Summary of Significant Accounting Policies - Reclassification Out Of AOCI, Simon Property Group, L.P. (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Significant Accounting Policies
Interest expense	$ (198,733)	$ (205,492)
Simon Property Group, L.P.
Significant Accounting Policies
Interest expense	(198,733)	(205,492)
Accumulated derivative gains (losses), net | Simon Property Group, L.P. | Amount reclassified from accumulated other comprehensive income (loss)
Significant Accounting Policies
Interest expense	$ (1,088)	$ (2,153)