment is considered more than minor. As of March 31, 2019 , the Company's investment in the limited partnership totaled $3.7 million and is included in "Other assets" in the accompanying Condensed Consolidated Balance Sheet. As of March 31, 2019 , the Company was committed to make additional capital contributions totaling $13.6 million if and when called by the general partner of the limited partnership and until September 2022. Investments in Consolidated Real Estate Entities The Company owns a 92.5% equity interest in a consolidated real estate entity that developed, constructed and operates a 359 -unit apartment community in Denver, Colorado. The owner of the remaining 7.5% equity interest, a private real estate company, was generally responsible for the development and construction of the community, which was completed during the year ended December 31, 2018 . The Company will continue to operate and manage the community. The entity was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the entity are consolidated by the Company. As of March 31, 2019 , the consolidated assets and liabilities included buildings and improvements and other, net of accumulated depreciation of $69.8 million ; land of $14.9 million ; and accrued expenses and other liabilities of $1.0 million . During the first quarter of 2019, the Company acquired an 80.0% equity interest in a consolidated real estate entity that will develop, construct and operate an apartment community in Phoenix, Arizona. The joint venture acquired the land site and initiated development of the apartment community in the first quarter of 2019. The owner of the remaining 20.0% equity interest, a private real estate company, is responsible for the development and construction of the community, and the Company will operate and manage the community upon its completion. The entity was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the entity are consolidated by the Company. As of March 31, 2019 , the consolidated assets and liabilities included development and capital improvements in process of $4.7 million ; land of $9.4 million ; and accrued expenses and other liabilities of $0.7 million . Fair Value Measurements The Company applies the guidance in Accounting Standards Codification, or ASC, Topic 820, Fair Value Measurements and Disclosures , to the valuation of real estate assets recorded at fair value, if any; 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 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. Leases In 2016, the Financial Accounting Standard 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 required to account for leases in a similar manner as previous lease accounting guidance but aligned with the newly 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 Quarterly Report on Form 10-Q 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. Thus, beginning with the effective date of the adoption of the new standard, January 1, 2019, 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 11. 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 will continue to be accounted for as operating leases; however, if contracts are modified subsequent to the adoption of ASC Topic 842, the Company will be 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" on its Condensed Consolidated Balance Sheets for leases in effect as of January 1, 2019. 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 have a weighted-average remaining lease term of approximately 33 years and a weighted-average discount rate of approximately 4.4% . Lease expense for the three months ended March 31, 2019 , recognized under ASC Topic 842, continued to be immaterial for the Company and was recognized in a similar manner as compared to the three months ended March 31, 2018 . Cash paid for amounts included in the measurement of operating lease liabilities during the three months ended March 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 market rent less adjustments for concessions, vacancy loss 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 to be reported in a single line, while non-lease reimbursable property revenues recognized prior to January 1, 2019 will continue to be reported as non-lease revenues and recognized in accordance with ASC Topic 606, Revenue Recognition. The guidance requires that revenue recognized outside of the scope of ASC Topic 842 is 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.

Earnings Per Common Share of _2

Earnings Per Common Share of MAA (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Common Share of MAA [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block]	For the three months ended March 31, 2019 and 2018 , MAA's diluted earnings per share was computed using the treasury stock method and the two-class method, respectively, as presented below (dollars and shares in thousands, except per share amounts): Three months ended March 31, 2019 2018 Calculation of Earnings per Common Share - basic Net income $ 65,958 $ 50,820 Net income attributable to noncontrolling interests (2,298 ) (1,801 ) Unvested restricted stock (allocation of earnings) (87 ) (79 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 62,651 $ 48,018 Weighted average common shares - basic 113,726 113,507 Earnings per common share - basic $ 0.55 $ 0.42 Calculation of Earnings per Common Share - diluted Net income $ 65,958 $ 50,820 Net income attributable to noncontrolling interests (1) (2,298 ) (1,801 ) Unvested restricted stock (allocation of earnings) (2) — (79 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 62,738 $ 48,018 Weighted average common shares - basic 113,726 113,507 Effect of dilutive securities (2) 207 — Weighted average common shares - diluted 113,933 113,507 Earnings per common share - diluted $ 0.55 $ 0.42 (1) For the three months ended March 31, 2019 and March 31, 2018 , 4.1 million OP Units and 4.2 million OP Units, respectively, and their related income are not included in the diluted earnings per share calculations as they are not dilutive. (2) For the three months ended March 31, 2018 , 0.2 million potentially dilutive securities and their related income are not included in the diluted earnings per share calculation as they are not dilutive.

Earnings Per OP Unit of MAALP (

Earnings Per OP Unit of MAALP (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per OP Unit of MAALP [Abstract]
Schedule of Earnings Per Unit, Basic and Diluted [Table Text Block]	For the three months ended March 31, 2019 and 2018 , MAA's diluted earnings per common unit was computed using the treasury stock method and the two-class method, respectively, as presented below (dollars and units in thousands, except per unit amounts): Three months ended March 31, 2019 2018 Calculation of Earnings per Common Unit - basic Net income $ 65,958 $ 50,820 Unvested restricted stock (allocation of earnings) (87 ) (79 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 64,949 $ 49,819 Weighted average common units - basic 117,837 117,689 Earnings per common unit - basic $ 0.55 $ 0.42 Calculation of Earnings per Common Unit - diluted Net income $ 65,958 $ 50,820 Unvested restricted stock (allocation of earnings) (1) — (79 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 65,036 $ 49,819 Weighted average common units - basic 117,837 117,689 Effect of dilutive securities (1) 207 — Weighted average common units - diluted 118,044 117,689 Earnings per common unit - diluted $ 0.55 $ 0.42 (1) For the three months ended March 31, 2018 , 0.2 million potentially dilutive securities and their related income are not included in the diluted earnings per share calculation as they are not dilutive.

