Summary of Significant Accounting Policies - Rollforward Of Noncontrolling Interest, Simon Group Property, Inc. (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Noncontrolling interests:
Noncontrolling interests, beginning of period	$ 744,905	$ 858,328	$ 973,226
Net income attributable to noncontrolling interests after preferred distributions and income attributable to redeemable noncontrolling interests in consolidated properties	289,594	309,740	241,023
Distributions to noncontrolling interest holders	(319,193)	(318,780)	(290,705)
Other comprehensive income (loss) allocable to noncontrolling interests:
Unrealized gain on derivative hedge agreements	5,444	2,543	617
Net loss (gain) reclassified from accumulated other comprehensive income into earnings	19,629	(9,925)	1,568
Currency translation adjustments	(209)	(22,749)	(14,858)
Changes in available-for-sale securities and other	216	(1,803)	14,945
Other comprehensive income (loss)	25,080	(31,934)	2,272
Adjustment to limited partners' interest from change in ownership in the Operating Partnership	(66,996)	(101,480)	(211,657)
Units issued to limited partners			84,910
Units exchanged for common shares	(73,756)	(7,942)	(1,297)
Units Redeemed		(14,843)	(1,463)
Long-term incentive performance units	48,324	47,279	49,938
Contributions by noncontrolling interests, net, and other	1,506	4,537	12,081
Noncontrolling interests, end of period	$ 649,464	$ 744,905	$ 858,328