Mid-America Apartments 10-Q 3 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	MAA
Entity Registrant Name	MID AMERICA APARTMENT COMMUNITIES INC
Entity Central Index Key	912,595
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		113,791,411
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Limited Partner [Member]
Document Information [Line Items]
Entity Registrant Name	MID-AMERICA APARTMENTS, L.P.
Entity Central Index Key	1,581,776
Entity Filer Category	Non-accelerated Filer

MAA Condensed Consolidated Bala

MAA Condensed Consolidated Balance Sheets - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Land	$ 1,836,417	$ 1,836,417
Buildings, Improvements, and Other	11,363,738	11,281,504
Development and capital improvements in progress	93,089	116,833
Real Estate Investment Property, at Cost	13,293,244	13,234,754
Less accumulated depreciation	(2,194,915)	(2,075,071)
Real Estate Investment Property, Net	11,098,329	11,159,683
Undeveloped land	50,198	57,285
Investments in real estate joint ventures	45,000	44,956
Real estate assets, net	11,193,527	11,261,924
Cash and cash equivalents	59,706	10,750
Restricted Cash	22,404	78,117
Other assets	135,039	135,807
Real Estate Held-for-sale	6,700	5,321
Total assets	11,417,376	11,491,919
Liabilities:
Unsecured notes payable	3,566,664	3,525,765
Secured notes payable	932,187	976,292
Accrued expenses and other liabilities	390,380	405,560
Total liabilities	4,889,231	4,907,617
Redeemable stock	7,782	10,408
Shareholders' equity:
Preferred Stock, Value, Outstanding	9	9
Common stock	1,135	1,134
Additional paid-in capital	7,127,740	7,121,112
Accumulated distributions in excess of net income	(840,642)	(784,500)
Accumulated other comprehensive income (losses)	3,000	2,157
Total MAA shareholders' equity	6,291,242	6,339,912
Noncontrolling interest	226,815	231,676
Total equity	6,518,057	6,571,588
Noncontrolling Interest in Joint Ventures	2,306	2,306
Permanent Equity Attributable to Parent and Noncontrolling Interest	6,520,363	6,573,894
Total liabilities and equity	$ 11,417,376	$ 11,491,919
Redeemable stock, shares issued and outstanding	85,289	103,504

MAALP Condensed Consolidated Ba

MAALP Condensed Consolidated Balance Sheets - Limited Partner [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Land	$ 1,836,417	$ 1,836,417
Buildings, Improvements, and Other	11,363,738	11,281,504
Development and capital improvements in progress	93,089	116,833
Real Estate Investment Property, at Cost	13,293,244	13,234,754
Less accumulated depreciation	(2,194,915)	(2,075,071)
Real Estate Investment Property, Net	11,098,329	11,159,683
Undeveloped land	50,198	57,285
Investments in real estate joint ventures	45,000	44,956
Real estate assets, net	11,193,527	11,261,924
Cash and cash equivalents	59,706	10,750
Restricted Cash	22,404	78,117
Other assets	135,039	135,807
Real Estate Held-for-sale	6,700	5,321
Total assets	11,417,376	11,491,919
Liabilities:
Unsecured notes payable	3,566,664	3,525,765
Secured notes payable	932,187	976,292
Accrued expenses and other liabilities	390,380	405,560
Due to general partner	19	19
Total liabilities	4,889,250	4,907,636
Redeemable units	7,782	10,408
Capital [Abstract]
Preferred Units, Preferred Partners' Capital Accounts	66,840	66,840
General Partners' Capital Account	6,221,216	6,270,758
Limited Partners' Capital Account	226,815	231,676
Accumulated other comprehensive income (losses)	3,167	2,295
Capital	6,518,038	6,571,569
Noncontrolling Interest in Joint Ventures	2,306	2,306
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	6,520,344	6,573,875
Total Liabilities and Capital	$ 11,417,376	$ 11,491,919
Redeemable units, units issued and outstanding	85,289	103,504

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Common stock, shares outstanding	113,745,207
General Partners' Capital Account, Units Outstanding	113,745,207
Limited Partners' Capital Account, Units Outstanding	4,141,780
Preferred Stock, Liquidation Preference Per Share	$ 50
Limited Partner [Member]
General Partners' Capital Account, Units Outstanding	113,745,207	113,643,166
Limited Partners' Capital Account, Units Outstanding	4,141,780	4,191,586
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	113,745,207	113,643,166
Common stock, shares outstanding	113,745,207	113,643,166
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, 2018	Mar. 31, 2017
Limited Partner [Member]
Operating revenues:
Total operating revenues	$ 386,017	$ 378,908
Property operating expenses:
Operating Expenses	89,148	87,300
Real estate taxes and insurance	55,256	53,973
Depreciation and amortization	120,744	129,997
Total property operating expenses	265,148	271,270
Property management expenses	12,880	10,981
General and administrative expenses	10,132	12,840
Business Combination, Merger and Integration Related Expenses	3,799	6,161
Income from continuing operations before non-operating items	94,058	77,656
Interest expense	(40,905)	(36,584)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	0	(73)
Gain on sale of non-depreciable real estate assets	150	0
Other Nonoperating Income (Expense)	(2,341)	2,711
Income before income tax expense	50,962	43,710
Income tax expense	(640)	(651)
Income from continuing operations before joint venture activity	50,322	43,059
Gain (loss) from real estate joint ventures	498	357
Consolidated net income	50,820	43,416
Preferred Unit Dividends, Income Statement Impact	922	922
Net income available for Mid-America Apartments, L.P. common unitholders	$ 49,898	$ 42,494
Earnings per common share - basic:
Net Income available for common shareholders	$ 0.42	$ 0.36
Earnings per common share - diluted:
Net income available for common shareholders	0.42	0.36
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.9225	$ 0.8700
Parent Company [Member]
Operating revenues:
Total operating revenues	$ 386,017	$ 378,908
Property operating expenses:
Operating Expenses	89,148	87,300
Real estate taxes and insurance	55,256	53,973
Depreciation and amortization	120,744	129,997
Total property operating expenses	265,148	271,270
Property management expenses	12,880	10,981
General and administrative expenses	10,132	12,840
Business Combination, Merger and Integration Related Expenses	3,799	6,161
Income from continuing operations before non-operating items	94,058	77,656
Interest expense	(40,905)	(36,584)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	0	(73)
Gain on sale of non-depreciable real estate assets	150	0
Other Nonoperating Income (Expense)	(2,341)	2,711
Income before income tax expense	50,962	43,710
Income tax expense	(640)	(651)
Income from continuing operations before joint venture activity	50,322	43,059
Gain (loss) from real estate joint ventures	498	357
Consolidated net income	50,820	43,416
Net income attributable to noncontrolling interests	1,801	1,511
Net income available for shareholders	49,019	41,905
Preferred Stock Dividends, Income Statement Impact	922	922
Net income available for MAA common shareholders	$ 48,097	$ 40,983
Earnings per common share - basic:
Net Income available for common shareholders	$ 0.42	$ 0.36
Earnings per common share - diluted:
Net income available for common shareholders	0.42	0.36
Dividends declared per common share	$ 0.9225	$ 0.8700

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Limited Partner [Member]
Consolidated net income	$ 50,820	$ 43,416
Unrealized loss from the effective portion of derivitave insturments	832	2,520
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(193)	672
Comprehensive income attributable to Mid-America Apartments, L.P.	51,459	46,608
Parent Company [Member]
Consolidated net income	50,820	43,416
Unrealized loss from the effective portion of derivitave insturments	832	2,520
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(193)	672
Total comprehensive income	51,459	46,608
Less: comprehensive income attributable to noncontrolling interests	(1,830)	(1,624)
Comprehensive income attributable to MAA	$ 49,629	$ 44,984

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Parent Company [Member]
Cash flows from operating activities:
Consolidated net income	$ 50,820	$ 43,416
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(121,361)	(130,082)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	0	73
Gain on sale of non-depreciable real estate assets	(150)	0
Stock compensation expense	4,024	3,018
Amortization of debt premium	(1,569)	(3,147)
Proceeds from Other Operating Activities	(21,782)	(40,669)
Net cash provided by operating activities	152,704	132,773
Cash flows from investing activities:
Purchases of real estate and other assets	0	(62,817)
Normal capital improvements	(51,775)	(86,338)
Contributions to Real Estate Joint Ventures	(750)	0
Proceeds from disposition of real estate assets	5,860	0
Net cash (used in) provided by investing activities	(46,665)	(149,155)
Cash flows from financing activities:
Proceeds from Lines of Credit	150,000	155,000
Repayments of Lines of Credit	(110,000)	(75,000)
Principal payments on notes payable	(41,042)	(18,871)
Repurchase of common stock	(2,912)	(4,734)
Payment for Debt Extinguishment or Debt Prepayment Cost	(3)	(1)
Proceeds from issuances of common shares	199	67
Proceeds from Stock Options Exercised	625	0
Distributions to noncontrolling interests	(3,865)	(3,667)
Dividends paid on common shares	(104,876)	(98,791)
Dividends, Preferred Stock, Cash	(922)	(922)
Net cash used in financing activities	(112,796)	(46,919)
Net (decrease) increase in cash and cash equivalents	(6,757)	(63,301)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	88,867	121,800
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	82,110	58,499
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	59,706	33,959
Restricted Cash	22,404	24,540
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	82,110	58,499
Supplemental disclosure of cash flow information:
Interest paid	24,889	24,785
Income Taxes Paid	2,522	10
Supplemental disclosure of noncash investing and financing activities:
Conversion of units to shares of common stock	2,780	167
Accrued construction in progress	14,640	21,810
Interest capitalized	795	2,020
Marked To Market Adjustment On Derivative Instruments	(1,363)	6,743
Limited Partner [Member]
Cash flows from operating activities:
Consolidated net income	50,820	43,416
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(121,361)	(130,082)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	0	73
Gain on sale of non-depreciable real estate assets	(150)	0
Stock compensation expense	4,024	3,018
Amortization of debt premium	(1,569)	(3,147)
Proceeds from Other Operating Activities	(21,782)	(40,669)
Net cash provided by operating activities	152,704	132,773
Cash flows from investing activities:
Purchases of real estate and other assets	0	(62,817)
Normal capital improvements	(51,775)	(86,338)
Contributions to Real Estate Joint Ventures	(750)	0
Proceeds from disposition of real estate assets	5,860	0
Net cash (used in) provided by investing activities	(46,665)	(149,155)
Cash flows from financing activities:
Proceeds from Lines of Credit	150,000	155,000
Repayments of Lines of Credit	(110,000)	(75,000)
Principal payments on notes payable	(41,042)	(18,871)
Repurchase of common units	(2,912)	(4,734)
Payment for Debt Extinguishment or Debt Prepayment Cost	(3)	(1)
Proceeds from issuances of common units	199	67
Proceeds from Stock Options Exercised	625	0
Distributions paid on common units	(108,741)	(102,458)
Dividends, Preferred Stock, Cash	(922)	(922)
Net cash used in financing activities	(112,796)	(46,919)
Net (decrease) increase in cash and cash equivalents	(6,757)	(63,301)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	88,867	121,800
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	82,110	58,499
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	59,706	33,959
Restricted Cash	22,404	24,540
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	82,110	58,499
Supplemental disclosure of cash flow information:
Interest paid	24,889	24,785
Income Taxes Paid	2,522	10
Supplemental disclosure of noncash investing and financing activities:
Accrued construction in progress	14,640	21,810
Interest capitalized	795	2,020
Marked To Market Adjustment On Derivative Instruments	$ (1,363)	$ 6,743