MAA Equity (Tables)

MAA Equity (Tables)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
MAA Equity [Abstract]
Shareholders' Equity [Table Text Block]	Changes in total equity and its components for the three months ended March 31, 2019 and 2018 were as follows (dollars in thousands): Mid-America Apartment Communities, Inc. Shareholders' Equity Preferred Stock Common Stock Additional Paid-In Capital Accumulated Distributions in Excess of Net Income Accumulated Other Comprehensive Income Noncontrolling Interests - Operating Partnership Noncontrolling Interests - Consolidated Real Estate Entities Total Equity EQUITY BALANCE DECEMBER 31, 2018 $ 9 $ 1,136 $ 7,138,170 $ (989,263 ) $ (212 ) $ 220,043 $ 2,306 $ 6,372,189 Net income — — — 63,660 — 2,298 — 65,958 Other comprehensive income - derivative instruments — — — — (3,088 ) (113 ) — (3,201 ) Issuance and registration of common shares — 1 1,128 — — — — 1,129 Shares repurchased and retired — — (3,023 ) — — — — (3,023 ) Exercise of stock options — — 208 — — — — 208 Shares issued in exchange for common units — — 336 — — (336 ) — — Redeemable stock fair market value adjustment — — — (1,351 ) — — — (1,351 ) Adjustment for noncontrolling interests in Operating Partnership — — (60 ) — — 60 — — Amortization of unearned compensation — — 4,785 — — — — 4,785 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock ($0.9600 per share) — — — (109,392 ) — — — (109,392 ) Dividends on noncontrolling interests units ($0.9600 per unit) — — — — — (3,941 ) — (3,941 ) Contribution from noncontrolling interest — — — — — — 2,860 2,860 EQUITY BALANCE MARCH 31, 2019 $ 9 $ 1,137 $ 7,141,544 $ (1,037,268 ) $ (3,300 ) $ 218,011 $ 5,166 $ 6,325,299	Mid-America Apartment Communities, Inc. Shareholders' Equity Preferred Stock Common Stock Additional Paid-In Capital Accumulated Distributions in Excess of Net Income Accumulated Other Comprehensive Income Noncontrolling Noncontrolling Interests - Consolidated Real Estate Entities Total Equity EQUITY BALANCE DECEMBER 31, 2017 $ 9 $ 1,134 $ 7,121,112 $ (784,500 ) $ 2,157 $ 231,676 $ 2,306 $ 6,573,894 Net income — — — 49,019 — 1,801 — 50,820 Other comprehensive loss - derivative instruments — — — — 610 29 — 639 Issuance and registration of common shares — 1 104 — — — — 105 Shares repurchased and retired — — (2,912 ) — — — — (2,912 ) Exercise of stock options — — 625 — — — 625 Shares issued in exchange for common units — — 2,780 — — (2,780 ) — — Shares issued in exchange for redeemable stock — 1,915 — — — — 1,915 Redeemable stock fair market value adjustment — — — 965 — — — 965 Adjustment for noncontrolling interests in Operating Partnership — — 92 — — (92 ) — — Cumulative adjustment due to adoption of ASU 2017-12 — (233 ) 233 — — Amortization of unearned compensation — — 4,024 — — — — 4,024 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock ($0.9225 per share) — — — (104,971 ) — — — (104,971 ) Dividends on noncontrolling interests units ($0.9225 per unit) — — — — — (3,819 ) — (3,819 ) EQUITY BALANCE MARCH 31, 2018 $ 9 $ 1,135 $ 7,127,740 $ (840,642 ) $ 3,000 $ 226,815 $ 2,306 $ 6,520,363

MAALP Capital (Tables)

MAALP Capital (Tables)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
MAALP Capital [Abstract]
Partners' Capital [Table Text Block]	Changes in total capital and its components for the three months ended March 31, 2019 and 2018 were as follows (dollars in thousands): Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interests- Consolidated Real Estate Entities Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2018 $ 220,043 $ 6,083,142 $ 66,840 $ (161 ) $ 2,306 $ 6,372,170 Net income 2,298 62,738 922 — — 65,958 Other comprehensive income - derivative instruments — — — (3,201 ) — (3,201 ) Issuance of units — 1,129 — — — 1,129 Units repurchased and retired — (3,023 ) — — — (3,023 ) Exercise of unit options — 208 — — — 208 General partner units issued in exchange for limited partner units (336 ) 336 — — — — Redeemable units fair market value adjustment — (1,351 ) — — — (1,351 ) Adjustment for limited partners' capital at redemption value (53 ) 53 — — — — Amortization of unearned compensation — 4,785 — — — 4,785 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders ($0.9600 per unit) (3,941 ) (109,392 ) — — — (113,333 ) Contribution from noncontrolling interest — — — — 2,860 2,860 CAPITAL BALANCE MARCH 31, 2019 $ 218,011 $ 6,038,625 $ 66,840 $ (3,362 ) $ 5,166 $ 6,325,280	Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interests - Consolidated Real Estate Entities Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2017 $ 231,676 $ 6,270,758 $ 66,840 $ 2,295 $ 2,306 $ 6,573,875 Net income 1,801 48,097 922 — — 50,820 Other comprehensive income - derivative instruments — — — 639 — 639 Issuance of units — 105 — — — 105 Units repurchased and retired — (2,912 ) — — — (2,912 ) Exercise of unit options — 625 — — — 625 General partner units issued in exchange for limited partner units (2,780 ) 2,780 — — — — Units issued in exchange for redeemable units — 1,915 — — — 1,915 Redeemable units fair market value adjustment — 965 — — — 965 Adjustment for limited partners' capital at redemption value (63 ) 63 — — — — Cumulative adjustment due to adoption of ASU 2017-12 — (233 ) — 233 — — Amortization of unearned compensation — 4,024 — — — 4,024 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders ($0.9225 per unit) (3,819 ) (104,971 ) — — — (108,790 ) CAPITAL BALANCE MARCH 31, 2018 $ 226,815 $ 6,221,216 $ 66,840 $ 3,167 $ 2,306 $ 6,520,344

