XML 64 R28.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Stock-Based Compensation (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2019
Stock Based Compensation [Abstract] |
Schedule of Share based Payment Award Restricted Stock Valuation Assumptions | The following is a summary of the key assumptions used in the valuation calculations for market based awards granted during the years ended December 31, 2019, 2018 and 2017:
|  | 2019 |  |  | 2018 |  |  | 2017 |
Risk free rate |  | 2.578% |  |  | 1.61% - 2.14% |  |  | 0.65% - 1.57% |
Dividend yield |  | 4.043% |  |  | 3.884% |  |  | 3.573% |
Volatility |  | 18.95% |  |  | 15.05% - 17.18% |  |  | 20.43% - 21.85% |
Requisite service period |  | 3 years |  |  | 3 years |  |  | 3 years |
Nonvested Restricted Stock Shares Activity | A summary of the status of the nonvested restricted shares as of December 31, 2019, and the changes for the year ended December 31, 2019, is presented below:
Nonvested Shares |  | Shares |  |  | Weighted Average Grant-Date Fair Value |
Nonvested as of January 1, 2019 |  |  | 187,777 |  |  | $ | 88.79 |
Issued |  |  | 173,174 |  |  |  | 88.59 |
Vested |  |  | (125,381 | ) |  |  | 74.35 |
Forfeited |  |  | (1,692 | ) |  |  | 95.44 |
Nonvested as of December 31, 2019 |  |  | 233,878 |  |  | $ | 96.33 |
Share-based Compensation, Stock Options, Activity | A summary of the status of the outstanding stock options as of December 31, 2019 and the changes for the year ended December 31, 2019 is presented below:
Stock Options |  | Options |  |  | Weighted Average Exercise Price |
Outstanding as of January 1, 2019 |  |  | 90,615 |  |  | $ | 77.16 |
Granted |  |  | — |  |  |  | — |
Exercised |  |  | (69,852 | ) |  |  | 76.96 |
Expired |  |  | — |  |  |  | — |
Outstanding as of December 31, 2019 |  |  | 20,763 |  |  | $ | 77.82 |

X
- Definition Schedule of Share-based Payment Award, Restricted Stock, Valuation Assumptions [Table Text Block] + References No definition available. + Details
Name: | maa_ScheduleofSharebasedPaymentAwardRestrictedStockValuationAssumptionsTableTextBlock
Namespace Prefix: | maa_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stock Based Compensation [Abstract] + References No definition available. + Details
Name: | maa_StockBasedCompensationAbstract
Namespace Prefix: | maa_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the changes in outstanding nonvested restricted stock shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
Name: | us-gaap_NonvestedRestrictedStockSharesActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration