Shareholders' Equity of MAA - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Equity [Line Items]
Common stock, shares outstanding	114,369,812	114,065,859	114,246,393
Total common shares and operating partnership units outstanding	118,428,070	118,140,136
Proceeds from Stock Options Exercised, Net	$ 0.1	$ 1.0
At The Market Offering
Equity [Line Items]
Common stock shares sold	0	0
Remaining common stock to be issued	3,900,000
Maximum [Member] | At The Market Offering
Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	4,000,000.0
Equity Option
Equity [Line Items]
Stock Issued During Period, Shares, New Issues	918	24,256
Noncontrolling Interest
Equity [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,058,258	4,074,277
Employee Stock Option
Equity [Line Items]
Common stock shares, outstanding option	19,845	45,390