Borrowings Borrowings (Tables)

Borrowings Borrowings (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	The following table summarizes the Company's outstanding debt as of March 31, 2019 (dollars in thousands): Balance Weighted Average Effective Rate Weighted Average Contract Maturity Unsecured debt Variable rate revolving credit facility $ 75,000 3.4 % 4/15/2020 Fixed rate senior notes 2,942,000 4.0 % 11/26/2025 Term loans fixed with swaps 300,000 2.3 % 3/1/2022 Variable rate term loans 600,000 3.4 % 1/22/2020 Debt issuance costs, discounts and fair market value adjustments (30,764 ) Total unsecured debt $ 3,886,236 3.8 % Fixed rate secured debt Individual property mortgages $ 665,588 4.5 % 5/2/2036 Debt issuance costs and fair market value adjustments (3,726 ) Total secured debt $ 661,862 4.5 % Total outstanding debt $ 4,548,098 3.9 %

Fair Value of Instruments and_2

Fair Value of Instruments and Derivatives Fair Value of Derivatives and Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Derivative Instruments, Gain (Loss) [Table Text Block]	The tables below present the effect of the Company's derivative financial instruments on the Condensed Consolidated Statements of Operations for the three months ended March 31, 2019 and 2018 (dollars in thousands): Derivatives in Cash Flow Hedging Relationships (Loss) Gain Recognized in OCI on Derivative Location of Gain Reclassified from Accumulated OCL into Income Gain Reclassified from Accumulated OCL into Interest Expense (1) Three months ended March 31, 2019 2018 2019 2018 Interest rate contracts $ (2,456 ) $ 832 Interest Expense $ 745 $ 193 (1) See the Condensed Consolidated Statements of Comprehensive Income for changes in accumulated other comprehensive loss as these changes are presented net of the allocation to noncontrolling interests. Derivatives Not Designated as Hedging Instruments Location of Loss Recognized in Income on Derivative Loss Recognized in Earnings on Derivative For the three months ended March 31, 2019 2018 Preferred stock embedded derivative Other non-operating (income) expense $ (524 ) $ (2,644 )

Shareholders' Equity of MAA Cum

Shareholders' Equity of MAA Cumulative Redeemable Preferred Stock Outstanding (Tables)	3 Months Ended
	Mar. 31, 2019
Class of Stock [Line Items]
Schedule of Stock by Class [Table Text Block]	As of March 31, 2019 , MAA had one outstanding series of cumulative redeemable preferred stock, which has the following characteristics: Description Outstanding Shares Liquidation Preference (1) Optional Redemption Date Redemption Price (2) Stated Dividend Yield Approximate Dividend Rate Series I 867,846 $50.00 10/1/2026 $50.00 8.50% $4.25 (1) The total liquidation preference for the outstanding preferred stock is $43.4 million . (2) The redemption price is the price at which the preferred stock is redeemable, at MAA's option, for cash.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Notes To Financial Statements [Abstract]
Revenues and NOI for Reportable Segment	Revenues and NOI for each reportable segment for the three months ended March 31, 2019 and 2018 were as follows (in thousands): Three months ended March 31, 2019 2018 Revenues: Same Store Rental revenues $ 372,441 $ 341,095 Reimbursable property revenues (1) — 23,002 Other property revenues 3,099 2,874 Total Same Store revenues $ 375,540 $ 366,971 Non-Same Store and Other Rental revenues $ 25,499 $ 17,945 Reimbursable property revenues (1) — 685 Other property revenues 139 416 Total Non-Same Store and Other revenues $ 25,638 $ 19,046 Total rental and other property revenues $ 401,178 $ 386,017 Net Operating Income: Same Store NOI $ 237,439 $ 231,655 Non-Same Store and Other NOI 14,362 9,958 Total NOI 251,801 241,613 Depreciation and amortization (122,789 ) (120,744 ) Property management expenses (13,842 ) (12,880 ) General and administrative expenses (13,153 ) (10,132 ) Merger and integration expenses — (3,799 ) Interest expense (45,700 ) (40,905 ) Loss on sale of depreciable real estate assets (13 ) — Gain on sale of non-depreciable real estate assets 8,963 150 Other non-operating income (expense) 935 (2,341 ) Income tax expense (641 ) (640 ) Income from real estate joint venture 397 498 Net income attributable to noncontrolling interests (2,298 ) (1,801 ) Dividends to MAA Series I preferred shareholders (922 ) (922 ) Net income available for MAA common shareholders $ 62,738 $ 48,097 (1) As a result of the adoption of ASC Topic 842 referenced in Note 1, for the three months ended March 31, 2019 , Same Store and Non-Same Store reimbursable property revenues of $23.0 million and $0.8 million , respectively, are reflected as rental revenues.
Assets for Reportable Segment	Assets for each reportable segment as of March 31, 2019 and December 31, 2018 were as follows (in thousands): March 31, 2019 December 31, 2018 Assets: Same Store $ 9,935,157 $ 9,991,538 Non-Same Store and Other 1,178,083 1,163,083 Corporate assets 190,522 169,160 Total assets $ 11,303,762 $ 11,323,781