Basis of Presentation and Princ

Basis of Presentation and Principles of Consolidation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
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" means 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, 2018 , MAA owned 113,745,207 OP Units (or approximately 96.5% of the total number of OP Units). MAA conducts substantially all of its business and holds substantially all of its assets 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 OP Units in the Operating Partnership; therefore, MAA does not conduct business itself, other than 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 OP Units, 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 presentation 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. Redeemable common units represent the number of outstanding OP Units as of the date of the applicable balance sheet, valued at the greater of the closing market price of MAA's common stock or the aggregate value of the individual partners' capital balances. Holders of OP Units (other than MAA and its corporate affiliates) 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. As of March 31, 2018 , the Company owned and operated 302 apartment communities through the Operating Partnership. As of March 31, 2018 , MAA also owned a 35.0% interest in an unconsolidated real estate joint venture and a 26.5% interest in an unconsolidated limited partnership. As of March 31, 2018 , the Company had two development communities under construction totaling 578 apartment units. Total expected costs for these two development projects are $125.8 million , of which $101.4 million had been incurred through March 31, 2018 . The Company expects to complete construction on one project by the third quarter of 2018 and the other project by the fourth quarter of 2018. Twenty-nine of the multifamily properties include retail components with approximately 620,000 square feet of gross leasable space. The Company also has four wholly-owned commercial properties with approximately 260,000 square feet of combined gross leasable area. On December 1, 2016, MAA completed a merger with Post Properties, Inc., or Post Properties. Pursuant to the Agreement and Plan of Merger, or the Merger Agreement, Post Properties merged with and into MAA, with MAA continuing as the surviving corporation, or the Parent Merger, and Post Apartment Homes, L.P, or Post LP, merged with and into MAALP, with MAALP continuing as the surviving entity, or the Partnership Merger. We refer to the Parent Merger, together with the Partnership Merger, as the Merger in this Quarterly Report on Form 10-Q. 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 approximately 92.5% 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, 92.5% 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 "Investment in Unconsolidated Affiliates" below). Changes in Presentation Please refer to the Company's Annual Report on Form 10-K for the year ended December 31, 2017 that was filed with the SEC on February 23, 2018 for discussions of the changes in presentation in the Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations and Condensed Consolidated Statements of Cash Flows, which are still applicable for this Quarterly Report on Form 10-Q. Noncontrolling Interests At March 31, 2018 , the Company had two types of noncontrolling interests, (1) noncontrolling interests related to the common unitholders of its Operating Partnership (see Note 9) and (2) noncontrolling interest related to its consolidated real estate entity (see "Investment in Consolidated Real Estate Joint Venture" below). Investment in Unconsolidated Affiliates The Company, together with other institutional investors in a limited liability company, or the Apartment LLC, indirectly owns one apartment community, Post Massachusetts Avenue, located in Washington, D.C. The Company owns a 35.0% equity interest in the unconsolidated real estate joint venture as of March 31, 2018 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. At March 31, 2018 , the Company's investment in the Apartment LLC totaled $45.0 million . During September 2017, a subsidiary of the Operating Partnership entered into a limited partnership together with a general partner and other limited partners to form Real Estate Technology Ventures, L.P. The Operating Partnership indirectly owns 26.5% 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. At March 31, 2018 , the Company's investment in the limited partnership totaled $2.0 million . The Company is committed to make additional capital contributions totaling $12.8 million if and when called by the general partner of the limited partnership prior to September 2022. Investment in Consolidated Real Estate Entity At March 31, 2018 , the Company owned a 92.5% equity interest in a consolidated real estate joint venture to develop, construct and operate a 359 -unit apartment community in Denver, Colorado, along with a private real estate company. The venture partner was generally responsible for the development and construction of the community, and the Company will continue to manage the community as construction on the development was completed during the three months ended March 31, 2018 . The joint venture was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the joint venture are consolidated by the Company. At March 31, 2018 , the consolidated assets, liabilities and equity included buildings and improvements and other, net of accumulated depreciation of $71.0 million ; land of $14.9 million ; and accrued expenses and other liabilities of $2.6 million . Assets Held for Sale During the first quarter of 2018, the criteria for classifying one land parcel as held for sale were met, and as a result, the land parcel was presented as held for sale in the Condensed Consolidated Balance Sheet as of March 31, 2018 . See Note 13 for details on the April 2018 disposition of this land parcel. The Randal Park land parcel that comprised the asset held for sale balance as of December 31, 2017, was sold during the first quarter as detailed on Note 12. 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. Revenue from Contracts with Customers The Company primarily leases multifamily residential apartments under operating leases generally with terms of one year or less, which are recorded as operating leases. Rental lease revenues are recognized in accordance with ASC Topic 840, Leases , using a method that represents a straight-line basis over the term of the lease. Rental income represents approximately 93% of the Company's total revenues and includes gross market rent less adjustments for concessions, vacancy loss and bad debt. Other non-lease revenues represent the remaining 7% of the Company's total revenues and are primarily driven by utility reimbursement revenue from its tenants. The Company's primary sources of reimbursement revenue are from water and cable utility services, which produced $9.8 million and $7.5 million , respectively, of revenues during the three months ended March 31, 2018, and $9.4 million and $7.7 million of revenues, respectively, during the three months ended March 31, 2017 . Other non-lease revenues are recognized in accordance with ASC Topic 606, Revenue Recognition , as a result of the Company's January 1, 2018 adoption of Accounting Standards Update, or ASU, 2014-09, Revenue from Contracts with Customers , using the modified retrospective approach. The guidance requires that revenue (outside of the scope of lease revenue accounting rules) 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. While ASU 2014-09 requires additional disclosure regarding the nature and timing of the Company's non-lease revenue transactions, which is provided here in Note 1 as well as Note 11, the adoption of the ASU did not have a material impact on the Company's consolidated financial statements or the Company's internal accounting policies and did not result in an opening adjustment to retained earnings. In addition, the Company elected the available practical expedients to the ASU’s requirement for disclosure on remaining performance obligations, which allow an entity to avoid disclosing the amount of the remaining performance obligations for contracts with an original expected duration of less than one year or those that meet the practical expedient in ASC 606-10-55-18 that permits the entity to recognize revenue as invoiced. See Note 11 for the disaggregation of our revenues in accordance with ASU 2014-09. Impact of Recently Adopted Accounting Standards on Condensed Consolidated Statements of Cash Flows Effective January 1, 2018, the Company adopted ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (a Consensus of the FASB Emerging Issues Task Force) , which clarifies how certain types of cash receipts and cash payments are to be presented and classified on the statement of cash flows. Management has determined three of the eight transactions in the ASU are relevant to the Company and its cash flows and include debt prepayment and extinguishment costs, proceeds from the settlement of insurance claims and distributions received from equity method investees. Upon adoption of ASU 2016-15, the Company recognized a $0.2 million increase to net cash provided by operating activities and a $0.2 million decrease to net cash used in investing activities for the three months ended March 31, 2017 . The Company adopted ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (A Consensus of the FASB Emerging Issues Task Force) , effective January 1, 2018. The ASU required restricted cash to be presented within cash and cash equivalents when reconciling the beginning and ending amounts in the statement of cash flow with retrospective adjustments to all periods presented. The Company previously reported the change in restricted cash within the operating and investing activities in the consolidated statement of cash flows. Upon adoption, cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2017 increased by approximately $24.5 million to reflect the restricted cash balances. Additionally, net cash provided by operating activities decreased by $5.5 million for the three months ended March 31, 2017 , while net cash used in investing activities decreased by $58.3 million for the three months ended March 31, 2017 . Recently Issued Accounting Pronouncements The Company believes the following recent accounting pronouncement is relevant to the readers of the Company's financial statements and could have a material effect on the Company's consolidated financial statements. In 2016, the Financial Accounting Standard Board, or FASB, issued a new lease accounting standard, ASU 2016-02, Leases (Topic 842) , which amends existing accounting standards and establishes the principles, presentation and disclosure requirements for lease accounting for both the lessee and lessor. Under the new standard, lessors will use an approach that is substantially equivalent to existing guidance but aligned with the newly adopted revenue recognition standard, while lessees will be required to record most leases on the balance sheet and recognize lease expense in the income statement in a manner similar to current 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 will be recognized on a straight-line basis, while those determined to be financing leases will be recognized following a front-loaded expense profile in which interest and amortization are presented separately in the income statement. The standard must be adopted using a modified retrospective transition approach for leases that exist or are entered into after the beginning of the earliest comparable period presented, with an option to elect certain transition relief. However, the FASB has proposed an alternative transition method that would allow entities the option to apply the new lease guidance as of the period of adoption without adjusting comparative periods presented. Further, prior period financial statements and disclosures would be presented in accordance with existing leases guidance under this proposed transitional practical expedient. Management is currently evaluating the impact the standard will have on the consolidated financial statements and related disclosures upon adoption on January 1, 2019.

