Summary of Significant Accounting Policies - Rollforward Of Noncontrolling Interest, Simon Group Property L.P. (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Noncontrolling interests:
Net income attributable to noncontrolling nonredeemable interests	$ 94,176	$ 72,945
Distributions to noncontrolling nonredeemable interest holders	(92,012)	(84,221)
Contributions by noncontrolling nonredeemable interests, net, and other	24	171
Simon Property Group, L.P.
Noncontrolling interests:
Noncontrolling nonredeemable interests in properties, beginning of period	3,738	5,116
Net income attributable to noncontrolling nonredeemable interests	527	675
Distributions to noncontrolling nonredeemable interest holders	(489)	(1,315)
Contributions by noncontrolling nonredeemable interests, net, and other	24	171
Noncontrolling nonredeemable interests in properties, end of period	$ 3,800	$ 4,647