Real Estate Acquisitions and _2

Real Estate Acquisitions and Dispositions Real Estate Acquisitions and Dispositions (Tables)	3 Months Ended
	Mar. 31, 2019
Real Estate [Line Items]
Schedule of Real Estate Asset Acquisitions and Dispositions [Table Text Block]	The following table reflects the Company's acquisition activity for the three months ended March 31, 2019 : Multifamily Acquisition (1) Market Units Date Acquired Novel Midtown Phoenix, AZ 345 February 2019 (1) This pre-purchase multifamily community development is being developed through a joint venture with a local developer. The Company holds an 80% interest in the joint venture. The following table reflects the Company's disposition activity for the three months ended March 31, 2019 : Land Disposition Market Acres Date Sold Peachtree Road - Outparcel Atlanta, GA 1 February 2019 Commercial Disposition Market Sq Ft Date Sold Poplar Avenue Office Memphis, TN 42,000 March 2019

Consolidation and Basis of Pres

Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018shares	Mar. 31, 2019	Mar. 31, 2019apartmentunits	Mar. 31, 2019Property	Mar. 31, 2019States	Mar. 31, 2019Communities	Mar. 31, 2019USD ($)	Mar. 31, 2019shares	Mar. 31, 2019ft²
Real Estate Properties [Line Items]
General Partners' Capital Account, Units Outstanding | shares		113,745,207							113,916,208
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	96.50%	96.50%
Number of owned or owned interests of apartment communities					303		303
Percentage Of Rental Revenue From Leasing Of Apartment Homes	93.00%
Percentage Of Reimbursable Revenue From Leasing Of Apartment Homes	6.00%
Percentage of Rental Revenue and Other Income From Non-leasing Activities	1.00%
Operating Lease, Liability								$ 33,557
Number of States in which Entity Operates | States						17
Minimum [Member]
Real Estate Properties [Line Items]
Percentage Of Ownership Interests			80.00%
Maximum [Member]
Real Estate Properties [Line Items]
Percentage Of Ownership Interests			100.00%
Development Properties [Member]
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities | Communities							5
Number of units under development community | Property					1,090
Development Properties [Member] | Expected Costs [Member]
Real Estate Properties [Line Items]
Development and capital improvements in progress								230,500
Development Properties [Member] | Costs Incurred to Date [Member]
Real Estate Properties [Line Items]
Development and capital improvements in progress								59,500
Retail
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities | Property					30
Square Footage of Real Estate Property | ft²										615,000
Commercial Real Estate [Member]
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities | Property					4
Square Footage of Real Estate Property | ft²										260,000
Real Estate Technology Ventures, L.P. [Member]
Real Estate Properties [Line Items]
Equity Method Investment, Ownership Percentage			20.70%
Real Estate Investments, Joint Ventures								3,700
Real Estate Technology Ventures, L.P. [Member] | Limited Partner Capital Contribution, Future Obligation [Member]
Real Estate Properties [Line Items]
Real Estate Investments, Joint Ventures								13,600
Post River North [Member]
Real Estate Properties [Line Items]
Percentage Of Ownership Interests			92.50%
Number of apartments included in a community | apartmentunits				359
Buildings, Improvements, and Other								69,800
Land								14,900
Accrued expenses and other liabilities								1,000
Post Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Equity Method Investment, Ownership Percentage			35.00%
Real Estate Investments, Joint Ventures								44,100
Phoenix Midtown [Member] [Domain]
Real Estate Properties [Line Items]
Percentage Of Ownership Interests			80.00%
Buildings, Improvements, and Other								4,700
Land								9,400
Accrued expenses and other liabilities								700
Accounting Standards Update 2016-02 [Member]
Real Estate Properties [Line Items]
Operating Lease, Right-of-Use Asset								54,300
Operating Lease, Liability								$ 33,600
Operating Lease, Weighted Average Remaining Lease Term	33 years
Operating Lease, Weighted Average Discount Rate, Percent			4.40%

Earnings Per Common Share of _3

Earnings Per Common Share of MAA Earnings Per Common Share of MAA (Details) - Parent Company [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share Disclosure [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 65,958	$ 50,820
Dividends, Preferred Stock, Cash		$ 922	$ 922
Weighted average common shares - basic		113,726	113,507
Effect of dilutive securities		207	0
Weighted average common shares - diluted		113,933	113,507
Calculation of Basic Earnings per Share [Member]
Earnings Per Share Disclosure [Line Items]
Income from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		$ 65,958	$ 50,820
Income from continuing operations attributable to noncontrolling interests		(2,298)	(1,801)
Income from continuing operations allocated to unvested restricted shares		(87)	(79)
Dividends, Preferred Stock, Cash		(922)	(922)
Income from continuing operations available for common shareholders, adjusted		$ 62,651	$ 48,018
Earnings per share - basic		$ 0.55	$ 0.42
Calculation of Diluted Earnings per Share [Member]
Earnings Per Share Disclosure [Line Items]
Income from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		$ 65,958	$ 50,820
Income from continuing operations attributable to noncontrolling interests	[1]	(2,298)	(1,801)
Income from continuing operations allocated to unvested restricted shares		0	(79)
Dividends, Preferred Stock, Cash		(922)	(922)
Adjusted Income (Loss) from Continuing Operations Available for Common Shareholders, Diluted		$ 62,738	$ 48,018
Earnings per share - diluted		$ 0.55	$ 0.42
Limited Partnership Units [Member]
Earnings Per Share Disclosure [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		4,100	4,200
Restricted Stock [Member]
Earnings Per Share Disclosure [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			200
[1]	(1) For the three months ended March 31, 2019 and March 31, 2018, 4.1 million OP Units and 4.2 million OP Units, respectively, and their related income are not included in the diluted earnings per share calculations as they are not dilutive.