Earnings Per Common Share of MA

Earnings Per Common Share of MAA	3 Months Ended
	Mar. 31, 2018
Earnings Per Common Share of MAA [Abstract]
Earnings Per Share [Text Block]	Earnings per Common Share of MAA Basic earnings per share is computed 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, 2018 and 2017 , MAA's basic earnings per share is computed using the two-class method, and MAA's diluted earnings per share was computed using the more dilutive of the treasury stock method or two-class method, as presented below (dollars and shares in thousands, except per share amounts): Three months ended March 31, 2018 2017 Common Shares Outstanding Weighted average common shares - basic 113,507 113,338 Weighted average partnership units outstanding — (1) 4,219 Effect of dilutive securities — (2) 307 Weighted average common shares - diluted 113,507 117,864 Calculation of Earnings per Common Share - basic Net income $ 50,820 $ 43,416 Net income attributable to noncontrolling interests (1,801 ) (1,511 ) Unvested restricted stock (allocation of earnings) (79 ) (73 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 48,018 $ 40,910 Weighted average common shares - basic 113,507 113,338 Earnings per common share - basic $ 0.42 $ 0.36 Calculation of Earnings per Common Share - diluted Net income $ 50,820 $ 43,416 Net income attributable to noncontrolling interests (1,801 ) (1) — Unvested restricted stock (allocation of earnings) (79 ) (2) — Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 48,018 $ 42,494 Weighted average common shares - diluted 113,507 117,864 Earnings per common share - diluted $ 0.42 $ 0.36 (1) For the three months ended March 31, 2018 , 4.2 million OP Units 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 calculations as they are not dilutive.

Earnings Per OP Unit of MAALP

Earnings Per OP Unit of MAALP	3 Months Ended
	Mar. 31, 2018
Earnings Per OP Unit of MAALP [Abstract]
Earnings Per Unit [Text Block]	Earnings per OP Unit of MAALP Basic earnings per OP Unit is computed 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 OP Unit. Diluted earnings per OP Unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units. A reconciliation of the numerators and denominators of the basic and diluted earnings per OP Unit computations for the three months ended March 31, 2018 and 2017 is presented below (dollars and units in thousands, except per unit amounts): Three months ended March 31, 2018 2017 Common Units Outstanding Weighted average common units - basic 117,689 117,557 Effect of dilutive securities — (1) 307 Weighted average common units - diluted 117,689 117,864 Calculation of Earnings per Common Unit - basic Net income $ 50,820 $ 43,416 Unvested restricted stock (allocation of earnings) (79 ) (73 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 49,819 $ 42,421 Weighted average common units - basic 117,689 117,557 Earnings per common unit - basic $ 0.42 $ 0.36 Calculation of Earnings per Common Unit - diluted Net income $ 50,820 $ 43,416 Unvested restricted stock (allocation of earnings) (79 ) (1) — Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 49,819 $ 42,494 Weighted average common units - diluted 117,689 117,864 Earnings per common unit - diluted $ 0.42 $ 0.36 (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 calculations as they are not dilutive.

MAA Equity

MAA Equity	3 Months Ended
	Mar. 31, 2018
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, 2018 and 2017 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 Interest - Consolidated Real Estate Entity 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 attributable to controlling interests — — — 49,019 — 1,801 — 50,820 Other comprehensive income - 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 — — — (104,971 ) — — — (104,971 ) Dividends on noncontrolling interests units — — — — — (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 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 Interest - Consolidated Real Estate Entity Total Equity EQUITY BALANCE DECEMBER 31, 2016 $ 9 $ 1,133 $ 7,109,012 $ (707,479 ) $ 1,144 $ 235,976 $ 2,306 $ 6,642,101 Net income attributable to controlling interests — — — 41,905 — 1,511 — 43,416 Other comprehensive loss - derivative instruments — — — — 3,079 113 — 3,192 Issuance and registration of common shares — 1 67 — — — — 68 Issuance and registration of preferred shares — — 2,007 — — — — 2,007 Shares repurchased and retired — — (4,734 ) — — — — (4,734 ) Shares issued in exchange for common units — — 167 — — (167 ) — — Shares issued in exchange for redeemable stock — — 1,482 — — — — 1,482 Redeemable stock fair market value adjustment — — — (298 ) — — — (298 ) Adjustment for noncontrolling interests in Operating Partnership — — 305 — — (305 ) — — Amortization of unearned compensation — — 3,139 (114 ) — — — 3,025 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock — — — (98,841 ) — — — (98,841 ) Dividends on noncontrolling interests units — — — — — (3,664 ) — (3,664 ) EQUITY BALANCE MARCH 31, 2017 $ 9 $ 1,134 $ 7,111,445 $ (765,749 ) $ 4,223 $ 233,464 $ 2,306 $ 6,586,832

MAALP Capital

MAALP Capital	3 Months Ended
	Mar. 31, 2018
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, 2018 and 2017 were as follows (dollars in thousands): Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interest - Consolidated Real Estate Entity 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 (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 Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interest - Consolidated Real Estate Entity Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2016 $ 235,976 $ 6,337,721 $ 64,833 $ 1,246 $ 2,306 $ 6,642,082 Net income 1,511 40,983 922 — — 43,416 Other comprehensive income - derivative instruments — — — 3,192 — 3,192 Issuance of units — 68 2,007 — — 2,075 Units repurchased and retired — (4,734 ) — — — (4,734 ) General partner units issued in exchange for limited partner units (167 ) 167 — — — — Units issued in exchange for redeemable units — 1,482 — — — 1,482 Redeemable units fair market value adjustment — (298 ) — — — (298 ) Adjustment for limited partners' capital at redemption value (192 ) 192 — — — — Amortization of unearned compensation — 3,025 — — — 3,025 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders (3,664 ) (98,841 ) — — — (102,505 ) CAPITAL BALANCE MARCH 31, 2017 $ 233,464 $ 6,279,765 $ 66,840 $ 4,438 $ 2,306 $ 6,586,813

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2018
Notes To Financial Statements [Abstract]
Notes Payable	Borrowings The following table summarizes the Company's outstanding debt as of March 31, 2018 (dollars in thousands): Borrowed Balance Effective Rate Contract Maturity Unsecured debt Variable rate revolving credit facility $ 450,000 2.8 % 4/15/2020 Fixed rate senior notes 2,292,000 4.0 % 11/13/2024 Term loans fixed with swaps 550,000 2.9 % 7/9/2020 Variable rate term loans 300,000 2.6 % 8/29/2020 Fair market value adjustments, debt issuance costs and discounts (25,336 ) Total unsecured debt $ 3,566,664 3.5 % Fixed rate secured debt Individual property mortgages $ 841,711 4.0 % 11/1/2019 Variable rate secured debt (1) Fannie Mae Facility 80,000 2.1 % 12/1/2018 Fair market value adjustments and debt issuance costs 10,476 Total secured debt $ 932,187 3.8 % Total outstanding debt $ 4,498,851 3.6 % (1) Includes capped balances. Unsecured Revolving Credit Facility MAALP maintains a $1.0 billion unsecured credit facility with a syndicate of banks led by KeyBank National Association, or the KeyBank Facility. The KeyBank Facility includes an expansion option up to $1.5 billion . The KeyBank 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 is currently bearing interest at 2.78% . The KeyBank Facility expires in April 2020 with an option to extend for an additional six months. At March 31, 2018 , the MAALP had $450.0 million outstanding under the KeyBank Facility with another approximately $2.5 million of additional capacity used to support outstanding letters of credit. Senior Unsecured Notes As of March 31, 2018 , MAALP had approximately $2.0 billion in principal amount of publicly issued senior unsecured notes and $292.0 million of privately placed senior unsecured notes. These senior unsecured notes had maturities at issuance ranging from seven to twelve years , averaging 6.6 years remaining until maturity as of March 31, 2018 . 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, respectively. 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. The Wells Fargo term loans have balances of $250.0 million and $300.0 million , respectively, mature in 2018 and 2022, respectively, and have variable interest rates of LIBOR plus spreads of 0.90% to 1.90% and 0.90% to 1.75% , respectively, based on the Company's credit ratings. 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, 2018 , the Company had $841.7 million of fixed rate conventional property mortgages with an average interest rate of 4.0% and an average maturity in 2019. In February 2018, the Company retired a $38.3 million mortgage associated with Highlands of West Village. The mortgage was scheduled to mature in May 2018. In addition to the debt retirement, the Company paid $2.7 million associated with property mortgage principal amortizations during the three months ended March 31, 2018 . Secured Credit Facility The Company maintains an $80.0 million secured credit facility with Prudential Mortgage Capital, which is credit enhanced by the Federal National Mortgage Association, or the Fannie Mae Facility. The Fannie Mae Facility matures on December 1, 2018. Borrowings under the Fannie Mae Facility totaled $80.0 million at March 31, 2018 , all of which was variable rate at an average interest rate of 2.1% . The available borrowing capacity at March 31, 2018 was $80.0 million . Guarantees MAA fully and unconditionally guarantees the following debt incurred by the Operating Partnership: • $80.0 million of the Fannie Mae Facility, all of which was borrowed as of March 31, 2018 ; and • $292.0 million of the privately placed senior unsecured notes.

