Summary of Significant Accounting Policies - Reclassification Out Of AOCI, Simon Property Group, L.P. (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Significant Accounting Policies
Interest expense	$ (206,624)	$ (207,174)	$ (412,115)	$ (405,373)
Simon Property Group, L.P.
Significant Accounting Policies
Interest expense	$ (206,624)	$ (207,174)	(412,115)	(405,373)
Accumulated derivative gains (losses), net | Simon Property Group, L.P. | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense			$ (4,339)	$ (5,059)