Partners' Capital of Mid-America Apartments, L.P. (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 01, 2016
Schedule of Capital Structure [Line Items]
Operating partnership units outstanding	117,952,415	117,827,046
General Partners' Capital Account, Units Outstanding	113,838,139	113,627,014
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	4,114,276
Noncontrolling Interest [Member]
Schedule of Capital Structure [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,114,276	4,200,032
Limited Partners' Capital Account	$ 412,168,169.68	$ 448,899,420.16
Redeemable Capital Shares Par Or Stated Value Per Share	$ 100.18	$ 106.88
Redeemable Preferred Stock [Member]
Schedule of Capital Structure [Line Items]
Preferred Stock, Shares Outstanding			867,846