Significant Accounting Policies - Reclassification Out of AOCI, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Significant Accounting Policies
Total accumulated other comprehensive income (loss)	$ (176,900)		$ (176,900)		$ (160,400)
Interest expense	(201,858)	$ (202,382)	(586,545)	$ (599,541)
Net income attributable to noncontrolling interests	(21,886)	(83,636)	(124,351)	(242,216)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OR UNITHOLDERS	145,926	544,254	837,744	1,588,053
Accumulated derivative losses, net, including noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	477	(1,087)	1,435	(3,261)
Accumulated derivative losses, attributable to noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests	(63)	144	(189)	431
Accumulated derivative gains (losses), net | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS OR UNITHOLDERS	$ 414	$ (943)	$ 1,246	$ (2,830)