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Partners' Capital of Mid-America Apartments, L.P. (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Schedule of Capital Structure [Line Items]      
Operating partnership units outstanding 117,792,242   79,667,188
General Partners' Capital Account, Units Outstanding 113,574,798   75,505,025
Limited Liability (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest 0.9641959103    
Percentage Of Ownership Interests 100.00%    
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest   94.80%  
Limited Partners' Capital Account, Units Outstanding 4,217,444    
Noncontrolling Interest [Member]      
Schedule of Capital Structure [Line Items]      
Common Shares Issuable Upon Conversion Of Convertible Stock 4,217,444 4,162,163  
Limited Partners' Capital Account $ 429.1 $ 425.4  
Redeemable Capital Shares Par Or Stated Value Per Share $ 101.74 $ 102.21