Earnings Per OP Unit of MAALP E

Earnings Per OP Unit of MAALP Earnings Per OP Unit of MAALP (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Limited Partner [Member]
Earnings Per Share Disclosure [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 65,958	$ 50,820
Dividends, Preferred Stock, Cash	$ 922	$ 922
Weighted average common units - basic	117,837	117,689
Earnings per unit - basic	$ 0.55	$ 0.42
Effect of dilutive securities	207	0
Weighted average common shares - diluted	118,044	117,689
Earnings per unit - diluted	$ 0.55	$ 0.42
Limited Partner [Member] | Calculation of Basic Earnings Per Unit [Member]
Earnings Per Share Disclosure [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 65,958	$ 50,820
Income from continuing operations allocated to unvested restricted shares	(87)	(79)
Dividends, Preferred Stock, Cash	(922)	(922)
Income from continuing operations available for common unitholders, adjusted	$ 64,949	$ 49,819
Earnings per unit - basic	$ 0.55	$ 0.42
Limited Partner [Member] | Calculation of Diluted Earnings Per Unit [Member]
Earnings Per Share Disclosure [Line Items]
Income from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	$ 65,958	$ 50,820
Income from continuing operations allocated to unvested restricted shares	0	(79)
Dividends, Preferred Stock, Cash	(922)	(922)
Income from continuing operations available for common unitholders, adjusted	$ 65,036	$ 49,819
Earnings per unit - diluted	$ 0.55	$ 0.42
Parent Company [Member]
Earnings Per Share Disclosure [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 65,958	$ 50,820
Dividends, Preferred Stock, Cash	$ 922	$ 922
Effect of dilutive securities	207	0
Weighted average common shares - diluted	113,933	113,507
Restricted Stock [Member] | Parent Company [Member]
Earnings Per Share Disclosure [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		200

MAA Equity (Details)

MAA Equity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Equity, Total [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Stock Options Exercised		$ 625,000
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares repurchased and retired		0
Stock Issued During Period, Value, Stock Options Exercised		0
Shares issued in exchange for units		0
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Stock Options Exercised		625,000
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common stock		$ 0
Parent Company [Member]
Equity [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.9600	$ 0.9225
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 65,958,000	$ 50,820,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	6,320,133,000		$ 6,369,883,000
Noncontrolling Interest in Joint Ventures	5,166,000	2,306,000	2,306,000	$ 2,306,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Value, Outstanding	9,000		9,000
Dividends, Preferred Stock, Cash	922,000	922,000
Other Noncontrolling Interests	2,860,000
Parent Company [Member] | Accumulated Distributions in Excess of Net Income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(989,263,000)	(784,500,000)
Net income attributable to MAA	63,660,000	49,019,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	0
Issuance and registration of common shares	0
Shares repurchased and retired	0
Stock Issued During Period, Value, Stock Options Exercised	0
Shares issued in exchange for units	0
Redeemable stock fair market value	(1,351,000)	965,000
Adjustment for noncontrolling interest ownership in operating partnership	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(233,000)
Amortization of unearned compensation	0	0
Dividends, Preferred Stock, Cash	922,000	922,000
Dividends on common stock	(109,392,000)	(104,971,000)
Dividends on noncontrolling interest units	0
Ending Balance	(1,037,268,000)	(840,642,000)
Parent Company [Member] | Preferred Stock [Member]
Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	9,000	9,000	$ 9,000	$ 9,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)		0
Issuance and registration of common shares		0
Shares repurchased and retired		0
Stock Issued During Period, Value, Stock Options Exercised		0
Shares issued in exchange for units		0
Redeemable stock fair market value		0
Adjustment for noncontrolling interest ownership in operating partnership		0
Amortization of unearned compensation		0
Dividends on common stock		0
Dividends on noncontrolling interest units		0
Parent Company [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,136,000	1,134,000
Issuance and registration of common shares	1,000	1,000
Shares repurchased and retired	0
Stock Issued During Period, Value, Stock Options Exercised	0
Shares issued in exchange for units	0
Ending Balance	1,137,000	1,135,000
Parent Company [Member] | Additional Paid-in Capital [Member]
Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	7,138,170,000	7,121,112,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	0
Shares repurchased and retired	(3,023,000)	(2,912,000)
Stock Issued During Period, Value, Stock Options Exercised	208,000
Shares issued in exchange for units	336,000	2,780,000
Shares issued in exchange for redeemable stock		1,915,000
Redeemable stock fair market value	0
Adjustment for noncontrolling interest ownership in operating partnership	(60,000)	92,000
Amortization of unearned compensation	4,785,000	4,024,000
Dividends on common stock	0
Dividends on noncontrolling interest units	0
Ending Balance	7,141,544,000	7,127,740,000
Parent Company [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	220,043,000	231,676,000
Net Income Attributable to Noncontrolling Interest	2,298,000	1,801,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(113,000)	29,000
Issuance and registration of common shares	0	0
Shares repurchased and retired	0
Stock Issued During Period, Value, Stock Options Exercised	0
Shares issued in exchange for units	(336,000)	(2,780,000)
Redeemable stock fair market value	0
Adjustment for noncontrolling interest ownership in operating partnership	60,000	(92,000)
Amortization of unearned compensation	0
Dividends on common stock	0
Dividends on noncontrolling interest units	(3,941,000)	(3,819,000)
Ending Balance	218,011,000	226,815,000
Parent Company [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(212,000)	2,157,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(3,088,000)	610,000
Issuance and registration of common shares	0
Shares repurchased and retired	0
Stock Issued During Period, Value, Stock Options Exercised	0
Shares issued in exchange for units	0
Redeemable stock fair market value	0
Adjustment for noncontrolling interest ownership in operating partnership	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		233,000
Amortization of unearned compensation	0
Dividends on common stock	0
Dividends on noncontrolling interest units	0
Ending Balance	(3,300,000)	3,000,000
Parent Company [Member] | Common Stock Including Additional Paid in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance and registration of common shares	1,128,000	104,000
Parent Company [Member] | Stockholders' Equity, Total [Member]
Equity [Line Items]
Noncontrolling Interest in Joint Ventures	2,860,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	6,372,189,000	6,573,894,000
Net Income Including Portion Attributable to Noncontrolling Interest	65,958,000	50,820,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(3,201,000)	639,000
Issuance and registration of common shares	1,129,000	105,000
Shares repurchased and retired	(3,023,000)	(2,912,000)
Stock Issued During Period, Value, Stock Options Exercised	208,000
Shares issued in exchange for units	0	0
Shares issued in exchange for redeemable stock		1,915,000
Redeemable stock fair market value	(1,351,000)	965,000
Adjustment for noncontrolling interest ownership in operating partnership	0	0
Amortization of unearned compensation	4,785,000	4,024,000
Dividends, Preferred Stock, Cash	922,000	(922,000)
Dividends on common stock	(109,392,000)	(104,971,000)
Dividends on noncontrolling interest units	(3,941,000)	(3,819,000)
Ending Balance	$ 6,325,299,000	$ 6,520,363,000

