Equity - Changes in Equity, Simon Property Group, Inc. (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Increase (Decrease) in Stockholders' Equity
Balance	$ 4,238,764
Treasury stock purchase	(227,901)
Redemption of limited partner units	(6,267)
LTIP Units	8,307
Purchase and disposition of noncontrolling interests, net and other	(13,207)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(697,609)
Distributions to noncontrolling other interest holders	(489)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $2,109 loss attributable to noncontrolling redeemable interests in properties	724,474
Balance	4,033,336
Comprehensive income attributable to preferred interests	479
Comprehensive loss attributable to noncontrolling redeemable interests in properties	619
Preferred Stock
Increase (Decrease) in Stockholders' Equity
Balance	43,077
Purchase and disposition of noncontrolling interests, net and other	(83)
Balance	42,994
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 $1,436 attributable to preferred interests in the Operating Partnership and a $2,109 loss attributable to noncontrolling redeemable interests in properties	7,706
Balance	(102,747)
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	(5,793)
Purchase and disposition of noncontrolling interests, net and other	2,026
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	36,221
Balance	9,647,272
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Balance	(4,782,173)
Purchase and disposition of noncontrolling interests, net and other	(14,935)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(606,086)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $2,109 loss attributable to noncontrolling redeemable interests in properties	621,488
Balance	(4,774,442)
Common Stock Held in Treasury
Increase (Decrease) in Stockholders' Equity
Balance	(1,079,063)
Treasury stock purchase	(227,901)
Purchase and disposition of noncontrolling interests, net and other	(239)
Balance	(1,307,203)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Balance	552,596
Exchange of limited partner units for common shares	(70)
Redemption of limited partner units	(474)
LTIP Units	8,307
Purchase and disposition of noncontrolling interests, net and other	24
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(36,221)
Distributions to common shareholders and limited partners, excluding Operating Partnership preferred interests	(91,523)
Distributions to noncontrolling other interest holders	(489)
Comprehensive income, excluding $1,436 attributable to preferred interests in the Operating Partnership and a $2,109 loss attributable to noncontrolling redeemable interests in properties	95,280
Balance	527,430
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