Summary of Significant Accounting Policies - Reclassification Out of AOCI, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Significant Accounting Policies
Interest expense	$ (198,733)	$ (205,492)
Net income attributable to noncontrolling interests	(82,638)	(94,036)
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS	548,475	620,654
Accumulated derivative losses, net, including noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	(1,088)	(2,153)
Accumulated derivative losses, attributable to noncontrolling interests | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Net income attributable to noncontrolling interests	143	282
Accumulated derivative gains (losses), net | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
NET INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS or UNITHOLDERS	$ (945)	$ (1,871)