Fair Value of Instruments and D

Fair Value of Instruments and Derivatives Fair Value of Instruments and Derivatives (Notes)	3 Months Ended
	Mar. 31, 2018
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 at March 31, 2018 and December 31, 2017 , totaled $3.1 billion and $3.2 billion , respectively, and had estimated fair values of $3.2 billion and $3.3 billion (excluding prepayment penalties) as of March 31, 2018 and December 31, 2017 , respectively. The carrying values of variable rate notes payable (excluding the effect of interest rate swap and cap agreements) at March 31, 2018 and December 31, 2017 , totaled $1.4 billion and $1.3 billion , respectively, and had estimated fair values of $1.4 billion and $1.3 billion (excluding prepayment penalties) as of March 31, 2018 and December 31, 2017 , 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. Management has determined the inputs used to value the outstanding debt fall within Level 2 of the fair value hierarchy, and therefore, the fair market valuation of debt is considered Level 2 in the fair value hierarchy. Financial Instruments Measured at Fair Value on a Recurring Basis The Company uses interest rate swaps and interest rate caps to add stability to interest expense and to manage its exposure to interest rate movements. 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 values of interest rate options are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates rise above the strike rate of the caps. The variable interest rates used in the calculation of projected receipts on the cap are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities. The fair value of interest rate derivative contracts designated as hedging instruments recorded in "Other assets" in the accompanying Condensed Consolidated Balance Sheets was $5.1 million and $3.6 million as of March 31, 2018 and December 31, 2017 , respectively. The fair value of interest rate derivative contract liabilities recorded in "Accrued expenses and other liabilities" in the accompanying Condensed Consolidated Balance Sheets was $1.6 million and $1.3 million as of March 31, 2018 and December 31, 2017 , respectively. 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 the fair value measurement 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 issued in connection with Merger 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 mark-to-market adjustments of non-cash expense recorded to reflect the change in fair value of the derivative asset in the three months ended March 31, 2018 , the fair value of the embedded derivative decreased to $18.5 million as of March 31, 2018 compared to $21.2 million as of December 31, 2017 . The Company has determined the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, and as a result, all of its derivatives held as of March 31, 2018 and December 31, 2017 were classified as Level 2 in the fair value hierarchy. Cash Flow Hedges of Interest Rate Risk As of January 1, 2018, the Company early adopted ASU 2017-12, Derivatives and Hedging (Topic 815), which clarifies hedge accounting requirements, improves disclosure of hedging arrangements and better aligns risk management activities and financial reporting for hedging relationships. The Company adopted the standard using a modified retrospective approach via the elimination of the previously recorded cumulative ineffectiveness for cash flow and net investment hedges existing at date of adoption as a cumulative-effect adjustment of $0.2 million to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings. The adoption of the ASU did not have a material impact on the consolidated financial statements or the Company's internal accounting policies. The changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in "Accumulated other comprehensive income" and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. In conjunction with the adoption of ASU 2017-12, 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 income" 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 $1.9 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. As of March 31, 2018 , the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk: Interest Rate Derivative Number of Instruments Notional Amount Interest Rate Cap 1 $ 25,000,000 Interest Rate Swaps (1) 12 $ 550,000,000 (1) Six forward rate swaps totaling $300.0 million, which hedge the first 10 years of interest payments on debt expected to be issued in 2018, are included in the number of instruments but excluded from the notional amount. These swaps are not included in the debt discussion in Note 6 or Management's Discussion and Analysis of Financial Condition and Results of Operations found elsewhere in this report. 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, 2018 and 2017 (dollars in thousands): Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in OCI on Derivative (Effective Portion) Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain (Loss) Reclassified from Accumulated OCI into Interest Expense (Effective Portion) Three months ended March 31, 2018 2017 2018 2017 Interest rate contracts $ 832 $ 2,520 Interest Expense $ 193 $ (672 ) Derivatives Not Designated as Hedging Instruments Location of (Loss) Gain Recognized in Income on Derivative Amount of (Loss) Gain Recognized in Earnings on Derivative For the three months ended March 31, 2018 2017 Preferred stock embedded derivative Non-operating (expense) income $ (2,644 ) $ 2,353 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, 2018 , 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 at the termination value of $1.2 million . 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. Changes in Accumulated Other Comprehensive Income The Company's other comprehensive income consists entirely of gains and losses attributable to the effective portion of its cash flow hedges. The table below reflects the change in the balance for the three months ended March 31, 2018 and 2017 (dollars in thousands): Affected Line Item in the Condensed Consolidated Statements Of Operations Three months ended March 31, 2018 2017 Beginning balance $ 2,157 $ 1,144 Other comprehensive income before reclassifications 832 2,520 Amounts reclassified from Accumulated other comprehensive income - interest rate contracts Interest expense (193 ) 672 Net current period other comprehensive income attributable to noncontrolling interests (29 ) (113 ) Cumulative adjustment due to adoption of ASU 2017-12 233 — Change in Accumulated other comprehensive income attributable to MAA 843 3,079 Ending balance $ 3,000 $ 4,223

Shareholders' Equity of MAA

Shareholders' Equity of MAA	3 Months Ended
	Mar. 31, 2018
Shareholders' Equity of MAA [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Shareholders' Equity of MAA On 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 issued and outstanding, representing a total of 117,886,987 shares and units. At March 31, 2017 , 113,574,798 shares of common stock of MAA and 4,217,444 OP Units were outstanding, representing a total of 117,792,242 shares and units. Options to purchase 95,838 shares of MAA's common stock were outstanding as of March 31, 2018 , compared to 147,282 outstanding options as of March 31, 2017 . During the three months ended March 31, 2018 , 32,391 shares of MAA's common stock were acquired from employees to satisfy minimum tax withholding obligations that arose upon vesting of restricted stock granted pursuant to approved plans. During the three months ended March 31, 2017 , 47,480 shares were acquired for such purposes. During the three months ended March 31, 2018 , we issued 12,600 shares related to the exercise of stock options. These exercises resulted in proceeds of $0.6 million . During the three months ended March 31, 2017 , there were no stock options exercised. Preferred Stock As of March 31, 2018 , 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, 2018
Partners' Capital of Mid-America Apartments, L.P. [Abstract]
Partners' Capital Notes Disclosure [Text Block]	Partners' Capital of MAALP OP Units Interests in MAALP are represented by OP Units. 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, MAALP's general partner. The remaining 4,141,780 OP Units were owned by non-affiliated limited partners, or Class A Limited Partners. As of March 31, 2017 , there were 117,792,242 OP Units outstanding, 113,574,798 or 96.4% of which were owned by MAA and 4,217,444 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 the Operating Partnership 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 the Operating Partnership's assets; and distribution of Operating Partnership 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, the Operating Partnership may issue Class A Units and Class B Units. Class A Units may only be held by limited partners who are not affiliated with MAA, in its capacity as general partner of the Operating Partnership, while Class B Units may only be held by MAA, in its capacity as general partner of the Operating Partnership, and as of March 31, 2018 , a total of 4,141,780 Class A Units in the Operating Partnership were held by limited partners unaffiliated with MAA, while a total of 113,745,207 Class B Units were held by MAA. In general, the limited partners do not have the power to participate in the management or control of the Operating Partnership'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 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 the Operating Partnership. Issuance or redemption of additional Class A Units or Class B Units changes the relative ownership percentage of the partners. The issuance of Class B Units generally occurs when MAA issues common stock and the proceeds from that issuance are contributed to the Operating Partnership 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, the Operating Partnership generally redeems an equal number of Class B 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 the Operating Partnership. Holders of the Class A Units may require MAA to redeem their Class A Units, in which case MAA may, at its option, pay the redemption price either in cash (in an amount per Class A 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 Unit so redeemed. At March 31, 2018 , a total of 4,141,780 Class A 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. At March 31, 2017 , a total of 4,217,444 Class A Units were outstanding and redeemable for 4,217,444 shares of MAA common stock, with an approximate value of $429.1 million , based on the closing price of MAA’s common stock on March 31, 2017 of $101.74 per share. The Operating Partnership pays the same per unit distribution in respect to the OP Units as the per share dividend MAA pays in respect to its common and preferred stock.

Legal Proceedings

Legal Proceedings	3 Months Ended
	Mar. 31, 2018
Disclosure Text Block [Abstract]
Legal Matters and Contingencies [Text Block]	Legal Proceedings In September 2010, the United States Department of Justice, or DOJ, filed suit against Post Properties, (and by virtue of the Merger, MAA) in the United States District Court for the District of Columbia alleging that certain of Post Properties’ apartments violated accessibility requirements of the Fair Housing Act, or FHA, and the Americans with Disabilities Act of 1990, or ADA. The DOJ is seeking, among other things, an injunction against MAA, requiring MAA to retrofit the properties and comply with FHA and ADA standards in future design and construction, as well as monetary damages and civil penalties. No trial date has been set. In December 2017, a non-profit civil rights organization filed suit against MAA and the Operating Partnership in the United States District Court for the District of Columbia. The suit alleges the Company maintained and enforced a criminal records screening policy at certain of its apartment communities, all of which are apartments acquired from Post Properties in the Merger, which violates the FHA. The suit seeks injunctive relief, actual and punitive damages and attorneys' fees and costs. The Company is subject to various other legal proceedings and claims that arise in the ordinary course of our 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 such matters, either individually or in the aggregate, will have a material adverse effect on the Company's financial position, results of operations or cash flows. 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. 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 expected ultimately 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, 2018 and December 31, 2017 , the Company's accrual for loss contingencies was $31.8 million and $32.1 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, 2018
Notes To Financial Statements [Abstract]
Segment Information	Segment Information The Company's segment information presents the measure used by the chief operating decision maker for purposes of assessing each operating segment's performance. The chief operating decision maker is the Company’s President and Chief Executive Officer. As of March 31, 2018 , the Company owned or had an ownership interest in 303 multifamily apartment communities in 17 different states and the District of Columbia from which it derived all significant sources of earnings and operating cash flows. The Company's chief operating decision maker 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 undergone 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 adjust 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 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. Effective January 1, 2018, the Company revised its reportable segment presentation. The revision eliminated the distinction between large and secondary same store markets and combined the two previously reported segments into the Same Store reportable segment referred to above. The communities acquired in the Merger became eligible for the same store designation on January 1, 2018 as the properties had been owned and stabilized for a full 12 months. The communities acquired from Post Properties are predominantly located in large markets, resulting in a more homogeneous property portfolio in terms of market dynamics. The chief operating decision maker no longer makes decisions about capital resource allocations, and does not assess operating performance, by large and secondary same store markets. Further, the chief operating decision maker no longer reviews financial information segregating the Company’s operating segments into large and secondary same store markets. The change in the Company’s portfolio caused the distinction between large and secondary markets to no longer be meaningful. As a result, the Company now discloses two reportable segments: Same Store and Non-Same Store and Other. There were no changes in the structure of the Company’s internal organization that prompted the change in reportable segments. Prior year amounts have been revised to conform to the current year presentation shown below. Revenues and NOI for each reportable segment for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Revenues: Same Store Rental revenues $ 331,683 $ 325,767 Reimbursable property revenues 22,349 21,821 Other property revenues 2,815 3,009 Total Same Store revenues $ 356,847 $ 350,597 Non-Same Store and Other Rental revenues $ 27,357 $ 25,098 Reimbursable property revenues 1,338 1,536 Other property revenues 475 1,677 Total Non-Same Store and Other revenues $ 29,170 $ 28,311 Total rental and other property revenues $ 386,017 $ 378,908 Net Operating Income: Same Store NOI $ 225,350 $ 221,183 Non-Same Store and Other NOI 16,263 16,452 Total NOI 241,613 237,635 Depreciation and amortization (120,744 ) (129,997 ) Property management expenses (12,880 ) (10,981 ) General and administrative expenses (10,132 ) (12,840 ) Merger and integration expenses (3,799 ) (6,161 ) Interest expense (40,905 ) (36,584 ) Loss on sale of depreciable real estate assets — (73 ) Gain on sale of non-depreciable real estate assets 150 — Other non-operating (expense) income (2,341 ) 2,711 Income tax expense (640 ) (651 ) Income from real estate joint venture 498 357 Net income attributable to noncontrolling interests (1,801 ) (1,511 ) Dividends to MAA Series I preferred shareholders (922 ) (922 ) Net income available for MAA common shareholders $ 48,097 $ 40,983 Assets for each reportable segment as of March 31, 2018 and December 31, 2017 were as follows (in thousands): March 31, 2018 December 31, 2017 Assets: Same Store $ 9,773,940 $ 9,864,321 Non-Same Store and Other 1,439,424 1,427,778 Corporate assets 204,012 199,820 Total assets $ 11,417,376 $ 11,491,919

Real Estate Acquisitions and Di

Real Estate Acquisitions and Dispositions	3 Months Ended
	Mar. 31, 2018
Notes To Financial Statements [Abstract]
Real Estate Acquisitions and Dispositions	Real Estate Acquisitions and Dispositions The Company did not acquire any apartment communities or land parcels during the three months ended March 31, 2018 . The following table reflects the Company's disposition activity for the three months ended March 31, 2018 : Community Market Acres Date Sold Craft Farms Residential - Outparcel Gulf Shores, AL 3 January 24, 2018 Randal Park - Outparcel Orlando, FL 34 February 27, 2018

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On April 19, 2018, the Company closed on the disposition of a 29 acre land parcel located in the Las Vegas, Nevada market, for proceeds of $9.5 million , resulting in an expected net gain of $2.8 million on the sale of non-depreciable real estate assets. This land parcel was classified as held for sale as of March 31, 2018 as described in Note 1. On April 26, 2018, the Company acquired a 374 unit multifamily apartment community, Sync36, located in Denver, Colorado.