MAALP Capital (Details)

MAALP Capital (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
General Partners' Capital Account [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Units Issued During Period, Value, Unit Options Exercised		$ 625
Total Partnership Capital [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Units Issued During Period, Value, Unit Options Exercised	$ 208	$ 625
Limited Partner [Member]
Capital Disclosure [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.9600	$ 0.9225
Noncontrolling Interest in Joint Ventures	$ 5,166	$ 2,306	$ 2,306	$ 2,306
Increase (Decrease) in Partners' Capital [Roll Forward]
Dividends, Preferred Stock, Cash	922	922
Other Noncontrolling Interests	2,860
Limited Partner [Member] | General Partners' Capital Account [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	6,083,142	6,270,758	6,270,758
Net Income Allocated to General Partners	62,738	48,097
Issuance of units	1,129	105
Units repurchased and retired	(3,023)	(2,912)
Units Issued During Period, Value, Unit Options Exercised	208
General partner units issued in exchange for limited partner units	336	2,780
Units issued in exchange for redeemable units		1,915
Redeemable stock fair market value	(1,351)	965
Adjustment for noncontrolling interest ownership in operating partnership	53	63
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(233)
Amortization of unearned compensation	4,785	4,024
Distributions	(109,392)	(104,971)
Ending Balance	6,038,625	6,221,216	6,083,142
Limited Partner [Member] | Total Partnership Capital [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	6,372,170	6,573,875	6,573,875
Net Income Available for Common Unitholders	65,958	50,820
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(3,201)	639
Issuance of units	1,129	105
Units repurchased and retired	(3,023)	(2,912)
General partner units issued in exchange for limited partner units	0	0
Units issued in exchange for redeemable units		1,915
Redeemable stock fair market value	(1,351)	965
Adjustment for noncontrolling interest ownership in operating partnership	0	0
Amortization of unearned compensation	4,785	4,024
Dividends, Preferred Stock, Cash	922	922
Distributions	(113,333)	(108,790)
Ending Balance	6,325,280	6,520,344	6,372,170
Limited Partner [Member] | Limited Partner [Member]
Capital Disclosure [Line Items]
Noncontrolling Interest in Joint Ventures	2,860
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	220,043	231,676	231,676
Net Income Allocated to Limited Partners	2,298	1,801
General partner units issued in exchange for limited partner units	(336)	(2,780)
Adjustment for noncontrolling interest ownership in operating partnership	(53)	(63)
Distributions	(3,941)	(3,819)
Ending Balance	218,011	226,815	220,043
Limited Partner [Member] | AOCI Attributable to Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	(161)	2,295	2,295
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	(3,201)	639
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		233
Ending Balance	(3,362)	3,167	(161)
Accumulated Distributions in Excess of Net Income [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Issuance of units	0	0	$ 66,840
Dividends, Preferred Stock, Cash	922	922
Preferred Stock Including Additional Paid in Capital [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Ending Balance	$ 66,840	$ 66,840

