Significant Accounting Policies - Reclassification Out Of AOCI, Simon Property Group, L.P. (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 COMMON STOCKHOLDERS	445,860	437,605
Simon Property Group, L.P.
Significant Accounting Policies
Total accumulated other comprehensive income (loss)	(185,300)		$ (155,800)
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 COMMON STOCKHOLDERS	510,085	504,263
Currency translation adjustments | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	4,948
Currency translation adjustments | Simon Property Group, L.P. | 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
Accumulated derivative gains (losses), net | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	422	417
Accumulated derivative gains (losses), net | Simon Property Group, L.P. | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	$ 483	$ 480