Significant Accounting Policies - Reclassification Out of AOCI, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Significant Accounting Policies
Total accumulated other comprehensive income (loss)	$ (162,000)		$ (136,200)
Gain on acquisition of controlling interest, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net	93,057	$ 962
Interest expense	(202,016)	(187,627)
Net income attributable to noncontrolling interests	(63,766)	(66,965)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	445,860	437,605
Currency translation adjustments, including noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Gain on acquisition of controlling interest, sale or disposal of, or recovery on, assets and interests in unconsolidated entities and impairment, net	5,660
Currency translation adjustments, attributable to noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests	(712)
Currency translation adjustments | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	4,948
Accumulated derivative losses, net, including noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	483	480
Accumulated derivative losses, attributable to noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests	(61)	(63)
Accumulated derivative gains (losses), net | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ 422	$ 417