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Notes Payable	$ 4,548,098
Debt Instrument, Interest Rate, Effective Percentage	3.90%
Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.43%
Proceeds from Loan Originations	$ 191,300
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Secured Debt [Member] | Mortgages [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Debt Instrument, Maturity Date	May 2, 2036
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate	$ 665,588
Unsecured Debt [Member]
Debt Instrument [Line Items]
Notes Payable	$ 3,886,236
Debt Instrument, Interest Rate, Effective Percentage	3.80%
Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	2.32%
Unsecured Debt [Member] | US Bank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150,000
Unsecured Debt [Member] | $1 billion unsecured revolving credit faciltiy [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Letters of Credit Outstanding, Amount	$ 2,500
Unsecured Debt [Member] | $1 billion unsecured revolving credit faciltiy [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Debt Instrument, Maturity Date	Apr. 15, 2020
Line of Credit Facility, Amount Outstanding	$ 75,000
Unsecured Debt [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Unsecured notes payable	$ 600,000
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Debt Instrument, Maturity Date	Jan. 22, 2020
Unsecured Debt [Member] | KeyBank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150,000
Unsecured Debt [Member] | Public Income Notes [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	2,700,000
Unsecured Debt [Member] | Private Placement [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	242,000
Unsecured Debt [Member] | Private Placement [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	242,000
Unsecured Debt [Member] | 3.95% Notes due 2029 [Member] [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Debt Instrument, Redemption Price, Percentage	99.72%
Debt Issuance Costs, Gross	$ 2,800
Proceeds from Debt, Net of Issuance Costs	297,200
Settlement of Forward Swaps	$ 300,000
Debt Instrument, Term	10 years
Debt Instrument, Interest Rate, Effective Percentage	4.24%
Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,000,000
Line of Credit Facility, Maximum Borrowing Capacity	1,500,000
Line of Credit Facility, Amount Outstanding	75,000
Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
Debt Instrument, Interest Rate, Effective Percentage	2.30%
Debt Instrument, Maturity Date	Mar. 1, 2022
Minimum [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	7 years
Minimum [Member] | Unsecured Debt [Member] | US Bank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Minimum [Member] | Unsecured Debt [Member] | KeyBank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Minimum [Member] | Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.85%
Minimum [Member] | Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Minimum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Maximum [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	12 years
Maximum [Member] | Unsecured Debt [Member] | US Bank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
Maximum [Member] | Unsecured Debt [Member] | KeyBank Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Maximum [Member] | Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%
Maximum [Member] | Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Maximum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.65%
years to maturity [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	6 years 8 months

Debt Structure (Details)

Debt Structure (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Total Outstanding Debt	$ 4,548,098
Debt Instrument, Interest Rate, Effective Percentage	3.90%
Mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.43%
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Secured Debt [Member] | Fair Market Value Adjustment and Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ (3,726)
Secured Debt [Member] | Mortgages [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate	$ 665,588
Debt Instrument, Interest Rate, Effective Percentage	4.50%
Contract Maturity	May 2, 2036
Secured Debt [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 661,862
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 3,886,236
Debt Instrument, Interest Rate, Effective Percentage	3.80%
Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
Unsecured Debt [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.40%
Contract Maturity	Jan. 22, 2020
Unsecured Debt	$ 600,000
Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.30%
Contract Maturity	Mar. 1, 2022
Debt Instrument, Face Amount	$ 300,000
Unsecured Debt [Member] | Senior Notes [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.00%
Contract Maturity	Nov. 26, 2025
Debt Instrument, Face Amount	$ 2,942,000
Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	75,000
Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member] | Fair Market Value Adjustment and Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ (30,764)

Fair Value of Derivatives and F

Fair Value of Derivatives and Financial Instruments (Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk) (Details) - Designated as Hedging Instrument - Interest Rate Swap $ in Millions	Mar. 31, 2019USD ($)Contract
Derivative
Number of Instruments | Contract	4
Derivative, Notional Amount | $	$ 300

Fair Value of Derivatives and_2

Fair Value of Derivatives and Financial Instruments (Effect of Derivative Instruments on Consolidated Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Designated as Hedging Instrument | Interest Expense
Derivative
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 745	$ 193
Designated as Hedging Instrument | Interest Rate Contract
Derivative
Unrealized (loss) gain from the effective portion of derivative instruments	(2,456)	832
Not Designated as Hedging Instrument | Interest Expense
Derivative
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(524)	(2,644)
Parent Company [Member]
Derivative
Unrealized (loss) gain from the effective portion of derivative instruments	$ (2,456)	$ 832
Minimum [Member] | Conventional Variable Rate Debt [Member]
Derivative
Debt Renewal Period	30 days
Maximum [Member] | Conventional Variable Rate Debt [Member]
Derivative
Debt Renewal Period	90 days

Fair Value of Derivatives and_3

Fair Value of Derivatives and Financial Instruments (Textual) (Details)	3 Months Ended
	Mar. 31, 2019USD ($)Contract$ / shares	Dec. 31, 2018USD ($)
Derivative
Preferred Stock, Redemption Price Per Share | $ / shares	$ 50
Preferred Stock, Redemption Date	Oct. 1, 2026
Designated as Hedging Instrument | Interest Rate Swap
Derivative
Derivative, Number of Instruments Held | Contract	4
Derivative, Notional Amount	$ 300,000,000
Designated as Hedging Instrument | Interest Expense
Derivative
Change in fair value of interest rate derivatives included in AOCI and expected to be reclassified in the next 12 months	1,600,000
Fixed Rate Debt
Derivative
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	3,600,000,000	$ 3,100,000,000
Notes Payable, Fair Value Disclosure	3,700,000,000	3,100,000,000
Floating Rate Debt [Member]
Derivative
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	1,000,000,000	1,100,000,000
Notes Payable, Fair Value Disclosure	$ 1,000,000,000	1,100,000,000
Minimum [Member] | Conventional Variable Rate Debt [Member]
Derivative
Debt Renewal Period	30 days
Maximum [Member] | Conventional Variable Rate Debt [Member]
Derivative
Debt Renewal Period	90 days
Fair Value, Measurements, Recurring [Member]
Derivative
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 18,100,000	18,600,000
Interest Rate Derivative Assets, at Fair Value	2,500,000	3,700,000
Interest Rate Derivative Liabilities, at Fair Value	0	$ 5,300,000
net liability position [Member]
Derivative
Credit Risk Related Contingent Features Termination Value	$ 0

