Recently Issued Accounting Literature - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 261,500		$ 261,500				$ 302,543
Change in fair value of marketable securities (see Note 7)	(824)	$ 0	(5,561)	$ 0
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings						$ 5,156
Macerich Interest
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in fair value of marketable securities (see Note 7)	$ (824)		$ (5,561)
Closing share price	$ 55.29		$ 55.29		$ 56.83		$ 65.68
Macerich Interest | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in fair value of marketable securities (see Note 7)	$ (824)		$ (5,561)