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Earnings Per OP Unit of MAALP (Tables) | 12 Months Ended
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Dec. 31, 2017
Earnings Per Unit [Abstract] |
Schedule of Calculation of Numerator and Denominator in Earnings Per Unit [Table Text Block] | A reconciliation of the numerators and denominators of the basic and diluted earnings per OP Unit computations for the years ended December 31, 2017, 2016, and 2015 is presented below (dollars and units in thousands, except per unit amounts):
| 2017 |  | 2016 |  | 2015 |
Common Units Outstanding |  |  |  |  |  |
Weighted average common units - basic | 117,617 |  |  | 82,661 |  |  | 79,361 |  |
Effect of dilutive securities | 280 |  |  | 298 |  |  | — |  | (1)
Weighted average common units - diluted | 117,897 |  |  | 82,959 |  |  | 79,361 |  |
Calculation of Earnings per Common Unit - basic |  |  |  |  |  |  |  |  |
Net income | $ | 340,536 |  |  | $ | 224,402 |  |  | $ | 350,745 |  |
Unvested restricted stock (allocation of earnings) | (535 | ) |  | (574 | ) |  | (772 | ) |
Preferred unit distributions | (3,688 | ) |  | (307 | ) |  | — |  |
Net income available for common unitholders, adjusted | $ | 336,313 |  |  | $ | 223,521 |  |  | $ | 349,973 |  |
Weighted average common units - basic | 117,617 |  |  | 82,661 |  |  | 79,361 |  |
Earnings per common unit - basic: | $ | 2.86 |  |  | $ | 2.70 |  |  | $ | 4.41 |  |
Calculation of Earnings per Common Unit - diluted |  |  |  |  |  |  |  |  |
Net income | $ | 340,536 |  |  | $ | 224,402 |  |  | $ | 350,745 |  |
Unvested restricted stock (allocation of earnings) | — |  |  | — |  |  | (772 | ) | (1)
Preferred unit distributions | (3,688 | ) |  | (307 | ) |  | — |  |
Net income available for common unitholders, adjusted | $ | 336,848 |  |  | $ | 224,095 |  |  | $ | 349,973 |  |
Weighted average common units - diluted | 117,897 |  |  | 82,959 |  |  | 79,361 |  |
Earnings per common unit - diluted: | $ | 2.86 |  |  | $ | 2.70 |  |  | $ | 4.41 |  |
(1) For the year ended December 31, 2015, 0.1 million potentially dilutive securities and their related income are not included in the diluted earnings per unit calculations as they are not dilutive.

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- Definition Schedule of Earnings Per Unit, Basic and Diluted [Table Text Block] + References No definition available. + Details
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Namespace Prefix: | maa_
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Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration