Significant Accounting Policies - Reclassification Out Of AOCI, Simon Property Group, L.P. (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Significant Accounting Policies
Total accumulated other comprehensive income (loss)	$ (194,700)		$ (194,700)		$ (160,400)
Interest expense	(197,061)	$ (198,425)	(384,688)	$ (397,160)
Simon Property Group, L.P.
Significant Accounting Policies
Total accumulated other comprehensive income (loss)	(224,300)		(224,300)		$ (184,800)
Interest expense	(197,061)	(198,425)	(384,688)	(397,160)
Simon Property Group, L.P. | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	$ 478	$ (1,086)	$ 958	$ (2,174)