Basis of Presentation and Pri21

Basis of Presentation and Principles of Consolidation (Policies)	3 Months Ended
	Mar. 31, 2018
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 approximately 92.5% 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, 92.5% 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 "Investment in Unconsolidated Affiliates" below). Changes in Presentation Please refer to the Company's Annual Report on Form 10-K for the year ended December 31, 2017 that was filed with the SEC on February 23, 2018 for discussions of the changes in presentation in the Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations and Condensed Consolidated Statements of Cash Flows, which are still applicable for this Quarterly Report on Form 10-Q. Noncontrolling Interests At March 31, 2018 , the Company had two types of noncontrolling interests, (1) noncontrolling interests related to the common unitholders of its Operating Partnership (see Note 9) and (2) noncontrolling interest related to its consolidated real estate entity (see "Investment in Consolidated Real Estate Joint Venture" below). Investment in Unconsolidated Affiliates The Company, together with other institutional investors in a limited liability company, or the Apartment LLC, indirectly owns one apartment community, Post Massachusetts Avenue, located in Washington, D.C. The Company owns a 35.0% equity interest in the unconsolidated real estate joint venture as of March 31, 2018 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. At March 31, 2018 , the Company's investment in the Apartment LLC totaled $45.0 million . During September 2017, a subsidiary of the Operating Partnership entered into a limited partnership together with a general partner and other limited partners to form Real Estate Technology Ventures, L.P. The Operating Partnership indirectly owns 26.5% 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. At March 31, 2018 , the Company's investment in the limited partnership totaled $2.0 million . The Company is committed to make additional capital contributions totaling $12.8 million if and when called by the general partner of the limited partnership prior to September 2022. Investment in Consolidated Real Estate Entity At March 31, 2018 , the Company owned a 92.5% equity interest in a consolidated real estate joint venture to develop, construct and operate a 359 -unit apartment community in Denver, Colorado, along with a private real estate company. The venture partner was generally responsible for the development and construction of the community, and the Company will continue to manage the community as construction on the development was completed during the three months ended March 31, 2018 . The joint venture was determined to be a VIE with the Company designated as the primary beneficiary. As a result, the accounts of the joint venture are consolidated by the Company. At March 31, 2018 , the consolidated assets, liabilities and equity included buildings and improvements and other, net of accumulated depreciation of $71.0 million ; land of $14.9 million ; and accrued expenses and other liabilities of $2.6 million . Assets Held for Sale During the first quarter of 2018, the criteria for classifying one land parcel as held for sale were met, and as a result, the land parcel was presented as held for sale in the Condensed Consolidated Balance Sheet as of March 31, 2018 . See Note 13 for details on the April 2018 disposition of this land parcel. The Randal Park land parcel that comprised the asset held for sale balance as of December 31, 2017, was sold during the first quarter as detailed on Note 12. 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. Revenue from Contracts with Customers The Company primarily leases multifamily residential apartments under operating leases generally with terms of one year or less, which are recorded as operating leases. Rental lease revenues are recognized in accordance with ASC Topic 840, Leases , using a method that represents a straight-line basis over the term of the lease. Rental income represents approximately 93% of the Company's total revenues and includes gross market rent less adjustments for concessions, vacancy loss and bad debt. Other non-lease revenues represent the remaining 7% of the Company's total revenues and are primarily driven by utility reimbursement revenue from its tenants. The Company's primary sources of reimbursement revenue are from water and cable utility services, which produced $9.8 million and $7.5 million , respectively, of revenues during the three months ended March 31, 2018, and $9.4 million and $7.7 million of revenues, respectively, during the three months ended March 31, 2017 . Other non-lease revenues are recognized in accordance with ASC Topic 606, Revenue Recognition , as a result of the Company's January 1, 2018 adoption of Accounting Standards Update, or ASU, 2014-09, Revenue from Contracts with Customers , using the modified retrospective approach. The guidance requires that revenue (outside of the scope of lease revenue accounting rules) 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. While ASU 2014-09 requires additional disclosure regarding the nature and timing of the Company's non-lease revenue transactions, which is provided here in Note 1 as well as Note 11, the adoption of the ASU did not have a material impact on the Company's consolidated financial statements or the Company's internal accounting policies and did not result in an opening adjustment to retained earnings. In addition, the Company elected the available practical expedients to the ASU’s requirement for disclosure on remaining performance obligations, which allow an entity to avoid disclosing the amount of the remaining performance obligations for contracts with an original expected duration of less than one year or those that meet the practical expedient in ASC 606-10-55-18 that permits the entity to recognize revenue as invoiced. See Note 11 for the disaggregation of our revenues in accordance with ASU 2014-09. Impact of Recently Adopted Accounting Standards on Condensed Consolidated Statements of Cash Flows Effective January 1, 2018, the Company adopted ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (a Consensus of the FASB Emerging Issues Task Force) , which clarifies how certain types of cash receipts and cash payments are to be presented and classified on the statement of cash flows. Management has determined three of the eight transactions in the ASU are relevant to the Company and its cash flows and include debt prepayment and extinguishment costs, proceeds from the settlement of insurance claims and distributions received from equity method investees. Upon adoption of ASU 2016-15, the Company recognized a $0.2 million increase to net cash provided by operating activities and a $0.2 million decrease to net cash used in investing activities for the three months ended March 31, 2017 . The Company adopted ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (A Consensus of the FASB Emerging Issues Task Force) , effective January 1, 2018. The ASU required restricted cash to be presented within cash and cash equivalents when reconciling the beginning and ending amounts in the statement of cash flow with retrospective adjustments to all periods presented. The Company previously reported the change in restricted cash within the operating and investing activities in the consolidated statement of cash flows. Upon adoption, cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2017 increased by approximately $24.5 million to reflect the restricted cash balances. Additionally, net cash provided by operating activities decreased by $5.5 million for the three months ended March 31, 2017 , while net cash used in investing activities decreased by $58.3 million for the three months ended March 31, 2017 . Recently Issued Accounting Pronouncements The Company believes the following recent accounting pronouncement is relevant to the readers of the Company's financial statements and could have a material effect on the Company's consolidated financial statements. In 2016, the Financial Accounting Standard Board, or FASB, issued a new lease accounting standard, ASU 2016-02, Leases (Topic 842) , which amends existing accounting standards and establishes the principles, presentation and disclosure requirements for lease accounting for both the lessee and lessor. Under the new standard, lessors will use an approach that is substantially equivalent to existing guidance but aligned with the newly adopted revenue recognition standard, while lessees will be required to record most leases on the balance sheet and recognize lease expense in the income statement in a manner similar to current 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 will be recognized on a straight-line basis, while those determined to be financing leases will be recognized following a front-loaded expense profile in which interest and amortization are presented separately in the income statement. The standard must be adopted using a modified retrospective transition approach for leases that exist or are entered into after the beginning of the earliest comparable period presented, with an option to elect certain transition relief. However, the FASB has proposed an alternative transition method that would allow entities the option to apply the new lease guidance as of the period of adoption without adjusting comparative periods presented. Further, prior period financial statements and disclosures would be presented in accordance with existing leases guidance under this proposed transitional practical expedient. Management is currently evaluating the impact the standard will have on the consolidated financial statements and related disclosures upon adoption on January 1, 2019.

Earnings Per Common Share of 22

Earnings Per Common Share of MAA (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Common Share of MAA [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block]	Basic earnings per share is computed 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, 2018 and 2017 , MAA's basic earnings per share is computed using the two-class method, and MAA's diluted earnings per share was computed using the more dilutive of the treasury stock method or two-class method, as presented below (dollars and shares in thousands, except per share amounts): Three months ended March 31, 2018 2017 Common Shares Outstanding Weighted average common shares - basic 113,507 113,338 Weighted average partnership units outstanding — (1) 4,219 Effect of dilutive securities — (2) 307 Weighted average common shares - diluted 113,507 117,864 Calculation of Earnings per Common Share - basic Net income $ 50,820 $ 43,416 Net income attributable to noncontrolling interests (1,801 ) (1,511 ) Unvested restricted stock (allocation of earnings) (79 ) (73 ) Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 48,018 $ 40,910 Weighted average common shares - basic 113,507 113,338 Earnings per common share - basic $ 0.42 $ 0.36 Calculation of Earnings per Common Share - diluted Net income $ 50,820 $ 43,416 Net income attributable to noncontrolling interests (1,801 ) (1) — Unvested restricted stock (allocation of earnings) (79 ) (2) — Preferred dividends (922 ) (922 ) Net income available for common shareholders, adjusted $ 48,018 $ 42,494 Weighted average common shares - diluted 113,507 117,864 Earnings per common share - diluted $ 0.42 $ 0.36 (1) For the three months ended March 31, 2018 , 4.2 million OP Units 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 calculations as they are not dilutive.

