Significant Accounting Policies - Noncontrolling Interests, Simon Property Group, Inc. (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Significant Accounting Policies.
Limited partners' interests in the Operating Partnership	$ 617,091	$ 644,348
Nonredeemable noncontrolling interests in properties, net	4,647	5,116
Total noncontrolling interests reflected in equity	$ 621,738	$ 649,464	$ 771,957	$ 744,905