Partners' Capital of Mid-America Apartments, L.P. (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016
Schedule of Capital Structure [Line Items]
Operating partnership units outstanding	79,564,446	79,685,786
General Partners' Capital Account, Units Outstanding	75,379,381	75,542,583
Percentage Of Ownership Interests		100.00%
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	94.70%
Limited Partners' Capital Account, Units Outstanding	4,185,065	4,143,203
Noncontrolling Interest [Member]
Schedule of Capital Structure [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,185,065	4,143,203
Limited Partners' Capital Account	$ 342.6	$ 389.4
Redeemable Capital Shares Par Or Stated Value Per Share	$ 81.87	$ 93.99