Earnings Per OP Unit of MAALP (

Earnings Per OP Unit of MAALP (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per OP Unit of MAALP [Abstract]
Schedule of Earnings Per Unit, Basic and Diluted [Table Text Block]	Basic earnings per OP Unit is computed 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 OP Unit. Diluted earnings per OP Unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units. A reconciliation of the numerators and denominators of the basic and diluted earnings per OP Unit computations for the three months ended March 31, 2018 and 2017 is presented below (dollars and units in thousands, except per unit amounts): Three months ended March 31, 2018 2017 Common Units Outstanding Weighted average common units - basic 117,689 117,557 Effect of dilutive securities — (1) 307 Weighted average common units - diluted 117,689 117,864 Calculation of Earnings per Common Unit - basic Net income $ 50,820 $ 43,416 Unvested restricted stock (allocation of earnings) (79 ) (73 ) Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 49,819 $ 42,421 Weighted average common units - basic 117,689 117,557 Earnings per common unit - basic $ 0.42 $ 0.36 Calculation of Earnings per Common Unit - diluted Net income $ 50,820 $ 43,416 Unvested restricted stock (allocation of earnings) (79 ) (1) — Preferred unit distributions (922 ) (922 ) Net income available for common unitholders, adjusted $ 49,819 $ 42,494 Weighted average common units - diluted 117,689 117,864 Earnings per common unit - diluted $ 0.42 $ 0.36 (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 calculations as they are not dilutive.

MAA Equity (Tables)

MAA Equity (Tables)	3 Months Ended
	Mar. 31, 2018
MAA Equity [Abstract]
Shareholders' Equity [Table Text Block]	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 Interest - Consolidated Real Estate Entity Total Equity EQUITY BALANCE DECEMBER 31, 2016 $ 9 $ 1,133 $ 7,109,012 $ (707,479 ) $ 1,144 $ 235,976 $ 2,306 $ 6,642,101 Net income attributable to controlling interests — — — 41,905 — 1,511 — 43,416 Other comprehensive loss - derivative instruments — — — — 3,079 113 — 3,192 Issuance and registration of common shares — 1 67 — — — — 68 Issuance and registration of preferred shares — — 2,007 — — — — 2,007 Shares repurchased and retired — — (4,734 ) — — — — (4,734 ) Shares issued in exchange for common units — — 167 — — (167 ) — — Shares issued in exchange for redeemable stock — — 1,482 — — — — 1,482 Redeemable stock fair market value adjustment — — — (298 ) — — — (298 ) Adjustment for noncontrolling interests in Operating Partnership — — 305 — — (305 ) — — Amortization of unearned compensation — — 3,139 (114 ) — — — 3,025 Dividends on preferred stock — — — (922 ) — — — (922 ) Dividends on common stock — — — (98,841 ) — — — (98,841 ) Dividends on noncontrolling interests units — — — — — (3,664 ) — (3,664 ) EQUITY BALANCE MARCH 31, 2017 $ 9 $ 1,134 $ 7,111,445 $ (765,749 ) $ 4,223 $ 233,464 $ 2,306 $ 6,586,832 Changes in total equity and its components for the three months ended March 31, 2018 and 2017 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 Interest - Consolidated Real Estate Entity 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 attributable to controlling interests — — — 49,019 — 1,801 — 50,820 Other comprehensive income - 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 — — — (104,971 ) — — — (104,971 ) Dividends on noncontrolling interests units — — — — — (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, 2018
MAALP Capital [Abstract]
Partners' Capital [Table Text Block]	Changes in total capital and its components for the three months ended March 31, 2018 and 2017 were as follows (dollars in thousands): Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interest - Consolidated Real Estate Entity 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 (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 Mid-America Apartments, L.P. Unitholders' Capital Limited Partner General Partner Preferred Units Accumulated Noncontrolling Interest - Consolidated Real Estate Entity Total Partnership Capital CAPITAL BALANCE DECEMBER 31, 2016 $ 235,976 $ 6,337,721 $ 64,833 $ 1,246 $ 2,306 $ 6,642,082 Net income 1,511 40,983 922 — — 43,416 Other comprehensive income - derivative instruments — — — 3,192 — 3,192 Issuance of units — 68 2,007 — — 2,075 Units repurchased and retired — (4,734 ) — — — (4,734 ) General partner units issued in exchange for limited partner units (167 ) 167 — — — — Units issued in exchange for redeemable units — 1,482 — — — 1,482 Redeemable units fair market value adjustment — (298 ) — — — (298 ) Adjustment for limited partners' capital at redemption value (192 ) 192 — — — — Amortization of unearned compensation — 3,025 — — — 3,025 Distributions to preferred unitholders — — (922 ) — — (922 ) Distributions to common unitholders (3,664 ) (98,841 ) — — — (102,505 ) CAPITAL BALANCE MARCH 31, 2017 $ 233,464 $ 6,279,765 $ 66,840 $ 4,438 $ 2,306 $ 6,586,813

Borrowings Borrowings (Tables)

Borrowings Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	The following table summarizes the Company's outstanding debt as of March 31, 2018 (dollars in thousands): Borrowed Balance Effective Rate Contract Maturity Unsecured debt Variable rate revolving credit facility $ 450,000 2.8 % 4/15/2020 Fixed rate senior notes 2,292,000 4.0 % 11/13/2024 Term loans fixed with swaps 550,000 2.9 % 7/9/2020 Variable rate term loans 300,000 2.6 % 8/29/2020 Fair market value adjustments, debt issuance costs and discounts (25,336 ) Total unsecured debt $ 3,566,664 3.5 % Fixed rate secured debt Individual property mortgages $ 841,711 4.0 % 11/1/2019 Variable rate secured debt (1) Fannie Mae Facility 80,000 2.1 % 12/1/2018 Fair market value adjustments and debt issuance costs 10,476 Total secured debt $ 932,187 3.8 % Total outstanding debt $ 4,498,851 3.6 %

Fair Value of Instruments and27

Fair Value of Instruments and Derivatives Fair Value of Derivatives and Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Interest Rate Derivatives [Table Text Block]	As of March 31, 2018 , the Company had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk: Interest Rate Derivative Number of Instruments Notional Amount Interest Rate Cap 1 $ 25,000,000 Interest Rate Swaps (1) 12 $ 550,000,000
Derivative Instruments, Gain (Loss) [Table Text Block]	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, 2018 and 2017 (dollars in thousands): Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in OCI on Derivative (Effective Portion) Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Amount of Gain (Loss) Reclassified from Accumulated OCI into Interest Expense (Effective Portion) Three months ended March 31, 2018 2017 2018 2017 Interest rate contracts $ 832 $ 2,520 Interest Expense $ 193 $ (672 ) Derivatives Not Designated as Hedging Instruments Location of (Loss) Gain Recognized in Income on Derivative Amount of (Loss) Gain Recognized in Earnings on Derivative For the three months ended March 31, 2018 2017 Preferred stock embedded derivative Non-operating (expense) income $ (2,644 ) $ 2,353
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income	Changes in Accumulated Other Comprehensive Income The Company's other comprehensive income consists entirely of gains and losses attributable to the effective portion of its cash flow hedges. The table below reflects the change in the balance for the three months ended March 31, 2018 and 2017 (dollars in thousands): Affected Line Item in the Condensed Consolidated Statements Of Operations Three months ended March 31, 2018 2017 Beginning balance $ 2,157 $ 1,144 Other comprehensive income before reclassifications 832 2,520 Amounts reclassified from Accumulated other comprehensive income - interest rate contracts Interest expense (193 ) 672 Net current period other comprehensive income attributable to noncontrolling interests (29 ) (113 ) Cumulative adjustment due to adoption of ASU 2017-12 233 — Change in Accumulated other comprehensive income attributable to MAA 843 3,079 Ending balance $ 3,000 $ 4,223

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2018
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, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Revenues: Same Store Rental revenues $ 331,683 $ 325,767 Reimbursable property revenues 22,349 21,821 Other property revenues 2,815 3,009 Total Same Store revenues $ 356,847 $ 350,597 Non-Same Store and Other Rental revenues $ 27,357 $ 25,098 Reimbursable property revenues 1,338 1,536 Other property revenues 475 1,677 Total Non-Same Store and Other revenues $ 29,170 $ 28,311 Total rental and other property revenues $ 386,017 $ 378,908 Net Operating Income: Same Store NOI $ 225,350 $ 221,183 Non-Same Store and Other NOI 16,263 16,452 Total NOI 241,613 237,635 Depreciation and amortization (120,744 ) (129,997 ) Property management expenses (12,880 ) (10,981 ) General and administrative expenses (10,132 ) (12,840 ) Merger and integration expenses (3,799 ) (6,161 ) Interest expense (40,905 ) (36,584 ) Loss on sale of depreciable real estate assets — (73 ) Gain on sale of non-depreciable real estate assets 150 — Other non-operating (expense) income (2,341 ) 2,711 Income tax expense (640 ) (651 ) Income from real estate joint venture 498 357 Net income attributable to noncontrolling interests (1,801 ) (1,511 ) Dividends to MAA Series I preferred shareholders (922 ) (922 ) Net income available for MAA common shareholders $ 48,097 $ 40,983
Assets for Reportable Segment	Assets for each reportable segment as of March 31, 2018 and December 31, 2017 were as follows (in thousands): March 31, 2018 December 31, 2017 Assets: Same Store $ 9,773,940 $ 9,864,321 Non-Same Store and Other 1,439,424 1,427,778 Corporate assets 204,012 199,820 Total assets $ 11,417,376 $ 11,491,919

Real Estate Acquisitions and 29

Real Estate Acquisitions and Dispositions Real Estate Acquisitions and Dispositions (Tables)	3 Months Ended
	Mar. 31, 2018
Real Estate [Abstract]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following table reflects the Company's disposition activity for the three months ended March 31, 2018 : Community Market Acres Date Sold Craft Farms Residential - Outparcel Gulf Shores, AL 3 January 24, 2018 Randal Park - Outparcel Orlando, FL 34 February 27, 2018

