Partners' Capital of MAALP - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule Of Capital Structure [Line Items]
Operating partnership units outstanding	118,140,136	117,952,415
General Partners' Capital Account, Units Outstanding	114,065,859	113,838,139
Limited Partners' Capital Account, Units Outstanding	4,074,277	4,114,276
Preferred Stock, Shares Outstanding	867,846		867,846
Redeemable Preferred Stock [Member]
Schedule Of Capital Structure [Line Items]
Preferred Stock, Shares Outstanding	867,846
Noncontrolling Interest
Schedule Of Capital Structure [Line Items]
Common Shares Issuable Upon Conversion Of Convertible Stock	4,074,277	4,114,276
Limited Partners' Capital Account	$ 529.7	$ 412.2
Redeemable Capital Shares Par Or Stated Value Per Share	$ 130.01	$ 100.18
M A A L P
Schedule Of Capital Structure [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	96.60%	96.50%