Equity - Changes in Equity, Simon Property Group, Inc. (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Increase (Decrease) in Stockholders' Equity
Balance	$ 4,238,764
Treasury stock purchase	(307,296)
Redemption of limited partner units	(7,619)
LTIP Units	15,769
Purchase and disposition of noncontrolling interests, net and other	(15,065)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(1,393,117)
Distributions to noncontrolling other interest holders	(964)
Comprehensive income, excluding $957 attributable to preferred interests in the Operating Partnership and a $559 loss attributable to noncontrolling redeemable interests in properties	1,340,892
Balance	3,878,628
Comprehensive income attributable to preferred interests	957
Comprehensive loss attributable to noncontrolling redeemable interests in properties	559
Preferred Stock
Increase (Decrease) in Stockholders' Equity
Balance	43,077
Purchase and disposition of noncontrolling interests, net and other	(165)
Balance	42,912
Common Stock
Increase (Decrease) in Stockholders' Equity
Balance	32
Balance	32
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity
Balance	(110,453)
Comprehensive income, excluding $957 attributable to preferred interests in the Operating Partnership and a $559 loss attributable to noncontrolling redeemable interests in properties	(4,832)
Balance	(115,285)
Capital in Excess of Par Value
Increase (Decrease) in Stockholders' Equity
Balance	9,614,748
Exchange of limited partner units for common shares	70
Redemption of limited partner units	(7,047)
Purchase and disposition of noncontrolling interests, net and other	(2,678)
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	52,717
Balance	9,657,810
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Balance	(4,782,173)
Purchase and disposition of noncontrolling interests, net and other	(18,076)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(1,210,168)
Comprehensive income, excluding $957 attributable to preferred interests in the Operating Partnership and a $559 loss attributable to noncontrolling redeemable interests in properties	1,169,327
Balance	(4,833,826)
Common Stock Held in Treasury
Increase (Decrease) in Stockholders' Equity
Balance	(1,079,063)
Treasury stock purchase	(307,296)
Purchase and disposition of noncontrolling interests, net and other	5,740
Balance	(1,380,619)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Balance	552,596
Exchange of limited partner units for common shares	(70)
Redemption of limited partner units	(572)
LTIP Units	15,769
Purchase and disposition of noncontrolling interests, net and other	114
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(52,717)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(182,949)
Distributions to noncontrolling other interest holders	(964)
Comprehensive income, excluding $957 attributable to preferred interests in the Operating Partnership and a $559 loss attributable to noncontrolling redeemable interests in properties	176,397
Balance	507,604
Accounting Standards Update 2016-01
Increase (Decrease) in Stockholders' Equity
Cumulative effect of accounting change	7,264
Accounting Standards Update 2016-01 | Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Cumulative effect of accounting change	$ 7,264