Consolidation and Basis of Pres

Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)shares	Mar. 31, 2018apartmentunits	Mar. 31, 2018Property	Mar. 31, 2018Communities	Mar. 31, 2018USD ($)	Mar. 31, 2018shares	Mar. 31, 2018ft²
Cash and Cash Equivalents [Member] | Accounting Standards Update 2016-18 [Member]
Real Estate Properties [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 24.5
Change in Cash Used in Investing Activities [Member] | Accounting Standards Update 2016-18 [Member]
Real Estate Properties [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		58.3
Change in Provided by Operating Activities [Member] | Accounting Standards Update 2016-18 [Member]
Real Estate Properties [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 5.5
General Partners' Capital Account, Units Outstanding | shares		113,574,798					113,745,207
Limited Liability (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	96.50%
Number of owned or owned interests of apartment communities				303	302
Percentage Of Rental Revenue And Other Income From Leasing Of Apartment Homes	93.00%
Percentage of Rental Revenue and Other Income From Non-leasing Activities	7.00%
Minimum [Member]
Real Estate Properties [Line Items]
Percentage Of Ownership Interests	92.50%
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					2
Number of units under development community | Property				578
Development Properties [Member] | Expected Costs [Member]
Real Estate Properties [Line Items]
Development and capital improvements in progress						$ 125.8
Development Properties [Member] | Costs Incurred to Date [Member]
Real Estate Properties [Line Items]
Development and capital improvements in progress						101.4
Retail
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities | Property				29
Square Footage of Real Estate Property | ft²								620,000
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	26.50%
Real Estate Investments, Joint Ventures						2
Real Estate Technology Ventures, L.P. [Member] | Limited Partner Capital Contribution, Future Obligation [Member]
Real Estate Properties [Line Items]
Real Estate Investments, Joint Ventures						12.8
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						71
Land						14.9
Accrued expenses and other liabilities						2.6
Post Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Equity Method Investment, Ownership Percentage	35.00%
Real Estate Investments, Joint Ventures						$ 45
Accounting Standards Update 2016-15 [Member]
Real Estate Properties [Line Items]
Net Cash Provided by (Used in) Operating Activities		$ 0.2
Net Cash Provided by (Used in) Investing Activities		0.2
Water Utility Revenue [Member]
Real Estate Properties [Line Items]
Tenant Reimbursements	$ 9.8	9.4
Cable Utility Revenue [Member]
Real Estate Properties [Line Items]
Tenant Reimbursements	$ 7.5	$ 7.7

Earnings Per Common Share of 31

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, 2018	Mar. 31, 2017
Earnings Per Share Disclosure [Line Items]
Weighted average common shares - basic		113,507	113,338
Weighted average partnership units outstanding	[1]	0	4,219
Effect of dilutive securities	[2]	0	307
Weighted average common shares - diluted		113,507	117,864
Dividends, Preferred Stock, Cash		$ 922	$ 922
Calculation of Basic Earnings per Share [Member]
Earnings Per Share Disclosure [Line Items]
Income from continuing operations		50,820	43,416
Income from continuing operations attributable to noncontrolling interests		(1,801)	(1,511)
Income from continuing operations allocated to unvested restricted shares		(79)	(73)
Dividends, Preferred Stock, Cash		(922)	(922)
Income from continuing operations available for common shareholders, adjusted		$ 48,018	$ 40,910
Earnings per share - basic		$ 0.42	$ 0.36
Calculation of Diluted Earnings per Share [Member]
Earnings Per Share Disclosure [Line Items]
Income from continuing operations		$ 50,820	$ 43,416
Income from continuing operations attributable to noncontrolling interests	[1]	(1,801)	0
Income from continuing operations allocated to unvested restricted shares	[2]	(79)	0
Dividends, Preferred Stock, Cash		(922)	(922)
Income from continuing operations available for common shareholders, adjusted		$ 48,018	$ 42,494
Earnings per share - diluted		$ 0.42	$ 0.36
Limited Partnership Units [Member]
Earnings Per Share Disclosure [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		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, 2018, 4.2 million OP Units and their related income are not included in the diluted earnings per share calculations as they are not dilutive.
[2]	(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 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) - Limited Partner [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share Disclosure [Line Items]
Weighted average common units - basic	117,689	117,557
Effect of dilutive securities	0	307
Weighted average common shares - diluted	117,689	117,864
Dividends, Preferred Stock, Cash	$ 922	$ 922
Calculation of Basic Earnings Per Unit [Member]
Earnings Per Share Disclosure [Line Items]
Income from continuing operations	50,820	43,416
Income from continuing operations allocated to unvested restricted shares	(79)	(73)
Dividends, Preferred Stock, Cash	(922)	(922)
Income from continuing operations available for common unitholders, adjusted	$ 49,819	$ 42,421
Earnings per unit - basic	$ 0.42	$ 0.36
Calculation of Diluted Earnings Per Unit [Member]
Earnings Per Share Disclosure [Line Items]
Income from continuing operations	$ 50,820	$ 43,416
Income from continuing operations allocated to unvested restricted shares	(79)	0
Dividends, Preferred Stock, Cash	(922)	(922)
Income from continuing operations available for common unitholders, adjusted	$ 49,819	$ 42,494
Earnings per unit - diluted	$ 0.42	$ 0.36
Restricted Stock [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, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares repurchased and retired		$ 0
Shares issued in exchange for units		0
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common stock		0
Parent Company [Member]
Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 50,820,000	43,416,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	6,518,057,000		$ 6,571,588,000
Noncontrolling Interest in Joint Ventures	2,306,000	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
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	233,000	0
Parent Company [Member] | Accumulated Distributions in Excess of Net Income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(784,500,000)	(707,479,000)
Net income attributable to MAA	49,019,000	41,905,000
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	965,000	(298,000)
Adjustment for noncontrolling interest ownership in operating partnership	0
Amortization of unearned compensation	0	(114,000)
Dividends, Preferred Stock, Cash	922,000	922,000
Dividends on common stock	(104,971,000)	(98,841,000)
Dividends on noncontrolling interest units	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(233,000)
Ending Balance	(840,642,000)	(765,749,000)
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
Preferred Stock, Value, Outstanding		0
Shares repurchased and retired		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] | Preferred Stock Including Additional Paid in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance and registration of common shares		2,007,000
Parent Company [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,134,000	1,133,000
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	1,135,000	1,134,000
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	7,121,112,000	7,109,012,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	0
Shares repurchased and retired	(2,912,000)	(4,734,000)
Stock Issued During Period, Value, Stock Options Exercised	625,000
Shares issued in exchange for units	2,780,000	167,000
Shares issued in exchange for redeemable stock	1,915,000	1,482,000
Redeemable stock fair market value	0
Adjustment for noncontrolling interest ownership in operating partnership	92,000	305,000
Amortization of unearned compensation	4,024,000	3,139,000
Dividends on common stock	0
Dividends on noncontrolling interest units	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
Ending Balance	7,127,740,000	7,111,445,000
Parent Company [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	231,676,000	235,976,000
Net Income Attributable to Noncontrolling Interest	1,801,000	1,511,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	29,000	113,000
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	(2,780,000)	(167,000)
Redeemable stock fair market value	0
Adjustment for noncontrolling interest ownership in operating partnership	(92,000)	(305,000)
Amortization of unearned compensation	0
Dividends on common stock	0
Dividends on noncontrolling interest units	(3,819,000)	(3,664,000)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
Ending Balance	226,815,000	233,464,000
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	2,157,000	1,144,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	610,000	3,079,000
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
Amortization of unearned compensation	0
Dividends on common stock	0
Dividends on noncontrolling interest units	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	233,000
Ending Balance	3,000,000	4,223,000
Parent Company [Member] | Common Stock Including Additional Paid in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance and registration of common shares	104,000	67,000
Parent Company [Member] | Stockholders' Equity, Total [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	6,573,894,000	6,642,101,000
Net Income Including Portion Attributable to Noncontrolling Interest	50,820,000	43,416,000
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	639,000	3,192,000
Issuance and registration of common shares	105,000	68,000
Proceeds from Issuance of Preferred Stock, Preference Stock, and Warrants		2,007,000
Shares repurchased and retired	(2,912,000)	(4,734,000)
Stock Issued During Period, Value, Stock Options Exercised	625,000
Shares issued in exchange for units	0	0
Shares issued in exchange for redeemable stock	1,915,000	1,482,000
Redeemable stock fair market value	965,000	(298,000)
Adjustment for noncontrolling interest ownership in operating partnership	0	0
Amortization of unearned compensation	4,024,000	3,025,000
Dividends, Preferred Stock, Cash	922,000	(922,000)
Dividends on common stock	(104,971,000)	(98,841,000)
Dividends on noncontrolling interest units	(3,819,000)	(3,664,000)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
Ending Balance	$ 6,520,363,000	$ 6,586,832,000

MAALP Capital (Details)

MAALP Capital (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Total Partnership Capital [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Units Issued During Period, Value, Unit Options Exercised	$ 625
Limited Partner [Member]
Capital Disclosure [Line Items]
Noncontrolling Interest in Joint Ventures	2,306	$ 2,306	$ 2,306	$ 2,306
Increase (Decrease) in Partners' Capital [Roll Forward]
Dividends, Preferred Stock, Cash	922	922
Limited Partner [Member] | General Partners' Capital Account [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	6,270,758	6,337,721	6,337,721
Net Income Allocated to General Partners	48,097	40,983
Issuance of units	105	68
Units repurchased and retired	(2,912)	(4,734)
Units Issued During Period, Value, Unit Options Exercised	625
General partner units issued in exchange for limited partner units	2,780	167
Units issued in exchange for redeemable units	1,915	1,482
Redeemable stock fair market value	965	(298)
Adjustment for noncontrolling interest ownership in operating partnership	63	192
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(233)
Amortization of unearned compensation	4,024	3,025
Distributions	(104,971)	(98,841)
Ending Balance	6,221,216	6,279,765	6,270,758	6,337,721
Limited Partner [Member] | Total Partnership Capital [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	6,573,875	6,642,082	6,642,082
Net Income Available for Common Unitholders	50,820	43,416
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	639	3,192
Issuance of units	105	2,075
Units repurchased and retired	(2,912)	(4,734)
General partner units issued in exchange for limited partner units	0	0
Units issued in exchange for redeemable units	1,915	1,482
Redeemable stock fair market value	965	(298)
Adjustment for noncontrolling interest ownership in operating partnership	0	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0
Amortization of unearned compensation	4,024	3,025
Distributions	(108,790)	(102,505)
Dividends, Preferred Stock, Cash	922	922
Ending Balance	6,520,344	6,586,813	6,573,875	6,642,082
Limited Partner [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	231,676	235,976	235,976
Net Income Allocated to Limited Partners	1,801	1,511
General partner units issued in exchange for limited partner units	(2,780)	(167)
Adjustment for noncontrolling interest ownership in operating partnership	(63)	(192)
Distributions	(3,819)	(3,664)
Ending Balance	226,815	233,464	231,676	235,976
Limited Partner [Member] | AOCI Attributable to Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning Balance	2,295	1,246	1,246
Other comprehensive (loss) income - derivatives insturments (cash flow hedges)	639	3,192
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	233
Ending Balance	3,167	4,438	2,295	1,246
Accumulated Distributions in Excess of Net Income [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Issuance of units	0	2,007	$ 66,840	$ 64,833
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, 2018USD ($)
Debt Instrument [Line Items]
Notes Payable	$ 4,498,851
Debt Instrument, Interest Rate, Effective Percentage	3.60%
Mortgages [Member]
Debt Instrument [Line Items]
Mortgage Loans on Real Estate	$ 2,700
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.80%
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 80,000
Line of Credit Facility, Amount Outstanding	$ 80,000
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.10%
Secured Debt [Member] | Mortgages [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.00%
Debt Instrument, Maturity Date	Nov. 1, 2019
Mortgage Loans on Real Estate	$ 841,711
Unsecured Debt [Member]
Debt Instrument [Line Items]
Notes Payable	$ 3,566,664
Debt Instrument, Interest Rate, Effective Percentage	3.50%
Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300,000
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	2.78%
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	2.80%
Debt Instrument, Maturity Date	Apr. 15, 2020
Line of Credit Facility, Amount Outstanding	$ 450,000
Unsecured Debt [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Unsecured notes payable	$ 300,000
Debt Instrument, Interest Rate, Effective Percentage	2.60%
Debt Instrument, Maturity Date	Aug. 29, 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	2,000,000
Unsecured Debt [Member] | Private Placement [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	292,000
Unsecured Debt [Member] | Private Placement [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	292,000
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	450,000
Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 550,000
Debt Instrument, Interest Rate, Effective Percentage	2.90%
Debt Instrument, Maturity Date	Jul. 9, 2020
Minimum [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	7 years
Minimum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
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%
Maximum [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	12 years
Maximum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
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%
Highlands of West Village [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Mortgage Loans on Real Estate	$ 38,300
years to maturity [Member] | Unsecured Debt [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Term	6 years 7 months 15 days