Shareholders' Equity of MAA - A

Shareholders' Equity of MAA - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 01, 2016
Preferred Stock, Liquidation Preference Per Share	$ 50
Preferred Stock, Redemption Date	Oct. 1, 2026
Preferred Stock, Redemption Price Per Share	$ 50
Common stock, shares outstanding	113,916,208	113,745,207
Total common shares and operating partnership units outstanding	118,021,379	117,886,987
Preferred Stock, Dividend Rate, Percentage	8.50%
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 4.25
Preferred Stock, Liquidation Preference, Value	$ 43.4
Equity Option [Member]
Stock Issued During Period, Shares, New Issues	2,827	12,600
Noncontrolling Interest [Member]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,105,171	4,141,780
Parent Company [Member]
Preferred Stock, Shares Outstanding	867,846		867,846
Preferred Stock, Liquidation Preference Per Share	$ 50		$ 50
Common stock, shares outstanding	113,916,208		113,844,267
Proceeds from Stock Options Exercised	$ 0.2	$ 0.6
Employee Stock Option [Member]
Common stock shares, outstanding option	87,788	95,838
Redeemable Preferred Stock [Member]
Preferred Stock, Shares Outstanding				867,846

Partners' Capital of Mid-Amer_2

Partners' Capital of Mid-America Apartments, L.P. (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 01, 2016
Schedule of Capital Structure [Line Items]
Operating partnership units outstanding	118,021,379	117,886,987
General Partners' Capital Account, Units Outstanding	113,916,208	113,745,207
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	96.50%	96.50%
Limited Partners' Capital Account, Units Outstanding	4,105,171
Noncontrolling Interest [Member]
Schedule of Capital Structure [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,105,171	4,141,780
Limited Partners' Capital Account	$ 448.8	$ 377.9
Redeemable Capital Shares Par Or Stated Value Per Share	$ 109.33	$ 91.24
Redeemable Preferred Stock [Member]
Schedule of Capital Structure [Line Items]
Preferred Stock, Shares Outstanding			867,846

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 8,800	$ 8,700
Operating Leases, Future Minimum Payments Due, Next Twelve Months	2,054
Operating Leases, Future Minimum Payments, Due in Two Years	2,744
Operating Leases, Future Minimum Payments, Due in Three Years	2,771
Operating Leases, Future Minimum Payments, Due in Four Years	2,767
Operating Leases, Future Minimum Payments, Due in Five Years	2,761
Operating Leases, Future Minimum Payments, Due Thereafter	68,516
Operating Leases, Future Minimum Payments Due	81,613
Net present value adjustment	(48,056)
Operating Lease, Liability	33,557
Cleven Litigation Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	54,600
Brown Litigation Case [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	$ 8,400

Segment Information - Additiona

Segment Information - Additional Information (Detail) - 3 months ended Mar. 31, 2019	Total	Property	States	Communities
Segment Reporting Information [Line Items]
Number of owned or owned interests of apartment communities		303		303
Number of States in which Entity Operates			17
Period properties owned and stabilized	12 months
Occupancy Level for Stabilized Communities	90.00%
Period Properties Stabilized	90 days
Same Store [Member]
Segment Reporting Information [Line Items]
Period properties owned and stabilized	12 months

Revenues and NOI for Reportable

Revenues and NOI for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Information
Total operating revenues	$ 401,178	$ 386,017
Net Operating Income	251,801	241,613
Depreciation and amortization	(122,789)	(120,744)
Other Cost and Expense, Operating	13,842	12,880
General and administrative expense	(13,153)	(10,132)
Business Combination, Merger and Integration Related Expenses	0	(3,799)
Interest expense	(45,700)	(40,905)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	(13)	0
Gain on sale of non-depreciable real estate assets	8,963	150
Other Nonoperating Income (Expense)	935	(2,341)
Income tax expense	(641)	(640)
Gain (loss) from real estate joint ventures	397	498
Net income attributable to noncontrolling interests	(2,298)	(1,801)
Preferred Stock Dividends, Income Statement Impact	(922)	(922)
Net income available for MAA common shareholders	62,738	48,097
Same Store [Member]
Segment Information
Revenue from Contract with Customer, Including Assessed Tax	372,441	341,095
Property Management Fee Revenue	23,000	23,002
Other Operating Income	3,099	2,874
Total operating revenues	375,540	366,971
Net Operating Income	237,439	231,655
Non-Same Store and Other
Segment Information
Revenue from Contract with Customer, Including Assessed Tax	25,499	17,945
Property Management Fee Revenue	800	685
Other Operating Income	139	416
Total operating revenues	25,638	19,046
Net Operating Income	$ 14,362	$ 9,958

Assets for Reportable Segment (

Assets for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 11,303,762	$ 11,323,781
Same Store [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	9,935,157	9,991,538
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,178,083	1,163,083
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 190,522	$ 169,160

Real Estate Acquisitions and _3

Real Estate Acquisitions and Dispositions - Additional Information (Details)	Mar. 31, 2019ft²aapartmentunits
Novel Midtown [Member]
Business Acquisitions and Dispositions [Line Items]
Number of Units in Real Estate Property | apartmentunits	345
Peachtree Road - outparcel [Member]
Business Acquisitions and Dispositions [Line Items]
Area of Land | a	1
Poplar Avenue Office [Member] [Member]
Business Acquisitions and Dispositions [Line Items]
Square Footage of Real Estate Property | ft²	42,000

Subsequent Events (Details)

Subsequent Events (Details)	Apr. 05, 2019a
Subsequent Event [Member]
Subsequent Event [Line Items]
Area of Land	2