Acquisitions - Narrative (Details) - USD ($) $ in Thousands					9 Months Ended
	Feb. 17, 2015	Nov. 14, 2014	Oct. 31, 2014	Jun. 04, 2014	Sep. 30, 2015
Fashion Outlets of Chicago | Affiliated Entity
Acquisition
Purchase price			$ 69,987
Purchase price funded by cash payment on acquisition			55,867
Purchase price paid through assumption of debt by the Company			$ 14,120
Contingent consideration					$ 10,743
Acquisition noncontrolling interest adjustment					76,141
Cascade Mall
Acquisition
Purchase price				$ 15,233
Additional ownership interest acquired (as a percent)				49.00%
Ownership interest at completion of acquisition (as a percent)				100.00%
PPRLP Queens Portfolio
Acquisition
Purchase price		$ 1,838,886
Purchase price paid through assumption of debt by the Company		$ 672,109
Additional ownership interest acquired (as a percent)		49.00%
Ownership interest at completion of acquisition (as a percent)		100.00%
Common stock issued (in shares)		$ 1,166,777
Inland Center
Acquisition
Purchase price	$ 51,250
Purchase price funded by cash payment on acquisition	26,250
Purchase price paid through assumption of debt by the Company	$ 25,000
Additional ownership interest acquired (as a percent)	50.00%
Ownership interest at completion of acquisition (as a percent)	100.00%
Incremental revenue					9,175
Incremental earnings					$ 910