Debt Structure (Details)

Debt Structure (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Debt Instrument [Line Items]
Total Outstanding Debt	$ 4,498,851
Debt Instrument, Interest Rate, Effective Percentage	3.60%
Mortgages [Member]
Debt Instrument [Line Items]
Mortgage Loans on Real Estate	$ 2,700
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	3.80%
Secured Debt [Member] | Mortgages [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Mortgage Loans on Real Estate	$ 841,711
Debt Instrument, Interest Rate, Effective Percentage	4.00%
Contract Maturity	Nov. 1, 2019
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 80,000
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Variable Rate Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.10%
Contract Maturity	Dec. 1, 2018
Line of Credit Facility, Amount Outstanding	$ 80,000
Secured Debt [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Variable Rate Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.10%
Secured Debt [Member] | $1 billion unsecured revolving credit facility [Member] | Fair Market Value Adjustment and Debt Issuance Cost [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 10,476
Secured Debt [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	932,187
Unsecured Debt [Member]
Debt Instrument [Line Items]
Total Outstanding Debt	$ 3,566,664
Debt Instrument, Interest Rate, Effective Percentage	3.50%
Unsecured Debt [Member] | Wells Fargo Term Loan 2018 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250,000
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	2.60%
Contract Maturity	Aug. 29, 2020
Unsecured Debt	$ 300,000
Unsecured Debt [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.90%
Contract Maturity	Jul. 9, 2020
Debt Instrument, Face Amount	$ 550,000
Unsecured Debt [Member] | Senior Notes [Member] | Fixed Rate Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.00%
Contract Maturity	Nov. 13, 2024
Debt Instrument, Face Amount	$ 2,292,000
Unsecured Debt [Member] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	450,000
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	$ (25,336)
Maximum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
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] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%
Minimum [Member] | Unsecured Debt [Member] | Wells Fargo Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
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] | $1 billion unsecured revolving credit facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.85%

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	Mar. 31, 2018USD ($)Contract
Interest Rate Cap
Derivative
Number of Instruments | Contract	1
Derivative, Notional Amount | $	$ 25,000,000
Interest Rate Swap
Derivative
Number of Instruments | Contract	12
Derivative, Notional Amount | $	$ 550,000,000

Fair Value of Derivatives and38

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, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging Instrument | Interest Expense
Derivative
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (193)	$ 672
Designated as Hedging Instrument | Interest Rate Contract
Derivative
Unrealized (loss) gain from the effective portion of derivative instruments	832	2,520
Not Designated as Hedging Instrument | Interest Expense
Derivative
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(2,644)	2,353
Parent Company [Member]
Derivative
Accumulated other comprehensive income (losses)	3,000	4,223	$ 2,157	$ 1,144
Unrealized (loss) gain from the effective portion of derivative instruments	$ 832	$ 2,520

Fair Value of Derivatives and39

Fair Value of Derivatives and Financial Instruments (Other Comprehensive Income) (Details) - Parent Company [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 2,157	$ 1,144
Other comprehensive income before reclassifications	832	2,520
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(193)	672
Net current-period other comprehensive income attributable to noncontrolling interest	(29)	(113)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	233	0
Net current-period other comprehensive income attributable to MAA	843	3,079
Ending balance	$ 3,000	$ 4,223

Fair Value of Derivatives and40

Fair Value of Derivatives and Financial Instruments (Textual) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivative
Preferred Stock, Redemption Price Per Share	$ 50
Preferred Stock, Redemption Date	Oct. 1, 2026
Net liability position
Derivative
Credit risk related contingent features termination value	$ 1,200
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	1,900
Parent Company [Member]
Derivative
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	233	$ 0
Fixed Rate Debt
Derivative
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	3,100,000		$ 3,200,000
Notes Payable, Fair Value Disclosure	3,200,000		3,300,000
Floating Rate Debt [Member]
Derivative
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	1,400,000		1,300,000
Notes Payable, Fair Value Disclosure	$ 1,400,000		1,300,000
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	$ 18,500		21,200
Interest Rate Derivative Assets, at Fair Value	5,100		3,600
Interest Rate Derivative Liabilities, at Fair Value	$ 1,600		$ 1,300

Shareholders' Equity of MAA - A

Shareholders' Equity of MAA - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	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	113,745,207	113,574,798
Total common shares and operating partnership units outstanding	117,886,987	117,792,242
Treasury Stock, Shares, Acquired	32,391	47,480
Preferred Stock, Dividend Rate, Percentage	8.50%
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 4.25
Preferred Stock, Liquidation Preference, Value	$ 43,400
Equity Option [Member]
Stock Issued During Period, Shares, New Issues	12,600	0
Noncontrolling Interest [Member]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,141,780	4,217,444
Parent Company [Member]
Preferred Stock, Shares Outstanding	867,846		867,846
Preferred Stock, Liquidation Preference Per Share	$ 50		$ 50
Common stock, shares outstanding	113,745,207		113,643,166
Proceeds from Stock Options Exercised	$ 625	$ 0
Employee Stock Option [Member]
Common stock shares, outstanding option	95,838	147,282
Redeemable Preferred Stock [Member]
Preferred Stock, Shares Outstanding				867,846

Partners' Capital of Mid-Amer42

Partners' Capital of Mid-America Apartments, L.P. (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Capital Structure [Line Items]
Operating partnership units outstanding	117,886,987	117,792,242
General Partners' Capital Account, Units Outstanding	113,745,207	113,574,798
Limited Liability (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	96.50%
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest		96.40%
Limited Partners' Capital Account, Units Outstanding	4,141,780
Noncontrolling Interest [Member]
Schedule of Capital Structure [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,141,780	4,217,444
Limited Partners' Capital Account	$ 377.9	$ 429.1
Redeemable Capital Shares Par Or Stated Value Per Share	$ 91.24	$ 101.74

Legal Proceedings (Details)

Legal Proceedings (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 31.8	$ 32.1

Segment Information - Additiona

Segment Information - Additional Information (Detail) - 3 months ended Mar. 31, 2018	Total	Property	Communities	States
Segment Reporting Information [Line Items]
Number of owned or owned interests of apartment communities		303	302
Number of states in which apartment units are located				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, 2018	Mar. 31, 2017
Segment Information
Total operating revenues	$ 386,017	$ 378,908
Net Operating Income	241,613	237,635
Depreciation and amortization	(120,744)	(129,997)
Property management expense	(12,880)	(10,981)
General and administrative expense	(10,132)	(12,840)
Business Combination, Merger and Integration Related Expenses	(3,799)	(6,161)
Interest expense	(40,905)	(36,584)
Gain (Loss) on sale of depreciable real estate assets excluded from discontinued operations	0	(73)
Gain on sale of non-depreciable real estate assets	150	0
Other Nonoperating Income (Expense)	(2,341)	2,711
Income tax expense	(640)	(651)
Gain (loss) from real estate joint ventures	498	357
Net income attributable to noncontrolling interests	(1,801)	(1,511)
Preferred Stock Dividends, Income Statement Impact	(922)	(922)
Net income available for MAA common shareholders	48,097	40,983
Same Store [Member]
Segment Information
Total property revenues	331,683	325,767
Tenant Reimbursements	22,349	21,821
Other Real Estate Revenue	2,815	3,009
Total operating revenues	356,847	350,597
Net Operating Income	225,350	221,183
Non-Same Store and Other
Segment Information
Total property revenues	27,357	25,098
Tenant Reimbursements	1,338	1,536
Other Real Estate Revenue	475	1,677
Total operating revenues	29,170	28,311
Net Operating Income	$ 16,263	$ 16,452

Assets for Reportable Segment (

Assets for Reportable Segment (Detail) - Parent Company [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 11,417,376	$ 11,491,919
Same Store [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	9,773,940	9,864,321
Non-Same Store and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,439,424	1,427,778
Corporate assets
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 204,012	$ 199,820

Real Estate Acquisitions and 47

Real Estate Acquisitions and Dispositions - Additional Information (Details)	Mar. 31, 2018a
Craft Farms Residential - Outparcel [Member]
Business Acquisitions and Dispositions [Line Items]
Area of Land	3
Randal Park - Outparcel [Member]
Business Acquisitions and Dispositions [Line Items]
Area of Land	34

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event [Member] $ in Millions	3 Months Ended
	Jun. 30, 2018USD ($)	Apr. 26, 2018apartmentunits	Apr. 19, 2018a
Subsequent Event [Line Items]
Area of Land | a			29
Gain (Loss) on Sale of Properties	$ 2.8
Proceeds from Sale of Property Held-for-sale	$ 9.5
Sync36 [Member]
Subsequent Event [Line Items]
Number of Units in Real Estate Property | apartmentunits		374